The risk of West Nile virus in Chicago is considered “high,” as health officials say the area is experiencing “a higher proportion of mosquitoes testing positive for West Nile virus than usual.”

Chicago reports its first three human cases of West Nile virus in 2025, with an early state case and citywide spraying efforts underway.

Local health officials say Chicago has reached a “high risk” level of the West Nile virus because mosquitoes are testing positive earlier and could lead to a longer lasting, heightened risk this