Skiptomaincontent COVID-19FUND—DONATENOW!WestNilevirusHomeTopicsWestNilevirusWestNilevirusWestNilevirusisamemberoftheflavivirusgenusandbelongstotheJapaneseencephalitisantigeniccomplexofthefamilyFlaviviridae.Itistransmittedbyinfectedmosquitoesbetweenandamonghumansandanimals,includingbirds,whicharethevirus'sreservoirhost.FirstisolatedintheWestNiledistrictofUgandain1937,WNVistodayfoundcommonlyinAfrica,Europe,theMiddleEast,NorthAmerica,andWestAsia.In1999aWNVcirculatinginIsraelandTunisiawasimportedintoNewYorkproducingalargeoutbreakthatspreadacrosstheUnitedStatesandeventuallyacrosstheAmericas,fromCanadatoVenezuela.WNVoutbreaksitesarefoundalongmajorbirdmigratoryroutes.KeyfactsEightin10peoplewhobecomeinfectedwithWNVshownosymptoms. About20%ofinfectedpeopledevelopmoderatesymptoms,includingfever,headache,fatigue,andbodyaches,nausea,rash,andswollenglands.Inabout1in150cases,WNVcausesseverediseasethatcanleadtoencephalitis,meningitis,paralysis,andevendeath.In2012,286peopleintheUnitedStatesdiedofWNV,accordingtotheU.S.CentersforDiseaseControlandPrevention(CDC).Preliminarydatafor2013indicateover1,200casesofneuroinvasivediseaseand114deathsduetoWNV.Peopleovertheageof50,thosewithunderlyingmedicalconditions,andsomeimmunocompromisedpersons(suchastransplantpatients)have thehighestriskofsevereillnessfromWNV.Averysmallproportionofhumaninfectionshaveoccurredthroughorgantransplant,bloodtransfusions,andbreastmilk.Inadditiontomosquitobites,WNVmaybetransmittedthroughcontactwithinfectedanimals,theirblood,orothertissues.MosquitoesofthegenusCulexaregenerallyconsideredtheprincipalvectorsofWNV,inparticular,Cx.pipiens.InEurope,Africa,theMiddleEast,andAsia,mortalityinbirdsassociatedwithWNVisrare.Incontrast,intheAmericas,thevirushasprovenhighlypathogenicforbirds.Vaccinesareavailableforuseinhorsesbutnotyetforpeople.FactsheetProtectyourselfandyourenvironmentVector-bornediseasescanbepreventedbyWearingclothingthatactsasabarriertoexposuretobitesUsingmechanismstokeepvectorsoutofhousessuchasscreensondoors,windo