Weather Updates

West Nile-carrying mosquitoes turning up in area

West Nile virus mosquitoes.

West Nile virus and mosquitoes.

storyidforme: 51228058
tmspicid: 6352739
fileheaderid: 2940509


Additional details about the West Nile virus, including the most recent surveillance information, can be found on these websites:

The Cook County Health Department also operates a West Nile virus hotline, which can be reached at 708-633-8025.

Article Extras
Story Image

Updated: July 26, 2013 6:35AM

Been bitten yet?

Mosquitoes have begun to make their presence known in Illinois, along with the distinct possibility that some extra misery lurks within a few of them.

No human illnesses have yet been reported this year, but the West Nile virus has shown up in several mosquito batches tested for the strain, including one found in Naperville on June 4. Others reported so far have been in Hillside, Harvard and Skokie.

In 2011, DuPage County’s first positive batch was found in the first week of July, in Lemont. Last year, which was marked by unusually dry conditions, it was May 17, in Westmont.

Still, nothing is very out of the ordinary in northern Illinois so far this season.

“We’re pretty much on schedule,” said Melaney Arnold, communications manager for the Illinois Department of Public Health. “The one thing that we’ve seen is a lot more rain, and cooler temperatures.”

Officials anticipated a substantial wave of floodwater mosquitoes, which did appear in the wake of this spring’s historically heavy rain. Arnold said altough they can be aggressive, that variety of mosquito is not especially menacing from an illness standpoint.

“Typically they do not carry West Nile virus,” she said.

That characteristic falls with the culex variety, commonly called the house mosquito for its habit of traveling no farther than about a mile during its lifetime from the place where it hatched. The culex prefers hot, dry weather.

“They kind of get you coming and going,” said Tom Schlueter, public information officer for the Kane County Health Department. “If it’s raining you’ve got one, and when it’s not, you’ve got the other.”

Still-water nest

Because the culex variety lays its eggs on the surface of stagnant water, residents usually are uged to make sure they don’t have rain water accumulating in such places as upturned garbage can lids, grill covers and children’s toys, and to replace the water in outdoor vessels regularly.

“We’re encouraging residents to empty bird baths, to empty wading pools, anything on their property that might hold water,” said Sean McDermott, spokesman for the Cook County Health Department. “Gutters are a particular concern right now, because seeds that have dropped off the trees can clog them.”

Female mosquitoes especially like to leave their eggs on still water that holds decaying organic matter, according to Mike Adam, a senior biologist with the Lake County Health Department. The eggs contain “a little air tube,” he said, which facilitates their access to oxygen and nutrients, so a robust downpour that churns the water’s surface will often interrupt the hatch.

“The culex tend to have higher cases of West Nile virus in the years when it’s hot and dry,” Adam said.

The hot and parched summer of 2012, which Schlueter described as a “perfect storm” for virus-bearing mosquitoes, was the second-worst on record for the state, with 290 cases reported.

“The potential for West Nile virus really kind of hinges on those hot, dry conditions,” said Vic Reato, spokesman for the Will County Health Department, which tallied a dozen human infections last summer, but no fatalities. “Certainly the expectation is there that if it is a hot, dry summer, it’ll be a bad year.”

The first human case last year was announced July 24 in Cook County, and the state’s first death from the virus came when longtime Lombard Village President Bill Mueller passed away Aug. 18 after West Nile complicated his ongoing struggle with cancer. By the end of the season, 12 people had succumbed to the illness statewide, including five in Cook County, five in DuPage and one in Kane. The other fatality occurred in midstate Sangamon County.

“It was hot and dry, and kind of a very serious summer last year,” Reato said.

The state’s worst year for West Nile so far was 2002, when the virus was newly discovered in Illinois and the first human cases were reported. Illinois wound up leading the nation that season, with 884 people sickened and 67 deaths attributed to the virus.

The state health department monitors animals and insects carefully for signs of the virus, testing dead crows, robins, blue jays, mosquitoes and horses. Included in the surveillance network are physicians specializing in infectious disease, hospital lab directors and infection control specialists, and local health departments.

DuPage County has heightened its profile in communicating the West Nile risk. Officials planned to launch Tuesday morning the Personal Protection Index, a means of providing residents with the most recent details of the virus’ activity locally and related information. The PPI will be updated weekly, using the county Health Department’s review of surveillance data, and it will remain accessible online through the season.

“It’ll be a weekly index of the current status of West Nile virus activity in the county,” said Health Department spokesman Jason Gerwig.

‘Anybody can get it’

While the encephalitis that develops from West Nile infection can be deadly, most people exposed to the virus show no symptoms at all. Sometimes the illness is mild, evidenced in little more than a slight fever or headache. When the infection is more severe, the person often experiences rapid onset of a high fever with head and body aches, disorientation, tremors, convulsions and occasionally paralysis or death. Symptoms typically appear from three days to two weeks after the bite by an infected mosquito. Although heightened risk is seen among people with compromised immune systems or other pre-existing health conditions, and those age 50 and older, no one is immune. Those sickened by the virus last year in Illinois ranged from age 9 to 89.

“I felt like I had the flu, and a migraine,” says Suzy, a young mother shown in a video on the Cook County Health Department’s website who contracted the virus last summer. “But the pain became so severe, I knew needed medical attention.”

The woman continues, saying her recovery has been slow and difficult for her four kids, and notes that there may be longterm effects that have not yet been discovered.

“Anybody can get it,” Schlueter said. “It’s just one of those things.”

Authorities advise prevention as the best protection against West Nile. Along with elimination of stagnant water sources, they recommend using insect repellents containing DEET, wearing long sleeves and other garments that cover the skin, and remaining indoors early in the day and around dusk, when mosquitoes are most active.

It’s impossible to say how the culex population will look for the remainder of the season. That depends largely on the weather, which has been cooperative — so far.

“Things can change pretty quick,” Lake County’s Adam said. “If all of a sudden the weather turns hot and dry, we could have some trouble in July and August.”

© 2014 Sun-Times Media, LLC. All rights reserved. This material may not be copied or distributed without permission. For more information about reprints and permissions, visit To order a reprint of this article, click here.