Prairie State Wire

The Illinois Department of Public Health (IDPH) has announced the confirmation of West Nile virus (WNV) in environmental samples from 17 counties across the state. This announcement coincides with National Mosquito Control Awareness Week, observed from June 15-21, as a reminder of the ongoing mosquito season and associated risks.

No human cases have been reported in Illinois this year. However, in 2024, there were 69 confirmed human cases, including 13 fatalities. IDPH Director Dr. Sameer Vohra emphasized the importance of taking precautions: “With mosquito season underway in Illinois, it is now time for Illinoisans, especially seniors and those with weakened immune systems, to start taking precautions to prevent mosquito bites.”

Dr. Vohra advises practicing the "Three R’s": reduce opportunities for mosquitoes to enter homes, repel them by using insect repellent outdoors, and report standing water where mosquitoes breed.

A county is deemed positive for WNV if a mosquito, horse, or human tests positive for the virus. The counties reporting WNV this year include Bureau, Christian, Cook, DeKalb, DuPage, Fulton, Grundy, Hancock, Henry, Marshall, McDonough, McHenry, Peoria, Scott, Stark, Tazewell and Winnebago. In 2024 WNV was found in 72 counties statewide.

The first positive mosquito batch this year was detected on May 9 in Rockford. Updated information on WNV is available on the IDPH West Nile Virus Surveillance page.

IDPH supports statewide mosquito control efforts with $2.8 million allocated to local health departments for vector surveillance and control activities. These efforts include larvicide application and public education on prevention measures.

Monitoring involves testing mosquito batches as well as sick horses and humans exhibiting symptoms similar to WNV. The virus is transmitted through a bite from an infected mosquito that has fed on an infected bird. Symptoms can range from fever and headache to severe illnesses like paralysis or encephalitis.

To mitigate risk during mosquito season IDPH recommends:

- REDUCE: Ensure screens are intact; eliminate standing water weekly.

- REPEL: Wear protective clothing outdoors; use EPA-approved repellents.

- REPORT: Notify authorities about stagnant water sources lasting over a week.

For more information about West Nile virus visit the IDPH website.