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1st mosquitoes to test positive for West Nile virus in 2021 have surfaced in Illinois

No human cases have been reported, but state health director warns residents to take precautions
Credit: KSDK

SPRINGFIELD, Illinois — Another rite of summer is about to descend on us: mosquitos. And they're bringing their usual public health risk.

The Illinois Department of Public Health confirmed it collected a batch of mosquitoes last week that tested positive for the West Nile virus. No human cases have been reported this year.

“We are starting to see West Nile virus make its annual appearance,” said Illinois Department of Public Health Director Dr. Ngozi Ezike on Wednesday. “Remember to take precautions to protect yourself from mosquitoes and the viruses they carry by wearing insect repellent and getting rid of standing water around your home.”

The positive test came from the North Shore Mosquito Abatement District last week, specifically from the Chicago suburb of Skokie.

Precautions being recommended in Illinois will likely be the same for Missouri in the not-so-distant future.

Symptoms in humans include fever, nausea, headache and muscle aches, and they may last from a few days to a few weeks. However, 4 out of 5 people infected with West Nile virus will not show any symptoms. In rare cases, 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.

Last year, 26 counties in Illinois reported a West Nile virus-positive mosquito batch, bird and/or human case. IDPH reported 39 human cases (although human cases are underreported), including four deaths.

Precautions include practicing the three “R’s” — 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 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.