“This is typically the time of year we start to see
human cases of West Nile virus in Illinois,” said Illinois
Department of Public Health (IDPH) Director Nirav D. Shah, M.D.,
J.D. “Although the flooding in northeastern Illinois may be
producing a large number of floodwater mosquitoes, those mosquitoes
do not carry West Nile virus. However, the hot, dry conditions we’ve
been seeing around the rest of Illinois, which leave small, stagnant
pockets of standing water, create ideal breeding sites for the type
of mosquito that does carry West Nile virus.”
The first human case of West Nile virus in 2016 was reported early
in the year, on June 6, 2016. Last year, 61 counties in Illinois
reported a West Nile virus positive mosquito batch, bird and/or
human case. For the 2016 season, IDPH reported 155 human cases
(although human cases are underreported), including six deaths.
Monitoring for West Nile virus in Illinois includes laboratory tests
for mosquito batches, dead crows, blue jays, robins and other
perching birds, as well as testing humans with West Nile virus-like
symptoms. People 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 Culex pipiens
mosquito, commonly called a house mosquito, which 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. However, four out of five people infected with West
Nile virus will not show any symptoms. In rare cases, severe illness
including meningitis or encephalitis, or even death, can occur.
People older than 50 and individuals with weakened immune systems
are at higher risk for severe illness from West Nile virus.
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While IDPH is also monitoring for Zika virus, which is primarily
transmitted through the bite of a mosquito, the main type of mosquito that
carries Zika virus, Aedes aegypti, is different and is very rarely found in
Illinois. However, taking some simple precautions can help you avoid mosquito
bites, regardless of the type of mosquito or the diseases they carry.
Precautions include practicing the three “R’s” – reduce, repel,
REDUCE - make sure doors and windows have tight-fitting screens. Repair
or replace screens that have tears or other openings. Try to keep doors and
Eliminate, or refresh each week, all sources of standing water where mosquitoes
can breed, including water in bird baths, ponds, flowerpots, wading pools, old
tires, and any other containers.
REPEL - 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.
REPORT – report locations where you see water sitting stagnant for more
than a week such as roadside ditches, flooded yards, and similar locations that
may produce mosquitoes. The local health department or city government may be
able to add larvicide to the water, which will kill any mosquito eggs.
Additional information about West Nile virus can be found on the IDPH website.
[Illinois Department of Public