West Nile threat quiet, but weather could change that
CHAMPAIGN — A cool, wet July may be delaying the threat of West Nile virus in East Central Illinois.
But keep your guard up and your bug spray handy.
Experts say a run of hot, dry weather is likely to bring more of the Culex, or northern house, mosquitoes that transmit the virus.
What's around and biting now are largely inland floodwater mosquitoes, a type that doesn't transmit West Nile Virus, according to University of Illinois Extension Entomologist Phil Nixon.
Floodwater mosquitoes thrive after rainy weather, because they lay eggs on low, dry land and wait for a good rain or flood to help them hatch.
Right now, there are enough of these mosquitoes that they're "literally driving people indoors," Nixon says.
Culex/house mosquitoes, on the other hand, like hot dry weather and breed in standing water and catch basins.
A way to distinguish floodwater mosquitoes from the northern house, or Culex, mosquitoes, is by sound. Floodwater mosquitoes buzz, Nixon says, and Culex mosquitoes are quiet biters.
Illinois Department of Public Health spokeswoman Melaney Arnold says it appears the weather has been a factor in West Nile Virus numbers so far.
As of the last update Wednesday, 1 percent of mosquito batches from counties around the state have tested positive for West Nile virus, compared to 4 percent at the same time last year and 14 percent at the same time in 2012. Positive test results, largely in mosquitoes, had been found in 22 of the state's counties — none of them East Central counties.
Symptoms of West Nile Virus, which affect about 20 percent of those who become infected, can include fever, headache, body ache, nausea, vomiting and sometimes swollen glands or a skin rash on the chest, stomach and back. The virus can be more serious for about one out of 150 people.
In Illinois, there were 117 human cases of West Nile Virus last year, and 290 in 2012.
The Champaign-Urbana Public Health District has been monitoring nine mosquito traps throughout Champaign, Urbana and Savoy, and checked them as recently as Friday.
"Our Culex count has been pretty low, and so far no positives," said program coordinator Jeff Blackford.
He recalls a 2012 West Nile virus season that started early with a warm and dry spring and summer and "not much of a winter," and last summer seeing the West Nile Virus wait to take off in August and September.
"It quit raining and it got really warm," he said.
That could happen this summer, too, he warns.
Culex/house mosquitoes can be prevalent into October, Nixon says, though the West Nile virus threat to people usually declines in early Sepember and that has more to do with human nature than mosquitoes.
School has started, evenings out on the deck wind down and people gravitate indoors and turn on the TV, he says.
"We become convinced the summer is over," he adds.
West Nile virus numbers to know:
Between 3 and 13: The number of days it takes to become ill after being bitten by an infected mosquito.
80%: The number of people infected by West Nile Virus who don't ever develop symptoms. There's no way to know in advance if you will or won't.
1 out of 150: The number of infected people who will become seriously ill with such symptoms as high fever, coma, convulsions, vision loss, numbness and paralysis.
Find out more:
Get more tips for outdoor activities Tuesday at 7:15 a.m. on WDWS-AM. Dave Gentry and Elizabeth Hess will visit with the Urbana Park District's Dana Mancuso.