Press Release

May 24, 2007


Cook County - third Illinois county testing positive for West Nile virus (amended)

SPRINGFIELD, Ill. – Dr. Eric E. Whitaker, state public health director, announced today a mosquito sample collected in Cook County has been confirmed as positive for West Nile virus.

The Illinois Department of Public Health (IDPH) was notified of the finding as part of its routine surveillance for West Nile virus. A positive mosquito sample was collected May 21 from Skokie.

“So far this year we’ve been seeing warmer temperatures, which is believed to increase the mosquito population and the risk of West Nile virus,” said Dr. Whitaker. “As counties begin to report their first positive test results for West Nile virus, people need to remember to protect themselves from mosquitoes.”

Other positive mosquito samples collected this year were in DuPage County on May 7 and Tazewell County on May 11.

In 2006, the first positive mosquito sample was reported May 24th in DuPage County. Last year 77 of the state’s 102 counties were found to have a West Nile positive bird, mosquito, horse or human case. A total of 215 human cases of West Nile disease, including 10 deaths, were reported last year in Illinois.

Surveillance for West Nile virus in Illinois began May 1st and includes laboratory tests on mosquitoes, dead crows, blue jays, robins and other perching birds as well as the testing of sick horses and humans with West Nile-like disease symptoms. Citizens who observe a sick or dying crow, blue jay, robin or other perching bird should contact their local health department, which will determine if the bird is to be picked up for testing.

West Nile virus is transmitted through the bite of a mosquito that has picked up the virus by feeding on an infected bird. Most people with the virus have no clinical symptoms of illness, but some may become ill three to 14 days after the bite of an infected mosquito. The first human case in Illinois is not usually reported until July or later.

Only about two persons out of 10 who are bitten by an infected mosquito will experience any illness. Illness from West Nile is usually mild and includes fever, headache and body aches, but serious illness, such as encephalitis and meningitis, and death are possible. Persons older than 50 years of age have the highest risk of severe disease.

The best way to prevent West Nile disease or any other mosquito-borne illness is to reduce the number of mosquitoes around your home and to take personal precautions to avoid mosquito bites. Precautions include:

  • Avoid being outdoors when mosquitoes are most active, especially between dusk and dawn. Use prevention methods whenever mosquitoes are present.

  • When outdoors, wear shoes and socks, long pants and a long-sleeved shirt, and apply insect repellent that includes DEET, picaridin or oil of lemon eucalyptus according to label instructions. Consult a physician before using repellents on infants.

  • 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, especially at night.

  • Eliminate all sources of standing water that can support mosquito breeding, including water in bird baths, ponds, flowerpots, wading pools, old tires and any other receptacles. In communities where there are organized mosquito control programs, contact your municipal government to report areas of stagnant water in roadside ditches, flooded yards and similar locations that may produce mosquitoes.

Public health officials believe that a hot summer could increase mosquito activity and the risk of disease from West Nile virus.

Additional information about West Nile virus can be found on the Department’s Web site at or people can call the West Nile Virus Hotline at 866-369-9710 Monday through Friday from 8:00am to 5:00pm.

The Illinois Department of Public Health will send news releases updating West Nile virus activity in the state every Wednesday during the season. Updates throughout the week can be found on the Department Web site.

idph online home
idph online home

Illinois Department of Public Health
535 West Jefferson Street
Springfield, Illinois 62761
Phone 217-782-4977
Fax 217-782-3987
TTY 800-547-0466
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