Youth isn’t enough armor anymore. Although until recently most West Nile virus victims have been older, reports of a 23-year-old Winnebago County woman testing positive for the mosquito-borne illness in early August proved college-age individuals are not immune.
Still, University of Wisconsin epidemiologist Craig Roberts emphasized the rarity of human infection.
“This is still an uncommon disease, but it’s always prudent to take precautions,” he said. “We don’t want people to freak out. Any time someone gets a fever, there are lots of things people should consider — not just West Nile.”
For now, Dane County’s human population remains unscathed, but county officials have confirmed the virus’ presence in area birds as well as one horse in Deerfield.
West Nile virus, first detected in Wisconsin in 2001, originated in the Middle East and is rapidly surging toward America’s West Coast. Transmitted to humans by infected mosquitoes, the virus multiplies in the blood system and causes an inflammation of the brain called West Nile encephalitis.
Symptoms include fever, headache, body aches and occasionally skin rashes. According to the Center for Disease Control, West Nile is not contagious, and less than 1 percent of those infected will develop severe illness.
“Many people who get infected don’t even become ill,” Roberts said. “That’s true with most infections.”
While experts recommend individual precautions such as using insect repellent containing DEET, wearing long-sleeved shirts and pants, staying indoors during dawn and dusk and eliminating pools of standing water, Madison officials are looking into other methods.
According to City of Madison environmental epidemiologist John Hausbeck, “discussions are going on right now” concerning the potential use of pesticides to control mosquito populations. He is currently preparing a paper for the Madison Health Department and said any mosquito-control actions must be approved by the city.
One mosquito abatement option Madison could consider is larvicide, a type of pesticide that specifically targets mosquito larvae. Two main types exist — one that interferes with growth hormones and another that uses a bacterium called Bacillus thuringiensis to destroy the larvae.
“The bacterium basically shuts down the guts of mosquito larvae,” distinguished entomology faculty associate Phil Pellitteri said.
Larvicide, placed in water as pellets or spray, is effective for three to four weeks, Pellitteri said. However, difficulties arise in finding and getting the authorization to apply the solution in the right areas. In Wisconsin, cities have the jurisdiction to use larvicide only within their boundaries, preventing large-scale organization.
In contrast, Illinois, a state historically plagued by mosquito-borne disease, has created “abatement districts,” large geographic areas where the state can use pesticides across municipal boundaries.
Pellitteri said political opposition in Wisconsin will most likely prevent this type of response.
“Until people start dying in droves, this probably is not going to happen,” he said. “We’ve never had disease problems to force us to organize on this level.”
Although West Nile remains a relatively low-risk disease, Pellitteri warned that the season is not over.
“I would not be surprised if we see more human instances in this state,” he said. “It’s still kind of early. Things should settle down in a month.”
