Kendall County Health Department monitors mosquitoes for West Nile virus

The Kendall County Health Department is trapping, identifying and testing mosquitoes for the West Nile virus in an annual campaign to keep residents safe.

While the vast majority of people who contract the virus never show any symptoms, West Nile is a potentially serious and even fatal disease.

From May to October, the department’s Environmental Health Services division places mosquito traps at locations throughout Kendall County.

A positive test for West Nile was recorded by the health department Aug. 1, but there have been none since then.

Overseeing the mosquito surveillance effort is Environmental Health Services Director Aaron Rybski and Well and Septic program coordinator Lauren Belville.

Perching birds such as robins, blue jays and crows carry the virus, but monitoring West Nile in the mosquito population is the superior method.

“Mosquitoes are a better way to see if the virus is present in our community,” Rybski said.

With the scientific name culex pipiens but more commonly known as the northern house mosquito, these creatures are smaller and more insidious than the larger, more common and more annoying biters that tend to swarm.

“They are sneaky,” Rybski said. “You don’t realize you got bit.”

In the early morning and at dusk is when people need to take precautions by wearing insect repellant and covering up arms and legs with light-colored clothing so as to more easily spot the mosquitoes.

“They like you,” Rybski said. “Protect yourself. They’re around whether you like it or not.”

Fever, chills and flu-like symptoms are experienced by some people with West Nile, but in rarer cases the disease can cause neurological problems, including swelling of the brain or spinal column, potentially leading to coma or death, Belville said.

The latest figures from the Illinois Department of Public Health show that positive mosquito test results for West Nile have occurred in 39 of the state’s 102 counties this year, but there have been no human cases so far.

The mosquito traps are created using a tub of stagnant water, above which rests a PVC pipe with a battery-powered fan inside that draws the mosquitoes up into a fabric net resembling a tiny round tent sitting atop the pipe.

“They want hot, dry weather and nasty water,” Belville said. The mosquitoes mature from egg to adult in just five to seven days.

The tub of water is treated with a larvicide so that the mosquitoes’ efforts to breed are unsuccessful, Belville said.

“We try to get a variety of locations,” Belville said, in both rural and more densely populated areas of the county.

The one positive test this year came from the trap that Environmental Health Services maintains outside the health department building on West John Street in Yorkville.

After collecting mosquitoes from the net, they are frozen overnight. Belville then empties the mosquitoes onto a hard surface to sift through the pile, separating the northern house variety from the rest.

Belville’s trained and experienced eyes can tell the difference between males and females. She notes that it is the females that bite, while the males serve as pollinators.

Using tweezers, Belville places about 15 of the mosquitoes into a vial. The testing process involves use of a centrifuge and serves to determine if the virus is present and whether or not it is strong enough to be transmissible to humans.

“We do the testing here in-house,” Belville said.

Everyone can help to keep the mosquito population in check and prevent the spread of West Nile, Rybski and Belville said.

Removing, emptying or flushing outdoor containers including garbage cans, flower pots and bird baths, along with old tires, rain gutters or anywhere stagnant water accumulates is the best way to prevent the mosquitoes from reproducing.

“They can breed in a bottle capful of water,” Belville said.