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West Nile Virus Detected In Illinois

West Nile Detected In Illinois

(CBS) -- For the first time this year, a batch of mosquitoes has tested positive for the potentially deadly West Nile virus in Illinois, but they're nowhere near Chicago.

Health officials in St. Clair County, 300 miles southwest of Chicago, found the infected mosquitoes Tuesday in O'Fallon, just north of St. Louis.

Although it is the only such discovery so far this year, Illinois Department of Public Health spokesperson Melaney Arnold said only one thing is certain: Infected mosquitoes will appear in the Chicago area soon.

She said Chicagoans would be well advised to begin taking precautions, such as avoiding walks outdoors at dusk and at dawn, when the most mosquitoes are out; using insect repellant and removing standing water.

Arnold said the mosquitoes that carry the disease like hot and dry weather the best, and the growth of potentially infected mosquito colonies depends largely on the weather. Flood mosquitoes bite but do not carry West Nile.

She said the first discovery is pretty much "on schedule." The first cases of human West Nile infection usually don't occur for another month.

West Nile virus is transmitted through the bite of a mosquito that has picked up the virus by feeding on an infected bird.  Common symptoms include fever, nausea, headache and muscle aches.  Symptoms may last from a few days to a few weeks.

While four out of five people infected with West Nile virus will not show any symptoms, Arnold said rare cases can lead to severe illness, including meningitis, encephalitis or even death.

Those who are 50 years and older or those with weakened immune systems are at higher risk for severe illness from West Nile virus.

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