News Release

Health Department Urges Mosquito Spraying for West Nile Risk in Larimer County

Department: Health & Environment
Release Date: Jul 31, 2013


Jane Viste, Larimer County Dept. of Health and Environment, office: 970-498-6750, cell: 970-412-2730,

The risk of human West Nile virus infection is rapidly escalating according to the Larimer County Department of Health and Environment (LCDHE) as two individuals, one from north Loveland and one from south Fort Collins, are hospitalized with serious (“neuroinvasive”) forms  of West Nile infections, one with encephalitis and one with meningitis. It’s likely that they were both infected during the second week of July, when the number of infected mosquitoes was a lot lower than it is today.  For every neuroinvasive case, an estimated 150-250 persons have become infected with West Nile Virus and 35-60 people will have symptomatic illness.

 “The time for communities, neighborhoods, and individuals to take protective action is NOW,” LeBailly stressed. “On average, human cases are reported to public health about 4 weeks after infections occur, so waiting for numerous human cases before taking action means waiting too long.” 
Recent results of mosquito trapping in Larimer County indicate that the numbers of Culex mosquitoes carrying West Nile virus are rising at a rapid rate, raising the risk of human infection substantially according to Dr. Adrienne LeBailly, director of the Health Department.
Wild birds are also indicators that West Nile is escalating. The Rocky Mountain Raptor Program reports having eight raptors with neurological symptoms in the past two weeks. They experienced a large spike in activity over the weekend and Monday. Necropsies showed encephalitis, and few raptors are surviving it. Calls to Animal Control at the Larimer Humane Society about sick or dead birds have increased in the past two weeks, mostly in crows, magpies, and blue jays which are highly susceptible to West Nile.
West Nile Prevention measures range from the community level (education, larviciding, and adult mosquito spraying) to measures that individuals should take. Now that many infected mosquitoes are here, education and larviciding alone will not be effective in preventing disease.
The Health Department is strongly recommending adult mosquito spraying in municipalities and adjacent urban-density areas of the county along Larimer County’s front range. In communities where mosquitoes are trapped and tested for West Nile infection, spraying should initially focus on the areas with the highest “vector index,” which is a measure of the risk of human disease. In areas where spraying does not occur, homeowners associations and neighborhoods can contract with a licensed mosquito control company to provide this service. Ultra-low volume (ULV) mosquito spraying is most effective when done on two nights, 3-5 days apart.
It is also very important for individuals to take preventive measures to protect themselves, their families, and their neighborhoods:
 For more tips on what you can do to prevent West Nile virus, or on repellent use, visit:
# # #