The following year, the state's first human cases and deaths from West Nile disease were recorded and all but two of the state's 102 counties eventually ...JumptonavigationAnyone12yearsofageandolderiseligiblefortheCOVID-19vaccine.Findyournearestvaccinationlocationhereorcall(833)621-1284toscheduleanappointmentnearyou.Home»Topics&Services»DiseasesandConditions»WestNileVirus(WNV)WestNileVirus(WNV)WestNilevirusemergedintheUnitedStatesintheNewYorkmetropolitanareainthefallof1999.Sincethen,thevirus,whichcanbetransmittedtohumansbythebiteofaninfectedmosquito,hasquicklyspreadacrossthecountry.InIllinois,WestNileviruswasfirstidentifiedinSeptember2001whenlaboratorytestsconfirmeditspresenceintwodeadcrowsfoundintheChicagoarea.Thefollowingyear,thestate'sfirsthumancasesanddeathsfromWestNilediseasewererecordedandallbuttwoofthestate's102countieseventuallyreportedapositivehuman,bird,mosquitoorhorse.Bytheendof2002,Illinoishadcountedmorehumancases(884)anddeaths(64)thananyotherstateintheUnitedStates.TheIllinoisDepartmentofPublicHealth(IDPH)maintainsasophisticateddiseasesurveillancesystemtomonitoranimalsandinsectsthatcanpotentiallycarrythevirus:deadcrows,robins,bluejays,mosquitoesandhorses.Mosquitoescaneithercarrythevirusorgetitbyfeedingoninfectedbirds.Thesurveillancesystemalsoincludesinfectiousdiseasephysicians,hospitallaboratorydirectorsandinfectioncontrolpractitioners,localhealthdepartmentsandstafffromIDPH'slaboratory,environmentalhealthandinfectiousdiseasesdivisionswhotestforandreportsuspectorconfirmedcasesofvariousdiseasesthatcanbecausedbymosquito-borneviruses.MildcasesofWestNileinfectionsmaycauseaslightfeverorheadache.Moresevereinfectionsaremarkedbyarapidonsetofahighfeverwithheadandbodyaches,disorientation,tremors,convulsionsand,inthemostseverecases,paralysisordeath.Usuallysymptomsoccurfromthreeto14daysafterthebiteofaninfectedmosquito.Personsatthehighestriskforseriousillnessarethose60yearsofageorolder.ThebestwaytopreventWestNileencephalitisandothermosquito-borneillnessesistoreducethe