Press Release

September 14, 2009


First Human West Nile Virus Case in Northern Illinois For 2009 Reported

SPRINGFIELD, Ill. – The Illinois Department of Public Health (IDPH) has confirmed the first human West Nile virus case reported in northern Illinois for 2009. The Chicago Department of Public Health reported a woman in her 70s with onset of illness in late August.

“As we head into fall it’s important for people to continue to protect themselves against West Nile virus. Mosquitoes that typically carry West Nile virus remain active until the first couple of hard freezes, or night’s below 28 degrees Fahrenheit,” Dr. Damon T. Arnold, Director of the Illinois Department of Public Health said. People should continue to protect themselves against mosquitoes by wearing insect repellent and by trying to reduce any standing water around their homes.”

To date, 30 counties have reported mosquito batches, birds, horses or humans testing positive for West Nile virus. The first human case of West Nile virus in Illinois this year was reported on August 31. So far there are three confirmed cases of West Nile virus in Illinois, one in each of the following counties; Cook, St. Clair and Williamson.

In 2008, IDPH reported the first positive mosquito samples on May 23 in DuPage and Tazewell counties. The Department reported the first human case of West Nile virus in 2008 on August 11. Last year, 28 of the state’s 102 counties reported having a West Nile positive bird, mosquito sample, horse or human case. Twenty human cases of West Nile disease, including one death, were reported for 2008.

Surveillance for West Nile virus in Illinois began on May 1 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 will 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 15 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 people in 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.
  • When outdoors, wear shoes and socks, long pants and a long-sleeved shirt, and apply 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.
  • 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 increases mosquito activity and the risk of disease from West Nile virus.

Additional information about West Nile virus can be found on the Illinois Department of Public Health’s Web site at

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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