UPDATED 05/23/12 6:28 a.m.

CHICAGO (CBS) – For the first time this year, the West Nile virus has been detected in a number of suburban areas.

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As WBBM Newsradio’s Michele Fiore reports, on May 16 and 17, mosquitoes and a dead crow tested positive in Clarendon Hills, Hinsdale, Lemont, Lisle, Norridge, Westmont and Woodridge.

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While the early outbreak is not common, it is not necessarily cause for alarm, officials say.

“Although it is a little earlier in the season than we normally find West Nile virus positive mosquito pools and birds, it is not unheard of,” Illinois Department of Public Health Director Dr. LaMar Hasbrouck said. “This is a good reminder as we head into the Memorial Day weekend and more people spend time outdoors, that it is important to protect yourself and wear insect repellent.”

Last year, 19 Illinois counties reported the virus in birds, mosquitoes or humans, the release said. Thirty-four Illinois residents contracted the virus last year and three died.

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The virus is transmitted through mosquitoes that have fed on an infected bird.

Twenty percent of people who are bitten by mosquitoes with West Nile contract the disease and 5 percent get severely sick.

Symptoms can include fever, headache and body aches. People over the age of 50 and those with chronic diseases such as heart disease or cancer may be more at-risk for meningitis or encephalitis, two life-threatening diseases, but people of any age can contract the disease.

The best way to prevent West Nile disease is to reduce the number of mosquitoes around the home and take precautions to avoid mosquito bites, state health officials say.

The Sun-Times Media Wire contributed to this report.

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