Chicago Department Of Public Health Conducts A Comprehensive Mosquito Surveillance And Control Program To Reduce Threat To Residents

June 13, 2023

First West Nile Virus-positive mosquitoes in Chicago reported for 2023

CDPH Public Information Office

CHICAGO – The Chicago Department of Public Health (CDPH) has confirmed the first West Nile Virus (WNV)-positive mosquito batch in the City for 2023. The Illinois Department of Public Health previously confirmed the first mosquitoes to test positive for WNV in the state on June 1, 2023. No human cases of WNV have been reported to date this year. West Nile Virus regularly circulates in Chicago and most of the United States, but it remains important to mitigate the spread of WNV and other mosquito-borne diseases.

CDPH has a robust mosquito control program, which includes treating 70,000 catch basins in Chicago with larvicide, collecting and testing mosquito samples every week, and spraying in specific geographic areas if indicated.

“As summer approaches, we want to ensure that all Chicago residents can remain safe and healthy,” said CDPH Commissioner Dr. Allison Arwady. “The best way to protect yourself from mosquitoes and the diseases they carry is to prevent mosquitoes around your home and avoid mosquito bites.”

Chicago residents are encouraged to take the following precautions against mosquitoes:

  • Use insect repellant that contains DEET, Picaridin, IR3535, or Oil of Lemon Eucalyptus according to label instructions.
  • Eliminate standing water. Empty water from any outdoor containers, such as flowerpots, gutters, tires, toys, pet water dishes, and birdbaths once weekly.
  • 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 pants, long-sleeved shirts, socks, and shoes.
  • Make sure that all screens, windows, and doors are tight-fitting and free of holes. Repair or replace screens that have tears or other openings.
  • Check on neighbors regularly, especially those who are older, live alone, or need additional assistance.

WNV is typically spread to humans via the bite of infected mosquitoes. Most mosquitoes do not carry the virus. 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-borne diseases, including symptoms and prevention, visit To report standing water, dead birds or high grass/weeds, call 311.