Overview

• Barron County reported Wisconsin’s first human West Nile virus infection of 2025, the state Department of Health Services said.
• The Hays County Health Department confirmed its first human West Nile virus case of the season, marking the county’s initial 2025 infection.
• Mosquito pools in Milwaukee and Lafayette counties tested positive for West Nile virus, prompting expanded vector monitoring.
• West Nile virus spreads through infected mosquito bites and humans serve as dead-end hosts incapable of transmitting the virus to others.
• Health agencies warn that people over 50 and immunocompromised individuals face higher risk of severe illness and recommend using repellents, wearing protective clothing and eliminating standing water.