West Nile virus is usually spread through the bite of an infected mosquito during the summer and fall. Your best bet to avoid the virus is to avoid mosquito bites when possible.

The Wisconsin Department of Health Services identified the first case of West Nile virus in the state in 2025, according to a news release on Monday. Officials said a human case of the virus was reported in a person in Barron County. They also collected mosquitoes in Milwaukee and Lafayette counties that tested positive.