Chicago, IL – Northern Illinois is reporting the majority of human West Nile virus (WNV) cases in 2025, with state health officials urging residents to take precautions as mosquito activity remains high.
According to the Illinois Department of Public Health (IDPH), 42 human cases of WNV have been confirmed across the state this year. Of those, 39 were detected in Northern Illinois, including Cook, Will, Lake, DuPage, and DeKalb counties. Cook County leads with 34 cases, while Will County confirmed its first patient in August, an individual in their 80s. Lake County reported two cases, and both DuPage and DeKalb counties each identified one.
Statewide, 3,575 mosquito batches from 67 counties have tested positive for WNV this season. The Will County Health Department reported positive mosquito pools in 11 communities, including Joliet, Bolingbrook, Frankfort, and Plainfield…