The state public health lab has confirmed that a 66-year-old Evanston is the state’s second person to come down with West Nile virus this year.

City health director Evonda Thomas says spraying by the North Shore Mosquito Abatement District helps control the mosquitoes that spread the virus, but residents need to take additional steps to protect themselves ” by wearing insect repellent and reducing any standing water around their homes to prevent mosquito breeding.”

So far this year, 25 Illinois counties have reported mosquito batches or birds testing positive for West Nile virus. The first WNV positive results this year were reported on May 13 and included two birds, one from Carroll County and the other from St. Clair County.

Along with local health department surveillance, the Illinois Natural History Survey, a division of the Institute of Natural Resource Sustainability at the University of Illinois, also monitors mosquito activity and has reported a dramatic upswing in positive West Nile virus samples, especially in Cook County.

“Although only six percent of the mosquito batches tested positive for West Nile virus in the last week of July, the analysis from the weeks of August 15 and 22 indicates that more 40 percent and 50 percent, respectively, of the mosquito samples from three mosquito abatement districts in Cook County were positive for West Nile virus,” according to Dr. Ephantus J. Muturi, Interim Medical Entomology Director at the Illinois Natural History Survey.

In 2009, IDPH reported the first positive mosquito samples on June 1 in Cook County. The Department reported the first human case of WNV in 2009 on August 31. Last year, 36 of the state’s 102 counties reported having a positive WNV tested bird, mosquito sample, horse or human case. Five human cases of WNV were reported for 2009.

WNV 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. Human cases of WNV are not usually reported until July or later in Illinois.

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

The best way to prevent WNV or any other mosquito-borne illness is to reduce the number of mosquitoes around your home or property 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; and
  • 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.

For more information, to report water that has been standing for more than five days or for instructions on dead bird disposal, call the Evanston Health Department at 847/866-2949 or email

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 online.

Bill Smith is the editor and publisher of Evanston Now.

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