A Chicago resident has died from West Nile virus, marking the city’s first death associated with the illness this year, according to the Chicago Department of Public Health. Several other cases have also been reported across Illinois.

West Nile virus most commonly reaches people through the bite of an infected mosquito. Birds are also part of the disease cycle, as mosquitoes can acquire the virus while feeding on infected birds and then transmit it to humans.

Chicago experienced unusually wet conditions during the summer, creating more opportunities for mosquito reproduction. "2026 has seen the rainiest summer in Chicago in years, giving mosquitoes ample opportunities to breed," CDPH Commissioner Garth Walker said in a statement.

Walker urged residents to focus on preventing bites and reducing places where mosquitoes can reproduce. "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."

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The CDPH has sprayed insecticide in 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 in an effort to prevent infections.

Most people infected with West Nile virus experience mild symptoms or no symptoms, according to the Centers for Disease Control and Prevention. Possible mild symptoms include fever, aches and rashes.

However, rare serious cases can occur when the virus invades the nervous system. These cases can lead to meningitis, encephalitis, paralysis or death, with encephalitis involving swelling of the brain.

People over 50 and those with compromised immune systems face the highest risk, experts caution. Dr. Tyler Evans said symptoms such as fever, headache and body aches can be difficult to distinguish from the flu.

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Evans is an infectious diseases and addiction medicine doctor and an associate professor at University of Southern California Keck School of Medicine. He is also the CEO and chief medical officer for Wellness Equity Alliance.

Severe neuroinvasive cases occur when the virus infects the brain. "When there's inflammation that leads to meningitis or encephalitis, that's very bad," Evans told Fox News Digital.

Evans warned that severe headaches, a stiff neck, disorientation, vision loss and confusion can signal the need for emergency management, particularly among people over 65 or those with immunocompromising conditions such as severe diabetes or cancers.

There are no vaccines or specific treatments for West Nile virus, although supportive treatments are available. Evans said people over 65 and those with immunocompromising conditions should seek immediate emergency help if confusion, headache or a stiff neck develops.

Avoiding mosquito bites is the first line of defense, according to Evans. "In areas where there are a lot of mosquitoes, DEET is going to be key," he said, recommending repellents containing at least 30% DEET for adults.

Evans also recommends avoiding outdoor activities during sundown in places with high mosquito burdens. Health officials advise wearing loose clothing with long sleeves, applying insect repellent, particularly at dawn and dusk, and making sure window screens are secure.

Residents can also reduce mosquito breeding opportunities by removing standing water around their homes. Buckets, tires and gutters are among the places where water can collect.

There have been 407 reported human cases of West Nile virus in the U.S. this year, according to preliminary CDC data current as of Sept. 1. That total includes 285 severe neuroinvasive cases and 23 deaths.

Most West Nile cases are reported during August and September. The Chicago death and other cases across Illinois underscore health officials’ warnings about preventing bites and limiting mosquito breeding around homes.