The Illinois Department of Public Health (IDPH) is reminding the public that mosquito season is now underway in Illinois and that positive batches of West Nile Virus have been reported in seven counties around the state. The reminder comes as public health officials around the country are highlighting the importance of taking protective action to “Fight the Bite” during National Mosquito Control Awareness Week.

No human cases of West Nile virus have been reported in Illinois so far in 2022, but there were 64 human cases and five deaths attributed to the disease in 2021.

“West Nile virus is a serious illness, and we want to remind everyone to protect themselves from mosquito bites at this time of year when so many of us are spending more time outdoors,”said IDPH Acting Director Amaal Tokars. “The most important things we can do are to wear insect repellent if we are spending time outside and eliminate standing water where mosquitos breed around our homes. These precautions are especially important for those with weakened immune systems”

The first mosquitoes to test positive for West Nile virus in the state this year were reported on May 24 in Roselle in DuPage County. Six more counties (Cook, Will, Logan, Edgar, Macoupin and Washington) have since reported batches of mosquitos that tested positive for the virus. The latest updates on where cases have been reported can be found here.

Last year, the first mosquitoes to test positive for West Nile were collected on June 9 in Skokie. A total of 48 counties in Illinois reported a West Nile virus positive mosquito batch, bird, horse, and /or human case in 2021.

Monitoring for West Nile virus in Illinois includes laboratory tests for mosquito batches, dead crows, blue jays, robins and other perching birds, as well as testing sick horses and humans with West Nile virus-like symptoms. Anyone who sees a sick or dying crow, blue jay, robin or other perching bird should contact their local health department, which will determine if the bird should be picked up for testing.

West Nile virus is transmitted through the bite of a Culex pipiens mosquito, commonly called a house mosquito, that has picked up the virus by feeding on an infected bird. Common symptoms include fever, nausea, headache and muscle aches. Symptoms may last from a few days to a few weeks. Four out of five people infected with West Nile virus will not show any symptoms. In rare cases, however, severe illness including meningitis, encephalitis or even death can occur. People older than 60 and individuals with weakened immune systems are at higher risk for severe illness from West Nile virus.

The IDPH encourages the public to Fight the Bite by practicing the three “R’s” – reduce, repel, and report:

  • REDUCE – make sure the doors and windows at home have tight-fitting screens. Repair or replace screens that have tears or other openings. Try to keep doors and windows shut. Eliminate or refresh weekly, all sources of standing water where mosquitoes can breed, including bird baths water, 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, and apply an EPA-registered insect repellent that contains DEET, picaridin, oil of lemon eucalyptus or IR 3535 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.

Additional information about West Nile Virus can be found here.