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.

Ques9ons?