THECHIMPANDTHERIVER

HowAIDSEmergedfromanAfricanForest

DAVIDQUAMMEN

W.W.Norton&CompanyNewYork•London

Tothemenandwomenwhohavesufferedthisdiseaseandthosewhocontinuetosufferit

CONTENTSIntroduction

TheChimpandtheRiver

Notes

Bibliography

Acknowledgments

Index

INTRODUCTION

AIDShasbeenwrittenaboutmanytimes,frommanyangles,butthestoryastoldhereisdrasticallydifferentfromanyversionyouarelikelytohaveread,heardabout,orotherwiseabsorbed.Themaindifferenceisthatthisisanaccountoftheultimatesourceofthepandemic.It’sessentiallyanecologicalnarrativeratherthanamedicalone—bywhichImeanthatitturnsontheinteractionofthreekindsofcreature:chimpanzee,human,andvirus.Ihavetriedtodescribehow,when,andwherethevirusinquestion(HIV-1groupM,thepandemicstrain),whichwaspreviouslyunknownamongpeople,gotitsstartinthehumanpopulation.Therewasasinglepointinspaceandtime.Therewasafatefulevent.TheworldbecamecognizantofAIDSintheearly1980s,ofcourse,butthatwasn’tthebeginning—farfromit.Therealmomentoforiginoccurreddecadesearlierandthousandsofmilesaway.It’snowpossibletosay,basedonpersuasiveresearchinmoleculargenetics,aspublishedinscientificjournalsbutlittlenoticedbythepublic,thattheviruspassedfromasinglechimpanzeeintoasingleperson,duringapresumablybloodyencounter,inthesoutheasterncornerofCameroon,nearaminortributaryoftheCongoRiver,around1908,giveortakeamarginoferror.KeycomponentsofthatresearchwereledbyBeatriceHahn,thenoftheUniversityofAlabamaatBirmingham,andMichaelWorobey,attheUniversityofArizona,bothofwhomfeatureinthislittlebook.

InTheChimpandtheRiverItracebackwardtothatmomentoforigin,reconstructit,andthenfollowitsconsequencesforwardagain,alongthepathwaysofsocialhistory,epidemiology,anddolorousaccident,tothepointwhenAIDS“suddenly”emergedasaglobalhumandisaster.

AIDSishorribleandunique,butit’salsopartofalargerpattern.Everythingcomesfromsomewhere,andstrangenewinfectiousdiseases,emergingabruptlyamonghumans,comemostlyfromnonhumananimals.Thediseasemightbecausedbyavirus,orabacterium,oraprotozoan,orsomeotherformofdangerousbug.Thatbugmightliveinconspicuouslyinakindofrodent,orabat,orabird,oramonkey,oranape.Crossingbyhappenstancefromitsanimalhideawayintoitsfirsthumanvictim,itmightfindsurprisinglyhospitableconditions;itmightreplicateaggressivelyandabundantly;itmightcauseillness,evendeath;andinthemeantime,itmightpassonwardfromitsfirsthumanvictimintoothers.There’safancytermforthisphenomenon,usedbyscientistswhostudyinfectiousdiseasesfromanecologicalperspective:zoonosis.Azoonosisisananimalinfectiontransmissibletohumans.Theanimalhideawayisknownasareservoirhost.Theeventoftransmission,fromonespeciesintoanother,iscalledspillover.

Thatbitofterminologygavemethetitleformy2012book,Spillover:AnimalInfectionsandtheNextHumanPandemic,inwhichTheChimpandtheRiverfirstappearedasalongchapter.Irevisedthatmaterialherejustenoughtomakeitaself-containednarrativewithitsownwidermeaninganditsowndireimplication.ItswidermeaningisthatpandemicAIDSresultedfromourdealingswiththenaturalworld,aswellasfromourdealingswithoneanother.Itsdireimplicationisthat,havinghappenedoncecatastrophically,andatleastelevenothertimes(asyou’lllearnfromthisstory)less

consequentially,thespilloverofanHIV-likevirusfromnonhumanprimatestohumansisnotahighlyimprobableevent.Itcouldcertainlyhappenagain.

Spilloverisabookaboutzoonoticdiseasesandtheirincreasingimportanceinourmodernworld—aworldwhere7billionhumansinteractevermorefrequently,evermoredisruptively,withthewildanimalsthatliveinwildplaces.Roughly60percentoftheinfectiousdiseasesknownamonghumansarezoonoticinthestrictsense,comingtouscontinuallyorwithinrecenthistoryfromanimals;mostifnotalloftheother40percent,includinghumanafflictionssuchasmeaslesandsmallpox,canbeconsideredzoonoticinabroadersense,giventhatwearearelativelyyoungspeciesandourtormentingbugshavetheirownhistoriesthatprecedeus.Everything,asI’vesaid,andwillsayagain,comesfromsomewhere.

Mylengthytreatmentofthissubject,inSpillover,focusesonaselectionofnastydiseases,somenewandsomeold,someinfamousandsomeobscure,andonthevirusesandothermicrobesthatcausethem:EbolainAfrica,NipahinBangladeshandMalaysia,SARSasitcameoutofChina,LymediseaseinthesuburbsofNewEngland,HendraamidthehorseculturesofAustralia,zoonoticmalariainBorneo,influenzaeverywhere,andafewothers.SARSkilledabouteighthundredpeopleduringitsfrighteningemergencebackin2003,butthenitwascontrolledbygoodscienceandrigorouspublichealthmeasures,andtheSARSvirushasnotre-emergedsince.Ebolavirusdiseaseisgruesomeandhighlylethalbutitsgeographicalreachanditstotalofhumanvictims,sofar,havebeenrelativelysmall(although,atthetimeofthiswriting,thereachofEbolahasincreasedalarminglyduringthe2014outbreakinWestAfrica;nooneyetknowswherethatwillend).Lymediseaseispunishinglyfamiliartomanypeoplebutitdoesn’tusuallykillthem.Nipahhasre-emergedrepeatedlyinBangladesh,usuallywhentheseasonalharvestofdate-palmsaphasbroughtsapharvestersandtheircustomersintounhealthycontactwiththeexcretionsofbats.Hendracanbeterrifyingifyou’reanAustralianwhoworkswithhorses,butithaskilledfewerthantenpeoplesinceitsfirstknownoccurrencein1994.Giventhelimitedscopeandpeculiaritiesofsuchproblems,whyshouldpeoplearoundtherestoftheworldconcernthemselveswiththesubjectofzoonoticdisease?

It’safairquestionbuttherearegoodanswers.Someofthoseanswersareintricateandspeculative.Othersareobjectiveandblunt.Thebluntestisthis:AIDS.

THECHIMP

ANDTHERIVER

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TherearemultiplebeginningstowhatwethinkweknowabouttheAIDSpandemic,mostofwhichdon’tevenaddressthesubjectofitsultimateorigininasinglechimpanzee.

Forinstance:Inautumnof1980,ayoungimmunologistnamedMichaelGottlieb,anassistantprofessorattheUCLAMedicalCenter,begannoticingastrangepatternofinfectionsamongcertainmalepatients.Thepatients,eventuallyfiveofthem,wereallactivehomosexualsandallsufferingfrompneumoniacausedbyausuallyharmlessfungusthenknownasPneumocystiscarinii.(Nowadays,afteranamechange,it’sPneumocystisjurovecii.)Thestuffisubiquitous;itfloatsaroundeverywhere.Theirimmunesystemsshouldhavebeenabletoclearit.Buttheirimmunesystemsevidentlyweren’tworking,andthisfungusfilledtheirlungs.Eachmanalsohadanothersortoffungalinfection—oralcandidiasis,meaningamouthfulofslimyCandidayeast,moreoftenseeninnewbornbabies,diabetics,andpeoplewithcompromisedimmunesystemsthaninhealthyadults.Bloodtests,doneonseveralofthepatients,showeddramaticdepletionsofcertainlymphocytes(whitebloodcells)thatarecrucialinregulatingimmuneresponses.Specifically,itwasthymus-dependentlymphocytes(Tcells,forshort)thatwere“profoundlydepressed”innumber.AlthoughGottliebnotedsomeothersymptoms,thosethreestoodout:Pneumocystispneumonia,oralcandidiasis,dearthofTcells.Inmid-Mayof1981,heandacolleaguewroteabriefpaper,withcooperationfromotherLosAngelesdoctors,describingtheirobservations.Theydidn’tspeculateaboutcauses.Theyjustsawthepatternasabefuddling,ominoustrendandfelttheyshouldpublishquickly.AneditoratTheNewEnglandJournalofMedicinewasinterestedbuthisleadtimewouldbeatleastthreemonths.

SoGottliebturnedtothestreamlinednewsletteroftheCentersforDiseaseControl(asthatagencywasthenknown)inAtlanta.TheCDCissuesMorbidityandMortalityWeeklyReporttodeliverbreakingnewsofdiseaseeventsinatimelyway.Gottlieb’sbarebonestext,lessthantwopageslong,appearedinMMWRonJune5,1981,underthedrytitle“PneumocystisPneumonia—LosAngeles.”Itwasthefirstpublishedmedicalalertaboutasyndromethatdidn’tyethaveaname.

Thesecondalertcameamonthlater,againintheCDCnewsletter.WhileGottliebnoticedPneumocystispneumoniaandcandidiasis,aNewYorkdermatologistnamedAlvinE.Friedman-Kienspottedaparalleltrendinvolvingadifferentdisease:Kaposi’ssarcoma.Arareformofcancer,notusuallytooaggressive,Kaposi’ssarcomawasknownprimarilyasanafflictionofmiddle-agedMediterraneanmales—thesortoffellowsyou’dexpecttofindinanAthenscafé,drinkingcoffeeandplayingdominoes.Thiscanceroftenshoweditselfaspurplishnodulesintheskin.Withinlessthanthreeyears,Friedman-Kienandhisnetworkofcolleaguessawtwenty-sixcasesofKaposi’ssarcomainyoungishhomosexualmen.SomeofthosepatientsalsohadPneumocystispneumonia.Eightofthemdied.Hmm.MorbidityandMortalityWeeklyReportcarriedFriedman-Kien’scommunicationonJuly3,1981.

Kaposi’ssarcomaalsofiguredprominentlyinasetofclinicalobservationsmadeinMiamiaroundthesametime.Thesymptomsamongthisgroupofpatientsweresimilar;theculturalprofilewasdifferent.Thesesickpeople,twentyofthem,hospitalizedbetweenearly1980andJune1982,wereallHaitianimmigrants.MosthadarrivedintheUnitedStatesrecently.Bytheirowntestimonyduringmedicalinterviewstheywereallheterosexuals,withnohistoryofhomosexualactivity.ButtheirclusterofailmentsresembledwhatGottliebhadseenamonggaymeninLosAngelesandFriedman-KienamonggaymeninNewYork:Pneumocystispneumonia,candidiasisinthethroat,plusotherunusualinfections,irregularitiesinlymphocytecounts,andaggressiveKaposi’ssarcoma.TenoftheHaitiansdied.Theteamofdoctorswhopublishedtheseobservationssawa“syndrome”thatseemed“strikinglysimilartothesyndromeofimmunodeficiencydescribedrecentlyamongAmericanhomosexuals.”TheearlyconnectiontoHaitianheterosexualswouldlatercometoseemlikeafalseleadandbelargelyignoredindiscussionsofAIDS.Itwashardtoconfirm,giventhelimitsofinterviewdata,andharderstilltoconstrue.Callingattentiontoitevencametoseempoliticallyincorrect.Then,laterstill,itsrealsignificancewouldemergefromworkatthelevelofmoleculargenetics.

AnotherperceivedstartingpointwasGaëtanDugas,theyoungCanadianflightattendantwhobecamenotoriousas“PatientZero.”You’veheardofhim,probably,ifyou’veheardmuchofanythingaboutthedawningofAIDS.Dugashasbeenwrittenaboutasthemanwho“carriedthevirusoutofAfricaandintroduceditintotheWesterngaycommunity.”Hewasn’t.Butheseemstohaveplayedanoversizedandculpablyheedlessroleasatransmitterduringthe1970sandearly1980s.Asaflightsteward,withalmostcost-freeprivilegesofpersonaltravel,heflewoftenbetweenmajorcitiesinNorthAmerica,joininginsybariticplaywherehelanded,notchingupconquests,livingthehighlifeofasexuallyvoraciousgaymanattheheightofthebathhouseera.Hewashandsome,sandy-haired,vainbutcharming,even“gorgeous”insomeeyes.AccordingtoRandyShilts,authorofAndtheBandPlayedOn(whichincludesmuchheroicresearchandabitofquestionablyreliablereimagining),Dugashimselfreckonedthatinthedecadesincebecomingactivelygayhehadhadatleasttwenty-fivehundredsexualpartners.Dugaspaidapriceforhisappetiteandhisdaring.HedevelopedKaposi’ssarcoma,underwentchemotherapyforthat,sufferedfromPneumocystispneumoniaandotherAIDS-relatedinfections,anddiedofkidneyfailureatagethirty-one.DuringthebriefstretchofyearsbetweenhisKaposi’sdiagnosisandhisfinalinvalidism,GaëtanDugasdidn’tslowdown.Butheseemstohavetipped,inhislonelydespair,fromhedonismtomalice;hewouldhavesexwithanewacquaintanceattheEighth-and-HowardbathhouseinSanFrancisco,thenturnupthelights—soRandyShiltsclaimed—displayhislesions,andsay:“I’vegotgaycancer.I’mgoingtodieandsoareyou.”

InthesamemonthasDugas’sdeath,March1984,ateamofepidemiologistsfromtheCDCpublishedalandmarkstudyoftheroleofsexualcontactinlinkingcasesofwhatbythenwascalledAIDS.Theworldhadalabelnowbutnotanexplanation.“AlthoughthecauseofAIDSisunknown,”wrotetheCDCteam,whoseleadauthorwasDavidM.Auerbach,“itmaybecausedbyaninfectiousagentthatistransmissiblefrompersontopersoninamanneranalogoustohepatitisBinfection.”HepatitisBisablood-bornevirus.

Itmovesprimarilybysexualcontact,intravenousdrugusewithsharedneedles,ortransfusionofbloodproductscarryingthevirusasacontaminant.Itseemedlikeatemplateforunderstandingwhatotherwisewasstillabewilderingconvergenceofsymptoms.“TheexistenceofaclusterofAIDScaseslinkedbyhomosexualcontactisconsistentwithaninfectious-agenthypothesis,”theCDCgroupadded.Notatoxicchemical,notanaccidentofgenetics,butsomekindofbug,iswhattheymeant.

AuerbachandhiscolleagueshadgatheredinformationfromnineteenAIDScasesinsouthernCalifornia,interviewingeachpatientor,ifhewasdead,hisclosecompanions.Theyspokewithanothertwenty-onepatientsinNewYorkandotherAmericancities,andfromtheirfortycasehistoriestheycreatedagraphicfigureoffortyinterconnecteddisks,likeaTinkertoystructure,showingwhowaslinkedsexuallywithwhom.Thepatients’identitieswerecodedbylocationandnumber,suchas“SF1,”“LA6,”and“NY19.”Atthecenterofthenetwork,connecteddirectlytoeightdisksandindirectlytoalltherest,wasadisklabeled“0.”Althoughtheresearchersdidn’tnamehim,thatpatientwasGaëtanDugas.RandyShiltslatertransformedthesomewhatbland“Patient0,”asmentionedinthispaper,tothemoreresonant“PatientZero”ofhisbook.Butwhattheword“Zero”belies,whatthenumber“0”ignores,andwhatthecentralpositionofthatonediskwithinthefigurefailstoacknowledge,isthatGaëtanDugasdidn’tconceivetheAIDSvirushimself.Everythingcomesfromsomewhere,andhegotitfromsomeoneelse.Dugashimselfwasinfectedbysomeotherhuman,presumablyduringasexualencounter—andnotinAfrica,notinHaiti,somewhereclosertohome.Thatwaspossiblebecause,asevidencenowshows,HIVhadalreadyarrivedinNorthAmericawhenGaëtanDugaswasavirginaladolescent.

IthadalsoarrivedinEurope,thoughonthatcontinentithadn’tyetgonefar.ADanishdoctornamedGretheRask,whohadbeenworkinginAfrica,departedin1977fromwhatwasthenZaireandreturnedtoCopenhagenfortreatmentofaconditionthathadbeendraggingherdownwardforseveralyears.DuringhertimeinZaire,Raskfirstranasmallhospitalinaremotetowninthenorth,thenservedaschiefsurgeonatalargeRedCrossfacilityinthecapital,Kinshasa.Somewherealongtheway,possiblyduringasurgicalproceduredonewithoutadequateprotectivesupplies(suchasrubbergloves),shebecameinfectedwithsomethingforwhichnooneatthetimehadadescriptionoraname.Shefeltillandfatigued.Drainedbypersistentdiarrhea,shelostweight.Herlymphnodesswelledandstayedswollen.Shetoldafriend:“I’dbettergohometodie.”BackinDenmark,testsrevealedashortageofTcells.Herbreathcamewithsuchdifficultythatshedependedonbottledoxygen.Shestruggledagainststaphinfections.Candidafungusglazedhermouth.BythetimeGretheRaskdied,onDecember12,1977,herlungswerecloggedwithPneumocystiscarinii,andthatseemstohavebeenwhatkilledher.

Itshouldn’thave,accordingtostandardmedicalwisdom.Pneumocystispneumoniawasn’tnormallyafatalcondition.Therehadtobeabroaderexplanation,andtherewas.Nineyearslater,asampleofRask’sbloodserumtestedpositiveforHIV.

Alltheseunfortunatepeople—GretheRask,GaëtanDugas,thefivemeninGottlieb’sreportfromLosAngeles,theKaposi’ssarcomapatientsknowntoFriedman-Kien,the

HaitiansinMiami,theclusterofthirty-nine(besidesDugas)identifiedinDavidAuerbach’sstudy—wereamongtheearliestrecognizedcasesofwhathasretrospectivelybeenidentifiedasAIDS.Buttheyweren’tamongthefirstvictims.Notevenclose.Insteadtheyrepresentmidpointsinthecourseofthepandemic,markingthestageatwhichaslowlybuilding,almostunnoticeablephenomenonsuddenlyrosetoacrescendo.TherealbeginningofAIDSlayelsewhere,andmoredecadespassedwhileafewscientistsworkedtodiscoverit.

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Intheearlyyearsafteritsdetection,thenewillnesswasashiftingshapethatcarriedseveraldifferentnamesandacronyms.GRIDwasone,standingforGay-RelatedImmuneDeficiency.Thatprovedtoorestrictedasheterosexualpatientsbegantoturnup:needle-sharingaddicts,hemophiliacs,otherunluckystraights.SomedoctorspreferredACIDS,forAcquiredCommunityImmuneDeficiencySyndrome.Theword“community”wasmeanttosignalthatpeopleacquireditoutthere,notinhospitals.Amorepreciseifclumsierformulation,favoredbrieflybytheCDC’sMorbidityandMortalityWeeklyReport,was“Kaposi’ssarcomaandopportunisticinfectionsinpreviouslyhealthypersons,”whichdidn’tabbreviateneatly.KSOIPHPlackedpunch.BySeptember1982,MMWRhadswitcheditsterminologytoAcquiredImmuneDeficiencySyndrome(AIDS),andtherestoftheworldfollowed.

Namingthesyndromewastheleastoftheearlychallenges.Moreurgentwastoidentifyitscause.Nooneknew,backwhenthosereportsfromGottliebandFriedman-Kienbegancapturingattention,whatsortofpathogencausedthiscombinationofpuzzling,lethalsymptoms—noreveniftherewasasinglepathogen.Thevirusideaarose,afterothermistakenhypotheses,asaplausibleguess.

OnescientistwhomadetheguesswasLucMontagnier,thenalittle-knownmolecularbiologistattheInstitutPasteurinParis.Montagnier’sresearchfocusedmainlyoncancer-causingviruses,especiallythegroupknownasretroviruses,someofwhichcausetumorsinbirdsandmammals.Retrovirusesarefiendishthings,evenmoredeviousandpersistentthantheaveragevirus.Theytaketheirnamefromthecapacitytomovebackward(retro)againsttheusualexpectationsofhowacreaturetranslatesitsgenesintoworkingproteins.InsteadofusingRNAasatemplatefortranslatingDNAintoproteins—theusualroutebywhichgeneticinformationbecomeslivingreality—aretrovirusconvertsitsRNAintoDNAwithinahostcell;itsviralDNAthenpenetratesthecellnucleusandgetsitselfintegratedintothegenomeofthehostcell,therebyguaranteeingreplicationoftheviruswheneverthehostcellreproducesitself.LucMontagnierhadstudiedthesethingsinanimals—chickens,mice,primates—andwonderedaboutthepossibilityoffindingtheminhumantumorstoo.AnotherdisquietingpossibilityaboutretroviruseswasthatthenewdiseaseshowingupinAmericaandEurope,AIDS,mightbecausedbyone.

Therewasstillnosolidproofthatitwascausedbyavirusofanysort.Butthreekindsofevidencepointedthatway,andMontagnierrecalledtheminhismemoir,abooktitledVirus.First,theincidenceofAIDSamonghomosexualslinkedbysexualinteractionssuggestedthatthiswasaninfectiousdisease.Second,theincidenceamongintravenousdruguserssuggestedablood-borneinfectiousagent.Third,thecasesamonghemophiliacsimpliedablood-borneagentthatescapeddetectioninprocessedbloodproductssuchasclottingfactor.So:Itwascontagious,blood-borne,infinitesimal.“AIDScouldnotbecausedbyaconventionalbacterium,afungus,orprotozoan,”Montagnierwrote,“sincethesekindsofgermsareblockedbythefiltersthroughwhichthebloodproductsnecessarytothesurvivalofhemophiliacsarepassed.Thatleftonlyasmallerorganism:theagent

responsibleforAIDSthuscouldonlybeavirus.”

Otherevidencehintedthat,amongallviralpossibilities,itmightbearetrovirus.Thiswasnewground,butthensowasAIDS.Theonlyknownhumanretrovirusasofearly1981wassomethingcalledhumanT-cellleukemiavirus(HTLV),recentlydiscoveredundertheleadershipofasmart,outgoing,highlyregarded,andhighlyambitiousresearchernamedRobertGallo,whoseLaboratoryofTumorCellBiologywaspartoftheNationalCancerInstituteinBethesda,Maryland.HTLV,asitsnameimplies,attacksTcellsandcanturnthemcancerous.Tcellsareoneofthethreemajortypesoflymphocyteoftheimmunesystem.(LatertheacronymHTLVwasrecasttomeanhumanT-lymphotropicvirus,whichisslightlymoreaccurate.)Arelatedretrovirus,felineleukemiavirus,causesimmunodeficiencyincats.Soasuspicionaroseamongcancer-virusresearchersthattheAIDSagent,destroyinghumanimmunesystemsbyattackingtheirlymphocytes(inparticular,asubcategoryofTcellsknownasT-helpercells),mightlikewisebearetrovirus.Montagnier’sgroupbeganlookingforit.

Gallo’slabdidtoo.Andthosetwoweren’talone.OtherscientistsatotherlaboratoriesaroundtheworldrecognizedthatfindingthecauseofAIDSwasthehottest,themosturgent,andpotentiallythemostrewardingquestinmedicalresearch.Bylatespringof1983,threeteamsworkingindependentlyhadeachisolatedacandidatevirus,andintheMay20issueofScience,twoofthoseteamspublishedannouncements.Montagnier’sgroupinParis,screeningcellsfromathirty-three-year-oldhomosexualmansufferingfromlymphadenopathy(swollenlymphnodes),hadfoundanewretrovirus,whichtheycalledLAV(forlymphadenopathyvirus).Gallo’sgroupcameupwithanewvirusalso,onethatGallotookforacloserelativeofthehumanT-cellleukemiaviruses(bynowtherewasasecond,calledHTLV-II,andthefirsthadbecomeHTLV-I)thatheandhispeoplehaddiscovered.HecalledthisnewestbugHTLV-III,nestingitproprietarilyintohismenagerie.TheFrenchLAVandtheGalloHTLVshadatleastonethingincommon:Theywereindeedretroviruses.Butwithinthatfamilyexistssomerichandimportantdiversity.AneditorialinthesameissueofSciencetrumpetedtheGalloandMontagnierpaperswithamisleadingheadline:HUMANT-CELLLEUKEMIAVIRUSLINKEDTOAIDS,despitethefactthatMontagnier’sLAVwasnotahumanT-cellleukemiavirus.Woops,mistakenidentity.Montagnierknewbetter,buthisSciencepaperseemedtoblurthedistinction,andtheeditorialoccludeditentirely.

Thenagain,neitherwasGallo’s“HTLV-III”anHTLV,onceitwasclearlyseenandcorrectlyclassified.ItturnedouttobesomethingnearlyidenticaltoMontagnier’sLAV,ofwhichMontagnierhadgivenhimafrozensample.Montagnierhadpersonallydeliveredthatsample,carryingitondryiceduringavisittoBethesda.

Confusionwasthussownearly—confusionaboutwhatexactlyhadbeendiscovered,whohaddiscoveredit,andwhen.Thatconfusion,irrigatedwithcompetitivezeal,fertilizedwithaccusationanddenial,wouldgrowrifefordecades.Therewouldbelawsuits.TherewouldbefightsoverroyaltiesfromthepatentonanAIDSblood-screeningtestthatderivedfromvirusgrowninGallo’slabbuttraceabletoMontagnier’soriginalisolate.(Contaminationfromoneexperimenttoanother,orfromonebatchof

samplestoanother,isafamiliarprobleminlabworkwithviruses.)Itwasn’tapettysquabble.Itwasabigsquabble,inwhichpettinessplayednosmallpart.Whatwasultimatelyatstake,besidesmoneyandegoandnationalpride,wasnotjustadvancingorretardingresearchtowardanAIDScureorvaccinebutalsotheNobelPrizeinmedicine,whicheventuallywenttoLucMontagnierandhischiefcollaborator,FrançoiseBarré-Sinoussi.

Meanwhilethethirdteamofresearchers,ledquietlybyamannamedJayA.LevyinhislabattheUniversityofCaliforniaSchoolofMedicine,inSanFrancisco,alsofoundacandidatevirusin1983butdidn’tpublishuntilmorethanayearafterward.Bysummerof1984,Levynoted,AIDShadaffected“morethan4000individualsintheworld;inSanFrancisco,over600caseshavebeenreported.”Thosenumberssoundedalarminglyhighatthetime,thoughinretrospect,comparedwith36milliondeaths,theyseempoignantlylow.Levy’sdiscoverywasalsoaretrovirus.Hisgroupdetecteditintwenty-twoAIDSpatientsandgrewmorethanahalfdozenisolates.BecausethebugwasanAIDS-associatedretrovirus,LevycalleditARV.Hesuspected,correctly,thathisARVandMontagnier’sLAVweresimplyvariantsamplesofthesameevolvingvirus.Theywereverysimilarbutnottoosimilar.“OurdatacannotreflectacontaminationofourcultureswithLAV,”hewrote,“sincetheoriginalFrenchisolatewasneverreceivedinourlaboratory.”Harmlessasthatmaysound,itwasanimplicitjabatRobertGallo.

Thedetailsofthisstory,thenear-simultaneoustriplediscoveryanditsaftermath,areintricateandcontentiousandseamyandtechnical,likearatatouilleofmolecularbiologyandpersonalpoliticsleftoutinthesuntoferment.Theyleadfarafieldfromthesubjectofzoonoticdisease.Forourpurposeshere,theessentialpointisthatavirusdiscoveredintheearly1980s,inthreedifferentplacesunderthreedifferentnames,becamepersuasivelyimplicatedasthecausalagentofAIDS.Adistinguishedcommitteeofretrovirologistssettledthenamingissuein1986.TheydecreedthattheviruswouldbecalledHIV.

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It’squiteappropriateandmorethancoincidental,giventhezoonoticdimensionofthisstory,thatthenextphasebeganwithaveterinarian.MaxEssexstudiedretrovirusesinmonkeysandcats.

Dr.Myron(Max)Essex,DVM,PhD,wasnotyourordinarysmall-animalvet.HewasaprofessorandaresearchscientistintheDepartmentofCancerBiologyattheHarvardSchoolofPublicHealth.Hehadworkedonfelineleukemiavirus(FeLV),amongotherthings,andcancer-causingvirusesformedthebroadframeofhisinterests.HavingseentheeffectsofFeLVinwreckingtheimmunesystemsofcats,hesuspectedasearlyas1982,alongwithGalloandMontagnier,thatthenewhumanimmunedeficiencysyndromemightbecausedbyaretrovirus.

Thensomethingstrangecametohisnotice,bywayofagradstudentnamedPhyllisKanki.Shewasaveterinarianlikehim,butnowworkingonadoctoratethereattheSchoolofPublicHealth.KankigrewupinChicago,spentheradolescentsummersdoingzoowork,thenstudiedbiologyandchemistryonthewaytowardveterinarymedicineandcomparativepathology.Duringthesummerof1980,whilestillamidherDVMstudies,sheworkedattheNewEnglandRegionalPrimateResearchCenter,whichwaspartofHarvardbutlocatedoutinSouthborough,Massachusetts.Thereshesawaweirdproblemamongthecenter’scaptiveAsianmacaques—someofthemweredyingofamysteriousimmunedysfunction.Amacaqueisakindofmonkey,andseveraloftheAsianspecies,suchastherhesusmacaqueandtheFormosanrockmacaque,arehighlyvaluedaslaboratoryanimalsformedicalresearch.Attheprimatecenter,whichheldalmosteighthundredanimalsofthemacaquegenus,Formosanrockmacaquesinparticularseemedtobesufferingthisimmune-systemfailure.TheirT-helperlymphocytecountswerewaydown.Theywastedawayfromdiarrheaorsuccumbedtoopportunisticinfections,includingPneumocystiscarinii.ItsoundedtoomuchlikeAIDS.KankilaterbroughtthistotheattentionofEssex,herthesisadviser,andtogetherwithcolleaguesfromSouthborough,theystartedtolookforwhatwaskillingthosemonkeys.BasedontheirknowledgeofFeLVandotherfactors,theywonderedwhetheritmightbearetrovirusinfection.

Takingbloodsamplesfrommacaques,theydidfindanewretrovirus,andsawthatitwascloselyrelatedtotheAIDSvirus.Becausethiswas1985,theyusedGallo’sslightlymisleadinglabel(HTLV-III)forwhatwouldsoonberenamedHIV.Theirmonkeyviruswouldberenamedtooandbecome,byanalogy,simianimmunodeficiencyvirus:SIV.ThegrouppublishedapairofpapersinScience,whichhadgrownhungryforAIDSbreakthroughs.Thisdiscovery,theywrote,couldhelpilluminatethepathologyofthedisease,maybeevenadvanceeffortstodevelopavaccine,byprovidingananimalmodelforresearch.Onlyasinglesentenceattheendofoneofthepapers,amodestbutpertinentcommentdroppedinlikeanafterthought,notedthatSIVmightalsobeacluetowardtheoriginofHIV.

Itwas.PhyllisKankiperformedthelabanalysisofsamplesfromthecaptivemacaquesandthenmadeitherbusinesstowonderwhetherthesamevirusmightexistinthewild.KankiandEssexlookedatotherAsianmacaques,testingbloodsamplesfromwild-caughtanimals.TheyfoundnotraceofSIV.TheytestedstillotherkindsofwildAsianmonkey.Again,noSIV.ThisledthemtosurmisethatthemacaquesatSouthboroughhadpickeduptheirSIVincaptivitybyexposuretoanimalsofanotherspecies.Itwasareasonableguess,giventhattheprimatecenteratonepointhadamonkeyplaypeninitslobby,whereAsianandAfricaninfantmonkeysweresometimesallowedtomingle.ButthenwhichkindofAfricanmonkeywasthereservoir?Whereexactlyhadtheviruscomefrom?AndhowmightitberelatedtotheemergenceofHIV?

“In1985,thehighestratesofHIVwerereportedintheU.S.andEurope,”EssexandKankiwrotelater,“butdisturbingreportsfromcentralAfricaindicatedthathighratesofHIVinfectionandofAIDSprevailedthere,atleastinsomeurbancenters.”Thefocusofsuspicionwasshifting:notAsia,notEurope,nottheUnitedStates,butAfricamightbethepointoforigin.CentralAfricaalsoharboredarichfaunaofnonhumanprimates.SotheHarvardgroupgotholdofbloodfromsomewild-caughtAfricansimians,includingchimpanzees,baboons,andAfricangreenmonkeys.NoneofthechimpsorthebaboonsshowedanysignofSIVinfection.SomeoftheAfricangreenmonkeysdid.Itwasanepiphany.MorethantwodozenofthemonkeyscarriedantibodiestoSIV,andKankigrewisolatesoflivevirusfromseven.ThatfindingtoowentstraightintoScience,andthesearchcontinued.KankiandEssexeventuallyscreenedthousandsofAfricangreenmonkeys,caughtinvariousregionsofsub-SaharanAfricaorheldcaptiveinresearchcentersaroundtheworld.Dependingonthepopulation,between30and70percentofthoseanimalstestedSIV-positive.

Butthemonkeysweren’tsick.Theydidn’tseemtobesufferingfromimmunodeficiency.UnliketheAsianmacaques,theAfricangreenmonkeys“musthaveevolvedmechanismsthatkeptapotentiallylethalpathogenfromcausingdisease,”EssexandKankiwrote.Maybethevirushadchangedtoo.“Indeed,someSIVstrainsmightalsohaveevolvedtowardcoexistencewiththeirmonkeyhosts.”Themonkeysevolvingtowardgreaterresistance,thevirusevolvingtowardlesservirulence—thissortofmutualadaptationwouldsuggestthatSIVhadbeeninthemalongtime.

Thenewvirus,SIVasfoundinAfricangreenmonkeys,becametheclosestknownrelativeofHIV.Butitwasn’tthatclose;manydifferencesdistinguishedthetwoatthelevelofgeneticcoding.Theresemblance,accordingtoEssexandKanki,was“notcloseenoughtomakeitlikelythatSIVwasanimmediateprecursorofHIVinpeople.”Morelikely,thosetwovirusesrepresentedneighboringtwigsonasinglephylogeneticbranch,separatedbylotsofevolutionarytimeandprobablysomeextantintermediateforms.Wheremightthemissingcousinsbe?“Perhaps,wethought,onecouldfindsuchavirus—anintermediatebetweenSIVandHIV—inhumanbeings.”TheydecidedtolookinWestAfrica.

Withhelpfromaninternationalteamofcollaborators,KankiandEssexgatheredbloodsamplesfromSenegalandelsewhere.Thesamplesarrivedwithcodedlabeling,forblind

testinginthelaboratory,sothatKankiherselfdidn’tknowtheircountryoforigin,norevenwhethertheyderivedfromhumansormonkeys.ShescreenedthemusingtestsforbothSIVandHIV.Despiteonepossiblemisstepinvolvingalabcontamination,herteamfoundwhattheyhadthoughttheymight:avirusintermediatebetweenHIVandSIV.Withthecodeunblinded,KankilearnedthatthepositiveresultscamefromSenegaleseprostitutes.Inretrospectitmadesense.Prostitutesareathighriskforanysexuallytransmittedvirus,includinganewonerecentlyspilledintohumans.AndthedensityoftheruralhumanpopulationinSenegal,whereAfricangreenmonkeysarenative,makesmonkey-humaninteractions(crop-raidingbymonkeys,huntingbyhumans)relativelyfrequent.

Furthermore,thenewbugfromSenegaleseprostituteswasn’tjusthalfwaybetweenHIVandSIV.ItmorecloselyresembledSIVstrainsfromAfricangreenmonkeysthanitdidtheMontagnier-GalloversionofHIV.Thatwasimportantbutpuzzling.WeretheretwodistinctkindsofHIV?

LucMontagniernowreentersthestory.HavingtussledwithGallooverthefirstHIVdiscovery,heconvergedmoreamicablywithEssexandKankionthisone.UsingassaytoolsprovidedbytheHarvardgroup,Montagnierandhiscolleaguesscreenedthebloodofatwenty-nine-year-oldmanfromGuinea-Bissau,atinycountry,formerlyaPortuguesecolony,alongthesouthborderofSenegal.ThismanshowedsymptomsofAIDS(diarrhea,weightloss,swollenlymphnodes)buttestednegativeforHIV.HewashospitalizedinPortugal,andhisbloodsamplewashand-deliveredtoMontagnierbyavisitingPortuguesebiologist.InMontagnier’slab,theman’sserumagaintestednegativeforantibodiestoHIV.ButfromacultureofhiswhitebloodcellsMontagnier’sgroupisolatedanewhumanretrovirus,whichlookedverysimilartowhatEssexandKankihadfound.Inanotherpatient,hospitalizedinParisbutoriginallyfromCapeVerde,anislandnationoffthewestcoastofSenegal,theFrenchteamfoundmorevirusofthesametype.MontagniercalledthenewthingLAV-2.Eventually,whenallpartiesembracedthelabelHIVinstead,itwouldbeHIV-2.TheoriginalbecameHIV-1.

Thepathsofdiscoverymaybesinuous,thelabelsmayseemmany,andmaybeyoucan’ttelltheplayerswithoutascorecard;butthesedetailsaren’ttrivial.ThedifferencebetweenHIV-2andHIV-1isthedifferencebetweenanastylittleWestAfricandiseaseandaglobalpandemic.

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Duringthelate1980s,asPhyllisKankiandMaxEssexandotherscientistsstudiedHIV-2,aflurryofuncertaintyaroseaboutitsprovenance.Somechallengedtheideathatitwascloselyrelatedto(andrecentlyderivedfrom)aretrovirusthatinfectsAfricanmonkeys.Analternativeviewwasthatsucharetrovirushadbeenpresentinthehumanlineageforaslongas—orlongerthan—wehaveexistedasaspecies.Possiblyitwasalreadywithus,apassengerridingtheslowchannelsofevolution,whenwedivergedfromourprimatecousins.Butthatviewleftanunresolvedconundrum:Iftheviruswasanancientparasiteuponhumans,unnoticedformillennia,howhaditsuddenlybecomesopathogenic?

Recentspilloverseemedmorelikely.Still,thecaseagainstthatideagotaboostin1988,whenagroupofJapaneseresearcherssequencedthecompletegenomeofSIVfromanAfricangreenmonkey.Thatis,theydetectedandassembledthelinearmessageofnucleotidebases—representedbythelettersA,T,C,andG—comprisingthatSIV’sgeneticinscription.ThehostanimalcamefromKenya.ThenucleotidesequenceofitsretrovirusprovedtobesubstantiallydifferentfromthesequenceforHIV-1,anddifferentinroughlythesamedegreefromHIV-2.Sothemonkeyvirusseemednomorecloselyrelatedtotheonehumanvirusthantotheother.ThatcontradictedthenotionthatHIV-2hadlatelyemergedfromanAfricangreenmonkey.AcommentaryinthejournalNature,publishedtoaccompanytheJapanesepaper,celebratedthisfindingbeneathadogmaticheadline:HUMANAIDSVIRUSNOTFROMMONKEYS.Buttheheadlinewasmisleadingtothepointoffalsity.Notfrommonkeys?Well,don’tbesosure.Itturnedoutthatresearcherswerejustlookingatthewrongkindofmonkey.

Confusioncamefromtwosources.Forstarters,thelabel“Africangreenmonkey”isalittlevague.Itencompassesadiversityofforms,sometimesalsoknownassavannahmonkeys,thatoccupyadjacentgeographicalrangesspreadacrosssub-SaharanAfrica,fromSenegalinthewesttoEthiopiaintheeastanddownintoSouthAfrica.Atonetimethoseformswereconsidereda“superspecies”underthenameCercopithecusaethiops.Nowadays,theirdifferenceshavingbeenmoreacutelygauged,theyareclassifiedassixdistinctspecieswithinthegenusChlorocebus.The“Africangreenmonkey”sampledbytheJapaneseteam,becauseitwas“ofKenyanorigin,”probablybelongedtothespeciesChlorocebuspygerythrus.ThespeciesnativetoSenegal,ontheotherhand,isChlorocebussabaeus.Nowthatyou’veseenthosetwonamesyoucanforgetthem.ThedifferencebetweenoneAfricangreenmonkeyandanotherisnotwhataccountsforthegeneticdisjunctionbetweenSIVandHIV-2.

ThetrailbackwardfromHIV-2ledtoanothermonkeyentirely:thesootymangabey.ThisisnotoneofthesixChlorocebusspecies,notevenclose.Itbelongstoadifferentgenus.

Thesootymangabey(Cercocebusatys)isasmoky-graycreaturewithadarkfaceandhands,whiteeyebrows,andflaringwhitemuttonchops,notnearlysodecorativeasmanymonkeysonthecontinentbutarrestinginitsway,likeanelderlychimneysweepof

dappertonsorialhabits.ItlivesincoastalWestAfrica,fromSenegaltoGhana,favoringswampsandpalmforests,whereiteatsfruit,nuts,seeds,leaves,shoots,androots—aneclecticvegetarian—andspendsmuchofitstimeontheground,movingquadrupedallyinsearchoffallentidbits.Sometimesitventuresoutofthebottomlandstoraidfarmsandricepaddies.Thesootymangabeyishardtohuntwithintheswampyforestsbut,becauseofitsterrestrialforaginghabitsanditstasteforcrops,easytotrap.Localpeopletreatitasanannoyingbutediblesortofvermin.Sometimesalso,ifthey’renottoohungry,theyadoptanorphanjuvenileasapet.

WhatbroughtthesootymangabeytotheattentionofAIDSresearcherswascoincidenceandanexperimentonleprosy.Itwasaninstanceoftheoldscientificveritythatsometimesyoufindmuchmorethanyou’relookingfor.

BackinSeptember1979,scientistsataprimateresearchcenterinNewIberia,Louisiana,southofLafayette,hadnoticedaleprosy-likeinfectioninoneoftheircaptivemonkeys.Thisseemedodd,becauseleprosyisahumandiseasecausedbyabacterium(Mycobacteriumleprae)notknowntobetransmissiblefrompeopletootherprimates.Butherewasaleprousmonkey.Theanimalinquestion,asootymangabey,female,aboutfiveyearsold,hadbeenimportedfromWestAfrica.TheresearcherscalledherLouise.Apartfromherskincondition,Louisewashealthy.Shehadn’t,sofarastherecordsshowed,yetbeensubjectedtoanyexperimentalinfection.Theywereusingherinastudyofdietandcholesterol.TheNewIberiafacilitydidn’thappentoworkonleprosyinfections,soonceLouise’sconditionhadbeenrecognizedshewastransferredtoaplace,alsoinLouisiana,thatdid:theDeltaRegionalPrimateResearchCenter,northofLakePontchartrain.TheresearchersatDeltaweregladtogether,foroneverypracticalreason.IfLouisehadacquiredherleprosynaturally,then(contrarytoprevioussuppositions)thediseasemightbetransmissibleinpopulationsofsootymangabey.Andifthatweretrue,thenthesootymangabeycouldprovevaluableasanexperimentalmodelforstudiesofhumanleprosy.Thisishowhumanmedicalresearchworks:attheexpenseofothercreatures.

SotheDeltateaminjectedsomeinfectiousmaterialfromLouiseintoanothersootymangabey.Thisonewasamale.UnlikeLouise,heisnamelessinthescientificrecord,rememberedonlybyacode:A022.Hebecamethefirstinachainofexperimentallyinfectedmonkeysthatturnedouttocarrymorethanleprosy.ThescientistsatDeltahadnoidea,notatfirst,thatA022wasSIV-positive.

TheleprosyfromLouisetookholdeasilyinA022,whichwasnotable,giventhatearlierattemptstoinfectmonkeyswithhumanleprosyhadfailed.WasthisstrainofMycobacteriumlepraeapeculiarlymonkey-adaptedvariant?Ifso,mightitsucceedinrhesusmacaquestoo?Thatwouldbeconvenientforexperimentalpurposes,becauserhesusmacaqueswerecheaperandmoreavailable,inthemedical-researchchainofsupply,thansootymangabeys.SotheDeltateaminjectedfourrhesusmacaqueswithinfectiousgunkfromA022.Allfourdevelopedleprosy.Forthreeofthefour,thatprovedtobetheleastoftheirtroubles.TheunluckythreealsodevelopedsimianAIDS.Sufferingchronicdiarrheaandweightloss,theywastedawayanddied.

Screeningforvirus,theresearchersfoundSIV.Howhadtheirthreemacaquesbecome

SIV-positive?Evidentlybywayoftheleprousinoculumfromthesootymangabey,A022.Washeunique?No.TestsofothersootymangabeysatDeltarevealedthattheviruswasquiteprevalentamongthem.Otherinvestigatorssoonfoundittoo,notjustamongcaptivesootymangabeysbutalsointhewild.Yetthesootymangabeys(nativetoAfrica),unliketheAsianmacaques,showednosymptomsofsimianAIDS.Theywereinfectedbuthealthy,whichsuggestedthatthevirushadalonghistoryintheirkind.Thesamevirusmadethemacaquessick,presumablybecauseitwasnewtothem.

Therosterofsimianimmunodeficiencyviruseswasgrowingmorecrowdedandcomplex.Nowtherewerethreeknownvariants:onefromAfricangreenmonkeys,onefromrhesusmacaques(whichtheyprobablyacquiredincaptivity),andonefromsootymangabeys.Needingawaytoidentifyanddistinguishthem,someonehitupontheexpedientofaddingtinysubscriptstotheacronym.SimianimmunodeficiencyvirusasfoundinsootymangabeysbecameSIVsm.TheothertwowerelabeledSIVagm(forAfricangreenmonkeys)andSIVmac(forAsianmacaques).Thislittleconventionmayseemesoteric,nottomentionhardontheeyes,butitwillbeessentialandluminouswhenIdiscussthefatefulsignificanceofavariantthatcametobeknownasSIVcpz.

Fornowit’senoughtonotetheupshotoftheleprosyexperimentinLouisiana.OnescientistfromtheDeltateam,awomannamedMichaelAnneMurphey-Corb,collaboratedwithmolecularbiologistsfromotherinstitutionstoscrutinizethegenomesofSIVsfromsootymangabeysandrhesusmacaques,andtocreateaprovisionalfamilytree.Theirwork,publishedin1989withVanessaM.Hirschasfirstauthor,revealedthatSIVsmiscloselyrelatedtoHIV-2.SoisSIVmac.“TheseresultssuggestthatSIVsmhasinfectedmacaquesincaptivityandhumansinWestAfrica,”thegroupwrote,placingtheonusoforiginationonsootymangabeys,“andevolvedasSIVmacandHIV-2,respectively.”Infact,thosethreestrainswereverysimilar,suggestingdivergencefairlyrecentlyfromacommonancestor.

“Aplausibleinterpretationofthesedata,”Hirschandhercoauthorsadded,tomakethepointplainly,“isthatinthepast30–40yearsSIVfromaWestAfricansootymangabey(orcloselyrelatedspecies)successfullyinfectedahumanandevolvedasHIV-2.”Itwasofficial:HIV-2isazoonosis.

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ButwhataboutHIV-1?Wheredidthegreatkillercomefrom?Thatwasalargermysterythattooksomewhatlongertosolve.ThelogicalinferencewasthatHIV-1mustbezoonoticinoriginalso.Butwhatanimalwasitsreservoir?When,where,andhowhadspilloveroccurred?Whyhadtheconsequencesbeensomuchmoredire?

HIV-2isbothlesstransmissibleandlessvirulentthanHIV-1.Themolecularbasesforthosefatefuldifferencesarestillsecretsembeddedinthegenomes,buttheecologicalandmedicalramificationsareclearandstark.HIV-2isconfinedmostlytoWestAfricancountriessuchasSenegalandGuinea-Bissau(thelatterofwhich,duringcolonialtimes,wasPortugueseGuinea),andtootherareasconnectedsociallyandeconomicallywithintheformerPortugueseempire,includingPortugalitselfandsouthwesternIndia.PeopleinfectedwithHIV-2tendtocarrylowerlevelsofvirusintheirblood,toinfectfeweroftheirsexualcontacts,andtosufferlesssevereorlonger-delayedformsofimmunodeficiency.Manyofthemdon’tseemtoprogresstoAIDSatall.AndmotherswhocarryHIV-2arelesslikelytopassittotheirinfants.Thevirusisbad,butnotnearlysobadasitcouldbe.HIV-1providesthecomparison.HIV-1isthethingthatafflictstensofmillionsofpeoplethroughouttheworld.HIV-1isthepandemicscourge.TounderstandhowtheAIDScatastrophehashappenedtohumanity,scientistshadtotraceHIV-1toitssource.

ThistakesustothecityofFranceville,insoutheasternGabon,CentralAfrica,andaninstitutioncalledtheCentreInternationaldeRecherchesMédicales(CIRMF),thesameplaceatwhichimportantworkonEbolavirushasbeendone.It’sanexusforthestudyof,andresponseto,emergingAfricandiseases.Attheendofthe1980s,ayoungBelgianwomannamedMartinePeetersworkedasaresearchassistantatCIRMFforayearorso,duringtheperiodbetweengettingherdiplomaintropicalmedicineandgoingonforadoctorate.TheCIRMFfacilitymaintainedacompoundofcaptiveprimates,includingthreedozenchimpanzees,andPeetersalongwithseveralassociateswastaskedwithtestingthecaptiveanimalsforantibodiestoHIV-1andHIV-2.Almostallofthechimpstestednegative—allexcepttwo.Bothexceptionswereveryyoungfemales,recentlycapturedfromthewild.Suchbabychimps,likeotherorphanprimates,aresometimeskeptorsoldoffaspetsafterthekillingandeatingoftheirmothers.Oneoftheseanimals,atwo-year-oldsufferingfromgunshotwounds,hadbeenbroughttoCIRMFformedicaltreatment.Shediedofthewounds,butnotbeforesurrenderingabloodsample.Theotherwasaninfant,maybesixmonthsold,whosurvived.BloodserumfromeachofthemreactedstronglywhentestedagainstHIV-1,lessstronglywhentestedagainstHIV-2.Thatmuchwasnotablebutslightlyambiguous.Antibodytestingisanindirectgaugeofinfection,relativelyconvenientandquick,butimprecise.GreaterprecisioncomeswithdetectingfragmentsofviralRNAor,betterstill,isolatingavirus—catchingthethinginitswholenessandgrowingitinquantity—fromwhichaconfidentidentificationcanbemade.MartinePeetersandherco-workerssucceededinisolatingavirusfromthebabychimp.Twentyyearslater,whenIcalledonheratherofficeataninstituteinsouthernFrance,

Peetersrememberedvividlyhowthatvirusshowedupinaseriesofmoleculartests.

“Itwasespeciallysurprising,”shesaid,“becauseitwassoclosetoHIV-1.”

Hadtherebeenanyprevioushints?

“Yes.AtthattimeweknewalreadythatHIV-2mostlikelycamefromprimatesinWestAfrica,”shesaid,alludingtothesootymangabeywork.“ButtherewasnovirusclosetoHIV-1alreadydetectedinprimates.Anduntilnow,it’sstilltheonlyvirusclosetoHIV-1.”Hergrouppublishedapaper,in1989,announcingthenewvirusandcallingitSIVcpz.TheydidnotcrowabouthavingfoundthereservoirofHIV-1.Theirconclusionfromthedatawasmoremodest:“IthasbeensuggestedthathumanAIDSretrovirusesoriginatedfrommonkeysinAfrica.However,thisstudyandotherpreviousstudiesonSIVdonotsupportthissuggestion.”Leftimplicit:Chimpanzees,notmonkeys,mightbethesourceofthepandemicbug.

BythetimeImether,MartinePeeterswasdirectorofresearchattheInstitutdeRecherchepourleDéveloppement(IRD),inMontpellier,ahandsomeoldcityjustofftheMediterraneancoast.Shewasasmall,blondewomaninablacksweaterandsilvernecklace,conciseandjudiciousinconversation.Whatsortofresponsemetthisdiscovery?Iasked.

“HIV-2,peopleaccepteditreadily.”Theyaccepted,shemeant,thenotionofsimianorigins.“ButHIV-1,peoplehadmoredifficultiestoacceptit.”

Whytheresistance?“Idon’tknowwhy,”shesaid.“Maybebecausewewereyoungscientists.”

The1989papergotlittleattention,whichseemspeculiarinretrospect,giventhenoveltyandgravityofwhatitimplied.In1992Peeterspublishedanother,describingathirdcaseofSIVcpz,thisoneinacaptivechimpanzeethathadbeenshippedtoBrusselsfromZaire.AllthreeofherSIV-positiveresultswerefrom“wild-born”chimpanzeestakencaptive(asdistinctfromanimalsbredincaptivity)butthatstillleftagapinthechainofevidence.Whataboutchimpsstillinthewild?

Withonlysuchtoolsofmolecularbiologyasavailableintheearly1990s,thescreeningofwildchimpswasdifficult(andunacceptabletomostchimpresearchers),becausethediagnostictestsrequiredbloodsampling.Lackofevidencefromwildpopulations,inturn,contributedtoskepticismintheAIDS-researchcommunityaboutthelinkbetweenHIV-1andchimps.Afterall,ifAsianmacaqueshadbecomeinfectedwithHIV-2intheircages,fromcontactwithAfricanmonkeys,mightnotSIV-positivechimpanzeessimplyreflectcage-contactinfectionstoo?Anotherreasonforskepticismwasthefactthat,bytheendofthe1990s,roughlyathousandcaptivechimpanzeeshadbeentestedbut,apartfromPeeters’sthree,notasingleonehadyieldedtracesofSIVcpz.Thesetwofactors—theabsenceofevidencefromwildpopulationsandtheextremerarityofSIVincaptivechimps—leftopenthepossibilitythatbothHIV-1andSIVcpzderiveddirectlyfromacommonancestralvirusinsomeotherprimate.Inotherwords,maybethosethreelonelychimpshadgottentheirinfectionsfromsomestill-unidentifiedmonkey,

andmaybethesameunidentifiedmonkeyhadgivenHIV-1tohumans.Withthatpossibilitydangling,theoriginofHIV-1remaineduncertainformuchofthedecade.

Inthemeantime,researchersinvestigatednotjustthesourceofHIVbutalsoitsdiversityinhumans,discoveringthreemajorlineagesofHIV-1.“Groups”becamethepreferredtermfortheselineages.Eachgroupwasaclusterofstrainsthatwasgeneticallydiscretefromtheotherclusters;therewasvariationwithineachgroup,sinceHIVisalwaysevolving,butthedifferencesbetweengroupswerefarlarger.Thispatternofgroupshadsomedarkimplicationsthatdawnedonscientistsonlygraduallyandstillhaven’tbeenabsorbedinthepopularunderstandingofAIDS.I’llgettothemshortly,butfirstlet’sconsiderthepatternitself.

GroupMwasthemostwidespreadandnefarious.TheletterMstoodfor“main,”becausethatgroupaccountedformostoftheHIVinfectionsworldwide.WithoutHIV-1groupM,therewasnoglobalpandemic,nomillionsofdeaths.GroupOwasthesecondtobedelineated,itsinitialstandingfor“outlier,”becauseitencompassedonlyasmallnumberofviralisolates,mostlytraceabletowhatseemedanoutlierarearelativetothehotspotsofthepandemic:Gabon,EquatorialGuinea,andCameroon,allinwesternCentralAfrica.Bythetimeathirdmajorgroupwasdiscovered,in1998,itseemedlogicaltolabelthatoneN,supposedlyindicating“non-M/non-O”butalsofillinginthealphabeticalsequence.(Yearslater,afourthgroupwouldbeidentifiedandlabeledP.)GroupNwasextremelyrare;ithadbeenfoundinjusttwopeoplefromCameroon.TherarityofNandOputgroupMdramaticallyinrelief.Mwaseverywhere.Whyhadthatparticularlineageofvirus,andnottheothertwo(orthree),spreadsobroadlyandlethallyaroundtheplanet?

ParallelresearchonHIV-2,thelessvirulentvirus,alsofounddistinctgroupsbutevenmoreofthem.Theirlabelingcamefromthebeginningofthealphabetratherthanthemiddle,andbytheyear2000sevengroupsofHIV-2wereknown:A,B,C,D,E,F,andG.(Aneighthgroup,turninguplater,becameH.)Again,mostofthemwereextremelyrare—represented,infact,byviralsamplestakenfromonlyoneperson.GroupsAandBweren’trare;theyaccountedforthemajorityofHIV-2cases.GroupAwasmorecommonthangroupB,especiallyinGuinea-BissauandEurope.GroupBwastraceablemainlytocountriesontheeasternendofWestAfrica,suchasGhanaandCôted’Ivoire.GroupsCthroughH,althoughtinyintotalnumbers,weresignificantinshowingarangeofdiversity.

Asthenewcenturybegan,AIDSresearchersponderedthisrosterofdifferentvirallineages:sevengroupsofHIV-2andthreegroupsofHIV-1.ThesevengroupsofHIV-2,distinctastheywerefromoneanother,allresembledSIVsm,thevirusendemicinsootymangabeys.(Sodidthelateraddition,groupH.)ThethreekindsofHIV-1allresembledSIVcpz,fromchimps.(Theeventualfourthkind,groupP,ismostcloselyrelatedtoSIVfromgorillas.)Nowhere’sthepartthat,asitpercolatesintoyourbrain,shouldcauseashudder:Scientiststhinkthateachofthosetwelvegroups(eightofHIV-2,fourofHIV-1)reflectsanindependentinstanceofcross-speciestransmission.Twelvespillovers.

Inotherwords,HIVhasn’thappenedtohumanityjustonce.Ithashappenedatleasta

dozentimes—adozenthatweknowof,andprobablymanymoretimesinearlierhistory.Thereforeitwasn’tahighlyimprobableevent.Itwasn’tasingularpieceofvastlyunlikelybadluck,strikinghumankindwithdevastatingresults—likeacometcomeknuckleballingacrosstheinfinitudeofspacetosmackplanetEarthandextinguishthedinosaurs.No.ThearrivalofHIVinhumanbloodstreamswas,onthecontrary,partofasmalltrend.DuetothenatureofourinteractionswithAfricanprimates,itseemstooccurprettyoften.

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Whichraisesafewlargequestions.IfthespilloverofSIVintohumanshashappenedatleasttwelvetimes,whyhastheAIDSpandemichappenedonlyonce?Andwhydidithappenwhenitdid?Whydidn’tithappendecadesorcenturiesearlier?Thosequestionsentanglethemselveswiththreeothers,moreconcrete,lessspeculative,towhichIalreadyalluded:When,where,andhowdidtheAIDSpandemicbegin?

Firstlet’sconsiderwhen.WeknowfromMichaelGottlieb’sevidencethatHIVhadreachedhomosexualmeninCaliforniabylate1980.WeknowfromthecaseofGretheRaskthatitlurkedinZaireby1977.WeknowthatGaëtanDugaswasn’treallyPatientZero.Butifthosepeopleandplacesdon’tmarkarealbeginningpointintime,whatdoes?Whendidthefatefulstrainofvirus,HIV-1groupM,enterthehumanpopulation?

Twolinesofevidencecallattentionto1959.

InSeptemberofthatyear,ayoungprint-shopworkerinManchester,England,diedofwhatseemedtobeimmune-systemfailure.BecausehehadspentacoupleyearsintheRoyalNavybeforereturningtohishometownandhisjob,thisunfortunatemanhasbeenlabeled“theManchestersailor.”Hishealthwentintodeclineafterhisnavalhitch,whichheservedmainlybutnotentirelyinEngland.Atleastonce,hesailedasfarasGibraltar.BackinManchesterbyNovember1957,hewastedaway,sufferingsomeofthesymptomslaterassociatedwithAIDS,includingweightloss,fevers,anaggingcough,andopportunisticinfections,includingPneumocystiscarinii,butnounderlyingcauseofdeathcouldbedeterminedbythedoctorwhodidtheautopsy.Thatdoctorpreservedsomesmallbitsofkidney,bonemarrow,spleen,andothertissuesfromthesailor—embeddingtheminparaffin,aroutinemethodforfixingpathologysamples—andreportedthecaseinamedicaljournal.Thirty-oneyearslater,intheeraofAIDS,avirologistattheUniversityofManchestertestedsomeofthosearchivedsamplesandfound(orthoughthefound)evidencethatthesailorhadbeeninfectedwithHIV-1.Ifthatwascorrect,thentheManchestersailorwouldberecognizedretrospectivelyasthefirstcaseofAIDSeverdocumentedinthemedicalliterature.

Butwait.RetestingofthesamesamplesbyapairofscientistsinNewYork,severalyearslater,showedthattheearlierHIV-positiveresultmusthavereflectedalaboratorymistake.Thebonemarrownowtestednegative.Thekidneymaterialagaintestedpositivebutinawaythatrangalarmsofdoubt:HIV-1evolvesquickly,andthegeneticsequenceofvirusfromthekidneysampleseemedfartoomodern.Itlookedmorelikeamodernvariantthanlikesomethingthatcouldhaveexistedin1959.Thatsuggestedcontaminationwithsomerecentstrainofthevirustoaccountforthepositivetests.Conclusion:TheManchestersailormayhavediedfromimmune-systemfailurebutHIVprobablywasn’tthecause.HiscasemerelyillustrateshowtrickyitcanbetomakearetrospectivediagnosisofAIDS,evenwiththepresenceofwhatseemstobegoodevidence.

SoonafterthatfalseleadfromManchesterwasdebunked,anotherleademergedinNewYork.Bynowitwas1998.AteamofresearchersincludingTuofuZhu,basedatthe

RockefellerUniversity,obtainedanarchivalspecimenfromAfricadatingbacktothesameyearasthesailor’s,1959.Thistimeitwasn’ttissues;itwasasmalltubeofbloodplasma,drawnfromaBantumaninwhathadbeenLéopoldville,capitaloftheBelgianCongo(nowadaysKinshasa,capitaloftheDemocraticRepublicoftheCongo),andstoredfordecadesinafreezer.Theman’snameandhiscauseofdeathweren’treported.Hissamplehadbeenscreenedduringanearlierstudy,in1986,alongwith1,212otherplasmas—somearchival,othersnew—fromvariouslocationsinAfrica.Thisman’swastheonlyonethattestedunambiguouslypositiveforHIV.TuofuZhuandsomecolleaguesprobedfurther,workingwithwhatlittleremainedoftheoriginalsampleandusingpolymerasechainreaction(PCR,abiochemicaltechniquethatinvolvesheatingandcoolingasampleinthepresenceofacertainenzyme)toamplifyfragmentsoftheviralgenome.Thentheysequencedthefragmentstoassembleageneticportraitoftheman’svirus.Intheirpaper,publishedinFebruary1998,theycalledthesequenceZR59,referencingZaire(asthecountryhadlongbeenknown)andtheyear1959.ComparativeanalysisshowedthatZR59wasquitesimilartobothsubtypeBandsubtypeD(finerdivisionswithintheHIV-1groupMlineage)butfellabouthalfwaybetween,whichsuggestedthatitmustcloselyresembletheircommonancestor.Inotherwords,ZR59wasaglimpsebackintime,agenuinelyoldformofHIV-1,notarecentcontamination.ZR59provedthatHIV-1hadbeenpresent—simmering,evolving,diversifying—inthepopulationofLéopoldvilleby1959.Infactitprovedmore.FurtheranalysisofZR59andothersequences,ledbyBetteKorberoftheLosAlamosNationalLaboratory,yieldedacalculationthatHIV-1groupMmighthaveenteredthehumanpopulationaround1931.

Foradecade,fromtheZhupublicationin1998until2008,thatlandmarkstoodalone.ZR59wastheonlyknownversionofHIV-1fromasampletakenearlierthan1976.Thensomeonefoundanother.ThisonebecameknownasDRC60,andbynowyoucanprobablydecodethelabelyourself:ItcamefromtheDemocraticRepublicoftheCongo(samenationasZaire,latestname,oftenabbreviatedasDRC)andhadbeencollectedin1960.

DRC60wasabiopsyspecimen,apieceoflymphnodesnippedfromalivingwoman.LiketheManchestersailor’sbitsofkidneyandspleen,ithadbeenlockedawayinalittlepatofparaffin.Thuspreserved,itneedednorefrigeration,letalonefreezing.Itwasasinertasadeadbutterflyandlessfragile.Itcouldbestoredandignoredonadustyshelf—asithadbeen.Aftermorethanfourdecades,itemergedfromaspecimencabinetattheUniversityofKinshasaandofferedanewjoltofinsighttoAIDSresearchers.

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TheUniversityofKinshasasitsonahilltopneartheedgeofthecity,reachablebyanhour’staxiridethroughthebrokenstreets,thesmoggysprawl,thesnarledtrafficofvansandbusesandpushcarts,pastthestreet-sidevendorsoffunerarywreaths,thecell-phone-rechargekiosks,thefruitmarkets,themeatmarkets,theopen-airhardwarestores,thetire-repairshopsandcementbrokers,thepilesofsandandgravelandgarbage,theawesomedecrepitudeofapostcolonialmetropolisshapedbyeightdecadesofBelgianopportunism,threedecadesofdictatorialmisruleandegregioustheft,thenadecadeofwar,butfilledwith10millionstrivingpeople,someofwhomaredangerousthugs(asinallcities)andmostofwhomareamiable,hopeful,andfriendly.Theuniversitycampus,onitshill,looselycalled“themountain,”presentsarelativelyverdantandhalcyoncontrasttothecitybelow.Studentsgothere,climbingbyfootfromacrowdedbusstop,tolearnandtoescape.

ProfessorJean-MarieM.Kabongoisheadofpathologyintheuniversity’sDepartmentofAnatomicPathology.He’sasmall,nattymanwithahugegrayinghandlebarmustacheandfullmuttonchops,makingaforcefulvisualimpressionthat’svitiatedbyhisgentlemanner.Hewearsheavybrownglassesandawhitelabcoatoverhisshirtandtie.WhenImettheprofessorinhisoffice,onthesecondfloorofabuildingthatoverlooksagrassyconcourseshadedwithacacias,hepleadedimperfectknowledgeofDRC60andthepatientfromwhomthatspecimencame.Anoldcase,afterall,goingbacklongbeforehistime.Yes,awoman,hebelieved.Hismemorywasvaguebuthecouldchecktherecords.HebegantakingnotesasIquestionedhimandsuggestedIcomebackinacoupledays,whenhemightbebetterpreparedwithanswers.ButthenIaskedabouttheroomwhereDRC60hadbeenstored,andhebrightened.Oh,ofcourse,hesaid,Icanshowyouthat.

Hefetchedakey.Downacorridorbeyondhisoffice,heunlockedabluedoor.Swingingitopen,hewelcomedmeintoalargesunlitlaboratorywithwallsofwhitetileandtwolong,lowtablesdownthemiddle.AgainstonewallstoodanoldGErefrigerator.Ononeofthelowtablesrestedanold-fashionedfolioledger,withcurlingpages,likesomethingfromChanceryinthetimeofDickens.Onthefarwindowsillstoodarowofbeakerscontainingliquidsinincrementsofcolor,beakerbybeaker,frompiss-yellowtovodka-clear.Theyellowest,ProfessorKabongotoldme,wasmethanol.Theclearestwasxylol.Weusetheseinpreparingatissuesample,hesaid.Thepointofsuchorganicsolventsistoextractthewater;desiccationisprerequisitetofixingtissuesforthelongterm.Themethanolwasdarkenedfromprocessingmanysamples.

Heshowedmeasmallorangeplasticbasket,withahingedlid,aboutthesizeandshapeofamatchbook.Thisisa“cassette,”ProfessorKabongoexplained.Youtakealumpoftissuefromalymphnodeorsomeotherorganandencloseitinsuchacassette;yousoakthewholethinginthebeakerofmethanol;fromthemethanol,itgoesthroughtheintermediatebathsinsequence;finallyyoudunkitinthexylol.Methanoldrawsoutthewater;xyloldrawsoutthemethanol,preparingyourspecimenforpreservationinparaffin.Andthisdevice,ProfessorKabongosaid,indicatingalargemachineononeofthetables,

deliverstheparaffin.Youtakealeachedtissuesamplefromitscassette,heexplained,andplaceitonalittlesilvertray,here.Fromthatspigot,youdribbleoutastreamofwarm,liquidparaffin.Itcoolsonthesamplelikeapatofbutter.Nowyouremovethecassettelidandlabelthebasewithanindividualcode—forinstance,A90orB71.That’syourarchivalspecimen,hesaid.“A”meansthatitcamefromanautopsy.“B”indicatesabiopsy.Sotheparaffin-cakedbitoflymphnodethatyieldedDRC60wouldhavebeenlabeledB-something,asabiopsyspecimen.Eachcodedspecimengetsrecordedinthebigledger.Thenthespecimensgointostorage.

Storage.Storagewhere?Iasked.

Atthefarendofthelabwasanotherdoorway,thisonehungwithabluecurtain.ProfessorKabongopushedthecurtainasideandIfollowedhimintoaspecimenpantry,narrowandtight,linedwithshelvesandcabinetsalongoneside.Theshelvesandcabinetscontainedthousandsofdustyparaffinblocksandoldmicroscopeslides.Theparaffinblockswereinstacksandcartons,someofthecartonsdated,somenot.Itappearedtobeorganizedchaos.Awoodenstoolawaitedusebyanycurious,tirelesssoulwishingtorummagethroughthesamples.AlthoughIdidn’tplantorummage,mytourhadsuddenlycometoitscrescendo.Here?Yes,justhere,saidtheprofessor.ThisiswhereDRC60satfordecades.Hecouldhaveadded,withlocalpride:beforebecomingaRosettastoneinthestudyofAIDS.

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Fromthepantrybehindthebluecurtain,thatsampleandhundredsofothershadtraveledacircuitousroute,toBelgiumandthentheUnitedStates,endingupinthelaboratoryofayoungbiologistattheUniversityofArizona.MichaelWorobeyisaCanadian,originallyfromBritishColumbia,whosespecialtyismolecularphylogenetics.AfterhisundergraduateworkhewenttoOxfordonaRhodesscholarship,whichordinarilymeanstwoyearsofmildlystrenuousacademicworkpluslotsoftea,sherry,tennisongrass,andgenteelanglophiliabeforethe“scholar”returnstoprofessionalschooloracareer.WorobeyputOxfordtomoreserioususe,stayingon,finishingadoctorateandthenapostdocfellowshipinevolutionarybiologyatthemolecularlevel.FromtherehereturnedtoNorthAmericain2003,acceptinganassistantprofessorshipatArizonaandbuildinghimselfaBSL-3lab(BiosafetyLevel3,thesecondmostsecurecategory)forworkonthegenomesofdangerousviruses.Severalyearslater,itwasWorobeywhodetectedevidenceofHIVinacertainCongolesebiopsyspecimenfrom1960.

Worobeyamplifiedfragmentsoftheviralgenome,piecedthefragmentstogether,recognizedthemasanearlyversionofHIV-1,andnamedthesequenceDRC60.ComparinghissequencewithZR59,theotherearliestknownstrain,hereachedadramaticconclusion:thattheAIDSvirushasbeenpresentinhumansfordecadeslongerthananyonethought.Thepandemicmayhavegottenitsstartwithaspilloverasearlyas1908.

ToappreciateWorobey’sdiscoveryandhowitsplasheddownamidpreviousideas,youneedalittlecontext.ThatcontextinvolvesaheateddisputeoverjusthowHIV-1enteredthehumanpopulation.Theprevailingnotionasoftheearly1990s,basedonwhathadbeenlearnedaboutHIV-2andthesootymangabey,amongotherfactors,wasthatHIV-1alsocamefromanAfricanprimate,andthatithadprobablygottenintohumansbywayoftwoseparateinstances(forgroupsMandO,theonesthenrecognized)ofbutcheringbushmeat.Thisbecameknownasthecut-hunterhypothesis.Ineachinstance,amanorawomanhadpresumablybutcheredthecarcassofanSIV-positiveprimateandsufferedexposurethroughanopenwound—maybeacutonthehand,orascratchonthearm,orarawspotonanyskinsurfacethatgotsmearedwiththeanimal’sblood.Awoundonthebackmighthavesufficed,ifthecarcassweredrapedovershouldersforcarryinghome.Awoundinthemouth,ifsomeofthemeatwereconsumedraw.Allthatmatteredwasblood-to-bloodcontact.Thecut-hunterhypothesiswasspeculativebutplausible.Itwasparsimonious,requiringfewcomplicationsandnounlikelihoods.Itfittheknownfacts,thoughtheknownfactswerefragmentary.Andthenin1992acontrarytheoryarose.

Thisonewasheterodoxandhighlycontroversial:thatHIV-1firstgotintohumansbywayofacontaminatedpoliovaccinetestedonamillionunsuspectingAfricans.Thevaccineitself,bythistheory,hadbeenanunintendeddeliverysystemforAIDS.Someone,accordingtothetheory,hadmonumentallygoofed.Someonewasculpable.Scientifichubrishadoverriddencaution,withhorrendousresults.Thescariestthingaboutthepolio-vaccinetheorywasthatitalsoseemedplausible.

Virusesaresubtle.Theygetinwheretheyshouldn’t.Laboratorycontaminationsoccur.Evenviralorbacterialcontaminationofavaccineattheproductionlevel—ithashappened.Backin1861,agroupofItalianchildrenvaccinatedagainstsmallpox,withmaterialdirectfroma“vaccinalsore,”camedownwithsyphilis.SmallpoxvaccineadministeredtokidsinCamden,NewJersey,atthestartofthetwentiethcentury,seemstohavebeencontaminatedwithtetanusbacillus,resultinginthedeathofninevaccinatedchildrenfromtetanus.Aroundthesametime,abatchofdiphtheriaantitoxinpreparedinSt.Louis,usingbloodserumfromahorse,alsoturnedouttocarrytetanus,whichkilledanothersevenchildren.Producersthenbeganfilteringvaccines,aneffectiveprecautionagainstbacterialcontamination;butvirusespassedthroughthefilters.Formaldehydewassometimesaddedtoinactivateatargetvirus,andthatsupposedlykilledunwantedvirusestoo,butthesuppositionwasn’talwayscorrect.Aslateasthemidcentury,someoftheearlybatchesoftheSalkpoliovaccinewereadulteratedwithavirusknownasSV40,endemicinrhesusmacaques.SV40invaccinebecameahotissue,severalyearslater,whensuspicionsarosethattheviruscausescancer.It’simportanttonotethatvaccinepurificationmethodsandsafetyprecautionshaveimprovedvastlysincethetimeoftheSalkvaccine,andthatadamantresistancetovaccinationbysomeactivistsinthepresenteraismisguided,unjustifiedbyscientificdata,andcostlytopublichealth.Butahalfcenturyago,thepossibilityofvaccinecontaminationdidexist.

WhethervaccinecontaminationhappenedwithHIV-1,aroundthesametimeastheSV40problemandfarmoreconsequentially,isanothermatter.ThatthevaccineinquestionhadbeengiventoAfricanswasnotindispute.Between1957and1960,aPolish-bornAmericanresearchernamedHilaryKoprowski—alesser-knowncompetitorinthesamevaccine-developmentracethatengagedJonasSalkandAlbertSabin—arrangedforhisoralpoliovaccinetobewidelyadministeredinareasoftheeasternBelgianCongoandadjacentcolonialholdings.ThesewerepartsofwhatwouldeventuallybeDRC,Rwanda,andBurundi.KoprowskihimselfvisitedStanleyville,in1957,andmadecontactswholateroversawthetrials.Childrenandadultslineduptrustingly,inplacesliketheRuziziValleynorthofLakeTanganyika,toreceivedosesofliquidvaccinefromatablespoonorasquirtingpipette.Spritz,you’regood.Next!Thenumbersareuncertain.Byoneaccount,roughlyseventy-fivethousandkidswerevaccinatedjustinLéopoldville.Theheterodoxtheoryarguedtwoadditionalpointsaboutthisenterprise:First,thatKoprowski’svaccinewasproducedbygrowingthevirusinchimpanzeekidneycells(ratherthaninmonkeykidneycells,thestandardtechnique);second,thatatleastsomebatchesofthatvaccinewereproducedfromchimpanzeekidneysdrawnfromanimalsinfectedwithSIVcpz.

Theresultofthatflawedvaccinating,certainpeoplehaveargued,wasiatrogenicinfection(diseasecausedbymedicaltreatment)ofanunknownnumberofCentralAfricanswithwhatlaterbecamerecognizedasHIV-1.Bythisnotion,knownforshortastheOPV(oralpoliovaccine)theory,asinglerecklessresearcherhadseededthecontinent—andtheworld—withAIDS.

TheOPVtheoryhasbeenaroundandnotorioussince1992,whenafreelancejournalistnamedTomCurtisdescribeditinalongarticleforRollingStone.Curtis’spieceranundertheheadline:THEORIGINOFAIDS:ASTARTLINGNEWTHEORY

ATTEMPTSTOANSWERTHEQUESTION,“WASITANACTOFGODORANACTOFMAN?”Severalotherresearchershadmootedtheideaearlier,moreobscurely,andoneofthemhadputTomCurtisontothestory.WhenCurtisstartedlookingintoit,someeminentscientistsrespondedwithdefensivedismissals,whichservedonlytosuggestthatmaybethetheorydidmeritconsideration.Curtisevendrewabrusqueandill-consideredcommentfromtheheadofresearchfortheWorldHealthOrganization’sGlobalProgrammeonAIDS,Dr.DavidHeymann:“TheoriginoftheAIDSvirusisofnoimportancetosciencetoday.”Hequotedanotherexpert,WilliamHaseltineofHarvard,assaying:“It’sdistracting,it’snonproductive,it’sconfusingtothepublic,andIthinkit’sgrosslymisleadingintermsofgettingtothesolutionoftheproblem.”Afterpublicationofthepiece,lawyersforHilaryKoprowskifiledalawsuitagainstCurtisandRollingStone,chargingdefamation,andthemagazinerana“clarification,”admittingthattheOPVtheoryandKoprowski’srolerepresentedjustanunsupportedhypothesis.ButasthedustsettledatRollingStone,anEnglishjournalistnamedEdwardHoopertookholdoftheOPVtheoryasapersonalobsessionandaninvestigativecrusade,givingitasecondlife.

Hooperspentyearsresearchingthesubjectwithformidabletenaciousness(thoughnotalwayscriticalgoodsense)andin1999madehiscaseinathousand-pagebooktitledTheRiver:AJourneytotheSourceofHIVandAIDS.Hooper’sriverwasametaphoricalone:theflowofhistory,thestreamofcause-and-effect,fromaverysmallbeginningtoanoceanofconsequences.Inthebook’sprologue,healludedtothequestbyVictorianexplorersforthesourceoftheNile.DoesthatriverbeginfromLakeVictoria,pouringoutatRiponFalls,oristhereanotherandmoreobscuresourceupstreamfromthelake?“ThecontroversysurroundingthesourceoftheNile,”Hooperwrote,“isstrangelyechoedbyanothercontroversyofacenturyandahalflater,thelong-runningdebateabouttheoriginsofAIDS.”TheVictorianexplorershadbeenwrongabouttheNileand,accordingtoHooper,sowerethemodernexpertswrongaboutthestartingpointoftheAIDSpandemic.

Hooper’sbookwasmassive,overwhelminglydetailed,seeminglyreasonable,exhaustingtoplodthroughbutmesmerizinginitsclaims,andsuccessfulatbringingtheOPVtheorytobroaderpublicattention.SomeAIDSresearchers(includingPhyllisKankiandMaxEssex)hadlongbeenawarethatvaccinecontamination,withSIVfrommonkeycells,wasatleastatheoreticalpossibility;theyhadevenconductedscreeningeffortsonvaccinelines,andfoundnoevidenceofsuchaproblem.Hooper,followingTomCurtis,raisedtheideafromaconcerntoanaccusation.Hisvastriverofinformationandhissteamboatofargumentdidn’tprovetheessentialthesis—thatKoprowski’svaccinehadbeenmadefromchimpcellscontaminatedwithHIV.Buthisworkdidseemtoraisethepossibilitythatthevaccinecouldhavebeenmadefromchimpcellsthatmighthavebeencontaminated.

Theissueofpossibilitythengavewaytotheissueoffact.Whathadactuallyhappened?Wherewastheevidence?AttheurgingofaneminentevolutionarybiologistnamedWilliamHamilton,whobelievedthattheOPVtheorydeservedinvestigation,theRoyalSocietyconvenedaspecialmeetinginSeptember2000todiscussthesubjectwithinitsbroadercontext.Hamiltonwasaseniorfigure,likedandrespected,whoseearlyworkinevolutionarytheoryhelpedinformEdwardO.Wilson’sSociobiologyandRichard

Dawkins’sTheSelfishGene.HeswungtheRoyalSocietyintogivingtheOPVtheoryafairhearing.EdwardHooper,thoughnotascientisthimself,wasinvitedtospeak.HilaryKoprowskialsocame,aswellasarosterofleadingAIDSresearchers.Bythetimethatmeetingconvened,though,WilliamHamiltonwasdead.

HediedsuddenlyinMarch2000,ofintestinalbleeding,afteranattackofmalariacontractedduringaresearchtriptotheDemocraticRepublicoftheCongo.Inhisabsence,hiscolleaguesattheRoyalSocietydiscussedawiderangeofmattersrelatedtotheoriginsofHIVandAIDS.TheOPVtheorywasjustonetopicamongmany,thoughimplicitlyitdrovetheagendaofthewholemeeting.Didtheavailabledatafrommolecularbiologyandepidemiologytendtosupport,ortorefute,thevaccine-contaminationscenario?Acorollarytothatquestionwas:WhenhadHIV-1firstenteredthehumanpopulation?Iftheearliestinfectionsoccurredbefore1957,thoseinfectionscouldn’thaveresultedfromKoprowski’sOPVtrials.ArchivalHIV-positivesmightthereforebedecisive.

ThisisthecontextthatbroughtDRC60outofKinshasa.AseniorCongolesevirologistnamedJ.J.Muyembe,awareofthearchivedpathologyspecimensattheUniversityofKinshasaandequallyawareoftheOPVdebate,tookituponhimselftoenlargethebodyofavailabledata.Muyembewentuptotheuniversity,rifledthroughthepantrybehindthebluecurtain,packed813paraffin-embeddedspecimensintoanordinarysuitcase,andcarrieditwithhimonhisnextprofessionalvisittoBelgium.TherehehandedthetrovetoacolleaguenamedDirkTeuwen,whohadtakenpartintheRoyalSocietymeetingacoupleyearsearlier.Teuwen,inaccordwithaprioragreementforcollaborativestudy,sentthemtoMichaelWorobeyinTucson.

Thesetwolinesofnarrativefoldbackintoeachother.Worobey,asagradstudent,knewbothBillHamiltonatOxfordandsomeofthediseasebiologistsinBelgium.ImpelledbyhisowninterestintheoriginsofHIV,WorobeyaccompaniedHamiltontoCongoonthatlastfatalfieldtrip.TheywentinJanuary2000,duringthechaoticaftermathofacivilwar,whichhadreplacedthelongtimepotentateMobutuSeseSekowiththeupstartLaurentKabilaaspresidentoftheDRC.Hamiltonwantedtocollectfecalandurinesamplesfromwildchimpanzees;thosespecimens,hehoped,mighthelpconfirmorrefutetheOPVtheory.Worobey,forhispart,putlittlestockintheOPVtheorybutwantedmoredatafromwhichtocharttheoriginandevolutionofHIV.ItwasacrazytimeintheDemocraticRepublicoftheCongo,morecrazythanusual,becausetworebelarmiesopposedtoLaurentKabilastillcontrolledmuchoftheeasternhalfofthecountry.HamiltonandWorobeyflewintoKisangani(formerlyStanleyville),aregionalcapitalalongtheupperCongoRiver,thesamecitywhereKoprowskihadbegunhisCongoenterprise.NowitwasoccupiedbyRwanda-backedforcesononeriverbankandUganda-backedforcesontheother.Commercialairlinesweren’tflying,becauseofthewar,sothetwobiologistssharedasmall,charteredplanewithadiamonddealer.InKisanganitheypaidtheirrespectstotheRwanda-backedcommander,whoseambitincludedmostofthecity,andasquicklyaspossiblegotoutintotheforest,wheretheywouldbesaferamongtheleopardsandsnakes.Theyspentamonthcollectingfecalandurinesamplesfromwildchimpanzees,withhelpfromlocalguides,andbythetimetheyleft,Hamiltonwassick.

NeitherhenorWorobeyknewhowsick,buttheycaughtthenextexitflighttheycould,whichtookthemtoRwanda.FromtheretheybouncedtoEntebbeinUganda,whereHamiltongotaconfirmeddiagnosisoffalciparummalariaandsometreatment,thenonwardtoNairobi,andfromNairobiuptoLondonHeathrow.BynowHamiltonseemedpasttheworstofhisillness;hewasfeelingmuchbetter.Theyhadaccomplishedtheirmissionandlifewasgood.AnAmericanfieldbiologistonceexpressedtomehowhefeltinsuchmoments.“That’sthenameofthegame:gettinghomewiththedata.”Thisman’sresearchtooinvolveddangers—shipwreck,starvation,drowning,snakebite,thoughnotmalariaandKalashnikovrifles.“Ifyoutaketoomanyrisks,youdon’tgethome,”hesaid.“Ifyoutaketoofew,youdon’tgetthedata.”HamiltonandWorobeygotthedata,gothome,thenlearnedthattheicecoolercontainingtheirpreciouschimpspecimenshadgoneastrayinluggagehandlingsomewherebetweenNairobiandLondon.

IvisitedMichaelWorobeyinTucsontohearaboutallthis.“Everythingwasfine,”hetoldme,“exceptwecheckedsixbags,includingthecoolerthathadsamples,andfiveofourbagscamethroughthecarouselandtheonewiththesamplesdisappeared.”HisfriendHamilton,feelingillagainthenextmorning,wenttoahospital—andhemorrhageddisastrously,perhapsduetoanti-inflammatorydrugshe’dbeentakingagainstthemalarialfever.WorobeyphonedandgotthenewsfromHamilton’ssister:WhoareyouwhyareyoucallingBillisinextremis.Worobeymeanwhilehadbeenhasslingbylong-distancephonewithaluggagehandlerinNairobi,whoassuredhimthatthecoolerhadbeenfoundandwouldarriveonthenextflight.Whatarrivedwassomeoneelse’scooler—fullofsandwichesorsomesuch,asherecalled.“SothatwasanextrabitofdramathatunfoldedasBillwasdyinginthehospital,”Worobeytoldme.ThecorrectcoolerarrivedtwodayslaterbutHamiltonwasinnoshapetocelebrate.Hewentthroughaseriesofsurgeriesandtransfusionsandthen,afterweeksofstruggle,hedied.

ThefecalsamplesfromCongolesechimps,forwhichHamiltonhadgivenhislife,yieldednoSIV-positives.Acoupleofurinesamplesregisteredintheborderlinezoneforantibodies.Thoseresultsweren’tclearordramaticenoughtomeritpublication.Gooddataarewhereyoufindthem,notalwayswhereyoulook.Severalyearslater,whenthehumanpathologysamplesfromKinshasareachedTucson—those813littleblocksoftissueinparaffin,theonesJ.J.MuyembehadcarriedtoBelgiuminasuitcase—MichaelWorobeywasready.HefoundDRC60amongthem,andittoldanunexpectedstory.

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Screeningparaffin-embeddedhunksofoldorgansamplestofindviralRNAisn’teasy,notevenforanexpert.Thoselittleblocks,Worobeysaid,turnedouttobe“someofthenastiestkindsoftissuestodomolecularbiologywith.”Theproblemwasn’tforty-threeyearsatroomtemperatureinadustyequatorialpantry.Theproblemwasthechemicalsusedinfixingthetissues—the1960equivalentofthebeakersofmethanolandxylolthatProfessorKabongohadshownme.Backinthosedays,pathologistsfavoredsomethingcalledBouin’sfixative,apotentlittlemixturecontainingmostlyformalinandpicricacid.Itworkedwellforpreservingthecellularstructureoftissues,likesalmoninaspic,sothatsamplescouldbeslicedthinandexaminedunderamicroscope;butitwashellonthelongmoleculesoflife.IttendedtobreakupDNAandRNAintotinyfragments,Worobeyexplained,andformnewchemicalbonds,leaving“sortofabig,tangledmessratherthananicestringofbeadsthatyoucandomolecularbiologyon.”Becausetheprocesswassolaborious,hescreenedjust27ofthe813tissueblocksfromKinshasa.Amongthosetwenty-seven,hefoundonecontainingRNAfragmentsthatunmistakablysignaledHIV-1.Worobeypersistedadeptly,untanglingthemessandfittingthefragmentstoassemblethesequenceofnucleotidebaseshenamedDRC60.

Thatwasthewetwork.Thedrywork,donelargelybycomputer,entailedbase-by-basecomparisonsbetweenDRC60andZR59.Italsoinvolvedbroadercomparisons,placingthosetwowithinafamilytreeofknownsequencesofHIV-1groupM.Thepointofsuchcomparisonswastoseehowmuchevolutionarydivergencehadoccurred.Howfaraparthadthesestrainsofvirusgrown?Evolutionarydivergenceaccumulatesbymutationatthebase-by-baselevel(otherwaystoo,butthosearen’trelevanthere),andamongRNAvirusessuchasHIV,themutationrateisrelativelyfast.Equallyimportant,theaveragerateofHIV-1mutationisknown—oranyway,itcanbecarefullyestimatedfromthestudyofmanystrains.Thatrateofmutationisconsideredthe“molecularclock”forthevirus.Everyvirushasitsownrate,andthereforeitsownclockmeasuringtheticktockofchange.Theamountofdifferencebetweentwoviralstrainscanthereforerevealhowmuchtimehaspassedsincetheydivergedfromacommonancestor.Degreeofdifferencefactoredagainstclockequalselapsedtime.ThisishowmolecularbiologistscalculateanimportantparametertheycallTMRCA:timetomostrecentcommonancestor.

Okaysofar?You’redoinggreat.Takeabreath.Nowthosebitsofunderstandingwillboostusacrossadeepgulfofmoleculararcanatoanimportantscientificinsight.Herewego.

MichaelWorobeyfoundthatDRC60andZR59,sampledfrompeopleinKinshasaduringalmostthesameyear,wereverydifferent.TheybothfellwithintherangeofwhatwasunmistakablyHIV-1groupM;neithercouldbeconfusedwithgroupNorgroupO,norwiththechimpvirus,SIVcpz.ButwithinM,theyhaddivergedfar.Howfar?Well,onesectionofgenomedifferedby12percentbetweenthetwoversions.Andhowdifferentwasthat,measuredintime?Aboutfiftyyears’worth,Worobeyfigured.Moreprecisely,heplacedthemostrecentcommonancestorofDRC60andZR59intheyear

1908,giveortakeamarginoferror.

Spilloverbackin1908?That’smuchearlierthananyonesuspected,andthereforethesortofdiscoverythatgetsintoanaugustjournalsuchasNature.Publishingin2008,acenturyafterthefact,withalistofcoauthorsthatincludedJ.J.MuyembeandJean-MarieKabongo,Worobeywrote:

Ourestimationofdivergencetimes,withanevolutionarytimescalespanningseveraldecades,togetherwiththeextensivegeneticdistancebetweenDRC60andZR59indicatethatthesevirusesevolvedfromacommonancestorcirculatingintheAfricanpopulationnearthebeginningofthetwentiethcentury.

Tomehesaid:“Thiswasn’tanewvirusinhumans.”

Worobey’sworkdirectlyrefutedtheOPVhypothesis.IfHIV-1existedinhumansasearlyas1908,thenobviouslyithadn’tbeenintroducedviavaccinetrialsbeginningin1958.Clarityonthatpointwasvaluable—butonlyasidebenefitofWorobey’scontribution.Evenmoreimportantwasthebasicfactofhisearlydate.Placingthecrucialspilloverintime,solongago,representedabigsteptowardunderstandinghowtheAIDSpandemicmayhavestartedandgrown.

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Placingthespilloverinspacewasequallyimportant,andachievedbyadifferentlaboratory.BeatriceHahnissomewhatolderthanWorobeyandhadbegunherworkontheoriginofAIDSlongbeforehefoundDRC60.

BorninGermany,HahntookamedicaldegreeinMunich,thencametotheUnitedStatesin1982andspentthreeyearsasapostdocinRobertGallo’slab,studyingretroviruses.ShemovednexttotheUniversityofAlabamaatBirmingham,whereshebecameProfessorofMedicineandMicrobiologyandcodirectorofacenterforAIDSresearch,withagroupofbrightpostdocsandgradstudentsworkingunderheraegis.(SheremainedatAlabamafrom1985to2011,aperiodencompassingmostoftheworkdescribedhere,andthenjoinedthePerelmanSchoolofMedicineattheUniversityofPennsylvania,inPhiladelphia.)ThebroaderpurposeofHahn’svariousprojects,andthegoalsheshareswithWorobey,istounderstandtheevolutionaryhistoryofHIVanditsrelativesandantecedents.ThefittestlabelforthatsortofresearchistheoneWorobeymentionedwhenIaskedhimtodescribehisfield:molecularphylogenetics.AmolecularphylogeneticistscrutinizesthenucleotidesequencesintheDNAorRNAofdifferentorganisms,comparingandcontrasting,forthesamereasonapaleontologistscrutinizesfragmentsofpetrifiedbonefromextinctgiantsaurians—tolearntheshapeoflineagesandthestoryofevolutionarydescent.ButforBeatriceHahnespecially,asamedicaldoctor,there’sanadditionalpurpose:todetecthowthegenesofHIVfunctionincausingdisease,towardtheprospectsofbettertreatment,prevention,andmaybeevenacure.

SomeveryinterestingpapershavecomeoutofHahn’slaboratoryinthepasttwodecades,manyofthempublishedwithajuniorresearcherasfirstauthorandHahninthelableader’sposition,last.Thatwasthecasein1999,whenFengGaoproducedaphylogeneticstudyofSIVcpzanditsrelationshiptoHIV-1.AtthetimetherewereonlythreeknownstrainsofSIVcpz,alldrawnfromcaptivechimps,withGao’spaperaddingafourth.TheworkappearedinNature,highlightedbyacommentarycallingit“themostpersuasiveevidenceyetthatHIV-1cametohumansfromthechimpanzee,Pantroglodytes.”Infact,GaoandhiscolleaguesdidmorethantraceHIV-1tothechimp;theiranalysisofviralstrainslinkedittoindividualsofaparticularsubspeciesknownasthecentralchimpanzee,Pantroglodytestroglodytes,whoseSIVhadspilledovertobecomeHIV-1groupM.ThatsubspecieslivesonlyinwesternCentralAfrica,northoftheCongoRiverandwestoftheOubangui.SotheGaostudyeffectivelyidentifiedboththereservoirhostandalsothegeographicalareafromwhichAIDSmusthavearisen.Itwasahugediscovery,asreflectedintheheadlineofNature’scommentary:FROMPANTOPANDEMIC.FengGaoatthetimewasapostdocinHahn’slab.

ButbecauseGaobasedhisgeneticcomparisons(asMartinePeetershaddoneearlier)onvirusesdrawnfromcaptivechimps,thesoupçonofuncertaintyaboutinfectionamongwildchimpanzeesremained,atleastforafewmoreyears.Then,in2002,MarioL.SantiagotoppedalistofcoauthorsannouncinginSciencetheirdiscoveryofSIVcpzinthe

wild.SantiagowasaPhDstudentofBeatriceHahn’s.

ThemostsignificantaspectofSantiago’swork,forwhichhegothisrichlydeserveddoctorate,wasthatonthewaytowarddetectingSIVinasinglewildchimpanzee(justoneanimalamongfifty-eighttested),heinventedmethodsbywhichsuchdetectionscouldbemade.Themethodswere“noninvasive,”meaningthataresearcherdidn’tneedtocaptureachimpanddrawitsblood.Theresearcherneededonlytofollowanimalsthroughtheforest,getunderthemwhentheypissed(or,betterstill,sendafieldassistantintothatyellowshower),collectsamplesinlittletubes,andthenscreenthesamplesforantibodies.Turnsoutthaturinecouldbealmostastellingasblood.

“Thatwasabreakthrough,”Hahntoldme,duringatalkatherlabinBirmingham.“Weweren’tsureitwouldwork.”ButSantiagotooktherisk,cookedupthetechniques,anditdidwork.TheveryfirstsampleofSIV-positiveurinefromawildchimpanzeecamefromtheworld’smostfamouscommunityofchimps:theonesatGombeNationalPark,inTanzania,whereJaneGoodallhaddoneherhistoricfieldstudy,beginningbackin1960.Thattraceofvirusdidn’tmatchquiteascloselywithHIV-1asFengGao’shaddone,anditcamefromachimpofadifferentsubspecies,theeasternchimpanzee,Pantroglodytesschweinfurthii.ButitwasSIVcpznonetheless.

TheadvantageofsamplingatGombe,Hahntoldme,wasthatthosechimpsdidn’trunaway.Theyweretrulywildbut,afterfourdecadesofstudybyGoodallandhersuccessors,wellhabituatedtohumanpresence.Foruseelsewhere,theurine-screeningmethodwasn’tpractical.“Because,youknow,non-habituatedchimpsdon’tstaycloseenoughsoyoucancatchtheirpee.”Youcouldcollecttheirpoopfromtheforestfloor,ofcourse,butfecalsampleswereuselessunlesspreservedsomehow;freshfecescontainanabundanceofproteases,digestiveenzymes,whichwoulddestroytheevidenceofviralpresencelongbeforeyougottoyourlaboratory.Thesearetheconstraintswithinwhichamolecularbiologiststudyingwildanimalslabors:therelativeavailabilityandotherparametersofblood,shit,andpiss.

AnotherofHahn’syoungwizards,BrandonF.Keele,soonsolvedtheproblemoffecalsampledecay.HediditbytinkeringwithaliquidstabilizercalledRNAlater,acommercialproductmadebyacompanyinAustin,Texas,forpreservingnucleicacidsintissuesamples.ThenicethingaboutRNAlateristhatitsnameissoliterallydescriptive:ThestuffallowsyoutoretrieveRNAfromasample…later.IfitworkedwithRNAintissues,Keelereasoned,maybeitcouldworkalsowithantibodiesinfeces.Andindeeditdid,afterheandhiscolleaguesuntangledthechemicalcomplicationsofgettingthoseantibodiesreleasedfromthefixative.Thistechniquevastlyenlargedthescopeofscreeningthatwaspossibleonwildchimpanzees.Fieldassistantscouldcollecthundredsoffecalsamples,scoopingeachintoalittletubeofRNAlater,andthosesamples—storedwithoutrefrigeration,transportedtoadistantlaboratory—wouldyieldtheirsecretslater.“Ifwefindtheantibodies,weknowthatchimpsareinfected,”Hahntoldme.“Andthenwecanhomeinonthoseweknowareinfected,andtrytogetthevirusesout.”Antibodyscreeningiseasyandquick.PerformingPCRamplificationandtheotherrequisitestepstoprobeforfragmentsofviralRNAisfarmorelaborious.ThenewmethodsallowedHahn

andhergrouptolookfirstatalargenumberofspecimensandthenworkmoreconcertedlyonaselectfew.TheycouldseparatetheShinolafromtheshit.

AndtheycouldexpandtheirfieldsurveyingbeyondGombe.TheycouldturntheirattentionbacktoPantroglodytestroglodytes,thesubspeciesofchimpwhoseSIVcpzmostcloselymatchedHIV-1.WorkingnowwithMartinePeetersofMontpellier,plussomecontactsinAfrica,theycollected446samplesofchimpanzeedungfromvariousforestsitesinthesouthandsoutheastofCameroon,afterwhichBrandonKeeleledthelaboratoryanalysis.DNAtestingshowedthatalmostallthesamplescamefromP.t.troglodytes(thoughacoupledozenderivedfromadifferentchimpsubspecies,P.t.vellerosus,whoserangelayjustnorthofamajorriver).Keelethenlookedforevidenceofvirus.Thesamplesyieldedtwosurprisingresults.

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Tohearaboutthosesurprises,IvisitedBrandonKeele,whobythistimehadfinishedhispostdocwithHahnandgoneofftoaresearchpositionatabranchoftheNationalCancerInstitute,inFrederick,Maryland.HewasstillstudyingviralphylogeneticsandAIDS,asheadofaunitdevotedtoviralevolution.HisnewofficeandlabwereonthegroundsofFortDetrick,ahigh-securityinstallationthatoncehousedtheU.S.biologicalweaponsprogramandstillencompassesUSAMRIID,thebigarmyresearchinstituteoninfectiousdiseases.SinceIwasenteringwithoutanescort,soldiersattheguardhousesearchedtheundersideofmyrentalcarforabombbeforelettingmepass.Keele,waitingtoflagmedownoutsidethedoorofhisbuilding,woreabluedressshirt,jeans,hisblackhairmoussedback,andatwo-daystubble.Heisatallyoungman,extremelypolite,raisedandeducatedinUtah.WesatinhissmallofficeandlookedatamapofCameroon.

ThefirstsurprisetoemergefromthefecalsampleswashighprevalenceofSIVcpzinsomecommunitiesofCameroonianchimps.Twothatscoredhighest,Keelesaid,wereatsiteslabeledMambele(nearacrossroadsbythatname)andLobeke(withinanationalpark).WhereasallothersamplingofchimpshadsuggestedthatSIVinfectionwasrare,thesamplinginsoutheasternCameroonshowedprevalenceratesupto35percent.Buteventhere,theprevalencewas“spotty,”Keelesaid.“Wecansamplehundredsofchimpsatasiteandfindnothing.”Butgojustalittlefarthereast,crossacertainriver,sampleagain,andtheprevalencespikesupward.Thatwasunexpected.Therateswereespeciallyhighinthefarthestsoutheasterncornerofthecountry,wheretworiversconverge,formingawedge-shapednationalboundary.ThiswedgeofCameroonappearstojabdownintotheRepublicoftheCongo(nottobeconfusedwiththeDRC),itsneighbortothesoutheast.ThewedgewasahotspotforSIVcpz.

Thesecondsurprisecameonceheextractedviralfragmentsfromthesamples,amplifiedthosefragments,sequencedthem,andfedthegeneticsequencesintoaprogramthatwouldcomparethesenewstrainswithmanyotherknownstrainsofSIVandHIV.Theprogramexpresseditscomparisonsintheformofamost-probablephylogeny—afamilytree.Keelerecalledwatchingtheresultsforacertainchimp,anindividuallabeledLB7,whosefeceshadbeencollectedatLobeke.“Wewerejustshocked,”hesaid.“Imean,Ihadtenpeoplearoundmycomputer,allwaitingtoseewhatthatsequencelookedlike.”WhatitlookedlikewastheAIDSvirus.

Whenhiscomputerdelivereditslatesttree,LB7’sisolateofSIVcpzshowedupasatwigamidthesamelittlebranchthatheldallknownhumanstrainsofHIV-1groupM.(Inscientificlingo,itfellwithinthesameclade.)Itwasatthatpoint“theclosestthing”toamatch,Keeletoldme,thathadeverbeenfoundinawildchimp.“Andthenwefindmore,right?Themorewedig,themorewefind.”Theotherclosematchescamefromthatsamelittlearea:southeasternCameroon.Achilling,historicepiphany,atwhichKeeleandhiscolleagueswerethrilled.“Youcan’tmakethisstuffup,asBeatricewouldsay.It’stoogood.”Theirjoylastedabouttenseconds,afterwhicheveryonebecamehungryformore

samplesandmoreresults.Yourcelebrationisalwaysprovisional,Keeletoldme,untilyou’vewrittenthepaperandgottenthatcongratulatorynoteofacceptancefromtheeditorsofScience.

Keeleandthegroupnowsequencedentiregenomes(notjustfragments)fromfoursamples,allcollectedinthesamearea,andonthosesequencesrantheirgeneticanalysesagain.AgaintheyfoundthenewSIVcpzshockinglysimilartoHIV-1groupM.Thesimilaritywassocloseastoleavealmostnochancethatanyothervariant,yetundiscovered,couldbemuchcloser.Hahn’slabhadlocatedthegeographicaloriginofthepandemic:southeasternCameroon.

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Somuchforwhereaswellaswhen.AIDSbeganwithaspilloverfromonechimptoonehuman,inornearthatsmallsoutheasternwedgeofCameroon,around1908(giveortakeamarginoferror).Fromthereitgrew,slowlybutinexorably,fromaspillovertoanoutbreaktoapandemic.Thatleavesourthirdquestion:how?

TheKeelepaperappearedinScience,onJuly28,2006,underthetitle“ChimpanzeeReservoirsofPandemicandNonpandemicHIV-1.”InadditiontoBrandonKeeleasfirstauthor,therewastheusuallistofcoauthors,includingMarioSantiago,MartinePeeters,severalpartnersfromCameroon,andlastagain,BeatriceH.Hahn.Thedatawerefascinating,theconclusionswerejudicious,thelanguagewascarefulandtight.Neartheend,though,theauthorsletsuppositionfly:

WeshowherethattheSIVcpzPttstrainthatgaverisetoHIV-1groupMbelongedtoavirallineagethatpersiststodayinP.t.troglodytesapesinsoutheasternCameroon.Thatviruswasprobablytransmittedlocally.FromthereitappearstohavemadeitswayviatheSanghaRiver(orothertributaries)southtotheCongoRiverandontoKinshasawherethegroupMpandemicwasprobablyspawned.

Butthephrase“transmittedlocally”wasopaque.Whatmechanism,whatcircumstances?Howdidthosecrucialeventsoccurandproceed?

Hahnherself,alongwiththreecoauthors,hadaddressedthatbackin2000,whenshefirstarguedtheideathatAIDSisazoonosis:“Inhumans,directexposuretoanimalbloodandsecretionsasaresultofhunting,butchering,orotheractivities(suchasconsumptionofuncookedcontaminatedmeat)providesaplausibleexplanationforthetransmission.”Shewasalludingtothecut-hunterhypothesis.Morerecentlysheaddresseditagain:“Thelikeliestrouteofchimpanzee-to-humantransmissionwouldhavebeenthroughexposuretoinfectedbloodandbodyfluidsduringthebutcheryofbushmeat.”Amankillsachimpanzeeanddressesitout,hacksitup,inthecourseofwhichhesuffersblood-to-bloodcontactthroughacutonhishand.SIVcpzpassesacrossthespeciesboundary,fromchimptohuman,andtakingholdinthenewhostbecomesHIV.Thiseventisunknowableinitsparticularsbutit’splausible,anditfitstheestablishedfacts.Somevariantofthecut-hunterscenario,occurringinaforestofsoutheasternCameroonaround1908,wouldaccountnotjustforKeele’sdatabutalsoforMichaelWorobey’stimeline.Butthenwhat?OnemaninsoutheasternCameroonisinfected.

“Ifthespilloveroccurredthere,”IaskedHahn,“howwasitthattheepidemicbeganinKinshasa?”

“Well,therearelotsofriversgoingdownfromthatregiontoKinshasa,”shesaid.“Andthespeculation,thehypothesis,isthatishowthevirustraveled—inpeople,notinapes.Itwasn’ttheapesthatgotintothecanoeforalittlevisitofKinshasa.Itwasthepeoplewhocarriedthevirusdown,mostlikely.”Sure,sheacknowledged,therewasaslimchancethatsomeonemighthavebroughtalivechimp,captive,infected,allthewaydownfromtheCameroonianwedge—“butIthinkitishighlyunlikely.”Morelikelythevirustraveledinhumans.

Sexualcontactsinthevillageskeptthechainofinfectionalive,thoughbarely,bythislineofspeculation,andthediseasedidn’texplodeasanotableoutbreak—notforalongwhile.Whensomeonediedofimmunodeficiency,thedeathmayhaveseemedunremarkableamidallothersourcesofmortality.Lifewashard,lifewasperilous,lifeexpectancywasshortevenapartfromthenewdisease,andmanyofthoseearliestHIV-positivepeoplemayhavesuccumbedtoothercausesbeforetheirimmunesystemsfailed.Therewasnoepidemic.Butthechainofinfectionsustaineditself.EachHIV-positivepersoninfected,onaverage,atleastoneotherperson.Thevirusseemstohavetraveledjustaspeopletraveledinthosedays:mainlybyriver.ItmadeitswayoutofsoutheasternCameroonalongtheheadwatersoftheSanghaRiver,thendowntheSanghatotheCongo,thendowntheCongotoBrazzavilleandLéopoldville,thetwocolonialtownsoneithersideofahugebroadeningoftheriver,whichwasthenknownastheStanleyPool.“Onceitgotintoanurbanpopulation,”Hahnsaid,“ithadanopportunitytospread.”

Butstillitmovedslowly,likealocomotivejustleavingthestation.Léopoldvillecontainedfewerthantenthousandpeoplein1908,andBrazzavillewasevensmaller.Sexualmoresandthefluidityofinteractionswereunlikewhatprevailedintheboondocks,butnotyetsounlikeastheywouldbecome.Thearithmeticoftheoutbreakwasstillmodest,withscarcelymorethanasingletransmissiononwardperinfectedperson.Inthelanguageofdiseaseecologists:thebasicreproductionrate(theaveragenumberofsecondaryinfectionsfromeachprimaryinfectionatthebeginning)barelyexceeded1.0,theminimallevelrequiredfortheoutbreaktocontinueindefinitely.Then,astimepassed,morepeopledriftedintothetowns,drawnbytheprospectofworkingforwagesorsellingtheirgoods.Habitsandopportunitieschanged.Womencameaswellasmen,thoughnotsomanyofthem,andamongthosewhodid,morethanafewenteredthesextrade.

By1914,Brazzavillecontainedaboutsixthousandpeopleandwas“ahardmissionfield,”accordingtooneSwedishmissionary,where“hundredsofwomenfromupperCongoareprofessionalprostitutes.”ItwasthecapitalofthecolonythenknownasFrenchEquatorialAfrica.ThemalepopulationincludedFrenchcivilservantswithinthecolonialadministration,soldiers,traders,andlaborers,andtheyprobablyoutnumberedfemalesbyasizablemargin,duetocolonialpoliciesthatdiscouragedmarriedmen,comingtheretowork,frombringingtheirfamilies.Thatgenderimbalanceheightenedthedemandforcommercialsex.Buttheformatforboughtfavors,inthoseearlyyears,wasgenerallydifferentfromwhattheword“prostitute”mightsuggest—grindinglyefficient,wham-bamencounterswithalongsuccessionofstrangers.Insteadthereweresinglewomen,knownasndumbasinLingalaandfemmeslibresinFrench,“freewomen”asdistinctfromwivesordaughters,whowouldprovidetheirclientswithasuiteofservices,rangingfromconversationtosextowashingclothesandcooking.Onesuchndumbamighthavejusttwoorthreemalefriendswhoreturnedonaregularbasisandkepthersolvent.Anothervariantwastheménagère,a“housekeeper”wholivedwithawhitecolonialofficialanddidmorethankeephouse.Commercialarrangements,yes,butthesedidn’trepresentthesortofprodigiouslyinterconnectedpromiscuitythatcouldcauseasexuallytransmittedvirustospreadwidely.

AcrossthepoolinLéopoldville,meanwhile,thedisparityofgenderswasevenworse.

Thistownwasessentiallyalaborcamp,controlledbyitsBelgianadministrators,inhospitabletofamilies,wherethemale-femaleratioin1910wastentoone.TravelthroughthecountrysideandentryintoLéopoldvillewererestricted,especiallyforadultfemales,thoughsomewomenmanagedtogetfalsedocumentsorevadethepolice.Ifyouwerearestless,imaginativegirlinoneofthevillages,poorlyfedandpoorlytreated,tobeandumbainLéopoldvillecouldwellhaveseemedenticing.Heretoo,though,evenwithtenhornymenforeachwoman,commercialsexdidn’thappeninbrothelsorbystreetwalking.Freewomenhadtheirspecialfriends,theirclients,maybeseveralcontemporaneously,buttherewasnodizzyingpermutationofmultiplesexualcontacts,notyet.Oneexperthascalledthis“alow-risktypeofprostitution,”withregardtotheprospectsofHIVtransmission.

Léopoldvillealsosupportedalivelymarketinsmokedfish.Ivory,rubber,andslavesweretradedthere,forexport,withprofitsgoingmainlytowhiteconcessionaires,wellintothecolonialera.AlthoughadeepcanyonandasetofforbiddingcataractsstoodbetweentheStanleyPoolandtheriver’smouth,isolatingbothcitiesfromtheAtlanticOcean,aportagerailwaybuiltin1898hadbreachedthatisolation,bringingmoregoodsandcommerce,whichbroughtmorepeople,andin1920LéopoldvillereplacedadownrivertownascapitaloftheBelgianCongo.By1940,itspopulationhadedgeduptoforty-ninethousand.Thenthedemographiccurvesteepened.Between1940andindependence,whichcamein1960,thecitygrewbyalmostanorderofmagnitude,toaboutfourhundredthousandpeople.LéopoldvillebecameKinshasa,atwentieth-centuryAfricanmetropolis,wherelifewasverydifferentfromwhatpassedinaCameroonianvillage.Thetenfoldpopulationincrease,alongwiththeconcomitantchangesinsocialrelations,mightgoalongwaytoexplainwhyHIV“suddenly”tookoff.By1959,theZR59carrierwasinfected,andayearlaterinthesamecitythecarrierofDRC60too.Bythattimethevirushadproliferatedtosuchadegree,mutatinganddiversifying,thatDRC60andZR59representedquitedifferentstrains.Thebasicreproductionratenowmusthavewellexceeded1.0,andthenewdiseasespread—throughthetwocitiesandeventuallybeyond.“Youknow,”Hahnsaid,“aviruswasattherightplaceattherighttime.”

WhenIreadKeele’spresentationofthechimpdataandtheanalysis,inearly2007,myjawdroppedlikeapoundofham.ThesefolkshadlocatedGroundZero,ifnotPatientZero.AndwhenIlookedatthemap—Figure1inKeele’spaper,showingtheCameroonianwedgeanditssurroundings—IsawplacesIknew.AvillagewhereIhadslept,onmywaytoaCongoassignmentforNationalGeographic.AriverIhadascendedinamotorpirogue.Itturnedoutthat,sevenyearsearlier,duringanarduousfootslogexpeditionthroughtheforestsoftheRepublicoftheCongoandGabon,withanAmericanecologistnamedJ.MichaelFay,heandIandhisforestcrewhadpassedverynearthecradleofAIDS.

AftertalkingwithBeatriceHahn,Ithoughtitmightbeilluminatingtogoback.

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DoualaisacityonCameroon’swesterncoast,withaseaportandaninternationalairport.Iescapedit,withmyowncrew,asquicklyaspossible.Werodeeastinabeat-upbutsturdyToyotatruck,leavingatdawn,gettingaheadofthecrush,ourgearstashedundertarpsinthepickup’sbed.MoïseTchuialeuwasmydriver,NevilleMbahmyCameroonianfixer,andMaxMviri,fromtheRepublicoftheCongo,wasalongtohandlethingswhenwereenteredhiscountryinthecourseofthecrazyloopIhadplanned.MaxandIhadflownupfromBrazzavillethenightbefore.Wewereagenialfoursome,eagertomoveafterthehasslesofpreparation,rollingpasttheclosedshopsandthebillboardstothecity’seasternfringe,wheretrafficthickenedinahazeofbluedieselexhaustandtheoutliermarketswerealreadyopenforbusiness,sellingeverythingfrompineapplestophoneminutes.HighwayN3wouldtakeusstraighttoYaoundé,Cameroon’sinlandcapital,andthenanotherbigtwo-laneonwardfromthere.

DuringastopinYaoundé,aroundmidday,ImetwithamannamedOfirDrori,headofanunusualgroupcalledLAGA(theLastGreatApeOrganization)thathelpsgovernmentagenciesinCentralAfricaenforcetheirwildlife-protectionlaws.IwantedtoseeDroribecauseIknewthatLAGAwasespeciallyengagedontheproblemofapes’beingkilledforbushmeat.IfoundhimtobealeanIsraeliexpatwithdark,alerteyesandapatchygoatee.Wearingablackshirt,blackjeans,ablackponytail,andanearring,helookedlikearockmusicianor,atleast,ahipNewYorkwaiter.Butheseemedtobeaseriousfellow.HehadcometoAfricaasanadventure-seekingeighteen-year-old,Droritoldme,andgotteninvolvedwithhuman-rightsworkinNigeria,thenmovedtoCameroon,didalittlegorillajournalism(orwasitguerrillajournalism?),andbecameapassionateantipoachingorganizer.HefoundedLAGA,hesaid,becauseenforcementofCameroon’santipoachinglawshadbeenterrible,nonexistent,foryears.Thegroupnowprovidedtechnicalsupporttoinvestigations,raids,andarrests.Subsistencehuntingforduikersandotherabundant,unprotectedkindsofanimalislegalinCameroon,butapes,elephants,lions,andafewotherspecieswereprotectedbylaw—andincreasinglybyactualenforcement.Perpetratorswerefinallygettingbusted,evendoingtime,fordealinginapefleshandothercontrabandwildlifeproducts.DrorigavemeaLAGAnewsletterdescribingtheeffortstostempoachingofchimpsandgorillas,andhewarnedmeagainstthemyththatapehuntingisaproblembecauselocalpeoplearehungry.Thereality,hesaid,isthatlocalpeopleeatduikersorratsorsquirrelsormonkeys—iftheyeatmeatatall—whereasthefancystuff,theillicitdelicacies,thechimpanzeebodyparts,thegobsofelephantflesh,thehippopotamussteaks,getsiphonedawaybyupscaledemandfromthecities,wherepremiumpricesjustifytherisksofpoachingandillegaltransport.“Whatbringsthemoneyaretheprotectedspecies,”hesaid.“Thingsthatarerare.”

Drori’snewslettermentionedaraidagainstahiddenstorageroom,atatrainstation,thatservedatleastthreedifferentdealers;theroomhadcontainedsixrefrigeratorsanditsseizedcontrabandincludedachimpanzeehand.Anotherbust,againstadealerwhosecarhadheldfiftykilosofmarijuanaplusayoungchimpwithabulletwound,suggested

diversifiedwholesalecommerce.Andifchimpmeattravelstowardmoney,chimpvirusespresumablydotoo.“Ifyou’rethinkingaboutinfection,”hesaid,knowingthatIwas,“don’tjustthinkofvillages.”Anychimpanzeekilledinthesoutheasterncornerofthecountry,includinganSIV-positiveindividual,mighteasilyenduphereinYaoundé,beingsoldformeatinabackalleyorservedthroughaverydiscreetrestaurant.

Weleftthecityinearlyafternoon,headedeastwardagain,movingagainstastreamoflogtruckshammeringtowardusintheoppositelane,eachoneburdenedtocapacitywithaloadofjustfiveorsixgiganticstems.Somewhereoutthere,inthatsparselypopulatedcornerofthecountry,old-growthforestswerebeingsheared.AroundsundownwereachedatowncalledAbongMbangandstoppedatthebestlocalhotel,whichmeantrunningwaterandalightbulb.Earlynextday,anhourbeyondAbongMbang,theblacktopendedthoughthelogtruckskeptcoming,nowonaribbonofredclay.Thetemperatureclimbedtowardmiddayequatorialheatand,whereverweencounteredalittlerainshower,theroadsteamedinred.Elsewherethelandscapewassodrythatpowderyredclaydustroseonthegustsfrompassingvehicles,coatingtreesalongtheroadsidelikebloodyfrost.Wehitapolicecheckpointandenduredaroutinebutannoyingshakedown,whichNevillehandledwithaplomb,makingtwophonecallstoinfluentialcontacts,refusingtopaytheexpectedbribe,andyetsomehowrecoveringourpassportsafteronlyanhour.Thisguyisgood,Ithought.Theroadnarrowedfurther,toabandofarsenicalredbarelywiderthanalogtruck,leavingushuggingtheshoulderwhenweencounteredone,andtheforestthickenedonbothsides.AroundnoonwecrossedtheKadéïRiver,greenishbrownandslow,meanderingsoutheast,areminderthatwewerenowattheheadwatersoftheCongobasin.Thevillagesthroughwhichwepassedbecamesmallerandlookedprogressivelymorespareandpoor,withfewgardens,littlelivestock,almostnothingforsaleexceptbananas,mangoes,orabowlofwhitemaniocchipssetoutforlornlyonanuntendedstand.Occasionallyagoatorachickenscamperedoutofourway.Inadditiontothelogtrucks,wenowmetflatbedsloadedwithmilledlumber,andIrememberedhearinghowsuchtruckssometimescarriedaconcealedstashofbushmeat,rumblingtowardtheblackmarketsofYaoundéandDouala.(AphotographerandactivistnamedKarlAmmanndocumentedthattacticwithaphoto,takenataroadjunctionhereinsoutheasternCameroon,ofadriverunloadingchimpanzeearmsandlegsfromtheenginecompartmentofhislogtruck.ThephotoappearedinabookbyDalePeterson,titledEatingApes,inwhichPetersonestimatedthatthehumanpopulationoftheCongobasinconsumesroughly5millionmetrictonsofbushmeateachyear.Muchofthatwildmeat—thoughnooneknowsjusthowmuch—travelsoutoftheforestascontrabandcargoonlogtrucks.)Apartfromthetrucks,todayonthisstretchofredclay,therewasalmostnotraffic.BylateafternoonwereachedYokadouma,atownofseveralthousand.Thenametranslatesas“FallenElephant,”presumablymarkingthesiteofamemorablekill.

WefoundalocalofficeoftheWorldWildlifeFundand,inside,twoearnestCameroonianemployeesnamedZacharieDongmoandHansonNjiforti.Dongmoshowedmeadigitalmapplottingthedistributionofchimpanzeenestsinthissoutheasterncornerofthecountry,whichincludesthreenationalparks—BoumbaBek,Nki,andLobeke.Achimpanzeenestissimplyasmallplatformofinterwovenbranches,oftenintheforkofa

smallishtree,whichprovidesjustenoughsupportfortheapetosleepcomfortably.Eachindividualmakesoneeachnight,thoughamotherwillshareherswithaninfant.Tallyingsuchnests,whichremainintactforweeksafteraone-nightuse,ishowbiologistsestimatechimpanzeepopulations.ThepatternonDongmo’smapwasclear:ahighdensityofnests(andthereforeofchimpanzees)withintheparks,alowdensityoutsidetheparks,andnoneatallinareasadjacenttotheroadsleadingtoYokadouma.Loggingandbushmeatwerethereasons.Loggingoperationsbringroadsandworkersandfirearmsintothedepthsoftheforest;deadwildlifeconsequentlytravelsout.DongmoandNjifortiexplaineditasaninformal,adhocformofcommerce.“Mostoftheillegaltradeisman-to-man,”Njifortisaid.“Apoachermeetsyouandsays,Ihavemeat.”Butit’salsowoman-to-man,headded:Muchofthetradingisdoneby“Buy’em–Sell’ems,”womenwhotravelbetweenvillagesaspettytraders,dealingopenlyincloth,orspices,orotherstaples,andcovertlyinbushmeat.Suchawomanbuysdirectlyfromthehunter,oftenpayinginbulletsorshotgunshells,andsellstowhomevershecan.Commerceisrelativelyfluid;manyofthesewomenhavecellphones.Andthereareallsortsoftricks,Njifortisaid,forgettingthemeatout.Itcouldbetuckedintoatruckloadofcocoapods,forinstance,acashcropfromthisregion.Thepoliceandthewildlifewardensmaygettippedoff,andtheycanstopatruckandsearchit,butatsomerisktothemselves.Ifyoustopatruckanddemanditbeunloaded,andthenthere’snoillegalcargo,Njifortisaid,“theguycansueyou.Theinformationhastobeverygood.”That’swhyOfirDrori’snetworkhasproveditselfuseful.

Mostofthepoachers,Dongmoadded,areKakos,atribefromthenorthwithastrongaffinityforbushmeat.Manyofthemhavedrifteddownheretothesoutheast,drawnbymaritalconnectionsoropportunityinthebush.ThelocalBakaPygmies,ontheotherhand,havetraditionalstricturesagainsteatingapes,whicharedeemedtooclosetohuman.Infact,Dongmoreckoned,therewasprobablylesseatingofapesdownherethaninsomeothersectorsofthecountry—apartfromthetotemicconsumptionofapepartsbyBakwelepeopleinconnectionwithacertaininitiationceremonyforadolescentboys.AndthatoffhandedcommentfromZacharieDongmowasthefirstI’dheardofaBakweleritualknownasbeka.

WelingeredinYokadoumafortwonightsandaday,longenoughformetowalkthedirtstreets,admiretheconcretestatueofanelephantgracingthetown’scentralroundabout,photographapiteouspangolinabouttobebutcheredformeat,andencounterafellowwhotoldmemoreaboutbeka.Thisman,whosenameIomit,hadwrittenasmallreportonthesubject,whichhisorganizationdeclinedtopublish.Hegavemeacopy.Yes,hesaid,theBakwelepeoplehereinthesoutheastusechimpandgorillameatintheirbekaceremony.Theyespeciallyfavorthearms.Asaresult,hesaid,“chimpsarebecomingmoreandmorescarce.”Soscarcethatgorillaarmsarenowoftenusedasasubstitute.

Hisreportdescribedatypicalbekainitiation,completewithslaughteredsheepandchickens,theneckofatortoise(becauseitresemblesapenis),and“virginlasses”inattendancethroughalongpreludethatculminatesatfourinthemorning.Theboytobeinitiatedisdressedinleavesandgivendrugstokeephimawake.Drumsbeatthroughthenightuntil,beforedawn,theboyisledintoaspecialareaofforest,wherehe’sobligedtoconfronttwochimpanzees.Someofwhatfollowsseemstobesymbolicenactment,some

ofitblood-real.“Agongissounded,”accordingtoaBakwelechiefwhoinformedmysource,“avoicecallsoutfromtheforest,andtwochimpanzeesrespond.Themalechimpanzeecomesoutfirstandtouchestheboy’shead.Thefemalechimpanzeeemergesminutesafterandtheboyisexpectedtokillit.”Atdawntheboybathes,thenstaysawakeuntillateafternoon,pacingandexpectant,atwhichpointthecircumcisercomesathimwithahomemadeknife.“Inursedmywoundfor45daysafter,”oneinitiatesaid.Butnowhewasaman,nolongeraboy.Theunpublishedreportadded:

Untilrecently,theBakweleshavebeenusingchimpsforthisritual.Theyclaimtwochimpscouldbeusedforcircumcisionofasmanyas36people.Theyamputatethearmsofthechimps.Thispartoftheanimaliseatenbyeldersofthevillage.Oflate,however,duetothescarcityofchimps,Bakwelesgoforgorillas.

Eightgorillaarmshadrecentlybeenseizedfromapoacherwhofledwhenconfrontedbygamerangers,leavingthemeatbehindinabag.Thearmswereintendedforanimpendingbeka.“Wecannotdowithouttheseanimals,”theBakwelechiefcomplained,“ifwemustperformthisimportanttraditionalrite.”

It’snocondescensionagainstBakweleculturetonotethatbutcheringchimpanzeestoeattheirarmsaspartofanancientandbloodyritualcouldbeaverygoodwaytoacquireSIVcpz.Thenagain,inalandscapeasleanandsevereassoutheasternCameroonin1908,bekamighthavebeensuperfluous.Sheerhungercouldaccountfortheoriginalspilloverjustaswell.

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Thirtymilesfarthersouth,atacrossroadsknownasMambeleJunction,withacentralroundaboutdefinedbythreetrucktirespileduplikecoins,wedinedbykerosenelanternatasmallcantina,eatingsmokedfish(atleast,Ihopeditwassmokedfish)inpeanutsauceanddrinkingwarmMuntzigbeer.ThishappenedtobetheplacewhereKarlAmmannsawchimpanzeearmsstashedunderthehoodofalogtruck.ItwasalsooneofthelocationsfeaturedinBrandonKeele’spaperonthechimpanzeeoriginsofHIV-1.Chimpfecalsamplesfromhereaboutshadshownhighprevalenceofthevirusinitsmostfatefulform.SomewhereverynearbywasGroundZerooftheAIDSpandemic.

Afterdinner,mycompadresandIsteppedbackoutsideandadmiredthesky.AlthoughthiswasSaturdaynight,thelightsofMambeleJunctiondidn’tamounttomuchanddespitetheirdimglowwecouldseenotjusttheBigDipper,Orion’sBelt,andtheSouthernCrossbuteventheMilkyWay,arcingoverheadlikeagreatsmearofglitter.Youknowyou’reintheboonieswhenthegalaxyitselfisvisibledowntown.

Twodayslater,atamodestbuildingnearbythatservedasheadquartersforLobekeNationalPark,Imetwiththepark’sconservateur,itsdirector,ahandsomelybaldmannamedAlbertMunga,dressedinafloralshirtand(unmatched)floralpants.Hesataloofathisdeskforseveralminutes,shufflingpapers,beforedeigningtonoticeme,andthenforawhilelongerheseemedcooltomyquestionsaboutchimpanzees.Theofficewasheavilyair-conditioned;everythingaboutitwascool.ButafterhalfanhourMr.Mungawarmed,loosened,andbegantosharesomeofhisdataandhisconcerns.Thepark’spopulationofgreatapes(chimpsandgorillascombined)hadfallenabruptlysince2002,hetoldme:fromaboutsixty-threehundredanimalstoabouttwenty-sevenhundred.Commercialpoachersweretheproblem,andbyhisaccounttheycamemainlyacrosstheeasternboundaryofthepark,theSanghaRiver,whichhappensalsotobethesoutheasternborderofCameroon.BeyondtheSanghalietheCentralAfricanRepublicand,slightlyfarthersouth,theRepublicoftheCongo,twocountriesthathaveknowninsurgencyandwarinthelastcoupledecades.Thosepoliticalconflictshavebroughtmilitaryweapons(especiallyKalashnikovrifles)intotheregion,vastlyincreasingthedifficultyofprotectinganimals.Bandsofwell-armedpoacherscomeacrosstheriver,mowdownelephantsandanythingelsetheysee,whackouttheivoryandtheelephantmeat,lopofftheheadsandlimbsoftheapes,takethesmallercreatureswhole,andescapebackacrossthewater.Orelsetheymovetheirbootydownriverbyboat.“ThereisahugebushmeattrafficontheSangha,”Mungatoldme,“andthedestinationisOuesso.”ThetownofOuesso,ariverportofsometwenty-eightthousandpeople,justovertheborderinCongo,isamajortradingnexusontheupperSangha.Bynocoincidence,itwasmydestinationtoo.

JustoutsideMr.Munga’soffice,IpausedinthecorridortolookatawallposterwithluridillustrationsandawarninginFrench:LADIARRHEAROUGETUE!Reddiarrheakills.AtfirstglanceIthoughtthatreferredtoEbolavirusdisease,anothergruesomeafflictionfacedbyCentralAfricanvillagers;butno.“GrandsSingesetVIH/SIDA,”read

thefinerprint.VIHistheFrenchequivalentofHIV,andSIDAlikewiseisAIDS.Thecartoonishbutunfunnydrawingsdepictedastarkparableabouttheconnectionbetweensimianbushmeatanddeath.Ilingeredlongenoughfortheoddnesstostrikeme.ThroughouttherestoftheworldyouseeAIDS-educationmaterialscryingout:Practicesafesex!Wearacondom!Don’tshareneedles!Herethemessagewas:Don’teatapes!

Wedroveonward,alongadirttrackbetweenwallsofgreen,stillfartherintoCameroon’ssoutheasternwedge.Thecountry’ssouthernborderouthereisformedbytheNgokoRiver,atributaryflowingeasttoitsjunctionwiththeSangha.TheNgoko,accordingtolocallore,isoneofthedeepestriversinAfrica,butifsotheremustbeasteepwrinkleofrockunderneath,becauseit’sonlyabouteightyyardswide.WereacheditaroundmiddayatatowncalledMoloundou,ascruffyplacespreadoversmallhillsabovetheriver.FromanygoodpointofvantageinMoloundou,theRepublicoftheCongowaseasilyvisibleacrossthewater—closeenoughthat,inthequietofevening,wecouldhearthechainsawsofillegalloggersatworkinthedarknessoverthere.Theselogpoacherswouldfelltreesdirectlyintothewaterandtanglethemintorafts,Iwastold,thenfloattheraftsdowntoOuesso,whereamilloperatorwouldpaycash,noquestionsasked.Ouessoagain:theoutlawentrepôt.Therewasnogovernmentpresence,nolaw,notimberconcessionairesdefendingtheirinterests,onthatside—sosaidscuttlebuttonthisside,anyway.Wehadreachedthefrontierzone,whichwasstillabitwildandwoolly.

Earlynextmorningwewalkeduptothemarketandwatchedsellerssettingouttheirgoodsinneatpilesandrows:localpeanutsandpumpkinseedsandredpalmnuts,garlicandonions,manioctubers,plantains,giantsnailsandsmoke-blackenedfish,hocksofmeat.Ihungbackdiscreetlyfromthemeatcounters,leavingNevilleandMaxtoinvestigatewhatwasavailable.Mostlyitwassmokedduiker,aformofsmallforestantelopethatservedasastaplewildfood;nosignofapemeatbeingsoldaboveboard;andevenpangolin,asellertoldNeville,wasoutofseason.Ihadn’texpecteddifferent.Anythingsovaluableasachimpanzeecarcasswouldchangehandsinprivate,probablybypriorarrangement,andnotbeslabbedoutatapublicmarket.

DownstreamfromMoloundou,thelastCameroonianoutpostontheNgokoRiverisKika,aloggingtownwithabigmillthatprovidesjobsandlodgingforhundredsofmenandtheirfamilies,plusadirtairstripfortheconvenienceofitsmanagerialelite.Therewasnodirectriversideroad(whywouldtherebe?theriverisaroad)sowecircledbackinlandtogetthere.ArrivinginKika,wereportedpromptlytothepolicestation,asmallshackneartheriverthatservedalsoasimmigrationpost,whereanofficernamedEkemeJustinrousedhimself,pulledonhisyellowT-shirt,andperformedthenecessaryformalitiesforMaxandme:stampingourpassportssortiedeCameroon.Wewouldexitthecountryhere.OfficerJustin,uponreceiptofafeeforhisstampwork,becameourgreatfriendandhost,offeringustentspacetherebesidethepolicepostandhelpinfindingaboat.HewentofftotownwithNeville,theall-purposefixer,andbysunsettheyhadarrangedcharterofathirty-footwoodenpirogue,withanoutboard,capableofgettingMaxandmeacrosstheriverborderanddowntoOuesso.

Iwasupat5:10thenextmorning,packingmytent,eagertoturnthecorneronthisbig

loopandheadbackintoCongo.Thenwewaitedthroughaheavymorningrain.Finallycameourboatman,alanguidyoungmannamedSylvaininagreentracksuitandflip-flops,tomounthisoutboardandbailthepirogue.Weloaded,coveredourgearwithatarpagainstthelingeringdrizzle,andafterwarmgood-byestothefaithfulNevilleandMoïse,alsoOfficerJustin,welaunched,catchingastrongcurrentontheNgoko.Wepointedourselvesdownriver.Forme,ofcourse,thisjourneywasallaboutthecut-hunterhypothesis.IwantedtoseetherouteHIV-1hadtraveledfromitssourceandimaginethenatureofitspassage.

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Let’sgivehimduestature:notjustacuthunterbuttheCutHunter.Assuminghelivedhereaboutsinthefirstdecadeofthetwentiethcentury,heprobablycapturedhischimpanzeewithasnaremadefromaforestvine,orinsomeotherformoftrap,andthenkilledtheanimalwithaspear.HemayhavebeenaBakaPygmyman,livingindependentlywithhisextendedfamilyintheforestorfunctioningasasortofserfunderthe“protection”ofaBantuvillagechief.Butprobablyhewasn’t,givenwhatIhadheardofBakascruplesabouteatingape.MorelikelyhewasBantu,possiblyoftheMpiemuortheKakooroneoftheotherethnicgroupsinhabitingtheupperSanghaRiverbasin.OrhemayhavebeenaBakwele,involvedinthepracticeofbeka.There’snowayofestablishinghisidentity,norevenhisethnicity,butthisremotesoutheasterncornerofwhatwasthenGermany’sKameruncolonyofferedplentyofcandidates.Iimaginethemanbeingthrilledandabitterrifiedwhenhefoundachimpanzeecaughtinhissnare.Hehadprovedhimselfasuccessfulhunter,aprovider,aproficientmemberofhislittlecommunity—andhewasn’tyetcut.

Thechimptoo,tetheredbyafootorahand,wouldhavebeenterrifiedasthemanapproached,butalsoangryandstronganddangerous.Maybethemankilleditwithoutgettinghurt;ifso,hewaslucky.Maybetherewasanuglyfight;hemightevenhavebeenpummeledbythechimp,orbadlybitten.Buthewon.Thenhewouldhavebutcheredhisprey,probablyonthespot(discardingtheentrailsbutnottheorgans,suchasheartandliver,whichweremuchvalued)andprobablywithamacheteoranironknife.Atsomepointduringtheprocess,perhapsashestruggledtohackthroughthechimp’ssternumordisarticulateanarmfromitssocket,themaninjuredhimself.

Iimaginehimopeningalong,suddensliceacrossthebackofhislefthand,intothemuscularwebbetweenthumbandforefinger,hisfleshsmilingoutpinkandrawalmostbeforehesawthedamageorfeltit,becausehisbladewassosharp.Andthenimmediatelyhiswoundbled.Byalagofsomeseconds,italsohurt.TheCutHunterkeptworking.He’dbeencutbeforeanditwasanannoyancethatbarelydimmedhisexcitementovertheprize.Hisbloodflowedoutandmingledwiththechimp’s,thechimp’sflowedinandmingledwithhis,sothathecouldn’tquitetellwhichwaswhich.Hewasuptohiselbowsingore.Hewipedhishand.Bloodleakedagainintohiscut,dribbledagainintoitfromthechimp,andagainhewiped.Hehadnowayofknowing—nolanguageofwordsorthoughtsbywhichtoconceive—thatthisanimalwasSIV-positive.Theideadidn’texistin1908.

Thechimpanzee’svirusenteredhisbloodstream.Hegotasizabledose.Thevirus,findinghisbloodtobenotsuchadifferentenvironmentfromthebloodofachimp,tookhold.Okay,Icanlivehere.Itdidwhataretrovirusdoes:penetratedcells,converteditsRNAgenomeintodouble-strandedDNA,thenpenetratedfurther,intothecells’nuclei,andinserteditselfasDNAintheDNAgenomeofthosehostcells.ItsprimarytargetswereTcellsoftheimmunesystem.Acertainproteinreceptor(CD4)onthesurfaceofthosecells,intheCutHunter,wasnotverydifferentfromtheequivalentreceptor(anotherCD4)

ontheTcellsofthebutcheredchimpanzee.Thevirusattached,enteredthehumancells,andmadeitselfathome.Onceintegratedintothecellulargenome,itwasthereforgood.Itwaspartoftheprogram.Itcouldproliferateintwoways:bycellreplication(eachtimeaninfectedTcellcopieditself,theretroviralgenomewascopiedalso)andbyactivatingitslittlesubgenometoprintoffnewvirusparticles,whichthenescapedfromtheTcellandfloatedofftoattackothercells.TheCutHunterwasnowinfected,thoughapartfromaslashonthehandhefeltfine.

ForgetaboutGaëtanDugas.ThismanwasPatientZero.

Maybehecarriedthechimpcarcass,orpartsofit,backtohisvillageintriumph.Maybe,ifhewasBaka,hedeliveredthewholethingtohisBantuoverlord.Hedidn’twanttoeatitanyway.IfhewasBantuhimself,hisfamilyandfriendsfeasted.Ormaybethechimpwasawindfallfromwhichhecouldaffordtotakespecialprofit.Iftheseasonhadbeenbounteous,withsomeduikersormonkeyskilled,someforestfruitsandtuberstoeat,agoodcropofmanioc,sothathisfamilywasn’tstarving,hemayhaveluggedhischimpanzeetoamarket,liketheoneinMoloundou,andtradedforcashorsomevaluableitem,suchasabettermachete.Inthatcase,themeatwouldhavebeenparceledoutretailandmanypeoplemayhaveeatenbitsofit,eitherroastedorsmokedordried.Butbecauseofhowthevirusgenerallyachievestransmission(blood-to-bloodorsexually)andhowitdoesn’t(throughthegastrointestinaltract),quitepossiblynoneofthosepeoplereceivedaninfectiousdoseofvirus,unlessbycontactofrawmeatwithanopencutonthehandorasoreinthemouth.ApersonmightswallowplentyofHIVparticlesbut,ifthosevirionsaregreetedbystomachacidsandnotblood,theywouldlikelyfailtoestablishthemselvesandreplicate.(Thegreatestdanger,leftunspecifiedinthat“Don’teatapes”posterIsaw,isnotintheswallowingbutinthekilling,handling,andbutcheringoftheanimal.)Let’ssupposethatfifteendifferentconsumerspartookofthechimpmeat,andthattheyallremainedfine.HIV-negative.Luckyfolks.Let’ssupposethatonlytheCutHunterbecameinfecteddirectlyfromthechimp.

Timepassed.Thevirusabidedandreplicatedwithinhim.Hisinfectiousnessrosehighduringthefirstsixmonths,asvirionsinmultitudebloomedinhisblood;thentheviremiadeclinedsomeashisbodymountedanearlyimmuneresponse,whileitstillcould,andleveledoff,foraperiodoftime.Henoticednoeffects.Hepassedthevirustohiswife,eventuallyalsotooneofthefourotherwomenwithwhomhehadsex.Hesufferednoimmunodeficiency—notyet.Hewasarobust,activefellowwhocontinuedtohuntintheforest.Hefatheredachild.Hedrankpalmwineandlaughedwithhisfriends.Andthenayearlater,let’ssay,hediedviolentlyinthecourseofanelephanthunt,anactivityevenmoreperilousthanbutcheringchimpanzees.Hewasoneofsevenmen,allarmedwithspears,andthewoundedelephantchosehim.Hetookatuskthroughthestomach,momentarilypinninghimtotheground.Youcouldseethetuskholeinthedirtafterward,asthoughabloodystakehadbeendriveninandpulled.Ofthemenwhoscoopedhimup,thewomenwhopreparedhimforburial,nonehadanopencutandsotheyweresparedinfection.HissonwasbornHIV-negative.

TheCutHunter’swidowfoundanewman.Thatmanwascircumcised,freeofgenital

sores,andlucky;hedidn’tbecomeinfected.TheotherwomanwhohadbeeninfectedbytheCutHuntertookseveralpartners.Sheinfectedone.Thisfellowwasalocalchief,withtwowivesandoccasionalaccesstoyoungvillagedaughters;heinfectedbothwivesandoneofthegirls.Thechief’swivesremainedfaithfultohim(byconstraintofcircumstanceifnotbychoice),infectingnoone.Theinfectedgirleventuallyhadherownhusband.Andso,onward.Yougettheidea.Althoughsexualtransmissionofthevirusoccurredlessefficientlyfromfemaletomale,andnotallsoefficientlyfrommaletofemale,itwasjustefficientenough.Afterafewyears,ahandfulofpeoplehadacquiredthevirus.Andthenstillmore,intime,butnotmany.Sociallifewasconstrainedbysmallpopulationsize,absenceofopportunity,andtosomedegreemores.Thevirussurvivedwithabasicreproductionratebarelyabove1.0.Itpassedtoasecondvillage,inthecourseofneighborlyinteractions,andthenathird,butitdidn’tproliferatequicklyinanyofthem.Noonedetectedawaveofinexplicabledeaths.Itsmolderedasanendemicinfectionatlowprevalenceinthepopulaceofthatlittlewedgeofterrain,betweentheNgokoRiverandtheupperSangha,wherelifetendedtobeshortandhard.Peoplediedyoungfromallmannerofmishapsandafflictions.Ifayoungman,HIV-positive,waskilledinafight,nooneknewanythingabouthisbloodstatusexceptthatithadbeenspilled.Ifayoungwoman,HIV-positive,diedofsmallpoxduringalocaloutbreak,likewisesheleftnounusualstory.

Insomecases,duringthoseearlyyears,aninfectedpersonmayhavelivedlongenoughtosufferimmunefailure.Thentherewereplentyofreadybugs,intheforest,inthevillage,tokillhimorher.Thatwouldn’thaveseemedremarkableeither.Peoplediedofmalaria.Peoplediedoftuberculosis.Peoplediedofpneumonia.Peoplediedofnamelessfever.Itwasroutine.Someofthosepeoplemighthaverecovered,hadtheirimmunesystemsbeencapable,butnoonenoticedanewdisease.Orifsomeonedidnotice,thereporthasn’tsurvived.Thisthingremainedinvisible.

Meanwhilethevirusitselfmayhaveadapted,atleastslightly,toitsnewhost.Itmutatedoften.Naturalselectionwasatwork.Givenamarginalincreaseinitscapacitytoreplicatewithinhumancells,leadingtoincreasedlevelsofviremia,itsefficiencyoftransmissionmayhaveincreasedtoo.BynowitwaswhatwewouldcallHIV-1groupM.Ahuman-infectingpathogen,rare,peculiar,confinedtosoutheasternCameroon.Maybeadecadewentby.Thebugsurvived.SpilloversofSIVcpzintohumanshadalmostcertainlyoccurredinthepast(plentyofchimpswerebutchered,plentyofhunterswerecut)andresultedinpreviouschainsofinfection,butthosechainshadbeenlocalizedandshort.Thesmolderingoutbreakhadalwayscometoacoldend.Thistimeitdidn’t.Beforesuchburnoutcouldoccur,anotherpersonenteredthesituation—alsohypotheticalbutfittedtothefacts—whomI’llcalltheVoyager.

TheVoyagerwasn’tahunter.Notanexpertanddedicatedone,anyway.Hehadotherskills.Bymyimagining,hewasafisherman.HelivednotinaforestclearingliketheoneatMambelebutinafishingvillagealongtheNgokoRiver.Ipicturehimasariverboyfromchildhood.Heknewthewater;heknewboats.Heownedacanoe,agoodone,sturdyandlong,madefromamahoganylogwithhisownhands,andhespenthisdaysinit.Hewasayoungmanwithnowife,nochildren,andjustabitofanappetiteforadventure.He

hadfallenawayfromhisnatalcommunityatanearlyage,becomingaloner,becausehisfatherdiedandthevillagecametodespisehismother,suspectingherofsorcerybasedonapieceofbadluckandagrudge.Hetookthisasadeeppersonalbruise;hedespisedthevillagersinreturn,screwthem,andwenthisownway.Itsuitedhimtobealone.HewasnotanobservantBakwele.Henevergotcircumcised.

TheVoyageratefish.Heatelittleelse,infact,besidesfishandbananas—andsometimesmanioc,whichhedidn’tplantorprocesshimselfbutwhichwaseasilyboughtwithfish.Helikedthetasteandhelovedtheideaoffish,andtherewasalwaysenough.Heknewwheretofindfish,howtocatchthem,theirvariedtypesandnames.Hedranktheriver.Thatwasenough.Hedidn’tmakepalmwineorbuyit.Hewasself-sufficientandcontainedwithinhissmallworld.

Heprovidedfishtohismotherandhertwoyoungerchildren,asIseehim,aloyalsonthoughanalienatedneighbor.Hismotherstilllivedatthefringeoftheoldvillage.Hissurpluscatchhedriedonracks,orinwetseasonsmokedoverafire,athissolitaryriverbankcamp.Occasionallyhemadeconsiderablejourneys,paddlingmilesupstreamordriftingdownstream,tosellaboatloadoffishinoneofthemarketvillages.Inthisway,hehadtastedtheempowermentofdealingforcash.Brassrodsweretheprevailingcurrency,orcowrieshells,andsometimeshemayevenhaveseendeutschmarks.Heboughtsomesteelhooksandonespoolofmanufacturedline,whichhadcomeallthewayfromMarseille.Thelinewasdisappointing.Thehookswereexcellent.OncehehadfloateddownstreamasfarastheconfluencewiththeSangha,amuchlargerriver,powerful,twiceaswideastheNgoko,andhadriddenitscurrentforaday—aheadyandfearfulexperience.Ontherightbankhehadseenatown,whichheknewtobeOuesso,vastandnotorious;hegaveitawideberth,holdinghimselfatmidriveruntilhewaspast.Atday’sendhestopped,sleptonthebank,andnextdayreversed,havingtestedhimselfenough.Ittookhimfourdaysofanxiousefforttopaddlebackup,huggingthebank(exceptagainatOuesso),climbingthrougheddies,buttheVoyagermadeit,relievedwhenheregainedhisownworld,thelittleNgokoRiver,andswollenwithnewconfidencebythetimehebeachedathiscamp.Thismighthaveoccurred,let’ssay,inthelongdryseasonof1916.

Onanotheroccasion,hepaddledupstreamasfarasNgbala,arivertownsomemilesaboveMoloundou.Itwasduringhisreturnfromthatjourney,asIposit,thathestoppedatMoloundouandthere,inhisboat,whereitwastiedforthenightinashadedcovejustbelowtown,hadsexwithawoman.

Shewasn’thisfirstbutshewasdifferentfromvillagegirls.Shewasarivertraderherself,aBuy’em–Sell’em,severalyearsolderthanhewasandconsiderablymoreexperienced.ShetraveledupanddowntheNgokoandtheSangha,makingalivingwithherwitsandherwaresandsometimesherbody.TheVoyagerdidn’tknowhername.Neverheardit.Shewasoutgoingandflirtatious,almostpretty.Hedidn’tthinkmuchaboutpretty.Sheworeaprintdressofbrightcalico,manufactured,notlocalraffia.Shemusthavelikedhim,oratleastlikedhisperformance,becauseshereturnedtohisboatintheshadowsthenextnightandtheycoupledagain,threetimes.Sheseemedhealthy;shelaughedmerrilyandshewasstrong.Heconsideredhimselfluckythatnight—luckyto

havemether,tohaveimpressedher,tohavegottenatnocostwhatothermenpaidfor.Buthewasn’tlucky.Hehadasmallopenwoundonhispenis,barelymorethanascratch,wherehe’dbeencaughtbyathornyvinewhilesteppingashorefromariverbath.Noonecanknow,noteveninthisimaginedscenario,whetherthelackofcircumcisionwascrucialtohissusceptibility,orthelittlethornwound,orneither.Hegavethewomansomesmokedfish.Shegavehimthevirus.

Itwasnoactofmaliceorirresponsibilityonherpart.Despiteswollenandachingarmpits,shehadnoideashewascarryingitherself.

16

Rivertravelthroughtropicaljungleisuncommonlysoothingandhypnotic.Youwatchthewallsofgreeneryslidebyand,unlessthechannelisnarrowenoughfortsetsefliestonoticeyourpassingandcomeoutfromtheshores,yousufferalmostnoneofthediscomforts.Becausetheriverbanksrepresentforestedges,admittingthefullblastofsunlight,asclosedcanopydoesnot,thevegetationisespeciallytangledandrife:treesdrapedwithvines,understoryimpenetrable,thickasthevelvetcurtainatanoldmovietheater.Itpresentsanillusionthattheforestitself,itsinterior,mightbeasdenseasasponge.Buttoarivertravelerthatdensityisimmaterialbecauseyouhaveyourownopenroutedownthemiddle.Ifyou’vewalkedtheforest,whichisdifficultthoughnotsponge-thick,riverjourneyingisanescapefromimpedimentsthatfeelsalmostakintoflight.

ForawhileafterleavingKika,wefavoredtheCongoside,ridingastrongchannel.Sylvainknewhispreferredline.Hisassistant,aBakamannamedJolo,handledtheoutboardwhileSylvainsupervised,signalingdirectionsfromthebow.ThepiroguewaslargeandsteadyenoughthatMaxandIcouldsitonthegunnels.Immediatelywepassedasmallpolicepostontherightbank,aCongolesecounterparttotheCameroonianoneatKika,andfortunatelynooneflaggedustostop.EverysuchcheckpointinCongoisanoccasionforpassport-stampingandminorshakedowns,andyouwanttoavoidthemwhenyoucan.Thenweputteredpastafewvillages,widelyspaced,eachjustaclusterofwattle-and-daubhousessitedonahighbanktoescapeinundationinwetseason.Thehousesweretoppedwiththatchandsurroundedbybananatrees,anoilpalmortwo,childreninragdressesandshorts.Thekidsstoodtransfixedaswepassed.Howmanyhourstoourdestination?IaskedSylvain.Depends,hesaid.Ordinarilyhewouldstopinvillagesalongthewayfortradingorpassengers,delayinglongenoughtoenterOuessobydarknesssoastoescapenoticebytheimmigrationpolice.Notlongafterthatexplanationhedidstop,guidingusashoreatavillageontheCongobank,towhichhedeliveredalargeplastictarpandfromwhich,ondeparture,wegainedapassenger.

ItwasmycharterbutIdidn’tmind.Shewasayoungwomancarryingtwobags,anumbrella,apurse,andapotoflunch.Sheworeanorange-and-greendressandabandanna.ImighthaveguessedifIhadn’tbeentold:ShewasaBuy’em–Sell’em.HernamewasVivian.SheliveddowninOuessoandwouldbegladfortheridehome.Shewaslivelyandplump,confidentenoughtobetravelingtheriveralone,tradinginrice,pasta,cookingoil,andotherstaples.Sylvainlikedtogiveheraliftbecauseshewashissister—astatementofstatusthatcouldbetakenliterallyornot.Shemighthavebeenhisgirlfriendorhiscousin.Beyondthis,Ididn’tlearnmuchfromVivianexceptthathernichestillexists,theBuy’em–Sell’emrole,offeringindependent-spiritedwomenaformofautonomynoteasilyfoundwithinvillagelife,oreventownlife,andthattheriverstillfunctionsasaconduitofeconomicandsocialfluidity.Mostlysheseemedacharmingthrowbackand,thoughthismightbeunfairtoher,putmeinmindofwomenthattheVoyagermighthavemetalmostacenturyearlier.Shewasapotentialintermediary.

Whentherainreturned,MaxandIandSylvainandVivianhunkeredbeneathourtarp,

headsdownbutpeekingout,whileJolotheBakastolidlymotoreduson.Wepassedasolitaryfishermaninhiscanoe,pullinganet.Wepassedanothervillagefromwhichchildrenstared.Thentheraindiedagainandthestormbreezefelloff;thegentlechopdisappeared,leavingtheriverasflatandbrownasacooledcaféaulait.Mangrovesreachedoutfromthebankslikegropingoctopuses.Inoticedafewegretsbutnokingfishers.InmidafternoonweapproachedtheconfluencewiththeSangha.Alongtheleftbank,thelandfellgraduallylowerandthentapered,sinkingawayintothewater.TheSanghaRivergrippedus,swungusaround,andIturnedtowatchthatsoutheasternwedgeofCameroonrecedetoavanishingpoint.ThecradleofAIDS.

Theairwarmedslightlywithanupstreambreeze.Wepassedalarge,woodedisland.Wepassedamanstandinguprightinhisdugout,paddlingcarefully.Andtheninthedistanceahead,throughhaze,Isawwhitebuildings.Whitebuildingsmeantbricksandwhitewashandgovernmentalpresenceinsomethinglargerthanavillage:Ouesso.

WithinhalfanhourwelandedattheOuessowaterfront,withitsconcreterampandwall,whereanofficerfromtheimmigrationpoliceandagaggleoftip-hungry,scutteringportersawaited.Steppingashore,wehadreenteredtheRepublicoftheCongo.WecompletedtheimmigrationformalitiesinFrenchandthenMaxdealtwiththebag-grabbingportersinLingala.SylvainandJoloandVivianmeltedaway.Maxwasashier,lessforcefulfellowthanNevillebutconscientiousandearnest,andnowitwashisturntobemyfixer.Hemadesomeinquiriesherealongthewaterfrontandsoonhadgoodnews:thatthebigboat,thecargo-and-passengerbargeknownaslebateau,wouldbedepartingtomorrowforBrazzaville,manymilesanddaysfurtherdownriver.Iwantedustobeonit.

Wefoundahotel,MaxandI,andinthemorningwalkedtotheOuessomarket,whichwascenteredinasquat,pagoda-shapedbuildingofredbrickjustblocksfromtheriver.Thepagodawasbigandstylishandold,withaconcretefloorandacircularhallbeneaththreetiersofcorrugatedmetalroof,datingbackatleasttocolonialtimes.Themarkethadfaroutgrownit,sprawlingintoawarrenofwood-framestallsandcounterswithnarrowlanesbetween,coveringmuchofacityblock.Businesswasbrisk.

AstudyofbushmeattrafficinandaroundOuesso,doneinthemid-1990sbytwoexpatresearchersandaCongoleseassistant,hadfoundabout12,600poundsofwildharvestpassingthroughthismarketeachweek.Thattotalincludedonlymammals,notfishorcrocodiles.Duikersaccountedformuchofitandprimatesweresecond,thoughmostoftheprimatemeatwasmonkey,notape.Eighteengorillasandfourchimpshadbeenbutcheredandsoldduringthefour-monthstudy.Thecarcassesarrivedbytruckandbydugoutcanoe.AsthebiggesttowninnorthernCongo,withnobeefcattletobeseen,Ouessowasdraininglargecrittersoutoftheforestformanymilesaround.

MaxandIsnoopedupanddownthemarketaisles,steppingaroundmudholes,dodginglowmetalroofs,browsingaswehaddoneinMoloundou.BecausethiswasOuesso,themerchandisewasfarmoreabundantanddiverse:boltsofcolorfulcloth,athleticbags,linens,kerosenelanterns,AfricanBarbiedolls,hairfalls,DVDs,flashlights,umbrellas,thermoses,peanutbutterinbulk,powderedfufu(instantmaniocpaste,justaddwaterandstirforhalfanhourwithastick)inpiles,mushroomsinbuckets,driedshrimp,

wildfruitsfromtheforest,freshlyfriedbeignets,blocksofbouillon,saltbythescoop,blocksofsoap,medicines,binsofbeans,pineapplesandsafetypinsandpotatoes.Ononecounterawomanhackedatlivecatfishwithamachete.Justacrossfromher,anotherwomanofferedaselectionofdeadmonkeys.Themonkeysellerwasalargemiddle-agedlady,herhairincornrows,wearingabrownbutcher’sapronoverherpaisleydress.Genialanddirect,sheslappedasmokedmonkeydownproudlyinfrontofmeandnamedherprice.Itsfacewastinyandcontorted,itseyesclosed,itslipsdriedbacktorevealadeathlysmileofteeth.Splitupthebellyandsplayedflat,itwasroughlythesizeandshapeofahubcap.Sixmillefrancs,shesaid.Besidethefirstmonkeyshetosseddownanother,incaseIwasparticular.Sixmilleforthatonetoo.ShewastalkinginCFA,theweakCentralAfricancurrency.Hersixthousandfrancsamountedtothirteendollars,andwasnegotiable,butIpassed.Shealsohadasmokedporcupine,fiveduikers,andanothersimian,thisonesofreshlykilledthatitsfurwasstillglossyandIcouldrecognizeitsspecies:Cercopithecusnictitans,thegreaterspot-nosedmonkey.That’sapremiumitem,Maxsaid,it’llgofast.Nearby,gobbetsofsmokedporkfromaredriverhogwerepricedatthreethousandfrancsperkilo.Alltheseanimalscouldbehuntedlegally(thoughnotwithsnares)andtradedopenlyinCongo.Therewasnosignofapes.IfyouwantchimpanzeeorgorillameatinOuessoitcanstillbehad,nodoubt,butyou’vegottomakeprivatearrangements.

Ourtripdownriveronthebateausufferedcomplicationsanddelayssothat,fourdayslater,MaxandIwerebackinOuesso.Revisitingthemarket,wepassedagainthroughthepagoda,downthenarrowaislesbetweenstalls,alongthecounterspiledwithcatfishandmonkeysandduikers,smokedandfresh.ThistimeInoticedawheelbarrowfullofsmallishcrocodilesandsawonecrocbeingwhackedapartonaplank.Youcouldlocatethemeatsectionfromanywhereinthemarketmaze,Irealized,bythatsound—thesteadythunk-thunk!ofmachetes.Andthenwecameagaintothebrown-apronedlady,whorememberedme.“You’vereturned,”shesaidinFrench.“Whydon’tyoubuysomething?”Thistimesheplunkeddownalittleduiker,moreasachallengethanasanoffering:Areyouashopperoravoyeur?Ipreferchicken,Isaidlamely.Orsmokedfish.Unsurprisedbythepusillanimityofthewhiteman,shesmiledandshrugged.Then,asaflyer,Isaid:Butifyouhadchimpanzee...Sheignoredme.

Orelephant,Maxadded.Nowshelaughednoncommittallyandturnedbacktoherrealcustomers.

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TheideaofOuessoanditsmarketservedasacrucialenticementtogettheVoyager,asIimaginehim,onhisway.That’swherethewildcatnotionofhiswildcatjourneybegan:Ouesso.Hehadn’tintendedtogofarther.AtripdowntoOuessoandback(hehadmeanttocomeback,thoughlifeunfoldedotherwise)wouldbeambitiousandriskyenough.ButevenbeforetheideaofOuesso,therewasthedizzyinghappenstanceofthetusks.IfitwasOuessothatpulledhim,itwasthetusksthatpushedhim.

Hehadnevergonelookingforivory.Itcamebyaccident.OnedayhewasupriverontheNgoko,workinghisnetatthemouthofafeederstreamthatdrainedfromtheCongoside.Itwasdryseason—neartheendofthelongdryseason,earlyMarch.Theriverwaslowandslowandwarm,whichwaswhyhehadthoughtthefresheningflowofthefeederstreammightattractfish.Asithappened,notmany.Thecatchtherescarcelyrepaidhiseffort.Soinmidafternoonhedecidedtowalkinland,back-followingthislittlestreamintotheforest,lookingforpoolswheresmallfishmightbetrappedandvulnerable.Hefoughthiswayalongthemudbanksforalmosthalfamile,throughthethornvines,overthecobbleofroots,findingfewpoolsandnofish.Itwasfrustratingbutnotsurprising.Hepausedforbreath,dippedupahandfulofwatertodrink,andfrownedahead,decidingwhethertocontinue.That’swhenhenoticedalargegraymoundinthestreambottomaboutfortyyardson.Toyouortomeitwouldhavelookedlikeagraniteboulder.ButtherearenogranitebouldersinnorthernCongoorsoutheasternCameroon,andtheVoyagerhadneverseenone.Heknewimmediatelywhatitwas:anelephant.Hisheartbeatsurgedandhisfirstinstinctwastorun.

Insteadhestared.Hislegsdidn’tgo.Helingered,unsurewhy.Hesensedterrorinthescenesomewhere,buttheterrorwasn’this.Thenherealizedwhatseemedwrong—theelephantwasdown,andnotinapositionthatmightsuggestsleep.Itsfacelaysmashedintothemud,itstrunksideways,itshipcantedup.Heapproachedcarefully.Henoticedthepurplishredholesalongitslowersidesandbelly.ProtrudingfromoneofthoseholeswasaBakaspear.Hecouldseetheawfulwaythebeasthadcollapseddownoveritsleftshoulder,itsfrontlegonthatsidebentoutataruinousangle.Bythetimehehadcreptwithintenyards,heknewthatitwasdead.

Asizablemale,ayoungishadult,withgoodivory.Lefttodiealoneinastreambottomandrot.QuicklytheVoyagermadesomedeductions.ProbablyithadbeenkilledbyahuntingpartyofBakamen—butnotquitekilled,justmortallywounded.Ithadbrokenaway,escaped,andtodothat,presumably,itwouldhavehadtokilloneortwooftheBakawhosurroundedit.Theothersmusthavelostheartforthechase.Maybethishadoccurredonthenorthsideoftheriver.Maybetheelephant,woundedanddesperate,hadswumacross.ButiftheBakatookupthetrail,gotthemselvesoverhere,andreappearednow—thatcouldbebadforhim.FindingtheVoyagerwiththeircostlytrophy,thePygmiesmightfillhimwithpurplespearholes.AssumingtheycouldsummontheaudacitytomurderaBantu.Soheworkedfast.Hewhaledintotheelephant’sfacewithhismachete,hackingthroughfleshandgristle,openinganuglymawthatnolongerlooked

elephantinebutlikesomethingelse,somethingexplodedandogrish,andwithinhalfanhourhehadtwistedbothtusksfree.Theysurrenderedwithrippingnoises,likeanytoothdrawnfromitsjaw.

Heshavedthetusksfreeoftissue,thenrubbedthemwithsandymudandrinsedthemwhiteinthestream.Heldinhishands,eachoneseemedhuge.Bounteous.Maybefifteenkilos.Hehadneverexperiencedsuchanarmloadofwealth.Hecouldonlyhandleoneatatime.Heexaminedeachinturn,passinghishanddownthesmoothwhitecurvetothepoint.Thenhegatheredupbothandstaggeredbacktohiscanoe,crouchinganddodgingthroughthevines,anddroppedthemintothebilgewithhisfewfish.Untiedtheboatquickly,caughtthecurrent,headeddownstream.Havingroundedonebend,hebegantoease,hisheartslowingbacktonormal.

Whathadjusthappened?Hehadstumbleduponhalfafortuneandstolenit,that’swhat.Claimedit,rather.Nowwhat?

Backathiscamp,theVoyagercachedthetuskshastilybeneathleavesandbranchesinarecessbesideafallentree.Midwaythroughthefirstnighthewoke,suddenlyawarethathishidingplacewasinadequate,stupidlyso,andhewaitedoutthedarknessimpatiently.Atdaylightherose,scrapedawaythecoalsandembersandashfromhiscampfire—hishearthsiteofseveralyears’custom—anddugapitonthatspot,crackingthroughthelayerofbakedearthwithhismachete,slappingdeepslicesintotheclaybeneath.Hewentdownfourfeet.Heshapedadeep,narrowslot.Hewrappedthetwotusksinngoungouleavesforprotectionandnestledthematthebottomofthetrench.Thenherefilledit,leveledthegroundcarefully,spreadtheoldashesbackwherethey’dbeen,replacedthecharredlogs,andlitanewfire.Nowhistreasurewassafe,maybe,forawhile.Andhecouldthinkaboutwhattodo.

Therewerenoeasyanswers.Therewasopportunityandtherewasrisk.Hewasnotamanwhohuntedelephant,andeveryonewhoknewhimknewthat.Hewasnotsupposedtohavetusks.IfhetookthemtoMoloundoutheagentsoftheFrenchconcessionaires,greedyforivory,leachingitfromtheforestbyallmannerofcompulsionandthreat,wouldsimplyimpoundthem.Hemightevenbepunished.Otherswouldtrytostealthem,ortotradeforthemwhilecheatinghimoftheirvalue.Hethoughtthroughthescenarios.Hewasn’tacunningmanbuthewastoughandstubborn.

Sixmonthspassed.Hecontinuedtoliveasbefore:fishingtheriver,dryingfishathiscamp,spendinghisdaysalone,makinginfrequentstopsatNgbalaorMoloundoufortrading.TherewasonemaninMoloundou,amerchant,notalocalBantuandnotaconcessionaire’sagentbutahalf-Portugueseoutsiderwithconnections,notoriouslyclever,knowntodealdiscreetlyinelephantmeatandivory.Onedayduringatransactionoverfish,salt,andfufu,theVoyageraskedthismerchantaboutthepricefortusks.Itwasjustaquestion!Themerchantlookedathimslylyandmentionedanumber.Thenumberseemedhighbutnotveryhigh,andtheVoyager’sfacemayhaveflickeredwithdisappointment.Hesaidnothingmore.

Twonightslater,theVoyagerreturnedfromupriverandfoundhiscampwrecked.Thehalf-Portuguesemerchanthadspokenwithsomeone,andthatsomeonehadgonestraight

torobhim.

Hishuthadbeenrippedapart,hisdryingracksbroken.Hisfewpossessions—hissecondnet,sometinpots,acampknife,ashirt,hisraffiamat,andtherest—hadbeenscattereddisdainfully.Hislittletinboxhadbeenbrokenopenandthefishhooksandtobaccodumpedout.Driedfishlayontheground,willfullytroddenupon.Thereweresignsofdigginghereandthere—besidethefallenlog,inthefloorofhishut,acoupleotherplacestoo.Desultory,petulantsearching.TheVoyager’scampfirehadbeenscattered,logsandasheskickedaway.Hisbreathcaughtwhenhesawthat.Butthedirtbeneaththeasheshadn’tbeendisturbed.Theyhadn’tfoundwhattheyhadcomefor.

SoheturnedhismindtowardOuesso.Hewaitedoutthenightinhisruinedcamp,besideafireburninglow,withhismacheteinhand.Atdawnheexcavatedhistusksand,leavingthemleaf-wrappedanddirty,withoutpausingtosavortheircoolpreciousweight,putthemintohiscanoe.Hecoveredthetuskswithdriedfish,ofwhichhehadplenty,andsmokedfish,ofwhichhehadjustabit,thencoveredthefishwithmorengoungouleavesinneatbundles,asthoughheweretakingthemtomarket.Ngoungouleaveshadtheirvalueaswrapping,butitwasminimal;apathetic,countryman’sproduct,andthereforeplausible.Atoptheleavesheplacedhismat.Hepushedoff,paddledout,andlethimselfbeswungdownriverontheNgoko,puttingMoloundoubehindhim.Hepaddledsteadilyforhours,reachedtheSangha,turneddownstreamthere,andcontinuedstraighttoOuesso.

Halfamilebelowthetown,hefoundaneddyandpulledhisboatupintotheforest.Therewasnolanding,notrail,nocamp,nosignofhumanpresence—whichwasgood.NextdayheconcealedthecanoebeneathleafybranchesandbushwhackednorthwestuntilhestrucktheouterlanesofOuesso.Hewalkedstraighttothemarketbyfollowingotherpeople.Hehadneverseensuchaconcentrationofhumansand,oncehewasamidthecrowd,hisheartbeganthumpingasithadwhenhestoodoverthedeadelephant.Butnoonehurthim;nooneevenlookedathimtwice,despitethefactthathisclotheswereshabbyandhecarriedamachete.Hesawothermenindirtyclothes,afew,andoneortwoofthemcarriedmachetesalso.Hebegantorelax.

Themarket,shelteredinahugeroundbuildingwithametalroof,waswondrous.Youcouldbuymeat,youcouldbuyfish,youcouldbuycolorfulclothinganddriedmaniocandvegetablesandfishnetsandthingshehadneverseen.TheVoyagerhadnomoneyofanysort,notfrancs,notbrassrods,buthewanderedamongthegoodsasthoughhemightwantsomething.Headmiredtheduikersandthemonkeys.Hepickedupagorillahand,whilethesellerwomanwatchedhimclosely,andsetitbackdown.ThepeoplespokeLingala.Heexchangedafewwordswithamansellingfish.TheVoyagerwasmorecautiousthanhehadbeeninMoloundou.DoyoubuysmokedfishifIhavesome?heasked.Maybe,whenIseeit,themansaid.TheVoyagertooknoteofanothermannearby,behindaplanktableuponwhichsatlargechunksofelephantmeat,smokyandgray.Amanwhosoldelephantmeatmightalsodealinivory.TheVoyagermemorizedthatman’sfacebutdidn’tspeakwithhim.Hewoulddoittomorrow.

Hewalkedbackoutoftownandintotheforest,satisfiedbyhisjudiciouspreliminaryexcursion,andwhenheemergedthroughtheundergrowthtohisriverbankhidingspot,he

washorrifiedtoseethecutbranchescastasideandsomeonebentoverhisboat.Horrifiedandenraged:athimselfforhisredoubledstupidity,attheworld,andespeciallyatthemancovetinghistusks.TheVoyagerraisedhismachete,ranforward,andstruckbeforetheinterloperhadhalfturnedaround,splittingtheman’sskulllikeadrycoconut.Thatmadeasickening,fatefulsound.Themanfellhard.Wherehisheadhadbrokenopen,pinkbrainsshowedandbloodsurgedaroundthepinkness,thenstopped.

ItwasscarcelymidafternoonoftheVoyager’sfirstdayinOuessoandhehadkilledsomeone.Whatsortofhellishplacewasthis?

Hisnextshockcamewhenherolledthedeadmanover.Itwasn’taman’sface;itwasaboy’s.Smoothskin,babycheeks,longjaw,barelyoldenoughforinitiation.TheVoyagerhadbeenfooledbyheight.Hehadkilledatallyoungster,aganglyboywhohaddaredtostoopoverhiscanoe.Aboyfromthetown,withrelativeswhowouldmisshim.Thiswasn’tgood.

TheVoyagerstoodforamoment,exhaustedandpained,calculatinghissituation.Thenagainhemovedquickly.Hedraggedtheboy’sbodytotheriver.Splashingintotheshallows,stumbling,hepulleditoffshorejustenoughtobesureofcurrent,releasedit,andwatcheditdriftaway.Thebodyfloatedlowinthewaterbutitfloated.Backonthebank,herifleddownintohiscanoeandconfirmedthatthetuskswerestillthere.Theywere.Hegrippedeachindividuallyatthetip,assuringhimself:one,two.Hepeeledbacktheleafwrapandlooked.Yes,ivory,twotusks.Hedraggedhiscanoetothewater,climbedin,andbeganpaddlingdownstream.Withinfiftyyardshecaughtupwiththeboy’sbodyandpasseditby.HedidnotglancebacktowardOuesso.

Nowhewaslaunched,untethered,nogoingback.Forthreeweekshejourneyeddownstream.Ormaybefourweeks;hedidn’tkeepatallyofthedays.Hehadhiscanoeandhistusks,hismachete,hisfishinglineandhooks,littleelse.Hisimmediatepurposewastostayalive,daybyday.Hisdrivinggoalwastorecoupalifefromtheivory.Heresumedfishingashewent,trollingwithhisline,seldomstoppingexceptforthenight.Heatewhathecaught,savingthedriedandsmokedfishforcontingency.Hewasonthewateragaineverymorningbyfulllight.Hepassedanothertown,avoidingitalongthefarbank,andpaddledthroughastretchwheretherivermeanderedslowlyamidswamplands.Hecouldseeitwastakinghimgenerallysouth.Therewereadventuresandmishapsandsomefurthernarrowescapesalongtheway.MaybeyoucanimaginethemaswellasIcan.Therewastheencounterwiththemenonthelograft,driftingdownriver,towhomhesoldfishandbywhomhewaswarnedabouttheBobangi,animperiouspeoplecontrollingtradeandpassageatthemouthoftheSangha.Hedidn’tknowwhatthatmeant,themouthoftheSangha;hepicturedthisrivergoingonforever.Therewastheambushbythecrocodile,anotherhatefulmoment,buthehadbeenluckythatmorning.Itwasanastyanimal,notlarge,barelysixfeet,presumptuousandstupidtoattackahuman,andhe’dhadhisrevenge.Heatethebellymeatandtailofthecrocodileforsixdaysafterward.Hehadnevereatenchickensotohimittastedlikefish.Heplacedthecrocodile’sseveredheadintoacolumnofdriverantsandtheycleaneditoffleshwithinanafternoon.Nowthesun-bleachedskullrodeatoptheothercargoinhiscanoe,toothyandgrinning,likea

totem.HereachedthemouthoftheSanghaandtriedtoeludetheBobangi,runningmidriveratnightandlayingupbyday.Buthecouldn’tstaywithhistreasureseverymoment.Helefttheboatunguardedonce,foronlyashorttime,togatherfruitbeneathamobeitree,andsotherewashisstandoffwiththesolitaryBobangimanwhomhefound,ashehadfoundtheTallBoy,committinganoutrage:lookingintohiscanoe.UnliketheTallBoy,thismanheardhimandturnedaround.

Themanhadgrayhairathistemplesandhislefteyewasmilkyblue.Hisrighteyewasnormal.Hewasoldbutnottoooldtobedangerous;hisbodyappearedstillstrong.Hecarriedasmallironknife,butnomachete,andalittlepacketinanimalhidestrungaroundhisneck.Helookedlikeamagusorasorcerer.HehadunwrappedtheVoyager’sivory.TheVoyagerknewthatthereweremanyotherBobangiontheriver,maybeevensomewithinearshot.TheVoyagerfelttrapped.HerememberedthesickeningsoundofhismacheteontheTallBoy’shead.Hedecided,veryquickly,uponadesperatecompromise.Headdressedtheblue-eyedmaninLingala,notsurewhetheraBobangiwouldunderstand.

Igiveyouonetusk,theVoyagersaid.

Nosignofresponse.

Igiveyouonetusk,herepeated,speakingveryclearly.Youdeliverittoyourchief.Or…youdon’t.

Hewaited,lettingtheblue-eyedmanponder.

Onetusk,hesaid.Heheldupafinger.OrIfightyouandIkillyoufortwo.

Itseemedalongdelay.TheVoyagerbeganwishinghehadsimplycrackedtheman’sskull,atleasttriedto,whatevertheconsequences.Thentheblue-eyedmanturnedbacktotheVoyager’scanoe.Herummaged,shovedawayleaves,and,withaneffortthatshowedinhisbackmuscles,liftedoutonetusk.Hestrokedit,testingthesmoothcoolsurface,andappearedsatisfied.TheVoyagerwatchedhim;willedhimonhisway.Allright.Takeit.Go.Butthen,no,themanstoopedagain.Hepickedupasinglesmokedfish.HegapedbackattheVoyagerwithanexpressionofshameless,bemuseddefiance.Theblueeyetwitched—orwasthatawink?Hetookthetuskandthefishandhedeparted.

ThatnighttheVoyagerpassedonwardthroughBobangiterritory,slippingbytheirbigvillagenearthemouthoftheSangha,wherethisriverdebouchedintoanother,unimaginablyhuge:theCongo.Hewasastonishedwhendaylightrevealedtheextentofitsbraidingchannels,islands,andstrongcurrents.Itwaslikeabundleofrivers,notjustone.Hepaddledharderthanevernow,butalsomorecarefully,learningwarinessoftheeddylinesthatcouldknockacanoesideways,thewhirlpoolsthatcouldsuckitunder.Hekeptadistancebetweenhimselfandothercanoes.Whenhesawmenonaraft,hepaddledwithinshoutingdistance,offeredtosellfish,soughtinformation.Onceheencounteredasteamboat,likeagreathouseproceedingupriverunderpower,withamachineinsidethumpingstupidly,passengersandbundledcargoonthedeck.Itwasastrangesight.ButtheVoyagerhadseenotherstrangesights—thespilledbrainsofaboy,theOuessomarket,ablue-eyedBobangithief—andbynowfeltalmostinuredtoastonishment.Theboatman

onthisnoisy,belchingvessel,hecouldsee,wasawhiteman.TheVoyagerhuggedtheoppositeshore.

Therivercontinuedsouth.HeenteredtheterritoryoftheTio,amoretractablepeoplethantheBobangi—eagerfortradebutnotdemandingmonopoly,accordingtowhattheVoyagerheard.MaybetheTiowerehumblerbecausetheriverwasnowsovast.Noonecouldimaginehimselfowningsuchariver.Notribe,even.HeretheVoyagersawdozensofotherboats.Itwasanewuniverse.Manycanoes,severalmoresteamboats,peopleholleringandtradingfromoneboattoanother.Themazeofchannelsandthetraffic,plustheincreasingdistancefromOuesso,gaveasenseofjumbleandanonymityandsecuritythatallowedtheVoyagertotravelbydaylight,whichwasfortunateintheseformidablewaters.HesoldfreshfishtoTioboatmenandswappedfishformanioc.Hechatted.Yes,I’vecomefromtheupperriver,veryfar.Buthedidn’tsaywhichriver.Hedidn’tmentionivory.Hegatheredintelligencewithoutrevealingmuch.Hewastired.

Hehadanintermediategoalnow,betweenthedailypurposeofsurvivalandthedreamofduerewardforhistroubles.Hehadadestination:aplacecalledBrazzaville.Itwasalargetown,downriver,somedaysahead.Itsatontheright,besideagreatpool.Hewouldknowitwhenhesawit—sohe’dbeentold.Anotherbigtownsatontheleftbank,acrossthepool,butthatonewasownedbytheBelgians.WhoaretheBelgians?heasked.AretheyatribeliketheBobangi?Worse.Yes,heheard,Brazzavillewasagoodmarketforfishorwhateveryouhad.

AndsotheVoyagerarrived.Heroundedalastbend,cametoagreatpoolwheretheriverseemedaswideasitwaslong,putalargeislandtohisleftasadvised,andsawwhitebuildingsontherightbank,someofthemtwiceastallasahouse,tallereventhanthecircularmarkethallatOuesso.Hepaddledtowardthewhitebuildings.Comingnear,heheldhimselfsomedistanceout,drifting,observing,untilhewaswellpastthedocksandthebigboatsandthebustleofworkingmen,thenbeachedhiscanoeinaquieterplace.Severalchildrengaped,aschildrendo,butnooneelsenoticedhim.PeoplewerebusyandnoadultsdivertedtheirattentiontothesightofastrongyoungBakwelecomingashoreintatteredclotheswithacrocodileskull,asinglefinetusk,andhalfaboatloadofrottenfish.

Hesteppedoutofthewaterandstoodalone.Noonegreetedhim.

Nooneknewwhathehaddone.NoonecomparedhimtoLewisandClark.NoonehailedhimastheMarcoPolooftheupperCongobasin.NooneknewthathewasHuckFinnandJim,JohnWesleyPowellontheColorado,TeddyRooseveltontheRiverofDoubt,FrankBormancirclingthemooninApollo8,andDr.RichardKimbleatlarge.Nooneknew.

TheVoyagerwalkedintotownandsoldhistuskthefirstafternoon,receiving120brassrods,whichwasagoodprice,hethought,butalsosomehowanticlimacticandunsatisfactory.Forhiscrocodileskull,atthebenignwhimoftheivorybuyer,hereceivedanothertenbrassrods.Heboughtsomepalmwine,gotdrunk,foundthatexperiencenottohisliking,andneverdiditagain.Therestofhismoneyhesaved,orrathersetaside,spendingitslowlyandvariouslyuntilitwasgone.Hehadarrived.

HefoundlodginginPoto-Poto,aneighborhoodeastofthecitycenter,fullofothersfromtheupperriver,andgotworkonthewaterfront.Hemadefriends.Hesettledin.Urbanlifesuitedhim.Hebecamesomethingofacolorfulfigure,confident,charminginhisriver-manway,withstoriestotell.Nooneviewedhimasthepariahsonofasorceress.Nooneguessedthathehadeverbeenasurlyyoungloner.Nooneknewhisrealnamebecausehehadinventedanother.Andtheotherthingnooneknew,notevenhe,wasthathehadbroughtanewelement,anewcircumstance,toBrazzaville.Avirus,inhisblood.Morespecifically:HehadbroughtHIV-1groupM.

Sevenandeightandnineyearslater,neartheendofhislife,theVoyagerwouldtellsomeofhisstoriestofriends,acquaintances,andafewofthewomenwithwhomhehadrelationships,transientorlonger:abouttheDeadElephant,theHalf-PortugueseMerchant,theTallBoy,theCrocodile,andtheBlue-EyedBobangi.Inhistelling,theTallBoybecameanadultandtheCrocodilewasverylarge,aleviathan.Noonedoubtedhisword.Theyknewhehadcomedowntheriveranditmusthavebeenperilous.Thecrocodileskullwasn’ttheretobeliehim.Duringthoseyearshesleptwiththirteenwomen,allofwhomwerefemmeslibrestoonedegreeoranother.Oneofthose,ayoungTiogirlwhohadrecentlyarrivedinBrazzavillefromupriver,andwhofoundthatshefanciedhimmorethanshedidherfreedom,becamehiswife.Eventuallyheinfectedherwiththevirus.Healsoinfectedoneother,arathermoreprofessionalwomanwholivedinasmallhouseintheBacongoneighborhood,westoftown,wherehevisitedheronanintermittentbasiswhenhiswifewaspregnant.Theotherelevenwomenhadonlyfleetingsexualcontactswithhimandwereluckier.TheyremainedHIV-negative.TheVoyager’spersonallifetimecontributiontothebasicreproductionratewasthereforeprecisely2.0.Peoplelikedhimandweresorrywhenhefellill.

TheBacongogirlfriendwasvivaciousandprettyandambitiousforwiderhorizons,soshecrossedthepooltoLéopoldville,whereshehadasuccessfulcareer,thoughnotalongone.

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IfthevirusreachedLéopoldvillein1920orso,thatstillleavesagapoffourdecadestothetimeofZR59andDRC60,thoseearliestarchivalHIVsequences.Whathappenedduringtheinterim?Wedon’tknow,butavailableevidenceallowsaroughsketchoftheoutlinesofpossibility.

Theviruslurkedinthecity.Itreplicatedwithinindividuals.Itpassedfromonepersontoanotherbysexualcontact,andpossiblyalsobythereuseofneedlesandsyringesfortreatmentofwell-knowndiseasessuchastrypanosomiasis.(Moreonthatpossibility,below.)Whateveritsmeansoftransmission,presumablyHIVcausedimmunodeficiency,eventuallydeath,amongmostorallpeopleinfected—exceptthosewhodiedearlyfromothercauses.Butitdidn’tyetassertitselfconspicuouslyenoughtoberecognizedasadistinctnewphenomenon.

ItmayalsohaveproliferatedslowlyinBrazzaville,acrossthepool,helpedalongtheretoobychangingsexualmoresandprogramsoftherapeuticinjection.ItmayhavelingeredinvillagesofsoutheasternCameroonorelsewhereintheupperSanghabasin.Andwhereveritwas,butdefinitelyinLéopoldville,itcontinuedtomutate.ThewidedivergencebetweenZR59andDRC60tellsusthat.Itcontinuedtoevolve.

StudyingtheevolutionaryhistoryofHIV-1is(notwithstandingthatill-advisedcommentbytheWHO’sDavidHeymanntoTomCurtis)morethananidleexercise.Thepointistounderstandhowonestrainofthevirus,groupM,hasmadeitselfsodeadlyandwidespreadamonghumans.Suchunderstanding,inturn,mayleadtowardbettermeasurestocontrolthedevastationofAIDS,possiblybywayofavaccine,morelikelybywayofimprovedtreatments.That’swhyscientistssuchasBeatriceHahn,MichaelWorobey,andtheircolleaguesexplorethemolecularphylogeneticsofHIV-1,HIV-2,andthevariousSIVs.Oneissuetheyaddressiswhetherthevirusbecamevirulentbefore,oronlyafter,itsspilloverfromPantroglodytes.Tostatethequestionmoreplainly:DoesSIVcpzkillchimps,orisitonlyaninnocuouspassenger?AnsweringthatonecouldrevealsomethingimportantabouthowhumanbodiesrespondtoHIV-1.

ForawhileafterthediscoveryofSIVcpz,theprevailingimpressionwasthatit’sharmlessinchimpanzees,anancientinfectionthatmayoncehavecausedsymptomsbutnolongerdoes.Thisimpressionwasbolsteredbythefactthat,intheearlieryearsofAIDSresearch,morethanahundredcaptivechimpanzeeshadbeenexperimentallyinfectedwithHIV-1andnonehadshownimmunesystemfailure.WhenasinglelabchimpanzeedidprogresstoAIDS(tenyearsafterexperimentalinfectionwiththreedifferentstrainsofHIV-1),itscasewasremarkableenoughtomeritasix-pagepaperintheJournalofVirology.Theresearchersimpliedthatthiswasgoodnews,finallyofferinghopethatchimpanzeesdorepresentarelevantexperimentalmodel(thatis,asufficientlyanalogoustestsubject)forstudyinghumanAIDS.Therewasevenareport,basedongeneticanalysisofcaptiveanimalsintheNetherlands,suggestingthatchimpanzeeshad“survivedtheirownAIDS-likepandemic”morethan2millionyearsago.Theyhademergedfromthe

experience,accordingtothislineofthought,withgeneticadaptationsthatrenderthemresistanttotheeffectsofthevirus.Theystillcarryitbutapparentlydon’tgetsick.Thatnotion,torepeat,wasfoundedoncaptivechimpanzees.AsforSIV-positivechimpsinthewild:Nooneknewwhethertheysufferimmunodeficiency.Itwasadifficultquestiontoresearch.

Thesesuppositionsandguessesjibedwithavailableinformationaboutothervariantsofthevirusinotherprimates.SIVishighlydiverseandbroadlydistributed,foundasanaturallyoccurringinfectioninmorethanfortydifferentspeciesofAfricanmonkeyandape.(Butitseemstobeuniquetothatcontinent.AlthoughsomeAsianprimateshaveacquiredthevirusincaptivity,ithasn’tshownupamongwildmonkeysineitherAsiaorSouthAmerica.)MostofthoseSIV-carryingAfricansimiansaremonkeys.EachkindofmonkeyharborsitsowndistincttypeofSIV,suchasSIVgsninthegreaterspot-nosedmonkey,SIVverinthevervet,SIVrcminthered-cappedmangabey,andsoforth.Basedonevidencepresentlyavailable,noneofthoseSIVsseemstocauseimmunodeficiencyinitsnaturalhost.Acloseevolutionarykinshipbetweentwokindsofsimian,suchasL’Hoest’smonkeyandthesun-tailedmonkey,bothclassifiedinthegenusCercopithecus,issometimesparalleledbyaclosesimilaritybetweentheirrespectiveSIVs.Thosedeeptaxonomicalignments,plustheabsenceofnoticeabledisease,ledresearcherstosuspectthatAfricanmonkeyshavecarriedtheirSIVinfectionsforaverylongtime—probablymillionsofyears.Thatlengthoftimewouldallowdivergenceamongthevirusesandmutualaccommodationbetweeneachtypeofvirusanditshost.

Thesametwo-parthypothesisappliedalsotochimps:thattheirvirus,SIVcpz,is(1)anancientinfectionthatnow(2)causesnoharm.Butforchimpsthosewerejusttenuousassumptions.Thennewevidenceandanalysesaddressedthem,andbothpartsturnedouttobewrong.

Thefirstpremise,thatSIVcpzhaslurkedwithinchimpanzeesforaverylongtime,begantolookdoubtfulin2003.That’swhenanotherteamofresearchers(ledbyPaulSharpandElizabethBailesoftheUniversityofNottingham,andincludingagainbothBeatriceHahnandMartinePeeters)noticedthatSIVcpzseemstobeahybridvirus.TheNottinghamgroupreachedthatconclusionbycomparingthegenomeofSIVcpzwiththegenomesofseveralmonkeySIVs.Theyfoundthatonemajorsectionofthechimpvirus’sgenomematchescloselytoasectionofSIVrcm.AnothermajorsectioncloselyresemblesasectioninSIVgsn.Inplainwords:Thechimpviruscontainsgeneticmaterialfromthevirusofred-cappedmangabeysandalsogeneticmaterialfromthevirusofgreaterspot-nosedmonkeys.Howdidithappen?Byrecombination—thatis,geneticmixing.Achimpanzeeinfectedwithbothmonkeyvirusesmusthaveservedasthemixingbowlinwhichtwovirusestradedgenes.Andwhendidithappen?Possiblyjusthundredsofyearsago,ratherthanthousandsortensofthousands.

Howdidasinglechimpanzeebecomeinfectedwithtwomonkeyviruses?Presumablythatoccurredthroughpredation,orthroughthecombinedcircumstancesofpredation(bringingaboardonevirus)plussexualtransmission(bringingaboardasecond),followed

byachancerearrangementofgenesbetweenonevirusandtheotherduringviralreplication.Chimpanzeesareomnivoreswholoveanoccasionaltasteofmeat.Theykillmonkeys,ripthemapart,fightoverthepiecesorshareoutgobbetsandjoints;thentheyeattheflesh,redandraw.Itdoesn’thappenoften,justwhenevertheopportunityandthehankeringarise.Suchgorefestsmustsometimesinvolveblood-to-bloodcontact.Chimpanzees,evenwithouttheuseofmachetes,sufferwoundsontheirhandsandintheirmouths.Bloodymeatplusanopensoreequalsexposure.WhattheNottinghamgroupsuggestedwasanotherchimpanzeeversionofthecut-hunterhypothesis—exceptinthiscasethecuthunterwasthechimp.

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SotheveryexistenceofSIVcpzisrelativelyrecent.Ithasnoancientassociationwithchimpanzees.Andnow,basedonastudypublishedin2009,parttwoofthetwo-parthypothesishasalsobeencastintodoubt.Thevirusisnotharmlessinitschimpanzeehost.EvidencefromthechimpsofGombe—JaneGoodall’sstudypopulation,knownandbelovedaroundtheworld—suggeststhatSIVcpzcausessimianAIDS.

I’vementionedalreadythatthefirstwildchimptotestSIV-positivewasatGombe.WhatIdidn’tsay,butwillhere,isthatSIV-positivestatusamongGombe’schimpanzeescorrelatesstronglywithfailinghealthandearlydeath.AgainitwasBeatriceHahnandhergroupwhomadethediscovery.

HavingfoundSIVcpzincaptivechimps,Hahnwantedtolookforitinthewild.ButsheandherteamofyoungmolecularbiologistsknewlittleaboutsamplingchimpanzeesinanAfricanforest.Whatdoyoudo—gooutanddartone?Knocktheapeoutwithketamine,takeblood,wakehimup,andsendhimonhisway?Egads,no!saidfieldprimatologists,horrifiedattheprospectofanysuchinvasiveviolationoftheirsensitive,trustingsubjects.ItwasanewrealmforHahn,withanewsetofconcernsandmethods,towhichshequicklybecameattuned.Atascientificmeetingthatbroughtprimateresearcherstogetherwithvirologists,shemetRichardWrangham,ofHarvard,highlyrespectedforhisworkonthebehavioralecologyandevolutionofapes.WranghamhasformanyyearsledastudyofchimpanzeesatKibaleNationalPark,inwesternUganda;beforethat,fourdecadesago,hedidhisownPhDfieldworkatGombe.HerespondedenthusiasticallytoHahn’sideaofscreeningwildchimps,andultimatelyitwasWrangham,sherecalled,“whoconvincedJanethatwewereokaytoworkwith.”ButbeforeanysuchworkbeganatGombe,theylookedatthechimpsofKibale,Wrangham’sownresearchsite.CrucialhelpcamefromaWranghamgradstudentnamedMartinMuller,whoin1998hadcollectedurinesamplesforastudyoftestosterone,aggression,andstress.MarioSantiago,ofHahn’slab,cookeduptherequisitetoolsfordetectingSIVcpzantibodiesinafewmillilitersofpiss,andMartinMullersuppliedsomefrozensamplesfromhiscollectionsatKibale.Forthispartofthestory,IwenttoAlbuquerqueandtalkedwithMuller,nowanassociateprofessorofanthropologyattheUniversityofNewMexico.

TheKibalesamplesalltestednegativeforSIV.“Wewereslightlydisappointed,”Mullerrecalled.“Thatwasbecause,atthetime,theconventionalwisdomwasthatthisdidn’thaveanynegativeimpactsonchimps.”Disappointmentatnegativeresultswasallowable,hemeant,becausepositiveresultswouldnothavespelleddoomforthoseKibalechimps—orsoitwasthought.Meanwhile,though,hewasgettingsomeinterestingresultsinhishormonestudyandwantedtobroadenhisdata.HeandWranghamagreedthatitmightbeinstructivetosampleafewotherchimppopulationsforcomparison.ThatledMullerdowntoGombe,inAugust2000,withhisurine-collectingbottlesandallthecumbersomeequipmentnecessarytokeepsamplesfrozen.Hestayedonlyacoupleweeks,trainingTanzanianfieldassistantstocontinuethecollecting,andbroughtawayjustafew

sampleshimself.BackhomeintheUnitedStates,hee-mailedHahntoaskwhethershewouldlikesixtubesoffrozenGombeurine,towhichshereplied:“YES,YES,YES.”Hesentthemwithcodedlabels,standardprocedure,soHahnhadnowayofknowingwhosewaswhose.TwoofthesixtestedpositiveforSIVantibodies.Breakingthecode,MullerinformedherthatbothsamplescamefromachimpnamedGimble,atwenty-three-year-oldmale.

Gimblewasawell-knownmemberofoneofthefamedGombefamilies;hismotherhadbeenMelissa,asuccessfulmatriarch,andhisbrothersincludedGoblin,whorosetobethecommunity’salphamaleandlivedtoageforty.Gimble’slifeandcareerwouldbedifferent—andshorter.

SoonaftergettingtheresultsonGimble,BeatriceHahnwrotealonge-mailtoJaneGoodall,explainingthecontextandtheimplications.Goodallherselfhadtrainedasanethologist(shetookaPhDatCambridge),notasamolecularbiologist,andtherealmofWesternblotanalysisforantibodieswasasalientoherasfieldsamplinghadbeentoHahn.HerworkonchimpanzeesbeganbackinJuly1960,atwhatwasthentheGombeStreamGameReserve,ontheeastshoreofLakeTanganyika,andwhichlaterbecameGombeNationalPark.SheestablishedtheGombeStreamResearchCenterin1965,basedinasmallconcretebuildingnearthelake,andcontinuedherstudyofchimpsinthehillyforestforanothertwenty-oneyears.In1986Goodallpublishedanimposingscientificopus,TheChimpanzeesofGombe,andthenendedherowncareerasafieldscientistbecause,appalledbythetreatmentofchimpanzeesinmedicallabsandothercaptivesituationsaroundtheworld,shefeltobligedtobecomeanactivist.ThestudyofGombe’schimpswentaheadinherabsence,thankstowell-trainedTanzanianfieldassistantsandlatergenerationsofscientists,addingdecadesofdataandpreciouscontinuitytowhatGoodallhadstarted.SheremainedcloselyconnectedtoGombeanditschimps,bothpersonallyandthroughtheprogramsofherJaneGoodallInstitute,butshewasn’toftenpresentattheoldresearchcamp,apartfromstoleninterludesofrestandreinvigoration.Insteadshetraveledtheworld,roughlythreehundreddaysayear,lecturing,lobbying,meetingwithmediapeopleandschoolchildren,deliveringherinspirationalmessage.HahnunderstoodtheintensityofGoodall’sprotectivenesstowardchimpsingeneral,towardGombe’schimpsinparticular,andofherwarinesstowardanythingthatmightputtheminmorejeopardyofexploitation,especiallyinthenameofmedicalscience.Attheendofthelonge-mail,Hahnwrote:

LetmefinishbysayingthatfindingSIVcpzintheGombecommunityisavirologist’sDREAM-COME-TRUE.Giventhewealthofbehaviouralandobservationaldatathatyouandyourcolleagueshavecollectedoverdecades,itistheIDEALsettingtostudythenaturalhistory,transmissionpatternsandpathogenicity(orlackthereof)ofnaturalSIVcpzinfectioninwildchimpanzees.Moreover,allthiscanbedoneentirelynon-invasively.ANDtherecertainlyarefundingopportunitiesforsuchauniquestudy.So,thevirologist’sdream-come-truedoesnothavetobetheprimatologist’snightmare,althoughIamsureitwilltakesometimebeforeIcanconvinceyouofthat.

EventuallyshedidconvinceGoodall,butnotbeforeanothernightmarishdiscoveryemergedfromthework.

Earlierinhere-mail,Hahnhadwritten:“Withrespecttothechimpanzees,itisprobablysafetosaythatSIVinfectionwillNOTcausethemtodevelop

immunodeficiencyorAIDS.”Onthatpoint,shewouldproveherselfwrong.

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JaneGoodalldescribedherownconcernswhenIcaughtupwithherduringoneofherstopovers.Wekneweachotherfrompreviousadventures—amongchimpsintheCongobasin,amongblack-footedferretsinSouthDakota,oversingle-maltscotchinMontana—butthiswasachancetositdownquietlyatahotelinArlington,Virginia,duringaparalyzingsnowstorm,andtalkaboutGombe.Thefiftiethanniversaryofherownchimpstudywasapproaching,andIwasassignedbyNationalGeographictowriteaboutit.Afterwediscussedherchildhoodinfluences,herdreamofbecominganaturalistinAfrica,hermentorLouisLeakey,herearlydaysinthefield,andhertimeasaPhDstudentatCambridge,sheherselfmentionedgeneticsandvirology.AtthatpointIturnedtheconversationtoSIV.

“Iwasreally,reallyapprehensiveaboutBeatriceHahn’sresearch,”Janevolunteered.“Wewere,alotofus,reallynervousabouttheresultofwhatmighthappenifshefoundHIV/AIDS.”ShehadmetHahn,talkedwithher,andwasreassuredbytheforceofHahn’sconcernforthechimps’welfare.“Butstill.Istillhavethisuneasebecause,eventhoughshecares,oncetheseresultsareout,astheyarenow,otherpeoplecanusethemindifferentways.”Forinstance?Whatsortofdangers,Iasked,didJanehaveinmind?“Thatthiswouldstartawholenewflurryofresearchoncaptivechimpsinmedicallabs.”ThenewsofchimpswithAIDS,shefeared,wouldsoundlikeapromisingopportunitytolearnmoreaboutAIDSinhumans,nevermindthechimps.

WhatabouttheimpactofthevirusatGombeitself?WebothknewthatHahnhadfoundsomethingresemblingAIDS,andbynowGimblewasdead.WhatabouttheprospectthatothermembersoftheGombecommunitymightdieofimmunefailure?“Yeah,exactly,”Janesaid.“That’saveryscarythought.”

Asscaryasitwas,though,shehadrealizedfromthestartofherconversationswithHahnthatsuchafindingcouldbetakentwoways.Ontheonehand,shesaid,therewasapossibleconsolation:IfpeopleheardthatwildchimpscarryanAIDS-causingvirus,theymightstophuntingandbutcheringandeatingthem.“Becausethey’llbeafraid.Thatwasonesideofit.Thentheothersideofitwas,well,peoplewillsay,‘Allthesecreaturesarereallydangerousforus,solet’skillthemall.’Itcouldhavegoneeitherway.”Janeisaperspicaciouswoman.Shehastheauraofasecularsaintbutisactuallyquitehuman,grounded,savvy,andcapableofambivalence.Asthingshavetranspiredsofar,shenoted,neitheroftheextremeoutcomeshasoccurred.

BrieflywediscussedHahn’snoninvasivesamplingmethodology:Urinemightcontainantibodies,andfecescouldyieldviralRNA.Janeallowedthatithadbeenreassuring,thatpartaboutnonecessityofknockingchimpsoutandjabbingthemwithneedles.“Don’tneedblood,”shesaid.“Justneedabitofpoo.”Amazingwhattheycandofromabitofpoo,Iagreed.

SoshehadgivenherconsentforHahn’sstudy,andtheworkproceeded.AttheendofNovember2000,Hahn’slabinAlabamareceivedthefirstbatchofmaterial,which

includedthreefecalsamplesfrompoorGimble.Hahn’sgradstudentMarioSantiagodidthescreening,andagainallthreeofGimble’ssamplestestedpositive.SantiagothenamplifiedaviralRNAfragmentandsequencedit,confirmingthatGimble’sviruswasindeedSIVcpz.Itseemedtobeanewstrain,distinctenoughfromotherknownstrainsthatitmightbeuniquetoEastAfrica.Thiswassignificantonseveralcounts.Yes,thechimpsofGombewereinfected.No,theycouldn’tbesourceanimalsforthehumanpandemic.ThevariantsofSIVfoundbyMartinePeetersinwesternAfrica(thiswasbeforeHahn’sownfindingsfromCameroon)morecloselymatchedHIV-1groupMthantheGombevirusdid.

Inmid-December,anothere-mailfromHahn’scomputerwentouttoRichardWrangham,JaneGoodall,MartinMuller,andothers.UnderthesubjectlineGOODNEWSATLAST,HahndescribedthefindingsfromGimbleandthepositionofhisstrainontheSIVfamilytree.Then,withhercharacteristicpenchantforuppercaseexuberance,shewrote:“THISISAHOMERUN!”

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Thatwasjustthebeginning.Fornineyearsthestudycontinued.FieldworkersatGombecollectedfecalsamplesfromninety-fourdifferentchimpanzees,eachofwhichwasknownbynameand,inmostcases,byitsindividualcharacterandfamilyhistory.BeatriceHahn’speopledidtheanalyses,findingthatseventeenofthoseninety-fourchimpswereSIV-positive.Astimepassed,somechimpsdied.Othersdisappearedintheforestandwerepresumeddeadwhentheyfailedtoreappear.Deathisoftenaprivatematterforwildcreatures,includingchimpanzees,especiallywhenitcomesuponthembyslowandpainfuldegrees.Theytendtogoabsentfromthesocialgroup,ifthereisasocialgroup,andmeettheendalone.GimblelastshowedhimselftotrackersonJanuary23,2007.Hisbodywasneverfound.

BackinBirmingham,therewasturnoverofadifferentsort,asgradstudentsandpostdocscycledthroughHahn’slab.MarioSantiagodeparted,headingoffforthenextstageofhiscareer,andBrandonKeelearrived.SamplescontinuedcomingfromGombe,inoccasionalbatches,andthosesampleswereanalyzed—aslowandlaboriousprocess.MuchoftheworkfelltoKeele,thoughevenforhimthiswas“abackburnerproject.”Keeledescribedtome,duringmyvisitwithhimatFortDetrick,themomentofrecognitionthatoccurredneartheendofhispostdocperiod,bringingthatprojecttothefrontburner.

“Iwastryingtoleaveandfinishup.Isaidtomyself,‘Iwonderwhat’shappeningwiththesechimps?’”HewasawarethatthenumberofknownSIV-positivesatGombehadincreasedasthesamplingstretchedon,andthattherewasevidenceofverticaltransmission(mothertoinfant)aswellassexualtransmissionaccountingfornewinfections.Hethoughtthestudymightyieldaninteresting,undramaticpaperabouthowaharmlessvirusspreadsthroughapopulation.“Andthenwestartedcompilingthedata,”hetoldme.Thatmeantbringinginadimensionofbehavioralobservationsfromthefield.SohecontactedcollaboratorsattheJaneGoodallInstitute’sresearchheadquartersinMinnesotaand,askingaboutoneindividualafteranother,heardadrumbeatofunsettlingnews.

“Oh,no,thatchimpisdead.”

“No,thatchimpisdead.Hediedin2006.”

“No,thatchimpisdead.”

Keelerecalledaskinghimself:“Whatthehellisgoingon?”Partoftheanswer,revealedwhenhesawanupdatedmortalitylist,wasthatawaveofuntimelydeathshadbeensweepingthroughSIV-positivemembersoftheGombepopulation.

HeandtheteamatHahn’slabhadrecentlywrittenanabstractforatalkheplannedtogiveatameeting,whichwouldleadintimetoajournalpublication.Thedraftabstract,byKeele’srecollection,containedasentencesuchas:“Itdoesn’treallyseemthatthereisadeathhazardtoinfectioninthesechimps.”Theyhadsentthedrafttotheirpartnersat

Gombe,whorespondedquicklywithnewsofsevenadditionalchimpanzeedeaths,aboutwhichKeelehadn’tevenknown.Hescrappedtheabstract,thoughtagainaboutwhathewasdoing,andbeganworkingmorecloselywithGombeandMinnesotatoassembleamorecompletesetofdata.Thentheywouldseewhereitled.

Aroundthesametime,springof2008,KeelealsoheardaboutsomeunusualpathologyresultsontissuesfromonedeadGombechimp.ThechimpwasknownasYolanda,atwenty-four-year-oldfemale.ShesickenedinNovember2007,ofanunknownailment,andcamedownfromthemountainstolanguishneartheresearchcenter.Peopletriedtofeedher,butYolandadidn’teat.Shesatintherainamidthickvegetation,weakenedandmiserable,andthendied.Theyputherbodyinafreezer.Twomonthslater,itwasthawedfornecropsy.

ThenecropsywasperformedbyJaneRaphael,aTanzanianveterinarianworkingattheGombeStreamResearchCenterandspeciallytrainedforthetask.NotknowingwhetherYolandahadbeenSIV-positive,Raphaeltookthestipulatedprecautions.SheworeafullTyveksuit,twolayersofgloves,anN95respiratormask,afaceshield,andrubberboots.ShesplitopenYolanda’sbelly,cutthroughtheribs,andspreadthemwidetoseewhatshecouldsee.

“Themainproblemwasintheabdominalcavity,”Raphaeltoldme,twoyearslater,aswesatinhersmallofficejustupfromtheshoreofLakeTanganyika.“Therewassomethinglikeabdominalperitonitis.Theintestineswereverymuchadheredtogether.”Raphael,aquietwoman,wearinganeatcornrowhairdoandafloweredprintdress,choseherwordscarefully.Shedescribedseparatingtheglommedgutswithherglovedhands.“Itwasunusual,”shesaid.Sheseemedtorememberitallvividly.“Themusclesunderneaththepelviswereverymuchinflamed.Red.Andtheyhadsomeblackishspots.”Whatcausedtheinflammation?Judiciouslyempirical,Raphaelsaidshedidn’tknow.

Herinspectiondone,shehadsnippedouttissuesamplesfromvirtuallyeveryorgan:spleen,liver,intestines,heart,lungs,kidneys,brain,lymphnodes.FortheSIV-positivecases,shesaid,lymphnodeswereespeciallyimportant.Yolanda’slymphnodesappearednormaltotheeye,buthistopathologywouldlaterpenetratethatillusion.Someofthesamples,preservedinRNAlater,wentofftoBeatriceHahn.Others,pickledinformalin,weredestinedforapathologistinChicago.Whentheresultscametogether,thiscasewouldchallengeprevailingideasaboutSIVinchimpanzees.“Previouslyitwassaid,theyareinfectedbuttheydon’tcomedownwiththedisease,”Raphaeltoldme.“Yolandamadeustostartthinkingotherwise.”

IfollowedthepickledsamplestoChicago,wherethepathologistwhohadexaminedthem,KarenTerio,welcomedmetoaglimpseoftheevidence.Teriotrainedasaveterinarian,atoneofthecountry’sbestvetschools,thendidaresidencyandadoctorateinpathology,specializingindiseasestransferredbetweenspecies.SheworkedfortheUniversityofIllinoisandconsultedfortheLincolnParkZoo,whichhelpsrunahealth-monitoringprojectatGombe.HencethelymphnodesandotherbitsofYolandacameforherexpertscrutiny.Teriocutupthetissues,sentthemtolaboratorytechniciansformountingandstaining,thensatdownforalookattheslides.“ItwasstrikingbecauseI

couldn’tfindanylymphocytes,”shetoldme.“WhenIsawthefirstlymphnode,Ithought,‘Hmm,thisisweird.’”Sheaskedherbosstohavealookthroughthemicroscope.Hedid,andagreedtherewassomethingverywrong.ShephonedacolleagueattheLincolnParkZoo,ElizabethLonsdorf,wholeadsthezoo’sworkonbehalfofwildAfricanapes,includingthehealthprojectatGombe.

“Wehaveaproblem,”TeriotoldLonsdorf.“Shedoesn’thaveanylymphocytes.”

“DoesthatmeanwhatIthinkitmeans?”

“Yes.Thelesionsinthisanimallooklikeanend-stageAIDSpatient.”

TogethersheandLonsdorfmadeacalltoBeatriceHahn.Hahn’sfirstquestionwas,“Areyousure?”Teriowasindeedsure,butshequicklye-mailedimagesoftheslidessothattheotherscouldjudgeforthemselves.BrandonKeelewasbynowintheloop.Teriosentactualslidestoanothercollaborator,anexpertonimmune-systempathology,torefinethediagnosis.Everyoneagreedand,withthesamplecodebroken,everyoneknewhowthesepiecesfittogether:ThechimpYolanda,deadatagetwenty-four,hadbeenSIV-positiveandsufferingimmunodeficiency.

Invitingmetoachairatherbigdouble-viewerOlympusmicroscope,KarenTeriobroughtoutthesameslidesshehadsharedwithHahnandLonsdorf.Fromherplaceatthescopeshecouldmanipulateacursor,alittleredarrow,movingitoverthefieldtopointoutwhatwewereseeing.Firstsheshowedmeathin-slicesectionfromalymphnodeofanormal,SIV-negativechimpanzee.Thiswasforcomparison.ItlookedlikeapeatbogasviewedonGoogleEarth,bulgingandrifewithsphagnumandhuckleberry,thick,rich,andriddledjustslightlywithnarrowspacesresemblingsmallsloughsandcreeks.Thetissuewasstainedmagentaandheavilyspeckledwithdarkerbluedots.Thedots,Terioexplained,werelymphocytesintheirhealthyabundance.Inanareawherethey’reespeciallydense,theypacktogetherintoafollicle,likeabagfullofjellybeans.Shejabbedherredarrowatafollicle.

Thensheplacedanotherslideintoviewingposition.TheslideheldaslicefromoneofYolanda’slymphnodes.Insteadofapeatbog,itlookedlikescrubdesertslashedbyalargedrywash,manydayssincethelastrain.

“Mmmm,”Isaid.

“Thisisessentiallytheconnectivetissue,”Teriosaid.Shemeantthatitwassupportivestructureonly,minustheworkinginnards.Sereandempty.“We’vegotvery,veryfewlymphocytesleftinthisanimal.”

“Yeah.”

“Andit’scollapsed.Yousee,thiswholethinghasjustsortofcollapsedonitself,’causethere’snothingintheretoholditup.”Herlittleredarrowwanderedforlornthroughthedesert.Nosphagnum,nofollicles,nolittlebluedots.IimaginedKarenTerio,backinApril2008,examiningtheseslidesonherlonesome—andencounteringsuchevidence,beforeanyoneelse,atatimewhentheillusionofnonpathogenicSIVcpzwasembracedbyresearcherseverywhere.

“Soyousatthere,andlookedatthis…”

“Andwent,‘Oh,no,’”shesaid.

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Terio’sfindings,plusthefielddatafromGombe,plusthemolecularanalysesfromHahn’slab—theseallcametogetherinapaperpublishedbyNatureduringthesummerof2009.BrandonKeelewasfirstauthor;BeatriceHahnwaslast.“IncreasedMortalityandAIDS-likeImmunopathologyinWildChimpanzeesInfectedwithSIVcpz”wasthecatchytitle.Ithinkofit—andI’mnotalone—as“theGombepaper.”ThelonglistofcoauthorsincludedKarenTerio,Terio’sboss,ElizabethLonsdorf,JaneRaphael,twoofHahn’sseniorcolleagues,theexpertonprimatecellpathology,thechiefscientistatGombe,andJaneGoodallherself.

“Well,Isortofhadtobe.ButIhadtheselongtalkswithBeatricefirst,”Janetoldme.“Shewasgoingtopublishitanyway.”Inthesweepofinevitabilityandthenameofscience,Dr.Goodallsignedon.

Thepaper’ssalientconclusionwasthat,contrarytoKeele’searlierdraftabstract,thereisindeedadeathhazardforSIV-positivechimpsatGombe.Oftheeighteenindividualsthatdiedduringthestudyperiod,sevenwereSIV-positive.Giventhatlessthan20percentofthepopulationwasSIV-positive,andadjustedfornormalmortalityatagivenage,thisreflectedariskofdeathtentimestosixteentimeshigherforSIV-positivechimpsthanforSIV-negatives.Repeat:tentosixteentimeshigher.Thetotalnumbersweresmallbutthemarginwassignificant.Infectedanimalswerefallingaway.Furthermore,SIV-positivefemaleshadlowerbirthratesandgreaterinfantmortality.Furtherstill,threenecropsiedindividuals(includingYolanda,thoughhernamewasn’tmentioned)showedsignsoflymphocytelossandotherdamageresemblingend-stageAIDS.

Theauthorssuggested,cautiouslybutfirmly,“thatSIVcpzhasasubstantialnegativeimpactonthehealth,reproductionandlifespanofchimpanzeesinthewild.”Soit’snotaharmlesspassenger.It’sahominoidkiller.Theirproblemaswellasours.

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Here’swhatyouhavecometounderstand.ThattheAIDSpandemicistraceabletoasinglecontingentevent.Thatthiseventinvolvedabloodyinteractionbetweenonechimpanzeeandonehuman.ThatitoccurredinsoutheasternCameroon,aroundtheyear1908,giveortake.Thatitledtotheproliferationofonestrainofvirus,nowknownasHIV-1groupM.Thatthisviruswasprobablylethalinchimpanzeesbeforethespilloveroccurred,andthatitwascertainlylethalinhumansafterward.ThatfromsoutheasternCameroonitmusthavetraveleddownriver,alongtheSanghaandthentheCongo,toBrazzavilleandLéopoldville.Thatfromthoseentrepôtsitspreadtotheworld.

Spreadhow?OnceitreachedLéopoldville,thegroupMvirusseemstohaveenteredavortexofcircumstancesunlikeanythingattheheadwatersoftheSangha.ItdifferedfromHIV-2biologically(havingadaptedtochimpanzeehosts)anditdifferedfromgroupsNandObychanceandopportunity(havingfounditselfinanurbanenvironment).WhateverhappenedtoitinLéopoldvilleduringthefirsthalfofthetwentiethcenturycanonlybeconjectured.Populationdensityofpotentialhumanhosts,ahighratioofmalestofemales,sexualmoresdifferentfromwhatprevailedinthevillages,andprostitution—thesewereallpartsofthemix.Butsexpluscrowdingmaynotbeasufficientexplanation.Afullerchainofconjecture,andmaybeabetterone,hasbeenofferedbyJacquesPepin,aCanadianprofessorofmicrobiologywho,duringthe1980s,workedforfouryearsatabushhospitalinZaire.Pepincoauthoredseveraljournalpapersonthesubjectand,in2011,publishedabooktitledTheOriginsofAIDS.Havingaddedsomedeephistoricalresearchtohisownfieldexperienceandmicrobiologicalexpertise,heproposedthatthecrucialfactorintermediatingbetweentheCutHunterandtheglobalpandemicwasthehypodermicsyringe.

Pepinwasn’treferringtorecreationaldrugsandtheworkssharedbyaddictsatshootinggalleries.Inapapertitled“NobleGoals,UnforeseenConsequences,”andthenatgreaterlengthinhisbook,hepointedinsteadtoaseriesofwell-intendedcampaignsbycolonialhealthauthorities,between1921and1959,aimedattreatingcertaintropicaldiseaseswithinjectablemedicines.Therewasamassiveeffort,forinstance,againsttrypanosomiasis(sleepingsickness)inCameroon.Trypanosomiasisiscausedbyapersistentlittlebug,Trypanosomabrucei,transmittedinthebiteoftsetseflies.Thetreatmentinthoseyearsentailedinjectionsofarsenicaldrugssuchastryparsamide—andapatientdidn’tgetjustoneshotbutaseries.InGabonandMoyen-Congo(theFrenchcolonialnameforwhat’snowtheRepublicoftheCongo),theregimenfortrypanosomiasissometimesentailedthirty-sixinjectionsoverthreeyears.Andthereweresimilareffortstocontrolsyphilisandyaws.Malariawastreatedwithinjectableformsofquinine.Leprosypatients,inthaterabeforeoralantibiotics,underwentacourseofinjectionswithextractofchaulmoogra(anIndianmedicinalplant),twoorthreeshotsperweekforayear.IntheBelgianCongo,mobileteamsofinjecteurs,peoplewithnoformaleducationbutasmallbitoftechnicaltraining,visitedtrypanosomiasispatientsintheirvillagestogiveweeklyshots.Itwasaperiodofmaniaforthelatestmedicalwonder:

needle-deliveredcures.Everyonewasgettingjabbed.

Ofcourse,thiswaslongbeforetheeraofthedisposablesyringe.Hypodermicsyringes,forinjectingmedicinesintomusclesorveins,wereinventedin1848and,untilafterWorldWarI,werehandmadeofglassandmetalbyskilledcraftsmen.Theywereexpensive,delicate,andmeanttobereusedlikeanyotherprecisionmedicalinstrument.Duringthe1920stheirmanufacturebecamemechanized,tothepointwhere2millionsyringeswereproducedgloballyin1930,makingthemmoreavailablebutnotmoreexpendable.TothemedicalofficersworkinginCentralAfricaatthattime,theyseemedinvaluablebutwereinshortsupply.AfamousFrenchcolonialdoctornamedEugèneJamot,workingjusteastoftheupperSanghaRiver(inaportionofFrenchEquatorialAfricathenknownasOubangui-Chari)during1917–1919,treated5,347trypanosomiasiscasesusingonlysixsyringes.Thissortofproduction-linedeliveryofinjectablemedicinesdidn’tallowtimeforboilingasyringeandneedlebetweenuses.It’sdifficultnow,basedonskimpysourcesandlaconictestimony,toknowexactlywhatsortofsanitaryprecautionsweretaken.ButaccordingtooneBelgiandoctor,writingin1953:“TheCongocontainsvarioushealthinstitutions(maternitycentres,hospitals,dispensaries,etc.)whereeverydaylocalnursesgivedozens,evenhundreds,ofinjectionsinconditionssuchthatsterilisationoftheneedleorthesyringeisimpossible.”ThismanwaswritingabouttheriskofaccidentaltransmissionofhepatitisBduringtreatmentforvenerealdiseases,butPepinquotedhisreportatlength,foritspotentialrelevancetoHIV:

Thelargenumberofpatientsandthesmallquantityofsyringesavailabletothenursingstaffprecludesterilisationbyautoclaveaftereachuse.Usedsyringesaresimplyrinsed,firstwithwater,thenwithalcoholandether,andarereadyforanewpatient.Thesametypeofprocedureexistsinallhealthinstitutionswhereasmallnumberofnurseshavetoprovidecaretoalargenumberofpatients,withveryscarcesupplies.Thesyringeisusedfromonepatienttothenext,occasionallyretainingsmallquantitiesofinfectiousblood,whicharelargeenoughtotransmitthedisease.

Howmuchofthiswenton?Verymuch.Pepin’sdiligentsearchthrougholdcolonialarchivesturnedupsomebignumbers.Intheperiod1927–1928,EugèneJamot’steaminCameroonperformed207,089injectionsoftryparsamide,plusaboutamillioninjectionsofsomethingcalledatoxyl,anotherarsenicaldrugfortreatingtrypanosomiasis.Duringjusttheyear1937,throughoutFrenchEquatorialAfrica,thearmyofdoctorsandnursesandsemiproinjectorsdelivered588,086needlesticksaimedattrypanosomiasis,nottomentioncountlessmoreforotherdiseases.Pepin’sarithmetictotaledup3.9millioninjectionsjustagainsttrypanosomiasis,ofwhich74percentwereintravenous(rightintoavein,notjustamuscle),themostdirectmethodofdrugdeliveryandalsothebestforunintentionallytransmittingablood-bornevirus.

Allthoseinjections,accordingtoPepin,mightaccountforboostingtheincidenceofHIVinfectionbeyondacriticalthreshold.Oncethereusableneedlesandsyringeshadputthevirusintoenoughpeople—say,severalhundred—itwouldn’tcometoadeadend,itwouldn’tburnout,andsexualtransmissioncoulddotherest.Someexperts,includingMichaelWorobeyandBeatriceHahn,doubtthatneedleswerenecessaryinanysuchwaytotheestablishmentofHIVinhumans—thatis,toitsearlytransmissionfromonepersontoanother.Buteventheyagreethatinjectioncampaignscouldhaveplayedarolelater,spreadingthevirusinAfricaonceitwasestablished.

Thisneedletheorydidn’toriginatewithJacquesPepin.Itdatesbackmorethanadecadetoworkbyanearlierteamofresearchers,includingPrestonMarxoftheRockefellerUniversity,whoproposeditin2000atthesameRoyalSocietymeetingonAIDSoriginsatwhichEdwardHooperspokeforhisoralpoliovaccinetheory.Marx’sgroupevenarguedthatserialpassageofHIVthroughpeople,bymeansofsuchinjectioncampaigns,mighthaveacceleratedtheevolutionofthevirusanditsadaptationtohumansasahost,justasexperimentallypassagingsomeothervirusthroughaseriesoflaboratorymicemightassistitsadaptationto,andincreaseitstransmissibilityamong,mice.JacquesPepinpickedupwherePrestonMarxleftoff,thoughwithlessemphasisontheevolutionaryeffectofserialpassage.Pepin’smainpointwassimplythatdirtyneedles,usedsowidely,musthaveraisedtheprevalenceofthevirusamongpeopleinCentralAfrica.UnliketheOPVtheory,thisonehasn’tbeendiscreditedbyfurtherresearch,andPepin’snewarchivalevidencesuggeststhatit’shighlyplausible,ifunprovable.

Mostofthoseinjectionsfortrypanosomiasisoccurredinthecountryside.Citydwellerswerelessexposedtotrypanosomiasis,partlybecausethetsetseflydoesn’tthriveinurbanjunglesaswellasitdoesingreenones.Onequestionthatoccurredtome,therefore,waswhetheranysuchmaniaforinjectinghadalsogrippedLéopoldville,whereHIVmetitsmostcrucialtest.Pepin’sanswerisunexpected,interesting,andpersuasive.Nevermindtrypanosomiasis.Hediscoveredadifferentbutequallyaggressivecampaignofinjections,aimedatlimitingsyphilisandgonorrheainthecity’spopulation.

In1929,theCongoleseRedCrossestablishedaclinicknownastheDispensaireAntivénérien,opentowomenandmenforthetreatmentofwhatweusedtocallvenerealdiseases.LocatedinaneighborhoodontheeastsideofLéopoldville,neartheriver,itwasaprivatefacilityprovidingapublicservice.Malemigrants,arrivingtoseekwork,wererequiredbycityregulationstoreporttotheDispensaireforanexam.Anyoneexperiencingsymptomscouldvisittheplacevoluntarily,andtherewasnochargefortreatment.Butthebulkofthecaseload,accordingtoPepin,“consistedofthousandsofasymptomaticfreewomenwhocameforscreeningbecausetheywererequiredtodosobylaw,intheoryeverymonth.”Thecolonialgovernmentacceptedprostitutionasanineradicablefactbutevidentlyhopedtokeepthetradehygienic—sofemmeslibreswereobligedtogetchecked.

Ifapersontestedpositiveforsyphilisorgonorrhea,heorshewouldbetreated.Butthediagnostictestingwasimprecise.Anyfreewomanormalemigrantwhohadoncebeenexposedtoyaws(causedbyabacteriumverysimilartothesyphilisbacterium,butnotsexuallytransmissible)mightflunkthebloodtest,beclassedassyphilitic,andreceivealongcourseofdrugscontainingarsenicorbismuth.Harmlessvaginalfloracouldbemistakenforgonococcus,theagentofgonorrhea.Awomandiagnosedgonorrheicmightbeinjectedwithtyphoidvaccine,oradrugcalledGono-yatren,or(evenJacquesPepinseemspuzzledbythisone)milk.Duringthe1930sand1940s,theDispensaireAntivénérienadministeredmorethan47,000injectionsannually.Mostwereintravenous.Straightintotheblood.WithincreasedmigrationtothecityfollowingWorldWarII,thenumbersrose.Intheearly1950s,thequackierremedies(intravenousmilk?)andthemetallicpoisonsgavewaytopenicillinandstreptomycin,whichhadlonger-lastingeffects

andthereforemeantfewershots.Thecampaignpeakedin1953,atabout146,800injections,orroughly400perday.Manyifnotmostofthoseinjectionswereadministeredtofemmelibres,sexworkers,ladiesofhospitality,howeveryouwanttodescribethem,whohadmultiplemaleclients.Theycameandwent.Thesyringeswererinsedandreused.ThisinacitywhereHIVhadarrived.

SixyearslatercamethebloodsamplethatyieldedtheHIVsequencenowknownasZR59.Oneyearafterthat,DRC60.Thevirushadspreadanddiversified.Itwasatlarge.NoonecansaywhethereitherofthosetwopatientshadevervisitedtheDispensaireAntivénérienforashot.Butiftheyhadn’t,theyprobablyknewsomeonewhohad.

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Fromthispointthestorygetshugeandvarious,literallygoingoffinalldirections.ItexplodesoutofLéopoldvillelikeaninfectiousstarburst.Iwon’ttrytotracethosedivergingtrajectories—ataskfortenotherbooks,withpurposesdifferentfrommine—butI’llsketchthepattern,thenfocusbrieflyononethat’sespeciallynotorious.

DuringitsdecadesofinconspicuoustransmissioninLéopoldville,theviruscontinuedtomutate(andprobablyalsotorecombine,mixinglargersectionsofgenomefromoneviriontoanother),andthosecopyingerrorsdroveitsdiversification.Mostmutationsareinsignificantchanges,orelsefatalmistakes,bringingthemutanttoadeadend,butwithsomanybillionsofvirionsreplicating,chancedidprovideasmall,richsupplyofviablenewvariants.Thecampaignsofinjectabledrugtreatments,attheDispensaireAntivénérienandelsewhere,mayhavehelpedfosterthisprocessbytransmittingthevirusquicklyintomorehumanhostsandincreasingitstotalpopulation.Themorevirions,themoremutations;themoremutations,themorediversity.

TheHIV-1groupMlineagebecamesplitintoninemajorsubdivisions,whicharenowknownassubtypesandlabeledwithletters:A,B,C,D,F,G,H,J,K.(Don’tconfusethose,ifyoucanhelpit,withtheeightgroupsofHIV-2,designatedAthroughH.AndwhyareEandImissing?Nevermindwhy.Suchedificesoflabelinggetbuiltpiecemeal,likeslumsofcardboardandtin,notwitharchitecturalforethought.)Astimepassed,asthehumanpopulationofLéopoldvillegrew,astravelincreased,virusesofthoseninesubtypesemergedfromthecity,radiatingoutwardacrossAfricaandtheworld.Someofthemwentbyairplaneandothersbymoremundanemeansoftransport:bus,boat,train,bicycle,hitchhikingonatranscontinentaltruck.Foot.SubtypeAgottoEastAfrica,probablyviathecityofKisangani,halfwaybetweenLéopoldvilleandNairobi.SubtypeCspreadtosouthernAfrica,probablyviaLubumbashi,waydownintheCongolesesoutheast.SeepingacrossZambia,achievingrapidtransmissioninminingtownsfullofworkersandprostitutes,subtypeCproliferatedthroughoutSouthAfrica,Mozambique,Lesotho,andSwaziland.ItwentontoIndia,whichislinkedtoSouthAfricabychannelsofexchangeasoldastheBritishempire,andtoEastAfrica.SubtypeDestablisheditselfalongsidesubtypesAandCinthecountriesofEastAfrica,exceptforEthiopia,whichforsomereasonbecameafflictedearlyandalmostexclusivelywithsubtypeC.SubtypeGgotupintoWestAfrica.SubtypesH,J,andKremainedmostlyinCentralAfrica,fromAngolatotheCentralAfricanRepublic.Inalltheseplaces,aftertheusuallagofyearsbetweeninfectionandfull-blownAIDS,peoplebegandying.Andthenthere’ssubtypeB.

Sometimearound1966,subtypeBcrossedfromLéopoldvilletoHaiti.

Howitdidthatisunknown,andcanprobablyneverbeknown,butJacquesPepin’sarchivalburrowingprovidesnewsupportforoneplausibleoldscenario.WhentheBelgiangovernmentabruptlyrelinquisheditsAfricancolony,onJune30,1960,underthesternencouragementofPatriceLumumbaandhisMouvementNationalCongolais,tensofthousandsofBelgianexpatriates—almostanentiremiddleclassofcivilservants,teachers,

doctors,nurses,technicalexperts,andbusinessmanagers—foundthemselvesunwelcomeanduncomfortableinthenewrepublic,andtheybeganfloodinghomeward.CrowdingtheplanesforBrussels.Theirdeparturecreatedavacuum,sincetheBelgianregimehadpointedlyavoidededucatingitscolonialsubjects.Therewasn’tasingleCongolesemedicaldoctor,forinstance.Fewteachers.Thecountrysuddenlyneededhelp.TheWorldHealthOrganizationresponded,sendingphysicians,andtheUnitedNations(throughitsEducational,Scientific,andCulturalOrganization,UNESCO)alsobeganenlistingskilledpeopletoworkinCongo:teachers,lawyers,agronomists,postaladministrators,andotherbureaucrats,technicians,andprofessionals.ManyofthoserecruitscamefromHaiti.Itwasanaturalfit:TheHaitiansspokeFrenchasdidtheCongolese,theycamefromAfricanroots,theyhadeducationbutverylittleopportunityathomeunderthedictatorshipofPapaDocDuvalier.

Duringthefirstyearofindependence,halftheteacherssentbyUNESCOtoCongowereHaitians.By1963,accordingtooneestimate,athousandHaitianswereemployedinthecountry.Anotherestimatesaysthatatotalofforty-fivehundredHaitiansservedhitchesinCongoduringthe1960s.Evidentlythere’snosurviving,authoritativemanifest.Anyway,lotsofHaitians,multiplethousands.Somebroughtfamilies,somecamealone.Amongthesinglemen,wecanassume,fewremainedcelibate.MostofthemprobablyhadCongolesegirlfriendsorvisitedfemmeslibres.Forafewyearsitmayhavebeenagoodlife.ButtheHaitianswerelessneededandlesswelcomeasCongobegantrainingitsownpeople,especiallyafterJosephDésiréMobutuseizedpowerin1965.Lessstillwhen,intheearly1970s,hechangedhisnametoMobutuSeseSeko(roughly,“theall-powerfulwarrior”),changedhiscountry’snametoZaire,andannouncedapolicyofZaireanisation.ManyormostoftheHaitians,duringthoseyears,wenthome.TheirtimeofbeingusefulandappreciatedblackbrothersfromtheAmericashadpassed.

Atleastoneofthosereturnees,probablyamongtheearliestofthem,seemstohavecarriedHIV.

Morespecifically:SomeonebroughtbacktoHaiti,alongwithCongolesememories,adoseofHIV-1groupMsubtypeB.

Youcanseewherethisisgoing,butyoumightnotexpecthowitgetsthere.JacquesPepin’sresearchhasshedsomenewlightonwhatmayhavehappenedinHaitiduringthelate1960sandearly1970stomultiplyandforwardthevirus.Onethingthathappenedwasthat,fromasingleHIV-positivepersonin1966orthereabouts,thevirusspreadfastthroughtheHaitianpopulation.Evidenceforthatspreadcamelater,frombloodsamplesgivenby533youngmothersinaPort-au-Princeslum,whoagreedin1982toparticipateinameaslesstudyatalocalpediatricclinic.Testedretrospectively,thosesamplesrevealedthat7.8percentofthewomenhadbeenHIV-positive.Thatnumberwasstartlinglyhigh,forsuchanewlyarrivedvirus,andcausedPepintosuspectthat“theremusthavebeenaveryeffectiveamplificationmechanism”operatinginHaitiduringtheearlyyears—moreeffectivethansex.Hefoundacandidate:thebloodplasmatrade.

Plasma,theliquidcomponentofblood(minusthecells),isvaluablestuffforitsantibodiesandalbuminandclottingfactors.Demandforitrosesharplyduringtheperiod

around1970,andtomeetthedemandaprocesscalledplasmapheresiswasdeveloped.Plasmapheresisentailsdrawingbloodfromadonor,separatingthecellsfromtheplasmabymeansoffilteringorcentrifuging,puttingthecellsbackintothedonor,andkeepingtheplasmaasaharvestedproduct.Oneadvantageofthisprocessisthatitallowsdonors(whoareusuallyinfactsellers,paidfortheirtroubleandneedingthemoney)tobetappedoftenratherthanjustacoupletimesperyear.Givingupyourplasma,forthegoodofothersorforprofit,doesn’tleaveyouanemic.Youcangobackandgiveagainthefollowingweek.Onedisadvantageoftheprocedure—andit’sahugeone,butwasn’trecognizedintheearlydays—isthataplasmapheresismachine,garglingyourbloodandthebloodofmanyotherdonorsoverthecourseofdays,caninfectyouwithablood-bornevirus.

ThishappenedtohundredsofpaidplasmadonorsinMexicoduringthemid-1980s.IthappenedtoaquartermillionlucklessdonorsinChina.JacquesPepinthinksithappenedinHaititoo.

HefoundreportsofaplasmapheresiscenterinPort-au-Prince,aprivatebusinessknownasHemoCaribbean,thatoperatedprofitablyduring1971and1972.ItwasownedbyanAmericaninvestor,amannamedJosephB.Gorinstein,basedinMiami,withlinkstotheHaitianMinisteroftheInterior.Donorsreceivedthreedollarsperliter.Theirvitalswerecheckedbeforetheycouldsellplasma,butofcoursenobodyscreenedthemforHIV—whichdidn’tyetexistasanacronym,oraninfamousglobalscourge,onlyasaquietlittlevirusthatlivedinblood.AccordingtoanarticlethatraninTheNewYorkTimesonJanuary28,1972,HemoCaribbeanwasthenexportingbetweenfiveandsixthousandlitersoffrozenbloodplasmatotheUnitedStateseachmonth.ThewholesalecustomerswereAmericancompanies,whichmarketedtheproductforuseintransfusions,tetanusshots,andothermedicalapplications.Mr.Gorinsteinwasn’tavailableforcomment.

PapaDochadmeanwhiledied,in1971,andbeensucceededbyhissonJean-Claude(BabyDoc)Duvalier.AnnoyedbytheTimespublicity,BabyDocorderedthatGorinstein’splasmapheresiscenterbeclosed.TheHaitianCatholicChurchcondemnedthebloodtradeasexploitation.Beyondthat,thestoryofHemoCaribbeandrewlittlenoticeatthetime.Nooneyetrealizedhowdevastatingblood-productcontaminationcouldbe.NordidtheCDC’sMorbidityandMortalityWeeklyReportmentionit,adecadelater,whenbreakingthenewsthatHaitiansseemedespeciallyatriskforthemysteriousnewimmune-deficiencysyndrome.RandyShiltsdidn’tmentionitinAndtheBandPlayedOn.TheonlyallusiontoHaitianbloodplasmathatIrecall,fromtheyearsbeforeJacquesPepin’sbook,cameduringmyconversationwithMichaelWorobeyinTucson.

ShortlybeforepublishingonDRC60andZR59,Worobeycoauthoredanothernotablepaper,datingtheemergenceofHIVintheAmericas.ThefirstauthorwasapostdocnamedTomGilbert,inWorobey’slab,andintheanchorpositionwasWorobeyhimself.Thiswasthework,basedonanalysesofviralfragmentsfromarchivedbloodcells,thatplacedthearrivalofHIVinHaititoabout1966.ItappearedintheProceedingsoftheNationalAcademyofSciences.Soonafterward,Worobeygotapeculiare-mailfromastranger.Notascientist,justsomeonewhohadcaughtwindofthesubject.Areaderofnewspapercoverage,alistenertoradio.“IthinkhewasfromMiami,”Worobeytoldme.

“Hesaidheworkedinanairportthatdealtwiththebloodtrade.”Themanhadcertainmemories.Maybetheyhauntedhim.Hewantedtosharethem.HewantedtotellWorobeyaboutcargoplanesarrivingfullofblood.

25

Thenextleapoftheviruswassmallindistanceandlargeinconsequence.Port-au-PrinceisjustsevenhundredmilesfromMiami.Aninety-minuteflight.PartoftheprojectthatTomGilbertundertook,inWorobey’slab,wastodatewhenHIVhadarrivedintheUnitedStates.Todothatheneededsamplesofoldblood.WhetherthebloodhadreachedAmericainbottles,inbags,orinimmigrantHaitiansdidn’tmuchmatterforthispurpose.

Worobey,servingasGilbert’sadviser,rememberedastudyofimmunodeficientHaitianimmigrants,publishedtwentyyearsearlier.(Ialludedtothesamestudyatthebeginningofthisbook,quotingitsobservationofsomethingthatseemed“strikinglysimilar”tothenewsyndromeofimmunodeficiencyamongAmericanhomosexuals.)ThatstudyhadbeenledbyaphysiciannamedArthurE.Pitchenik,workingatJacksonMemorialHospitalinMiami.Pitchenikwasanexpertontuberculosis,andbeginningin1980henoticedanunusualincidenceofthatdisease,aswellasPneumocystispneumonia,amongHaitianpatients.HehadsoundedthefirstalarmaboutHaitiansasariskgroupforthenewimmune-deficiencysyndrome,alertingtheCDC.Inthecourseofclinicalworkandresearch,Pitchenikandhiscolleaguesdrewbloodfrompatientsandcentrifugedit,separatingserumfromcells,sotheycouldlookatcertaintypesoflymphocyte.Theyalsofrozesomesamples,ontheassumptionthosemightbeusefultootherresearcherslater.Theywereright.Butforalongtimenooneseemedinterested.Then,aftertwodecades,ArthurPitchenikgotacallfromMichaelWorobeyinTucson.Yes,Pitcheniksaid,hewouldbegladtosendsomematerial.

Worobey’slabreceivedsixtubesoffrozenbloodcells,andTomGilbertmanagedtoamplifyviralfragmentsfromfive.Thosefragments,aftergeneticsequencing,couldbeplacedintocontextaslimbsonanotherfamilytree—justasWorobeyhimselfwouldlaterdowithDRC60andZR59,andasBeatriceHahn’sgroupwasdoingwithSIVcpz.Itwasmolecularphylogeneticsatwork.Inthiscase,thetreerepresentedthediversifiedlineageofHIV-1groupMsubtypeB.ItsmajorlimbsrepresentedthevirusasknownfromHaiti.Oneofthoselimbsencompassedabranchfromwhichgrewtoomanysmalltwigstoportray.Sointhefigureaseventuallypublished,thatbranchanditstwigswereblurred—depictedsimplyasasolidconeofbrown,likeasepiashadow,withinwhichappearedalistofnames.ThenamestoldwheresubtypeBhadgone,afterpassingthroughHaiti:theUnitedStates,Canada,Argentina,Colombia,Brazil,Ecuador,theNetherlands,France,theUnitedKingdom,Germany,Estonia,SouthKorea,Japan,Thailand,andAustralia.IthadalsobouncedbacktoAfrica.ItwasHIVglobalized.

ThisstudybyGilbertandWorobeyandtheircolleaguesdeliveredoneotherpiquantfinding.Theirdataandanalysisindicatedthatjustasinglemigrationofthevirus—oneinfectedpersonoronecontainerofplasma—accountedforbringingAIDStoAmerica.Thatsorryadventhadoccurredin1969,plusorminusaboutthreeyears.

Soitlurkedhereformorethanadecadebeforeanyonenoticed.Formorethanadecade,itinfiltratednetworksofcontactandexposure.Inparticular,itfollowedcertain

pathsofchanceandopportunityintocertainsubcategoriesoftheAmericanpopulace.Itwasnolongerachimpanzeevirus.Ithadfoundanewhostandadapted,succeedingbrilliantly,passingfarbeyondthehorizonsofitsoldexistencewithinPantroglodytes.Itreachedhemophiliacsthroughthebloodsupply.Itreacheddrugaddictsthroughsharedneedles.Itreachedgaymen—reacheddeeplyanddevastatinglyintotheircirclesofloveandacquaintance—bysexualtransmission,possiblyfromaninitialcontactbetweentwomales,anAmericanandaHaitian.

Foradozenyearsittraveledquietlyfrompersontoperson.Symptomswereslowtoarise.Deathlaggedsomedistancebehind.Nooneknew.Thisviruswaspatient,unlikesuchhasty,peremptorybugsasEbolaandMarburgandtheonethatcausesSARS.Morepatienteventhanrabies,butequallylethal.SomebodygaveittoGaëtanDugas.SomebodygaveittoRandyShilts.Somebodygaveittoathirty-three-year-oldLosAngelesman,whoeventuallyfellillwithpneumoniaandaweirdoralfungusand,inMarch1981,walkedintotheofficeofDr.MichaelGottlieb.

NOTESAnumberoftheprincipalswhofeatureinthisaccountgavemetheirgenerouscooperationbywayofsittingforinterviewsorrespondingtoquestionsbye-mailorphone:RobertGallo,JaneGoodall,BeatriceHahn,Jean-MarieKabongo,PhyllisKanki,BrandonKeele,ElizabethLonsdorf,MartinMuller,J.J.Muyembe,MartinePeeters,JaneRaphael,DirkTeuwen,KarenTerio,andMichaelWorobey.Directsourcingfromthoseconversations,andfrommyfieldreporting,isclearfromcontext.Thesenotesrefertoprintedsources.

18.Gottlieb’sbarebonestext:Gottliebetal.(1981),250.

19.MorbidityandMortalityWeeklyReportcarriedFriedman-Kien’scommunication:Friedman-Kien.(1981),305–306.

19.sawa“syndrome”thatseemed“strikinglysimilar”:Pitcheniketal.(1983),353–354.

19.whobecamenotoriousas“PatientZero”:Shilts(1987),23.ButseealsoAuerbachetal.(1984),489.

19.asthemanwho“carriedthevirusoutofAfrica”:e.g.,http://en.wikipedia.org/wiki/Gaëtan_Dugas.

20.even“gorgeous”insomeeyes:Shilts(1987),21,47.

20.Dugashimselfreckoned:Shilts(1987),83.

20.andsay:“I’vegotgaycancer”:Shilts(1987),165.

20.“AlthoughthecauseofAIDSisunknown”:Auerbachetal.(1984),490.

21.RandyShiltslatertransformed:Shilts(1987),23.

21.HIVhadalreadyarrivedinNorthAmericawhen:Gilbertetal.(2007),18566,18568.

22.ADanishdoctornamedGretheRask:Shilts(1987),4–7;Bygbjerg(1983),925.

22.“I’dbettergohometodie.”:Shilts(1987),6.ShiltsseemstohaveinterviewedBygbjerg(butnotRaskherself),aswellasdrawingfromBygbjerg(1983).

22.Nineyearslater,asampleofRask’sbloodserum:Hooper(1999),95,879.

23.GRIDwasone,standingfor:Shilts(1987),121;Engel(2006),6.

23.SomedoctorspreferredACIDS:Shilts(1987),138.

23.“Kaposi’ssarcomaandopportunisticinfections”:MorbidityandMortalityWeeklyReport,June11,1982,294.

23.BySeptember1982,MMWRhadswitched:MorbidityandMortalityWeeklyReport,September24,1982,507.

24.Montagnier’sresearchfocusedmainly:Montagnier(2000),27–30,38,47.

25.“AIDScouldnotbecausedbyaconventionalbacterium”:Montagnier(2000),42.

25.Theonlyknownhumanretrovirusasofearly1981:Gallo(1991),91–93,99.

25.Arelatedretrovirus,felineleukemiavirus:Barré-Sinoussi(2003a),844.

25.Montagnier’sgroupinParis,screeningcells:Barré-Sinoussietal.(1983),868;Montagnier(2000),57.Barré-SinoussiandMontagnierdidn’tnameitLAVintheoriginal1983paper,butslightlylater.

26.Gallo’sgroupcameupwith:Galloetal.(1983),865–866;Gallo(1991),92–93,99,117.GallousesArabicnumerals(e.g.,HTLV-1,HTLV-2)inhisbook;butinthescientificpapers,heandothersuseRomannumerals.

26.HecalledthisnewestbugHTLV-III:Galloetal.(1984),500,502;Popovicetal.(1984),497.

26.AneditorialinthesameissueofScience:Marx(1983),806.

26.Thenagain,neitherwasGallo’s:GalloandMontagnier(1988),44;Gallo(1991),186;Crewdson(2002),163–166.

26.Montagnierhadpersonallydelivered:Montagnier(2000),60–62,68–69.

27.Meanwhilethethirdteamofresearchers:Crewdson(2002),143,158.

27.“morethan4000individualsintheworld”:Levyetal.(1984),840.

27.“Ourdatacannotreflectacontamination”:Levyetal.(1984),842.

28.Adistinguishedcommitteeofretrovirologists:Crewdson(2002),179–180,236.

29.Thereshesawaweirdproblem:EssexandKanki(1988),67;Letvinetal.(1983),2718–2719.

29.theydidfindanewretrovirus:Danieletal.(1985);Kankietal.(1985b).

29.forwhatsoonwouldberenamedHIV:i.e.,theyreferredtotheAIDSvirusasHTLV-IIIandcalledtheirmacaquevirusSTLV-III.

29.Thisdiscovery,theywrote:Danieletal.(1985)andKankietal.(1985b),lastparagraphofeach.

29.Onlyasinglesentenceattheend:Kankietal.(1985b),1201.

30.KankiandEssexlookedatotherAsianmacaques:EssexandKanki(1988),67–68.

30.“In1985,thehighestrates”:EssexandKanki(1988),68.

30.Kankigrewisolatesoflivevirus:Kankietal.(1985b),952–953.

31.“musthaveevolvedmechanisms”:EssexandKanki(1988),68.

31.Thesamplesarrivedwithcodedlabeling:EssexandKanki(1988),69;Kankietal.(1986),238.

31.Despiteonepossiblemisstep:Kankietal.(1986),238;regardingcontaminationandconfusion,cf.Montagnier(2000),80–81;Hooper(1999),108;Kestleretal.(1988),619,andEssexandKanki’sreplytoKestler,sameissue,621–622;Barinetal.(1985),1387.

32.ItmorecloselyresembledSIVstrains:Barinetal.(1985),1387.

32.Montagnierandhiscolleaguesscreenedtheblood:Montagnier(2000),79–81;Claveletal.(1986),343–344.

32.ThismanshowedsymptomsofAIDS:Claveletal.(1986),343–344;Montagnier(2000),79–80.

32.Eventually,whenallpartiesembracedthelabel:Clavel(1986),346;Montagnier(2000),81.

33.Possiblyitwasalreadywithus:SeeFukasawaetal.(1988),460;Mulder(1988),396.

33.whenagroupofJapaneseresearchers:Fukasawaetal.(1988),457.

33.Thenucleotidesequenceofitsretrovirus:Fukasawaetal.(1988),457,459;Mulder(1988),396.

34.AcommentaryinthejournalNature:Mulder(1988),396.

35.hadnoticedaleprosy-likeinfection:Gormusetal.(2004),216.

35.notknowntobetransmissiblefrompeople:Wolfetal.(1985),529.

35.Theanimalinquestion,asootymangabey:Gormus(2004),216.ThestoryunfoldsfromGormus(inretrospect)toWolfetal.(1985)toMurphey-Corbetal.(1986).

36.revealedthattheviruswasquiteprevalentamongthem:Murphey-Corbetal.(1986),437.

36.Otherinvestigatorssoonfoundittoo:Hirschetal.(1989),389,anditscitationnotes9–11.

37.Nowtherewerethreeknownvariants:Kanki(1986);Danieletal.(1985).TheSIVnamecamelater,however,aftertheystoppedusingHTLVandSTLV.

37.“TheseresultssuggestthatSIVsmhasinfectedmacaques”:Hirschetal.(1989),389.

38.HIV-2isconfinedmostlytoWestAfricancountries:thissentenceandthenextthree,ReevesandDoms(2002),1254–1255.

39.Peetersalongwithseveralassociateswastasked:thisparagraph,Peetersetal.(1989),625–626.

40.announcingthenewvirusandcallingitSIVcpz:Peetersetal.(1989),625,627.Moreprecisely,theycalleditSIVcpz-GAB-1,indicatingnotjustthenewstrainofvirusbuttheidentityofthespecificisolate.

40.“IthasbeensuggestedthathumanAIDS”:Peetersetal.(1989),629.

40.In1992Peeterspublishedanother:Peetersetal.(1992),448.

41.notasingleonehadyieldedtracesofSIVcpz:SharpandHahn(2010),2488.

42.bytheyear2000sevengroupsofHIV-2:ReevesandDoms(2002),1253.

43.Sodidthelateraddition,groupH:Santiagoetal.(2005),12515.

43.Theeventualfourthkind,groupP:Plantieretal.(2009),1–2.

43.Scientiststhinkthateachofthosetwelvegroups:ReevesandDoms(2002),1253regardingHIV-2;SharpandHahn(2010),2487,regardingHIV-1.

44.InSeptemberofthatyear,ayoungprint-shopworker:ZhuandHo(1995),503;Hooper(1999),21–22,122ff.

44.Thirty-oneyearslater,intheeraofAIDS:Corbittetal.(1990),citedinZhuandHo(1995).

45.musthavereflectedalaboratorymistake:ZhuandHo(1995),503–504.

45.AteamofresearchersincludingTuofuZhu:ZhuandHo(1995),503–504.

45.asmalltubeofbloodplasma,drawnfromaBantuman:Nahmiasetal.(1986),1279.

45.theonlyonethattestedunambiguouslypositive:Zhuetal.(1998),594.

46.Intheirpaper,publishedinFebruary1998:Zhuetal.(1998).

46.DRC60wasabiopsyspecimen:Worobeyetal.(2008),661.

50.withaspilloverasearlyas1908:Worobeyetal.(2008),661.

51.Thisonewasheterodoxandhighlycontroversial:Hooper(2001),803.HooperpresentssomewhatdifferentnumbersinHooper(1999),265–277,378–379.

51.viralorbacterialcontaminationofavaccine:e.g.,withSV40insomeoftheSalkvaccines,ShahandNathanson(1976),3.

51.agroupofItalianchildren:Willrich(2001),181.

51.SmallpoxvaccineadministeredtokidsinCamden:Willrich(2001),171–176,192,201.

51.abatchofdiphtheriaantitoxinpreparedinSt.Louis:Willrich(2001),178.

51.Formaldehydewassometimesadded:Oshinsky(2006),281.

52.someoftheearlybatchesoftheSalkpoliovaccine:ShahandNathanson(1976),2;Shah(2004),2061.

52.ThatthevaccineinquestionhadbeengiventoAfricans:Koprowski(2001);Plotkin(2001).

52.KoprowskihimselfvisitedStanleyville:Hooper(1999),267–273,523–524.

52.Childrenandadultslineduptrustingly:Hooper(1999),268–269,273–274.

52.roughlyseventy-fivethousandkids:Hooper(1999),275.

53.chimpanzeekidneysdrawnfromanimalsinfected:Hooper(2001),803–805,versusPlotkin(2001),815–816.

53.Theresultofthatflawedvaccinating:Hooper(2001),803.

53.certainpeoplehaveargued:e.g.,Hooper,LouisPascal,WilliamHamilton,Tom

Curtis.

53.hadputTomCurtisontothestory:i.e.,BlaineElswood,asmentionedinCurtis(1992),3(paginationofdigitalversion).

53.“TheoriginoftheAIDSvirusisofnoimportance”:Curtis(1992),21.

53.“It’sdistracting,it’snonproductive”:Curtis(1992),21.

53.lawyersforHilaryKoprowskifiledalawsuit:Hooper(1999),254,456.

54.“ThecontroversysurroundingthesourceoftheNile”:Hooper(1999),4.

59.hescreenedjust27ofthe813tissueblocks:Worobey(2008),661,663.

60.Theybothfellwithintherange:Worobey(2008),661–662.

60.differedby12percentbetweenthetwoversions:actually,11.7percent:Worobey(2008),662.

60.heplacedthemostrecentcommonancestor:Worobey(2008),663,Table1.

60.“Ourestimationofdivergencetimes”:Worobey(2008),663.

62.“themostpersuasiveevidenceyet”:WeissandWrangham(1999),385.

62.theiranalysisofviralstrainslinkedit:Gaoetal.(1999),436–437.

62.onvirusesdrawnfromcaptivechimps:thenewchimpinGao’sdatawasMarilyn,captiveintheUnitedStates:Gaoetal.(1999),437.

63.MarioL.Santiagotoppedalistofcoauthors:Santiagoetal.(2002),465.

63.heinventedmethods:Santiagoetal.(2002),465.

65.theycollected446samplesofchimpanzeedung:Keeleetal.(2006),523.

66.prevalenceratesupto35percent:Keeleetal.(2006),525,mapon523.

66.atwigamidthesamelittlebranch:Keeleetal.(2006),524–525,Figures3and4.

67.shockinglysimilartoHIV-1groupM:Keeleetal.(2006),525.

68.“WeshowherethattheSIVcpzPttstrain”:Keeleetal.(2006),526.

68.“Inhumans,directexposuretoanimalblood”:Hahnetal.(2000),611.

68.“Thelikeliestrouteofchimpanzee-to-humantransmission”:SharpandHahn(2010),2492.

70.Léopoldvillecontainedfewerthantenthousandpeople:Worobey(2008),663,Figure3anditscaption,citingChitnisetal.(2000).

70.“ahardmissionfield,”accordingtooneSwedishmissionary:Martin(2002),20,25.

70.duetocolonialpoliciesthatdiscouragedmarriedmen:Pepin(2011),70–73.Therestofthisparagraph,andthenext:Pepin(2011).

71.alivelymarketinsmokedfish:Harms(1981),229.

71.Ivory,rubber,andslavesweretradedthere:Harms(1981),227–229.

72.By1940,itspopulationhadedgedup:Chitnisetal.(2000),6.

74.apes,elephants,lions,andafewotherspecieswereprotected:WildlifeJustice,No.2(May2006),8.

74.DrorigavemeaLAGAnewsletter:WildlifeJustice,No.4(November2006).

74.Drori’snewslettermentionedaraid:WildlifeJustice,No.4(November2006),5.

75.Anotherbust,againstadealer:WildlifeJustice,No.4(November2006),5;WildlifeJustice,No.2(May2006),2,12.

76.adriverunloadingchimpanzeearmsandlegs:Peterson(2003),46,159.

76.roughly5millionmetrictonsofbushmeat:Peterson(2003),65.

80.whereKarlAmmansawchimpanzeearmsstashed:Peterson(2003),46.

80.Chimpfecalsamplesfromhereabouts:Keeleetal.(2006),525.

84.possiblyoftheMpiemuortheKako:Giles-Vernick(2002),22.

94.AstudyofbushmeattrafficinandaroundOuesso:thissentenceandtherestoftheparagraph:HennesseyandRogers(2008),179–183.

109.theprevailingimpressionwasthatit’sharmlessinchimpanzees:e.g.,Novembreetal.(1997),11748,11752.

109.WhenasinglelabchimpanzeedidprogresstoAIDS:Novembreetal.(1997),4086.

110.“survivedtheirownAIDS-likepandemic”:Cohen(2002),15.CohenwasreportingondeGrootetal.(2002).

110.anaturallyoccurringinfectioninmorethanfortydifferentspecies:SharpandHahn(2010),2487.

110.ithasn’tshownupamongwildmonkeysineitherAsia:SharpandHahn(2010),2487.

110.noneofthoseSIVsseemstocauseimmunodeficiency:SharpandHahn(2010),2490.

110.aclosesimilaritybetweentheirrespectiveSIVs:Sharpetal.(2005),3893.

111.Thatlengthoftimewouldallowdivergence:Sharpetal.(2005),3893.

111.noticedthatSIVcpzseemstobeahybridvirus:Bailesetal.(2003),1713.

111.Possiblyjusthundredsofyearsago:WertheimandWorobey(2009),5–6;Pepin(2011),41,citingWertheimandWorobey(2009).

112.WhattheNottinghamgroupsuggested:Bailes(2003),1713.

124.theseallcametogetherinapaper:Keeleetal.(2009),515.

126.aseriesofwell-intendedcampaigns:Pepin(2011),117;PepinandLabbé(2008).

127.2millionsyringeswereproducedgloballyin1930:Druckeretal.(2001),1989.SeealsoMarxetal.(2001),914.

127.treated5,347trypanosomiasiscases:Pepin(2011),122,163.

127.“TheCongocontainsvarioushealthinstitutions”:Beheyt(1953),quotedinPepin(2011),164.

128.“Thelargenumberofpatients”:Beheyt(1953),quotedinPepin(2011),164.

128.performed207,089injectionsoftryparsamide:thissentenceandtherestoftheparagraph:Pepin(2011),125–128.

128.doubtthatneedleswerenecessaryinanysuchway:Worobey(2008),inVolberdingetal.(2008),18.

129.Itdatesbackmorethanadecade:Marxetal.(2001),911.

129.JacquesPepinpickedupwherePrestonMarxleftoff:PepinandFrost(2011),421–422.

130.aclinicknownastheDispensaireAntivénérien:Pepin(2011),160.

130.“consistedofthousandsofasymptomaticfreewomen”:Pepin(2011),161.

130.Anyfreewomanormalemigrant:thissentenceandtherestoftheparagraph,Pepin(2011),160–163.

132.TheHIV-1groupMlineagebecamesplit:Tayloretal.(2008),1591;Worobey(2008),inVolberding(2008),15.

132.SubtypeAgottoEastAfrica:Pepin(2011),212–213.

132.SubtypeDestablisheditselfalongsidesubtypesAandC:Tayloretal.(2008),1595,Table2;Hemelaaretal.(2006),W17,Table2,andW18,Table3.

133.subtypeBcrossedfromLéopoldvilletoHaiti:Gilbertetal.(2007),18566,18568,Figure2.

133.newsupportforoneplausibleoldscenario:TherecognitionofHaitianprofessionalshavinggonetoCongoafterIndependencedatesbackatleasttoShilts(1987),392–393.Thisparagraphandthenext:Pepin(2011),187–190.

134.SomeonebroughtbacktoHaiti:Gilbertetal.(2007),18566.

134.thosesamplesrevealedthat7.8percentofthewomen:Boulosetal.(1990),7222–7223,andcitedinPepin(2011),196.

134.“theremusthavebeenaveryeffectiveamplificationmechanism”:Pepin(2011),196.

135.hundredsofpaidplasmadonorsinMexico:Pepin(2011),199.

135.aquartermillionlucklessdonorsinChina:Pepin(2011),200.

135.reportsofaplasmapheresiscenterinPort-au-Prince:Pepin(2011),201–202;Severo(1972).PepincitesSevero,butIusedSeverodirectly.Pepinhyphenatesthename,Hemo-Caribbean,butSeverodoesn’tandthere’sstillsuchacompany,listedonlineasHemoCaribbean.

136.orderedthatGorinstein’splasmapheresiscenterbeclosed:Pepin(2011),202.

136.NordidtheCDC’sMorbidityandMortalityWeeklyReportmentionit:MorbidityandMortalityWeeklyReport,July9,1982,31(26):354.

136.RandyShiltsdidn’tmentionit:thoughhecameclose,discussingHaitiansandblood,e.g.,Shilts(1987),135.

137.beginningin1980henoticed:Pitcheniketal.(1983),277,278,table.

137.HehadsoundedthefirstalarmaboutHaitians:MorbidityandMortalityWeeklyReport,July9,1982,31(26):354ff.

138.TomGilbertmanagedtoamplify:Gilbertetal.(2007),18569.

139.walkedintotheofficeofDr.MichaelGottlieb:Gottliebetal.(1981),250.

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ACKNOWLEDGMENTSAlthoughTheChimpandtheRiverfocusesprimarilyontheecologicaloriginsofHIV,andonthescientificworkdonetotracethoseorigins,thescopeofthehumancatastrophethatistheAIDSpandemicmustbenotedagain,firstandforemost,evenhereinabriefnotetorecordliterarydebts.Weallstandchastened,grieved,anddiminishedbythemiseriesandlossesthathavebeensufferedbyourfellowmenandwomen,aswellasawedbyandgratefulforthecourage,determination,andheartofthosewhohavefoughtagainstthiscatastropheinsomanyways.

Asnotedabove,anumberofbusyscientistsgavetheirgenerouscooperationtomyresearchtowardthisbook,bysittingforinterviewsorrespondingtoe-mailortelephonequestions:RobertGallo,JaneGoodall,BeatriceHahn,Jean-MarieKabongo,PhyllisKanki,BrandonKeele,ElizabethLonsdorf,MartinMuller,J.J.Muyembe,MartinePeeters,JaneRaphael,DirkTeuwen,KarenTerio,andMichaelWorobey.Mostofthosepeople,inaddition,didmethevitalfavorofreadingandcorrectingdraftpages.Threeotherscientists,whoseworkdoesnotdirectlyinvolveAIDS,alsoreadthisbookinitsoriginalform(asalongchapterofSpillover)andofferedkeeneditorialadvice:CharlieCalisher,MikeGilpin,andJensKuhn.I’mdeeplygratefultothemall.

MygratitudeextendsalsotoPatrickAtimnedi,AntonCollins,ZacharieDongmo,OfirDrori,MikeFay,BarbaraFruth,ShadrackKamenya,IddiLipende,JuliusLutwama,PegueManga,NevilleMbah,ApollonaireMbala,AchileMengamenya,JeanVivienMombouli,AlbertMunga,MaxMviri,HansonNjiforti,MoïseTchuialeu,andLeeWhite,allofwhomassistedmyinquiriesaboutHIV’soriginsinAfrica.TherewereotherswhohelpedinmanywaysduringthebroadereffortofresearchingSpillover(includingmyeditorsandothercolleaguesatNationalGeographic,amongwhomthatlargerprojecthaditsbeginning),andthoughtheirfieldsofexpertiseoractivitylayoutsidetheimmediateframeoftheHIV/AIDSstory,theycontributedmuchtowardallowingmetoplacethatstorywithinitsappropriatecontext:asthemostconsequentialofallmoderninstancesofzoonoticdisease.IthankedthembynameinSpillover,andIthankthemagaincollectivelyhere.

MyothersignaldebtsofgratitudearetoMariaGuarnaschelli,mylongtimeeditoratW.W.Norton,whogaveherkeeneye,herastutejudgment,andherliterarypassiontothisbookaswellasahalfdozenotherswe’vecollaboratedonoverthepasttwenty-fiveyears;andtoAmandaUrban,mywonderfullyferociousandsmartagentatICM.ManyotherpeopleatNortonandICMhavealsocontributedtothisproject,andIverymuchappreciatetheirwork.RenéeGolden,BinkyUrban’spredecessorinmyprofessionallife,helpedmefordecadesalongtheroutethatledtowardthissortofproject.GloriaThiede,faithfulGloria,transcribedalltheinterviewsquotedhere.EmilyKriegercombinedassiduousresearchwithareader’ssenseofflow,bothcrucial,inservingasmyfact-checker.DaphneGillamdrewtheartful,human-handedmap.MyamazingwifeBetsywasalwaysnearbytolisten,toread,todiscuss,tocounsel,andtoholdthefamilytogether,evenwhilefulfillingherownprofessionalduties.Harry,Nick,Stella,Oscar:Thanksforallyougive.I’vebeenblessedwithanextraordinarynetworkofcolleagues,sources,

professionalpartners,friends,andlovedones,andI’mquiteawarethattheworkcouldn’thappenwithoutthem.

INDEXPagenumberslistedcorrespondtotheprinteditionofthisbook.Youcanuseyourdevice’ssearchfunctiontolocateparticulartermsinthetext.

AbongMbang,Cameroon,75

Africa:

Central,seeCentralAfrica

East,118,132

southern,132

sub-Saharan,34

West,37,38,40,118,132

Africangreenmonkey(Chlorocebus),30–32,33–34

AIDS:

inchimpanzees,112,116,117,122–25

emergenceof,17–23,43–139

ingaymen,17–18,23,24,44,139

geographicaldisseminationof,131–39

inHaitians,19,22,133–38

inhemophiliacs,23,24,138

Kinshasaemergenceof,68–69,71–72,108–9,125–26,129–33

aspandemic,38,80,125

R0of,69,70,72,87,108

sexualmoresand,70,109,126

sexualtransmissionof,20,24,108,128

syringereuseand,23,24,108,126–31,139

thresholddensityof,128

transmissibilityof,20

aszoonoticdisease,17,125

seealsoHIV-1

Ammann,Karl,76,80

AndtheBandPlayedOn(Shilts),20,136

Angola,132

antibodies,screeningfor,63,64

toHIV,32,39

toSIV,30,113,114

atoxyl,128

Auerbach,DavidM.,20–21,22

Bailes,Elizabeth,111

Bakwelepeople,77–79,85

Barré-Sinoussi,Françoise,27

basicreproductionrate,seeR0

beka(initiationceremony),78–79

BelgianCongo,seeCongo,DemocraticRepublicofthe

Belgium,133

biosafetylevel3(BSL-3)laboratories,50

bloodplasmatrade,134–36

bloodtransfusions,hepatitisBand,20–21

Bobangipeople,103–5

BoumbaBekNationalPark,Cameroon,76

Brazzaville,ROC,70,73,106–8,109,125

Burundi,52

bushmeat,50–51,74,76,94–96

greatapesas,77–79,81,94

Buy’em-Sell’ems,77,90–91,92–93

Cameroon,126,128

HIVin,42

aslocusofHIVspillover,65,66–73,79,80,109,118,125

loggingin,75–77

poachingin,74–75,80–81

Candidayeast,17–18,22

CapeVerde,32

CD4proteinreceptor,85

CentersforDiseaseControlandPrevention(CDC),AIDSand,18,20,21,137

CentralAfrica:

HIVin,42,132

aslocusofHIV-1spillover,30,62

trypanosomiasisinoculationsin,126–29

CentralAfricanRepublic,80–81,132

CentreInternationaldeRecherchesMédicales(CIRMF),39

Cercocebusatys(sootymangabey),34–37,38,40,43,50

“ChimpanzeeReservoirsofPandemicandNonpandemicHIV-1”(Keeleetal.),68

chimpanzees(Pantroglodytes):

AIDSin,112,116,117,122–25

bushmeatfrom,77–79,94

central(P.t.troglodytes),62,65,68

eastern(P.t.schweinfurthii),63

asHIVreservoirs,39–41,62

P.t.vellerosus,65

SIVin,seesimianimmunovirus(SIV),inchimpanzees

ChimpanzeesofGombe,The(Goodall),115

China,bloodplasmadonorsin,135

Chlorocebus(Africangreenmonkeys),30–32,33–34

Congo,DemocraticRepublicofthe(DRC;Zaire),52,55,56,126

emergenceofAIDSpandemicin,22,44,46,68–69,71–72,108–9,125–26

Haitiansin,133–34

Congo,Republicofthe(ROC),66,73,80–81,82,83,93–94

emergentAIDScasesin,69–70,72–73

loggingin,82

Congobasin,72,76

CongoleseRedCross,130

CongoRiver,62,68,69–72,105–6,125

Côted’Ivoire,42

Curtis,Tom,53,54

CutHunter,83–87,126

cut-hunterhypothesis,50–51,68–69,83–91,96–108,112,126

dead-endhosts,128

deforestation,75–77

DeltaRegionalPrimateResearchCenter,35–37

diphtheria,51

disease,seeinfectiousdisease

DispensaireAntivénérien,130–32

DNA,inretroviruses,24,85

Dongmo,Zacharie,76–78

Douala,Cameroon,73

DRC60,46–50,55,58,59–60,72,131,138

Drori,Ofir,73–75,77

Dugas,Gaëtan(PatientZero),19–21,44,85,139

duikers,74,94

Duvalier,François“PapaDoc,”133,136

Duvalier,Jean-Claude“BabyDoc,”136

EatingApes(Peterson),76

Ebolavirus(Zaireebolavirus),39,81,139

ecosystems,human-causeddisruptionof,75–77,82

epidemics,thresholddensityin,128

seealsoinfectiousdisease

EquatorialGuinea,42

Essex,Myron“Max,”28–33,54

Ethiopia,132

Europe,AIDSin,42

evolution,33

ofHIV,56,59–61,109,125,129

Fay,J.Michael,73

fecalsampling,64–65,66,117–19

felineleukemiavirus(FeLV),25,28

femmeslibres(freewomen),71,130–31,134

Franceville,Gabon,39

freewomen(femmeslibres),71,130–31,134

FrenchEquatorialAfrica(FEA),70–71,127–28

Friedman-Kien,AlvinE.,18–19,22,23

Gabon,126

AIDSin,42,72

Gallo,Robert,25–26,27,28,29,32

Gao,Feng,62,63

Ghana,42

Gibraltar,44

Gilbert,Tom,136–38

Gimble(chimpanzee),114,117,118,119

GombeNationalPark,Tanzania,63,112–25

GombeStreamResearchCenter,114–15,120

gonorrhea,129,130

Goodall,Jane,63,112,113,114–18

gorillas,bushmeatfrom,78,79,94

Gorinstein,JosephB.,135,136

Gottlieb,Michael,17–18,22,23,44,139

greatapes,80–81

asbushmeat,77–79,81,94

seealsochimpanzees;gorillas

greaterspot-nosedmonkeys,110,111

Guinea-Bissau,32,38,42

Hahn,Beatrice,111

andGombeSIVresearch,112–25

insearchfororiginsofHIV-1,61–64,67–70,72,73,109,128–29,138

Haiti,bloodplasmatradein,134–36

Haitians,AIDSin,19,22,133–38

Hamilton,William,55,56–58

HarvardSchoolofPublicHealth,28

Haseltine,William,53

HemoCaribbean,135–36

hemophiliacs,AIDSin,23,24,138

hepatitisB,20–21,127

Heymann,David,53

Hirsch,VanessaM.,37–38

HIV(humanimmunodeficiencyviruses):

discoveryof,24

asretroviruses,24–28

SIVasprogenitorof,29–31

HIV-1,32–33

evolutionarydivergenceof,59–61,109,125,129

genomeof,33,41–42

groupN,42,125

groupO,42,50,125

lethalityof,124–25

mutationof,59–60,88,131–32

pathogenicmechanismof,62

recombinationin,131

searchforreservoirof,38–41

seealsoAIDS

HIV-1,groupM,42,44,50,107,109,118

chimpanzeesasreservoirof,39–41,62

DRC60genesequenceof,46–50,58,59–60,72,131,138

geographicaldisseminationof,131–39

SIVcpzasprogenitorof,29–31,62,63,65,66–67,68–69,80,125

subtypeBof,132–39

subtypesof,132

ZR59genesequenceof,46,59–60,72,108,131,138

HIV-2,32–33,125

genomeof,33,34,108

geographicaldisseminationof,38–39

groupsof,42,43,132

transmissibilityof,38

virulenceof,38

aszoonosis,38,50

HIVspillovers,38,40,41–43,46,50–51,60–61,62

Cameroonaslocusof,62,65,66–73,79,80,108–9,125

CentralAfricaaslocusof,62

cut-hunterhypothesisof,50–51,68–69,83–91,96–108,112,125,126

mechanicsof,67–108,112,125

oralpoliovaccine(OPV)hypothesisof,51–56,60–61,129

homosexuals,male,AIDSin,17–18,19,24,44,139

Hooper,Edward,54–55,129

host-virusrelationship,virulenceand,31

humans,ecosystemdisruptionby,75–77,82

humanT-lymphotropicviruses(HTLVs),25–26,29

seealsoHIV

iatrogenicinfections,53

immunodeficiency,17,19

“IncreasedMortalityandAIDS-likeImmunopathologyinWildChimpanzeesInfectedwithSIVcpz”(Keeleetal.),124–25

India,AIDSin,132

infectiousdisease:

basicreproductionratein,seeR0

dead-endhostsand,128

thresholdsof,128

seealsoepidemics;specificdiseasesandpathogens

InstitutPasteur,24

intravenousdrugusers:

AIDSin,23,24

hepatitisBin,21

Jamot,Eugène,127,128

JaneGoodallInstitute,115,119–20

Jolo(boatman),92,93,94

JournalofVirology,110

Justin,Ekeme,83

Kabila,Laurent,56

Kabongo,Jean-MarieM.,47–49,60

KadéïRiver,75–76

Kakopeople,77

Kanki,Phyllis,28–33,54

Kaposi’ssarcoma,18–19,20,22

Keele,BrandonF.,64–67,69,72,80,119–20,122,124

Kenya,33,34

KibaleNationalPark,Uganda,113–14

Kika,Cameroon,82–83,92

Kinshasa,Universityof,46,47,55,56,60

Kinshasa(Léopoldville),DRC,22

emergenceofAIDSpandemicin,68–69,71–72,108–9,125–26,129–33

Kisangani,DRC,52,56–57,132

Koprowski,Hilary,52,53–54,55,56

Korber,Bette,46

LaboratoryofTumorCellBiology,25

LAGA(LastGreatApeOrganization),73–74

LAV(lymphadenopathyvirus),26

seealsoHIV

Leakey,Louis,116

Léopoldville,seeKinshasa,DRC

leprosy,35–36,126–27

Lesotho,132

Levy,JayA.,27

Lobeke,Cameroon,66

LobekeNationalPark,Cameroon,76,80

logging,75–77,82

Lonsdorf,Elizabeth,122

LosAngeles,Calif.,earlyAIDScasesin,17–18,21,22,139

Lumumba,Patrice,133

Lumumbashi,DRC,132

lymphocytes,137

depletedlevelsof,18,19,122–23,125

seealsoTcells

macaques:

rhesus(M.mulatta),36,37,52

SIVin,29–30

SV40in,52

malaria,126

causeof,seePlasmodium

falciparum(malignant),57

Mambele,Cameroon,66,79–80

“Manchestersailor,”44–45

mangabeys:

red-capped,110,111

sooty(Cercocebusatys),34–37,38,40,43,50

Marburgvirus,139

Marx,Preston,129

Mbah,Neville,73,82,83,94

Mexico,135

Miami,Fla.,earlyAIDScasesin,19,22

MobutuSeseSeko,56,134

molecularphylogenetics,61–62,109,138

Moloundou,Cameroon,82,99

Montagnier,Luc,24–27,28,32

MorbidityandMortalityWeeklyReport,18,19,23,136

Moyen-Congo,seeCongo,Republicofthe

Mozambique,132

Muller,Martin,113–14,118

Munga,Albert,80–81

Murphey-Corb,MichaelAnne,37

mutation:

ofHIV-1,59–60,88,131–32

naturalselectionand,88

Muyembe,J.J.,55–56,58,60

Mviri,Max,73,82–83,92,93–96

Mycobacteriumleprae,35–36

NationalCancerInstitute,25

NationalGeographic,117

naturalselection,mutationand,88

Nature,34,60,62

ndumbas,seefreewomen

NewEnglandJournalofMedicine,18

NewEnglandRegionalPrimateResearchCenter,28–29

NewIberia,La.,35

NewYork,N.Y.,earlyAIDScasesin,18–19,21

NewYorkTimes,135,136

Ngbala,Cameroon,90,99

NgokoRiver,81–82,87,89,90,92–93

Njiforti,Hanson,76,77

NkiNationalPark,Cameroon,76

“NobleGoals,UnforeseenConsequences”(Pepin),126

noninvasivesamplecollecting,63–64,113,117

Nottingham,Universityof,111,112

opportunity,spilloverand,70,72,87,133,138

oralcandidiasis,17–18,22,139

oralpoliovaccine(OPV)hypothesis,51–56,60–61,129

OriginsofAIDS,The(Pepin),126

Oubangui-Chari,FEA,127

OubanguiRiver,62

Ouesso,ROC,81,82,83,90,92,93–97,100–102

pathogenicity,seevirulence

PatientZero(GaëtanDugas),19–21,44,85,139

Peeters,Martine,39–41,65,68,111,118

penicillin,130

Pepin,Jacques,126,127–30,133,134,135,136

Peterson,Dale,76

phylogeny,ofSIVandHIV,66–67

Pitchenik,ArthurE.,137

plasmapheresis,134–36

Plasmodium,P.falciparum,57

seealsomalaria

“PneumocystisPneumonia—LosAngeles”(Gottlieb),18

pneumonia,Pneumocystiscarinii,17–18,19,20,22,29,44,137

poliomyelitis:

vaccinefor,51–56,60–61,129

polymerasechainreaction(PCR)amplification,45,64

populationdensity,126

Port-au-Prince,Haiti,134,135

ProceedingsoftheNationalAcademyofSciences,136

prostitutes,31–32,70–71,126,130,132

seealsofreewomen

proteinreceptors,85

R0(basicreproductionrate),ofAIDS,69,70,72,87,108

rabies,139

Raphael,Jane,120–21

Rask,Grethe,22,44

recombination:

inHIV-1,131

inSIV,111–12

red-cappedmangabeys,110,111

retroviruses:

characteristicsof,24,85

HIVas,24–28

rhesusmacaque(Macacamulatta),36,37,52

River,The:AJourneytotheSourceofHIVandAIDS(Hooper),54–55

RNA:

inretroviruses,24,85

viral,58,59,64,118

RNAlater,64,121

RollingStone,53,54

RoyalSociety,55,56,129

Rwanda,52

Sabin,AlbertB.,52

Salk,Jonas,52

Salkvaccine,52

SanFrancisco,Calif.,earlyAIDScasesin,20,21,27

SanghaRiver,68,69,80,81,87,90,93,103,125,127

Santiago,MarioL.,63,68,113,118,119

Science,25,26,29,30,63,68

Senegal,31–33,34,35,38

sexualmores,AIDSand,70,109,126

Sharp,Paul,111

Shilts,Randy,20,21,136,139

simianimmunovirus(SIV),29–32

inAfricangreenmonkeys(SIVagm),30–32,33–34,37

genomeof,33–34,109,111

ingreaterspot-nosedmonkeys(SIVgsn),110,111

inmacaques(SIVmac),36–37

prevalenceratesof,66

recombinationin,111–12

inred-cappedmangabeys,110,111

insootymangabeys(SIVsm),34–38,40,43,50

simianimmunovirus(SIV),inchimpanzees(SIVcpz),37,40–41,43,52–53,79,85

ageof,111

Gombestudyof,112–25

asHIV-1progenitor,29–31,62,63,65,66–67,68–69,80,88,125

sexualtransmissionof,119

verticaltransmissionof,119

virulenceof,109–10,111,112

sleepingsickness(trypanosomiasis),108,126–29

smallpox,51

sootymangabey(Cercocebusatys),34–37,38,40,43,50

SouthAfrica,34,132

spillover,opportunityand,70,72,87,133,138

seealsospecificdiseases

StanleyPool,72

Stanleyville,seeKisangani,DRC

streptomycin,130

susceptiblepopulations,increaseddensityof,126

SV40virus,52

Swaziland,132

Sylvain(boatman),83,92,93,94

syphilis,129,130

syringes,reuseof,AIDSand,23,24,108,126–31,139

Tanzania,63

Tcells(thymus-dependentlymphocytes),18,22,25,85

Tchuialeu,Moïse,73,83

Terio,Karen,121–23,124

tetanus,51

Teuwen,Dirk,56

T-helpercells,25

thresholds,ofinfectiousdiseases,128

Tiopeople,105–6

TMRCA(timetomostrecentcommonancestor),60

transmissibility:

blood-borne,20–21,24

human-to-human,20–21

vertical(mother-to-offspring),119

seealsospillover;specificdiseasesandpathogens

Trypanosomabrucei,126

trypanosomiasis(sleepingsickness),108,126–29

tryparsamide,126,128

tsetseflies,126,129

tuberculosis(TB),137

UCLAMedicalCenter,17–18

UNESCO,133

urinesampling,63,113,114,117

USAMRIID(USArmyMedicalResearchInstituteofInfectiousDiseases),65

virions,85,86

virulence,andevolutionofhost-virusrelationship,31

seealsospecificpathogens

Virus(Montagnier),24

viruses:

RNA,58,59,64,118

transmissibilityof,seetransmissibility

virionsof,85,86

virulenceof,seevirulence

Vivian(Buy’em-Sell’em),92–93,94

Voyager,88–91,96–108

WorldHealthOrganization(WHO),133

WorldWildlifeFund,74

Worobey,Michael,49–50,56–62,69,109,128–29,136–38

Wrangham,Richard,113,114,118

Yaoundé,Cameroon,73–75

yaws,130

Yokadouma,Cameroon,76–78

Yolanda(chimpanzee),120–25

Zaire,seeCongo,DemocraticRepublicofthe

Zaireanisation,134

Zaireebolavirus,seeEbolavirus

Zambia,132

Zhu,Tuofu,45–46

ZR59,46,50,59–60,72,108,131,138

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