zika, a new mosquito-borne virus in the americas, and ... · pdf file6/3/2017 ·...
TRANSCRIPT
Zika,aNewMosquito-borneVirusintheAmericas,andVirginia’sPlans
forZikaPreven?on
Dr.DavidN.GainesPublicHealthEntomologistVDH-OfficeofEpidemiology
ABriefHistoryofZikaVirusZikaviruswasdiscoveredintheZikaForest,Uganda1947From 1947 – 2007, serologicalandotherlabevidenceofZikavirusinfec?onshadbeenfoundinpeoplefromAfricatoAsiaandtheWesternPacificna?ons.
ThefirstlargeZikaoutbreakeverrecorded-YapIsland,Micronesiain2007.AsecondlargeZika outbreak-FrenchPolynesiaandotherPacificIslands2013–14.ZikaarrivedinBrazilin2014andspreadtootherpartsoftheAmericas2015–2016.
2007
2014
2013 - 2014 2014 -
2016
ABriefHistoryofZikaVirusanditsTransmission
TheZikavirusistransmi\edina“mosquito-to-human-to-mosquitocycle”andisknowntohave“African”and“Asian” variants.
TheZikavirusvariantthatcausedthe2007outbreakonYapIsland,andallofthesubsequentlargeoutbreakshasbeenthe“Asianvariant”.
ItispossiblethattheAsianvariantofZikavirushasevolvedtheabilitytocausemuchlargerdiseaseoutbreaksthantheAfricanvariant.
Aedesaegyp*(yellowfevermosquito)washistoricallyassociatedwithZika transmission,butothercloselyrelatedAedesmosquitospeciesin“StegomyiaSubgenus”havealsobeenassociatedwithZikatransmissionandinclude:
Aedeshensilli-onYapIslandAedespolynesiensis–inFrenchPolynesiaandotherPolynesianIslandchainsand,Aedesalbopictus,theAsian?germosquitoinGabonandinSingapore.
Asian?germosquitoesareverycommonthroughoutthesoutheasternU.S.,butAedesaegyp*mosquitoesareonlycommoninthemostsouthernareasoftheU.S.(SouthernFloridaandSouthernTexas).
YapIslandZikaOutbreak,2007Inves?gatorsoftheYapIslandoutbreakwereonlyabletoobserveandrecordZikasymptomsin31symptoma?cpa?entsthathadlaboratoryconfirmedZikainfec?ons.
NumberofPatients(%) IllnessSignorSymptom
28(90%) Macularorpapularrash
20(65%) Fever
20(65%) Arthritisorarthralgia
19(55%) Conjunctivitis(redeyes)
15(48%) Myalgia(bodyaches)
14(45%) Headache
12(39%) Painbehindeyes
6(19%) Swellingoflimbs
3(10%) Vomiting
Up to 80% of persons infected with Zika do not develope symptoms.
FrenchPolynesianOutbreak,ZikaSymptomsThemuchlargerPolynesianoutbreakprovidedanopportunitytoobtainmoredetailsonZikasymptoms.
Itwasnotedthatpersonswitharashcouldexperienceintenseitching,andthatjointpainoccurredmostlyinsmalljointsoftheextremi?es(e.g.,hands,feet).Pa?entsmayalso haveswellingoftheextremi?es.
ZikaRashes
Conjunc?vi?s
Jointpainand
Swelling
BrazilOutbreak,ZikaIden?fiedasPossibleCauseofBirthDefectsandGuillain–BarreSyndrome
InOctoberof2015,BrazilianstatesthathadthelongestrunningandlargestZikaoutbreaksbegantoseeagreatincreaseinthenumberofbabiesbornwithmicrocephaly.
Microcephalyisabirthdefectthatresultsinbabieswithabnormallysmallbrainsandheads;itcanresultintheprematuredeathofthebaby,orinchildrenthatarementallydeficientandunabletofunc?onnormally.
APPhoto/FelipeDanaByJanuaryof2016,Brazilhadalsocounted121casesofGuillain-BarreSyndromeinpersonsthathadZika–likesymptoms.
RecentFindingsontheClinicalOutcomesforPeopleandHumanFetusesinfectedwiththeZikaVirus
AsZikahascon?nuedtocauseillnessthroughouttheAmericas,moredetailshaveemergedaboutitseffectsonhumanpa?entsandfetuses.
AsmallpercentageofZikaviruspa?entsmaysufferfrom:1. Guillain-Barresyndrome(immunesystema\acksthenervoussystem)2. Acutedisseminatedencephalomyeli?s(adisorderthata\acksbrain’smyelin;resul?nginsymptomssimilartomul?plesclerosis)
3. Severethrombocytopeniasyndrome(ahemorrhagicdisorder)
Zikavirusinfec?onsofthefetusmaycause:1. Fetaldeath/miscarriage2. Microcephaly3. Otherbirthdefectssuchas:intracranialcalcifica?ons,eyedefects,hearingdefects,clubfoot,congenitaljointcontractures,impairedgrowth ventriculomegaly,andbraindevelopmentdisorders(lissencephalyandpachygyria).
ClinicalSignsandSymptomsinZikaVirusPa?ents(N=683)inPuertoRico,November1,2015–April14,2016
SignsandSymptoms No.ofpa9ents (%)
Rash 505 74%Myalgia(bodypain) 462 68%Headache 433 63%Fever 429 63%Arthralgia(jointpain) 428 63%Eyepain 350 51%Chills 344 50%Sorethroat 233 34%Petechiae 213 31%Conjunc9vi9s 137 20%Nausea/Vomi9ng 123 18%Diarrhea 115 17%
Pa9entswereaged35days–89years(medianage==34years);TraveloutsideofPuertoRicoandU.S.inthe14daysbeforeillnessonset;AllGBSpa9entswerehospitalized;Signsandsymptomswerereportedbythepa9ents’clinicians
Symptoms seen in >50% of patients
Pa?ents(N=683)withZikaVirusinPuertoRicoNovember1,2015–April14,2016
Pa9entswereaged35days–89years(medianage==34years)TraveloutsideofPuertoRicoandU.S.inthe14daysbeforeillnessonsetAllGBSpa9entswerehospitalizedDefinedasbloodplateletlevels<100,000cells/mm3Sinsandsymptomswerereportedbythepa9ents’clinicians
Characteris9cNo.ofpa9ents (%)
Female 436 64%Pregnant 65 10%Hospitalized 17 2%SevereThrombocytopenia 9 >1%SuspectedGuillain-BarreSyndrome 5 <1%Deaths(SevereThrombocytopenia) 1 <1%
TheVariousMeansofZikaVirusTransmission
Zikavirusmaybetransmi\edby:
1. Infec?ousmosquitobites;Aedesaegyp*andAedesalbopictus.
2.Infec?onofunbornchildrenbytheirinfectedmothers.
3.SexualtransmissionofZikavirusininfectedsperm.
4.Bloodtransfusionsfromasymptoma?c,Zika-infectedblooddonors.
Zikavirusreservoirhosts(theanimalsfromwhoseblood,mosquitoesbecomeinfected):
1.CurrentlytheonlyknownreservoirsofZikavirusformosquitoesareprimates(i.e.,apes,monkeys,orpeople).
2.Itisnotyetknownifothermammalsoranimalspar?cipateintheZikatransmissioncycle?
TwoMosquitoSpeciesareCapableofTransmilngtheZikaVirusinVirginia
Aedes albopictus the Asian tiger mosquito
Aedes aegypti the yellow fever mosquito
Aedes aegypti, the yellow fever mosquito are the most efficient vector of Zika because they feed almost exclusively on primates including humans, and as humans serve as reservoirs for this virus, this mosquito will only vector the virus from one person to another.
Ae. albopictus the Asian tiger mosquito is a much less efficient Zika vector because although it likes to feed on people, it also likes to feed on a variety of other animals including dogs and cats (which are not known reservoir species), so it is less likely to become infected with the Zika virus, and is less likely to transmit Zika to a person if it is infected.
Currently,themostcommonurban/suburbanpestmosquitoinVirginiaistheAsian?germosquito
Asian tiger mosquito - Aedes albopictus
Aedesaegyp*mosquitoesareknowntohaveanoldestablishedpopula?ononCapitolHillinWashingtonD.C.,andtheyareoccasionallyfoundatsitesaroundnorthernVirginia,butsofar,theyhavenotbecomecommoninVirginia
Aedesaegyp*andAsian?germosquitoeslayeggsexclusivelyinar?ficialandnaturalcontainersofwater.
Natural Containers Artificial Containers
treeholes
Thesecontainerbreedinghabitatsaremostomenfoundaroundhomes,andpopula?onsofthesemosquitoescanbeabundantinshadyneighborhoods.
wheelbarrows birdbaths
wadingpools/trashbuckets
Mosquitolarvae
Plas?csheets/tarpsholdingwater Plas?cdownspoutextensionsholdingwater
Plantpottrays Old?res
Unmaintainedpools Themosteffec?veandenvironmentallysoundmethodofelimina?ngAsian?germosquitoes
Asthecontainersusedbythesemosquitoesaremostlyfoundonpeople’sprivateproperty,thismethodofcontrolcanonlybeaccomplishedwiththecompletecoopera?onandassistanceofthepublic.
andAe.aegyp*istoeliminate,dump,ortreattheircontainerhabitats.
Virginia’sPlanforZikaPreven?on
In2016,theVirginiaDepartmentofHealth(VDH)puttogetheraZikaResponsePlantopreventthelocalspreadofZikavirus.
In2016Zikacasesurveillancebyhealthdepartmentepidemiologistsiden?fiedZikacasesanddeterminedifthey:
Pa?entswhowerelikelytohavecontractedZikainVirginia,orwhowerelikelytobeviremic,andwhohadexposuretomosquitoesortomosquitobitesinVA,wereaskedifmosquitosurveillancepersonnelcouldvisittheirhomeandanyothersiteswheretheyhadbeenexposedtomosquitoes.
1.contractedthevirusoutsideofVirginia,orinVirginia;
2.werelikelytos?llbeviremic(hadviruscircula?ngintheirblood);basedonexposuredates,laboratorytestresults,andillnessonsetdates.
3.hadmosquitoesaroundtheirhomes,orexposuretomosquitoesathomeorelsewhereinVA.
Virginia’sPlanforZikaPreven?onWhenpa?entsconsentedtoahomesiteinspec?on,mosquitosurveillancepersonnelwouldinspecttheproperty,settrapstocollectmosquitoes,anddump,treatorrecommendtreatmentforanycontainerspresent.
Forpa?entswhowerelikelytohavecontractedZikainVirginia,mosquitosurveillanceandcontrolopera?onsmaybeextendedoutintothesurroundingneighborhoodinaradiusofupto1,500m.
Ifsignificantmosquitopopula?onswerefound,adul?cide-ULVorbarriertreatmentswouldbemade,orrecommended,andinspec?onforcontrolofcontainerhabitatsand/oradultmosquitocontrolmaybeextendedtoneighboringproper?es.
Ifnosignificantmosquitopopula?onwasfoundonaproperty,thepa?entwouldbecounseledtoavoidmosquitobitesforseveralweeks.
For patients with imported Zika infections, surveillance and control effort would focus on immediate area around the patient’s home.
Virginia’sPlanforZikaPreven?onInjurisdic?onsthathadmosquitosurveillanceandcontrolcapabili?es,homesitevisitswereperformedbylocalmosquitocontrolpersonnel.
As EH personnel and roving surveillance personnel had no license /certification to apply insecticides, they would provide “consumer packaged larvicide products” to homeowners that had mosquito breeding containers that could not be dumped and they would recommend contract adult mosquito control for the properties that had excessive adult mosquitoes.
Injurisdic?onsthathadnomosquitosurveillanceandcontrolcapabili?es,pa?enthomesiteinspec?onswereperformedbyHealthDepartment-EnvironmentalHealth(EH)Personnelorbycontract“rovingmosquitosurveillancepersonnel”whoworkedoutoftheVDHcentralofficeinRichmond.
Consumer Larvicide Products
Mosquitocontrolguidedbymosquitosurveillance
Mosquitocontrolonly
VirginiaJurisdic?onshavingMosquitoSurveillanceandControlCapabili?es
MosquitocontrolprogramsarefoundprimarilyinsomeofVirginia’smostheavilypopulatedjurisdic?ons.
Virginia’sPlanforZikaPreven?onDuringthecourseof2016,theVirginiaDepartmentofHealthputoutabidforcontractproposalsbymosquitocontrolcompanies,andestablishedcontractswithtwocompaniestoconductmosquitocontrolinVirginiajurisdic?onswithoutcontrolcapability.
Contractedmosquitocontrolac?vi?eswouldinclude:1.Doortodooreduca?onaloutreachinatargetneighborhood,2.Mosquitotrapping/surveillance,3.Iden?fica?on,dumpingandortreatmentofcontainerhabitats,4.Adul?cidetreatments(ULV,orbarriertreatmentsinyards),5.Truck-mountedULVadul?cidetreatmentsifnecessary,6.Aerial(aircram)applica?onofULVadul?cidesifnecessary
*Thecontractiscurrentlybeingmodifiedtoaddtruck-mountedapplica?onofaerosollarvicides
7.Aerial(aircram)applica?onoflarvicidedropletsifnecessary*
Virginia’sPlanforZikaPreven?onInaddi?ontomosquitosurveillanceandcontrolac?vi?es,VDHalsoworkedtoimprovepubliceduca?onaboutmosquitopreven?onandZikaavoidancethroughpublicinforma?oncampaigns
Thisoutreachac?vityincluded:
1.ThePrin?nganddistribu?onofeduca?onalmaterialssuchasdoorhangers,flyers,andeduca?onalmaterialsforpregnantwomen.
2.TheScreeningofshortZikapreven?onvideosonTVscreensinVirginia’sinterna?onalairports,andonmovietheaterscreensaroundVA.
3.Distribu?onofself-protec?onkitscontainingpreven?onliterature,condoms,andmosquitorepellentstobehandedouttopregnantwomenbyclinicsaroundVA.