Magazine R65

News focus

Bird flu developments stoke fearsEvidence that H5N1 bird flu may have infected more people more widelybut sometimes with milder symptoms is still raising worries about itspotential to be the cause of the next human pandemic. Nigel Williamsreports.

The appearance of the H5N1 strainof bird flu in Europe, andparticularly the outbreak reportedlast month in Turkey, hasheightened already raisedconcerns about the spread of thevirus and its potential to seed thenext human pandemic.

There are new worries abouthow the disease appeared toinfect birds almost simultaneouslyin 13 provinces scattered aroundTurkey and further concerns aboutwhy more people seemed to beinfected than in any other outbreaksince the disease first beganinfecting humans in 2003.

Tempering these concerns is thenews that relatively few of the

Turkish victims have so far diedfrom the disease compared withthe previous outbreaks, in whichup to half the human cases provedfatal.

Doctors and health officials,worried about the threat of ahuman pandemic, aren’t even sureif these developments constitutegood news or bad. But they dosuggest that the H5N1 bird flu is agrowing challenge.

Researchers last month at theWorld Influenza Centre of theNational Institute for MedicalResearch in London discovered amutation in the virus isolated froma Turkish child who died of thedisease.

Michael Purdue, who isoverseeing the response to theavian flu outbreak in Turkey onbehalf of the WHO, said themutation had been spotted beforein east Asia — where the diseasehad killed more than 70 people —in Hong Kong in 2003 and Vietnamin 2005. It was too soon to saywhat it meant, he believed.

The mutation was in a surfaceprotein, haemagglutinin, which thevirus uses to attach to therespiratory tract. Purdue said itwas “clearly not a constantchange” as it had been seen onlytwice so far.

A recent study by a team fromthe Karolinska Institute inStockholm working in Vietnamsuggested that many more peoplethan previously thought may havebeen infected with the bird fluvirus. They reported that hundreds

Turkish plight: Outbreaks of known cases of the H5N1 bird flu reported across the country last month have heightened fears aboutthe spread of the virus and there are continuing worries that it may lead to the next human pandemic. Here children help in the round-up of poultry and wildfowl in eastern Turkey. (Photograph: EMPICS.)

Current Biology Vol 16 No 3R66

Cuban biotech has been growingquietly but steadily over the lasttwo decades. It saw its mostspectacular success so far in July2004, when the development ofthe first ever fully syntheticvaccine that is effective against ahuman disease appeared inScience magazine.

The synthetic vaccine againstHaemophilus influenzae B (HiB),which was developed at theLaboratory for Synthetic Antigensat the University of Havana, ismuch more affordable fordeveloping countries than thebiological vaccine availablepreviously (Curr. Biol. (2004) 14,R401). As it could save the lives ofmore than half a million childrenper year, it made headlines aroundthe world. Since then, researchersin other countries have become

increasingly interested in tappingthe Cuban expertise in fields suchas glycobiology, vaccinedevelopment and immunology.

Biologically oriented chemistsfrom leading UK universitiesvisited the Caribbean island toexperience the developments firsthand, to start new collaborationsand to consolidate existing ones.The three-day binational‘Symposium on Chemistry andLife Sciences’ was held inpicturesque Old Havana. It wasco-chaired by Oxford chemistrychairman Graham Richards andHavana University’s Luis Monteroand backed by several UKinstitutions, including the RoyalSociety of Chemistry (RSC) andOxford University.

As sugar is both a key resourceof the Cuban economy and a basis

Cuban efforts bolsteredA high profile delegation of UK researchers travelled to Havana lastmonth to discuss collaborative projects targeted at the life sciences.Michael Gross reports.

of people may have contractedbird flu but were not diagnosedbecause their symptoms were toomild. The findings suggest somepopulations have developednatural resistance to the virus.

The study of more than 45,000people in Vietnam, reveals that upto 750 people are likely to havebecome infected with the strainafter handling sick birds.

Anna Thorson, who led thestudy, said the real figurepotentially extended intothousands. The cases were notpicked up because, while peopledeveloped coughs and a fever,they either failed to seek medicalhelp because their symptomswere mild, received treatment fromunregistered practitioners or weremissed by the doctors inspectingthem.

The researchers studiedinterviews with more than 45,000people in FilaBavi, a Vietnamesedemographic surveillance site withconfirmed outbreaks of H5N1 inpoultry during April to June 2004.Eighty-four per cent lived inhouseholds that kept poultry andmore than 25 per cent reportedbirds falling ill or dying of flu in thattime. Of those between 650 and750 people suffered flu-likesymptoms after handling the birds.

Although there are somequestions about the study and thedifficulty in diagnosing symptomsin such a rural community, thework has raised new issuessurrounding the virus.

The outbreak in Turkey has alsoraised questions about theapparent mildness of the virus insome cases in this country. Part ofthis may have been the result ofmedical care which included theadministration of anti-viral drugssuch as Tamiflu but otherexplanations for why the Turkishdeath rate has been lower havenot been discounted. It could be,for instance, that people in Turkeyare more resistant to the virus thansome of the Asian populations. Orperhaps Turkish authorities wereable to detect cases more quickly.

Gene-sequencing informationcan confirm where the victimcaught the disease — and so farthat seems in every case to befrom birds directly. “It’s not clearyet that the situation we’re

observing in Turkey, the number ofinfections, the virulence, is anydifferent than what we’ve beenseeing in Vietnam,” says theMRC’s Alan Hay.

Professor Peter Dunhill, anexpert on vaccines for avian flu atUniversity College London, saidrural communities in Vietnam havebeen living with bird flu for morethan 10 years and may havedeveloped resistance to it. “It maywell be that there is someimmunity in Turkey too.”

Recent developments in Turkeyand other countries on the easternedge of Europe have promptedcalls for the establishment of aEuropean task force that can bemobilised to fight the virus.

Albert Osterhaus, a virologist atthe Erasmus Medical Centre in theNetherlands and chairman of theEuropean scientific group oninfluenza, believes morecoordination is needed in Europeto tackle bird flu.

“I think we should form aEuropean influenza task force thatbrings together all our knowledge,so that if you have outbreaks inthe future you could form

delegations to work together withlocal experts in the area where itoccurs,” he told a meeting inLondon last month.

But other researchers believethe new findings and the currentpattern of bird flu, the humaninfections and human influenzamay mean that a pandemic is stillsome time away. While that maygive government authorities a littlemore breathing space, there isgrowing consensus that, if theH5N1 strain leads to the nexthuman pandemic, theconsequences could becatastrophic.

Writing recently, Neil Ferguson,a specialist in infectious diseaseepidemiology at Imperial CollegeLondon said: “the odds are thatthere will be no human pandemicin the next five years. However,this is no reason for complacencyor a reduction in preparednessplanning. As the emergence of apandemic is, in essence, a chanceevent, we cannot predict exactlywhen the next pandemic will strikeor how severe its consequenceswill be. That it will strike eventuallyis certain.”