Most people infected with West Nile virus either don't develop signs or symptoms or have only minor ones, such as a fever and mild headache.Scheduleyourappointmentnowforsafein-personcare.Learnmore:MayoClinicfactsaboutcoronavirusdisease2019(COVID-19)Our COVID-19patient andvisitorguidelines,plustrustedhealthinformationLateston COVID-19vaccination bysite:ArizonapatientvaccinationupdatesArizona,FloridapatientvaccinationupdatesFlorida,RochesterpatientvaccinationupdatesRochesterandMayoClinicHealthSystempatientvaccinationupdatesMCHSSkiptositenavigationSkiptoContentThiscontentdoesnothaveanEnglishversion.ThiscontentdoesnothaveanArabicversion.SectionsforWestNilevirusSymptoms&causesDiagnosis&treatmentPrintOverviewAmosquito-transmittedviruscausesmostcasesofWestNileinfection.MostpeopleinfectedwithWestNileviruseitherdon'tdevelopsignsorsymptomsorhaveonlyminorones,suchasafeverandmildheadache.However,somepeopledevelopalife-threateningillnessthatincludesinflammationofthespinalcordorbrain.MildsignsandsymptomsofaWestNilevirusinfectiongenerallygoawayontheirown.Butseveresignsandsymptoms—suchasasevereheadache,fever,disorientationorsuddenweakness—needimmediateattention.ExposuretomosquitoeswhereWestNilevirusexistsincreasesyourriskofgettinginfected.Youcanloweryourriskbyprotectingyourselffrommosquitoesbyusingmosquitorepellentandwearingclothingthatcoversyourskin.Products&ServicesBook:MayoClinicFamilyHealthBook,5thEditionNewsletter:MayoClinicHealthLetter—DigitalEditionShowmoreproductsfromMayoClinicSymptomsMostpeopleinfectedwiththeWestNilevirushavenosignsorsymptoms.MildinfectionsignsandsymptomsAbout20%ofpeopledevelopamildinfectioncalledWestNilefever.Commonsignsandsymptomsinclude:FeverHeadacheBodyachesVomitingDiarrheaFatigueSkinrashSeriousinfectionsignsandsymptomsInlessthan1%ofinfectedpeople,theviruscausesaseriousnervoussystem(neurological)infection.Thismayincludeinflammationofthebrain(encephalitis)orofthemembranessurroundingthebrainandspinalcord(meningitis).Signsandsymptomsofneurologicalinfectio