Public Health Madison and Dane County announced the finding Monday.
West Nile virus spreads to birds, animals and people through the bites of infected mosquitoes. Mosquitoes get the virus by feeding on infected birds.
The Wisconsin State Journal reports peak season is approaching for the virus. To reduce risk, health officials say people should limit time spent outside at dawn and dusk, apply insect repellant to clothing and exposed skin, make sure window and door screens are in good repair, trim tall grass, weeds and vines, and eliminate standing water.
Since 2002, there have been 234 human cases of West Nile virus statewide, with 23 reported in Dane County.