Second mosquito pool tests positive for West Nile virus

By on September 6, 2009

COUNTY—The Kane County Health Department announced recently that a second mosquito pool has tested positive for West Nile virus. The mosquito sample pool was collected in St. Charles. The first detected in July was from the Montgomery area.

There was one reported human case in or Illinois so far this year. Last year, Kane County saw three human cases, in 2007 there were 13 cases. In 2006 there were four, 17 in 2005, two in 2004, none in 2003 and nine in 2002.

Stagnant pools of water can become excellent breeding grounds for the Culex species, the mosquito which is the most common mosquito to carry West Nile virus.

“If hot, dry weather returns, the Culex mosquito breeding activity could increase. Residents still need to take precautions against West Nile virus at least until the first hard frost,” Health Department Executive Director Paul Kuehnert said. “Until then, the potential exists to identify more positive mosquito pools and for human cases to occur in Kane County.”

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.

Only about two persons out of 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 and meningitis, and death are possible. 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.

Following heavy rains and flooding, there is usually an increase in nuisance mosquito activity. The nuisance mosquito (Aedes species), which breeds in flood waters and temporary pools of water, does not typically transmit West Nile virus disease, but it is an aggressive and hard biter and is active throughout the day not just at dusk and dawn.

Additional information about West Nile virus can be found on the Kane County Health Department’s website, or the Illinois Department of Public Health’s website at

More information is available by calling the IDPH West Nile Virus Hotline at (866) 369-9710 Monday through Friday from 8 a.m. to 5 p.m.

First human West Nile virus case in Illinois for 2009 reported
SPRINGFIELD—The Illinois Department of Public Health (IDPH) has confirmed the first human West Nile virus case reported in Illinois for 2009. The St. Clair County Health Department reported a person in their 50s with onset of illness in late August.

“We’ve seen cooler temperatures this summer and not as much West Nile virus activity compared to warmer summers. However, this first human case of West Nile virus in Illinois should remind people that the threat is still there. People should protect themselves against mosquitoes by wearing insect repellent and by trying to reduce any standing water around their homes, especially with the upcoming holiday weekend,” said Dr. Damon T. Arnold, Director of the Illinois Department of Public Health.

So far this year, 24 counties have reported mosquito batches or birds testing positive for West Nile virus.

In 2008, IDPH reported the first positive mosquito samples on May 23 in DuPage and Tazewell counties. The department reported the first human case of West Nile virus in 2008 on Aug. 11. Last year, 28 of the state’s 102 counties reported having a West Nile positive bird, mosquito sample, horse or human case. Twenty human cases of West Nile disease, including one death, were reported for 2008.

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.

Precautions against West Nile include:

• Avoid being outdoors when mosquitoes are most active, especially between dusk and dawn. Use prevention methods whenever mosquitoes are present.

• When outdoors, wear shoes and socks, long pants and a long-sleeved shirt, and apply insect repellent that includes DEET, picaridin or oil of lemon eucalyptus 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 flowerpots, clogged roof gutters, old tires and any other receptacles. Change water in bird baths weekly. Properly maintain wading pools and stock ornamental ponds with fish. Cover rain barrels with 16 mesh wire screen. 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.