Mosquitoes collected in Wauwatosa are among the first in the state this year to test positive for West Nile Virus as Wisconsin heads into the season that typically experiences the highest infection rates.
The City of Wauwatosa announced the test results July 30 in an online news release. The cases of West Nile Virus are the first detected in Wauwatosa since the latest surveillance efforts began in mid-June, the city said.
Statewide, six cases of West Nile Virus have been found in birds and mosquitoes this year in four counties: Bayfield, Lafayette, Milwaukee and Saint Croix. No human cases have been reported yet in Wisconsin, according to online data maintained by the Wisconsin Department of Health Services.
West Nile Virus can be spread to humans and other animals by the bite of an infected mosquito. It is not transmitted from infected humans to other humans.
Most cases are mild or asymptomatic. Symptoms can include fever, chills, headache, muscle ache, rash, and fatigue. Some rarer cases can be more debilitating, particularly in those with compromised immune systems, and medical care should be sought.
In an average year, the number of human cases reported in Wisconsin ranges from a handful to a few dozen. The state logged 27 cases in 2025. August and September are the most common months when human cases are reported. Older residents are more likely to be infected than young people.
The Wauwatosa Health Department, in releasing the news of the local mosquito infection, offered several tips for preventing human infections, by reducing the likelihood of bites and eliminating potential mosquito breeding sites.
Tips include wearing insect repellant, minimizing outdoor activities in the morning and evening hours and wearing loose-fitting clothes with long sleeves and long pant legs. Remove standing water from around your property, and trim tall grass and weeds.
Additional information is available on the Department of Health Services website.
