West Nile reported in four counties in 2023, IDPH warns to ‘Fight the Bite’

The Illinois Department of Public Health is reminding the public that, along with the start of summer, mosquito season is getting underway in Illinois. Batches of mosquitos that tested positive for West Nile virus have been reported in four counties around the state. The reminder comes as public health officials around the country are highlighting the importance of taking action to “Fight the Bite” during National Mosquito Control Awareness Week, June 18 to 24.

IDPH supports mosquito control efforts throughout the state by providing $2.5 million in funding to the 97 local health departments in Illinois for vector surveillance and control activities. This includes purchasing and applying larvicide, working with local municipal governments and local news media for WNV prevention, and education and investigating mosquito production sites and nuisance mosquito complaints. Local health departments collect mosquitoes for West Nile virus testing and also collect sick or dead birds for West Nile virus testing.

While no human cases of West Nile virus have been reported in Illinois so far this year, there were 34 human cases, which are significantly underreported, and eight deaths attributed to the disease in 2022. This number of deaths was the most in any year since 2018, when there were 17. A total of 10 batches of mosquitos that tested positive for West Nile virus have been reported this year in Cook, La Salle, Morgan and St. Clair counties.

Updates on where cases have been reported can be found on the IDPH West Nile Virus Surveillance page.

The first batch of mosquitos to test positive for WNV this year was reported May 30 in Evanston. In 2022, the first batch of mosquitoes to test positive were collected May 24 in DuPage County. Last year, 44 counties reported a West Nile virus positive mosquito batch, bird, horse, and/or human case. The youngest person to report a case of West Nile virus in Illinois last year was 26 years old, while the median age of human cases was 64.

IDPH encourages the public to Fight the Bite by practicing the three “Rs” – reduce, repel and report:

• REDUCE: Make sure doors and windows have tight-fitting screens. Repair or replace screens that have tears or other openings. Try to keep doors and windows shut. Eliminate, or refresh each week, all sources of standing water where mosquitoes can breed, including water in bird baths, ponds, flowerpots, wading pools, old tires, and any other containers.
• REPEL: When outdoors, wear shoes and socks, long pants and a light-colored, long-sleeved shirt. Apply an EPA-registered insect repellent that contains DEET, picaridin, oil of lemon eucalyptus, IR 3535, para-menthane-diol (PMD), or 2-undecanone according to label instructions. Consult a physician before using repellents on infants.
• REPORT: Report locations where you see water sitting stagnant for more than a week such as roadside ditches, flooded yards and similar locations that may produce mosquitoes. The local health department or city government may be able to add larvicide to the water, which will kill any mosquito larvae.

Information about West Nile virus can be found on the IDPH website.