Press Release

June 21, 2010


Mosquitoes in Northern Illinois Test Positive for
West Nile Virus

SPRINGFIELD, Ill. – Dr. Damon T. Arnold, state public health director, today announced mosquito samples collected in Rock Island County have been confirmed as the first positive mosquito West Nile virus test results in northern Illinois this year.

The Rock Island County Health Department collected the positive mosquito batch in the City of Rock Island on June 15. To date, 10 counties have reported either mosquitoes or birds testing positive for West Nile virus this year: Carroll, Gallatin, Greene, Jo Daviess, McLean, Mercer, Rock Island, St. Clair, Stephenson and Tazewell counties.

“We’ve recently been seeing higher temperatures across the state, which could mean we will start seeing human cases of West Nile virus,” said Dr. Arnold. “To help reduce the number of mosquitoes, make sure to get rid of any stagnant water around your home and protect yourself by wearing insect repellent.”

In 2009, the first positive mosquito samples were reported June 1 in Cook County. Last year, 36 of the state’s 102 counties were found to have a West Nile positive bird, mosquito, horse or human case. A total of five human cases of West Nile disease were reported in Illinois last year, the first reported on August 31. In hotter summers, such as 2005 and 2006, more human cases have been reported:

  • 2008 – 20
  • 2007 – 101
  • 2006 – 215
  • 2005 – 252
  • 2004 – 60
  • 2003 - 54
  • 2002- 884

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 been infected with 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.

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, 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 includes 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 could increase 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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