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Here's where mosquitoes carrying West Nile Virus have been found in Illinois this year

Warning issued about West Nile virus with mosquito season beginning
Warning issued about West Nile virus with mosquito season beginning 01:03

CHICAGO (CBS) — More batches of mosquitoes carrying the West Nile Virus are being found in Illinois this year. The latest were found in Niles.

The North Shore Mosquito Abatement District found the positive mosquitoes in one batch collected on July 24 and tested them in their lab on July 30.

The first human case of the virus was confirmed on July 17 in Glenview, Illinois. The person was said to be in their 60s and lives in suburban Cook County, according to the Illinois Department of Public Health.

How is West Nile Virus transmitted?

West Nile is transmitted through the bite of a Culex mosquito, or house mosquito, that has picked up the virus after feeding on an infected bird, according to the Illinois Department of Public Health. 

Locations where positive mosquitoes were found

So far, confirmed batches have been located in the following cities and villages:

Cook County

  • Kenilworth
  • Lincolnwood
  • Chicago
  • Skokie
  • Evanston
  • Glenview
  • Morton Grove
  • Wilmette
  • Northbrook
  • Northfield
  • Hoffman Estates
  • Glencoe
  • Winnetka
  • Niles

Lake County

  • Highland Park

Morgan County

  • Jacksonville

What are the symptoms of West Nile?

The Centers for Disease Control and Prevention says 70 to 80% of people infected with West Nile do not develop symptoms. Those who may have the virus may experience common symptoms, including fever, nausea, headache, and muscle aches.

Most will not show symptoms, but in rare cases, it can lead to severe illness, including meningitis, encephalitis, or even death. People older than 60 and those with weakened immune systems are at higher risk for severe illness.

Symptoms can last up to a few days to a few weeks.

How to reduce the risk of West Nile Virus

The district is advising residents to take action to reduce mosquito bites, such as using insect repellent containing DEET, picaridin, IR3535, or oil of lemon eucalyptus, wearing loose-fitting clothing, and avoiding peak mosquito feeding times, typically around dawn and dusk.

Residents are also advised to eliminate items that can hold water, including small items that can be easily missed from their property.

There have not been any deaths related to the virus so far this year. The last reported death was a person who was said to be in their 90s and lived in suburban Cook County in 2023.

The worst West Nile outbreak in the U.S. to date came in 2002. In Illinois alone, there were 884 cases across the state and 67 deaths, with 42 of them in Cook County.

This year, scientists note they are seeing more West Nile cases earlier than normal this summer, bringing about concerns of a "blockbuster year" for the virus in 2024. There are usually about 2,500 cases in the U.S. overall.

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