First Mosquitoes in Illinois Test Positive for West Nile Virus
SPRINGFIELD – Dr. Damon T. Arnold, state public
health director, today announced a mosquito sample
collected in Tazewell County has been confirmed as
the first positive West Nile virus test results in
Illinois this year.
The Tazewell County Health Department collected the
positive mosquito batch in Delavan on June 10.
“During June and July mosquitoes that typically carry
West Nile virus are breeding, particularly during hot
weather,” 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 2010, the first positive mosquito samples were
collected on June 3 in Gallatin County. Last year,
30 of the state’s 102 counties were found to have a
West Nile positive bird, mosquito, horse or human
case. A total of 61 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:
• 2009- 5
• 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
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
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
• 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 www.idph.state.il.us/envhealth/wnv.htm.