Lt. Thomas Flahive, 58, of the Chicago Fire Department died Thursday evening at Advocate Lutheran General Hospital in Park Ridge, according to the Chicago Tribune.
Because he was experiencing flu-like symptoms and had recently been bitten by a mosquito, the family suspects West Nile Virus, the paper said.
Earlier: West Nile cases quadruple this year
CBS2 News reported that Flahive's fellow firefighters at a station at Milwaukee Avenue and Laramie Street, not far from Niles, said he was healthy and strong.
Flahive was a 23-year veteran of the fire department, and highly regarded, reported ABC7 news.
Experts are warning that, even though the weather is cooling, the danger from West Nile virus is not over, and that people should continue to take precautions.
These include wearing repellent from dusk to dawn, wearing long sleeves and long pants, not leaving standing water on your home's property and more.