Dengue:Epidemiology,clinicalmanagementandcontrol
PORNTHIPCHAICHOMPOO
SCBM 346 Tropical infectious diseases and controls
DEPARTMENT OF PATHOBIOLOGY, FACULTY OF SCIENCE, MAHIDOL UNIVERSITY
References
Learningobjectives
Atthecompletionofthisunitthestudentwillbeableto:
• Explainbiologyandinfectioncycle ofdenguevirus• Discusstheepidemiologyofdengueinfectionandpublichealthproblem
• Demonstrateclinicalmanagement,preventionandcontrol ofdengueinfection
• (+)ssRNA virus• Family Flaviviridae• Genera Flavivirus• SpeciesDenguevirus
(DEN-1,DEN-2,DEN-3&DEN-4)• ArbovirusArthropod,Mosquito,born
(Aedes aegypti)• Pathogenic diseasesDenguefever/DHF/DSS
BiologyofDenguevirus
DENGUEVIRUS
Screaton G,etal.NatRevImmunol.2015Dec;15(12):745-59.
Infectiouscycle:Immature
Mature
host-encoded furin protease
Infected person
Healthy person
Infected mosquito
Incubation Period: 3 to 14 daysMost commonly 4 to 7 days
Denguetransmissioncycle
Otherroutesoftransmission
• Transplantation:Blood/Bonemarrow,organ(renaltransplantation)
• Verticaltransmission:DENVcanbetransmittedfromthemothertothefetusinuteroortotheneonateatparturition.
Aedes aegypti
Vector
InfectedFemaleMosquito
rarelyAedes albapticus
PathogenesisofDengueinfection
Navarro-Sa´nchez E, et al.Archi Med Res.2005; 36:425–35.9
Webster DP, et al. Lancet.2009;9(11):678-87.
PathogenesisofDengueinfection
10
Dengueasanemergingdisease
• DENwasaminor,geographicallyrestricteddiseaseuntilmid-20thcentury
• WorldWarII/globalcargotransportofAedesmosquitoeslikelyresponsiblefordissemination
• DEN/DHFpresentintheWHOregionsoftheAmericas,South-EastAsia,EasternMediterraneanandWesternPacific;AfricareportsDENbutonlysporadicDHF
• DHFfirstdocumentedin1950sinthePhilippinesandThailand
DengueasanemergingdiseaseAverageannualnumberofdenguefever(DF)anddenguehemorrhagicfever(DHF)casesreportedtoWHO,andofcountriesreportingdengue,1955–2007
DengueintheSouth-EastAsiaRegion
• Since2000,epidemicdenguehasspreadtonewareasandhasincreasedinthealreadyaffectedareasoftheregion.
• EpidemicdengueisamajorpublichealthprobleminIndonesia,Myanmar,SriLanka,ThailandandTimor-Leste.
• InThailand,dengueisreportedfromall4regions:Northern,Central,North-EasternandSouthern.
• InJune2007,outbreakswerereportedfromTratprovince,Bangkok,Chiangrai,Phetchabun,Phitsanulok,Khamkaeng Phet,NakhonSawan andPhit Chit.
• Atotalof58,836caseswerereportedfromJanuarytoNovember2007.Thecase-fatalityrateinThailandisbelow0.2%.
©WorldHealthOrganization2009
DengueintheWesternPacificRegion
• DengueisamajorpublichealthproblemintheWesternPacificRegion• Allfourserotypes(DENV-1,-2,-3,-4)arepresentintheRegion
• Occursthroughouttheyearbutratesincrease1-2monthsafterthestartoftherainyseasoninJune
• Lackofreportingremainsanimportantchallengeinpreventionandcontrol
DengueintheEasternMediterraneanRegion
©WorldHealthOrganization2009
DengueintheAmericas
©WorldHealthOrganization2009
• Thebiggestoutbreakoccurredin2002 withmorethan1millionreportedcases.
• 2001-2007,>30countriesoftheAmericasnotifiedatotalof4,332,731casesofdengue.
• ThenumberofcasesofDHF inthesameperiodwas106,037.
• Thetotalnumberofdenguedeathsfrom2001to2007was1299,withaDHFcasefatalityrateof1.2%.
• Thefourserotypesofthedenguevirus(DEN-1,DEN-2,DEN-3andDEN-4)circulateintheregion.
DengueintheAfricanRegion
©WorldHealthOrganization2009
• EasternAfrica,theavailableevidencesofarindicatesthatDEN-1,-2and-3appeartobecommoncausesofacutefever.
• WesternAfricainthe1960s,DEN-1,-2and-3wereisolatedforthefirsttimefromsamplestakenfromhumansinNigeria.
• DenguemaynotappeartobeamajorpublichealthprobleminAfrica comparedtothewidespreadincidenceofmalariaandHIV/AIDS.
• Severalcombiningfactorsproduceepidemiologicalconditionsintropicalandsubtropicaldevelopingcountriesthatfavouring viraltransmissionbyAedes aegypti:
Dengueasanemergingdisease
• Rapidpopulationgrowth• Rural–Urbanmigration• Inadequatebasicurban
infrastructure• Increaseinvolumeofsolid
wastewhichprovidelarvalhabitatsinurbanareas.
• Dengueinflictsserioushealthandsocioeconomicburden• DALY’slosttodengue=528in20011
• TheoverallcostofadenguecaseisUS$8282
• Estimatesignore:• underreportingofcases• substantialcostsassociatedwithdenguesurveillanceandvectorcontrolprogrammes.
Diseaseburden
1 Cattand et al. Tropical Diseases Lacking Adequate Control Measures: Dengue, Leishmaniasis, and AfricanTrypanosomiasis. Disease Control Priorities in Developing Countries, World Bank, 2006.2 Suaya et al. Costs of dengue cases in 8 countries in the Americas and Asia: A prospective study. Am J Trop MedHyg, 2009, 80:846-855.
Patientassessment forDengueinfection
Step1:Historytaking
Step2:Clinicalexamination
Step3:Investigations
Step4:Diagnosis,phaseofdiseaseandseverity
Step1:Historytaking
Step1:Historytaking
DENGUECASEINVESTIGATIONREPORT
Step2:Clinicalexamination
DENGUECASEINVESTIGATIONREPORT
DENGUECASEINVESTIGATIONREPORT
HemodynamicAssessment– STABLECIRCULATION
HemodynamicAssessmentinCOMPENSATEDSHOCK
HemodynamicAssessmentinCOMPENSATEDSHOCK
KEY:Clinicalexaminationofdenguepatients
Step3:Investigation
Step3:Investigation
Step3:Investigation
Step4:Diagnosis,phaseofdiseaseandseverity
1.Doesthepatienthavedengueorotherillnesses?2.Whichphaseofdengue(febrile/critical/recovery)?3.Whatisthehydrationstate?4.Aredenguewarningsignspresent?5.Whatisthehemodynamicstate?6.Whatisthebestmedicalplanforthepatient?
Primaryprevention
• Avoidbeingbitten(justafterdawnuntiljustaftersunset)
• BugGuardagents• Oiloflemoneucalyptus:Repel• Wearlong-sleevedshirtandlongpantswhenoutdoors• Usescreensinhouse
• Killadultmosquitoesandlarvainyourhome
Prevention&Controldengueinfection
Vector control
1. Environmentalmanagement2. Chemicalcontrol:larvicides3. Chemicalcontrol:adulticides4. Safeuseofinsecticides5. Monitoringofinsecticidesusceptibility6. Individualandhouseholdprotection7. Biologicalcontrol8. Towardsimprovedtoolsforvectorcontrol
Delivery of vector control interventions
Prevention&Controldengueinfection
1. Linkstoepidemiologicalservices2. Advocacy,socialmobilizationandlegislation3. Socialmobilizationandcommunication4. Collaborationwithinthehealthsectorandwithothersectors5. Integratedapproachestocontrol6. Strengtheningcapacity7. Operationalresearch8. Monitoringandevaluation
Denguepreventionandcontrol:examplesofgoodandbadpractice
Assignment• Oneassignmentpergroup• Brainstorm30min• Presentation&Discussion20min/group
Assignment1
DevelopcontrolstrategiestoaddressdengueinfectioninJapan
Dengue Virus Type 2 in Travelers Returning to Japan from Sri Lanka, 2017
Emerging Infectious Diseases2017;23(11):1931-3.
Assignment2
• Developcontrolstrategiesto effectiveeliminatemosquitoes
Would it be wrong to eradicate mosquitoes?
Assignment3
• Developcontrolstrategiestomanagedenguecaseclassificationandlevelsofseverityinprimarycare(outsideBangkok).