The Illinois Department of Public Health was notified by the DuPage
County Health Department of the findings as part of its routine
surveillance for West Nile virus. A positive mosquito sample each
was collected May 7 from the communities of Naperville, Lisle and
Woodridge."It's not unexpected to receive a report of the first
positive West Nile virus mosquitoes this time of May, but this
positive sample is slightly ahead of reports from previous years in
Illinois," Whitaker said. "West Nile virus activity has been present
in the state since August 2001, and we expected to see activity
again this year. This positive report should serve as a reminder to
people to take precautions to protect themselves against
mosquitoes."
In 2006, the first positive mosquito sample was reported May 24
in DuPage County. Last year 77 of the state's 102 counties were
found to have a West Nile-positive bird, mosquito, horse or human
case. A total of 215 human cases of West Nile disease, including 10
deaths, were reported last year in Illinois.
Surveillance for West Nile virus in Illinois began 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 disease symptoms like West Nile. 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 is to 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 14 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 out of 10 people 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. People older than 50 years of age have the highest risk of
severe disease.
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