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Cook County confirms first human West Nile virus cases of season
Cook County health officials are warning of a high risk of West Nile virus infection after confirming the first four human cases in the suburbs this season.
CHICAGO - Chicago health officials are reporting the city's first two human cases of West Nile virus this year, including the first death linked to the virus in 2026.
Chicago West Nile virus
The backstory:
The Chicago Department of Public Health said the Illinois Department of Public Health has also confirmed several additional West Nile cases elsewhere in the state.
Officials are urging residents to take precautions against mosquito bites, especially after a rainy summer created more opportunities for mosquitoes to breed.
"2026 has seen the rainiest summer in Chicago in years, giving mosquitoes ample opportunities to breed," CDPH Commissioner Garth Walker said in a statement. "The best way to protect yourself from West Nile virus is to avoid mosquito bites and take measures to stop them from breeding around your home."
West Nile virus is the most common cause of mosquito-borne disease in Chicago and across the United States. The virus is generally spread to people through the bite of an infected mosquito and is not typically transmitted from person to person.
By the numbers:
Most people infected with West Nile virus do not develop symptoms. About 1 in 5 infected people develop a fever and flu-like symptoms, while severe illness occurs in about 1 in 150 cases and is most likely among people over 60.
The risk is also greater for people with chronic medical conditions and those who are immunocompromised.
Over the past several weeks, CDPH has sprayed insecticide in 15 community areas, including Beverly, Burnside, Chatham, East Garfield Park, the Lower West Side, Morgan Park, the Near West Side, North Lawndale, O'Hare, Pullman, Roseland, South Deering, Washington Heights, West Lawn and West Pullman.
Health officials recommend using EPA-registered insect repellent containing ingredients such as DEET, picaridin, IR3535 or oil of lemon eucalyptus. Residents should also empty standing water from items such as flowerpots, gutters, pet dishes and birdbaths at least once a week.
What you can do:
Keeping grass and weeds short can reduce places where adult mosquitoes hide. Residents are also encouraged to wear loose-fitting, light-colored clothing, long sleeves, pants, socks and shoes when outdoors between dusk and dawn.
Officials recommend making sure doors, windows and screens are properly fitted and free of holes and using air conditioning when possible. People who are immunocompromised should consider avoiding outdoor activity during peak mosquito hours.
Residents can report standing water, dead birds or high grass and weeds by calling 311.
The Source: The information in this report came from the Chicago Department of Public Health.