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 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.
So far this season, nothing is very out of the ordinary.
“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, they’re 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 isn’t drawn by rain, but it does swarm around stagnant water, which is where it mates.
“If you have pools of water that just sort of sit there, that’s when you start to see them,” Arnold said.
The first human case of West Nile in Illinois 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 the second-worst year for the virus in Illinois in terms of human toll. The worst was 2002, when the virus was newly discovered in the state and the first human cases were reported. Illinois wound up leading the nation that year, 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 is planning to take a higher profile in communicating the West Nile risk. Officials on Tuesday will launch 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 be 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. “It’s all part of this public health initiative we’ll be announcing Tuesday.”
While the encephalitis that develops from West Nile infection can be deadly, the virus isn’t always serious. 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. Anyone can fall ill from the virus, but people age 50 and older are at highest risk.
Authorities advise prevention as the best protection against West Nile, including the elimination of stagnant water sources, the use of 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 is always anybody’s guess.
“If from here on out if we have hot, dry conditions, we’ll see more,” Arnold said.