Across the state, Colorado counties have reported six cases of human West Nile Virus in 2011. That’s relatively low compared to last year’s count of 81 illnesses.Health officials are quick to point out that the season is still ongoing. It won’t end until the first frost, which will kill off a prime carrier of the virus: the culex mosquito. So far, Archuleta, Boulder, Denver, La Plata and Larimer counties have reported human cases.
Jane Viste is public information officer for the Larimer County Department of Health and the Environment, which has reported only one case so far. She says the relatively low number of culex mosquitoes this year was surprising to some, who expected rain at the beginning of the summer to produce more.
“There’s a lot of conjecture out there,” she says. “Does the beginning season being wet make more mosquitoes? Or because we had so much rain and so much was running off, were their larvae being washed away early in the season?”
State health officials say another possible explanation could be a substantial decrease in testing at the public health level. The state’s most active year for West Nile Virus was 2003, when 63 Coloradans died and almost 3,000 people were infected.