The Kane County Health Department is reporting that a batch of mosquitoes collected in a trap in Montgomery has tested positive for the West Nile Virus.
This is the fourth time this year that traps have shown evidence of the disease in Kane County. Last week, a trap in Aurora was positive for West Nile virus. Last month, a trap near Algonquin administered by the Illinois Department of Public Health was found to contain mosquitoes that tested positive for the disease two weeks in a row.
Tom Schlueter, a spokesman for the health department, said the county has 10 of its own traps that it monitors. The state health department has two collection sites in Kane County, in Algonquin and Sleepy Hollow, a spokeswoman said.
The recent wet weather reduced the breeding ability of the culex pipiens and culex quinquefasciatus mosquitoes that develop in urban areas. Culex mosquitoes rely on hot, dry weather to breed, Schlueter said.
"The culex mosquito species associated with vector diseases breeds in stagnant water and has to have hot, dry weather," Schlueter said. "A lot of rain actually inhibits their breeding because rain stirs up the water. They lay eggs right on the water, so more rain actually is better to prevent West Nile."
That is why the public is encouraged not to allow water to get stagnant in birdbaths, pools, ponds, clogged gutters, flower pots, old tires or any abandoned debris that will hold water, Schlueter said.
Wet conditions are not prime for the culex to breed, but such conditions are ideal for other nuisance mosquitoes, because of the way those mosquitoes lay their eggs, he said.
"When water rises to those eggs, that causes them to hatch, and that is why we get so many," Schlueter said. "But nuisance mosquitoes typically don't carry diseases."
West Nile is transmitted through the bite of a mosquito that has picked up the virus by feeding on an infected bird.
As part of its West Nile program, the health department is collecting dead birds to be sent to the state lab for testing. Call 630-444-3040 to report the presence of freshly dead birds without signs of decay or trauma, to determine whether testing is recommended.
Most people with the virus have no clinical symptoms of illness, but some might become ill three to 14 days after the bite of an infected mosquito.
Illness from West Nile usually is mild and includes fever, headache and body aches, but serious illness, such as encephalitis and meningitis, as well as death, are possible. Those older than 50 have the highest risk of severe disease.
County residents are urged to avoid being outdoors at dusk when they are most active and wear shoes, socks, long pants and a long-sleeved shirt.
Repellent that includes DEET, picaridin or oil of lemon eucalyptus is also recommended.
More information is available on the health department website, http://www.kanehealth.com/west_nile.htm and the state site, www.idph.state.il.us/envhealth/wnv.htm.