The first case of West Nile virus (WNV) in humans in Wisconsin was reported in 2002.
In 2019, Wisconsin had four confirmed and probable cases of West Nile virus.
From 2015 through 2019, an average of 22 cases of West Nile virus have been reported each year. West Nile virus is preventable.
You can see the statewide data for West Nile virus in the table.
For information on national data, visit the Centers for Disease Control and Prevention (CDC) Statistics and Epidemiology page for West Nile virus.
Case numbers are updated routinely during mosquito season.
Updated October 18, 2021
|Counties reporting WNV activity||1|
* Probable cases have presumptive positive laboratory results without confirmatory testing at CDC.
** The deaths are included among the confirmed and probable cases.
West Nile Virus Data
West Nile Virus Cases in Wisconsin (2002-2019)
Cases Reported by Month and Age
Month of Illness Onset
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