CDPH Confirms Chicago's First Human Cases, One Death from West Nile Virus in 2026

CHICAGO - The Chicago Department of Public Health (CDPH) is reporting Chicago's first two human cases and first death from West Nile virus (WNV) in 2026. The Illinois Department of Public Health has also confirmed several additional cases of WNV in the state of Illinois.

"2026 has seen the rainiest summer in Chicago in years, giving mosquitoes ample opportunities to breed," said CDPH Commissioner Garth Walker, MD, MPH. "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."

"The year's first death in Illinois related to West Nile virus is a sobering reminder to take mosquito-borne illness seriously," said IDPH Director Dr. Sameer Vohra. "While most people won't experience serious symptoms, West Nile virus can lead to severe illness in high-risk groups such as older adults, individuals with chronic medical conditions, and immunocompromised persons. We encourage everyone to Fight the Bite and take the appropriate precautions against mosquito bites: wear protective clothing and use EPA-approved insect repellent, make sure doors and screens are intact to keep mosquitoes out, and report areas of stagnant water where mosquitoes can breed."

West Nile virus is the most common cause of mosquito-borne disease in Chicago and the United States. CDPH has a robust mosquito control program, which includes treating over 80,000 catch basins in Chicago with larvicide to kill immature mosquitoes, collecting and testing mosquitoes for WNV, and spraying in specific geographic areas to kill adult mosquitoes if needed.

CDPH has sprayed insecticide in 15 different community areas over the last several weeks, including Beverly, Burnside, Chatham, East Garfield Park, Lower West Side, Morgan Park, Near West Side, North Lawndale, O'Hare, Pullman, Roseland, South Deering, Washington Heights, West Lawn, and West Pullman. West Nile virus risk in Chicago is currently rated as moderate, and all Chicagoans are encouraged to take precautions against mosquitoes:

• Use EPA-registered insect repellant that contains ingredients such as DEET, picaridin, IR3535, or oil of lemon eucalyptus according to label instructions.
• Eliminate standing water: empty water from any indoor or outdoor containers, such as flowerpots, gutters, pet water dishes, and birdbaths on a weekly basis.
• Keep grass and weeds short to eliminate hiding places for adult mosquitoes.
• When outside between dusk and dawn, wear loose-fitting, light-colored clothing, long sleeves, pants, socks, and shoes.
• Make sure that all screens, windows, and doors are tight-fitting and free of holes. Use air conditioning when possible.
• People who are immunocompromised should consider avoiding outdoor activity during peak mosquito hours from dusk to dawn.

WNV is typically spread to humans via the bite of an infected mosquito and is not generally spread from person to person. While most people infected with WNV do not feel sick, about 1 in 5 people develop a fever and flu-like symptoms. Severe illness can occur in about 1 in 150 people and is most likely in people over age 60. Because there are no specific medications to treat WNV in people, the most effective method to prevent infection is to prevent mosquito bites.

For more information about mosquito levels in Chicago and mosquito-borne diseases, including symptoms and prevention, visit chicago.gov/westnilevirus. To report standing water, dead birds or high grass/weeds, call 311.

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