Infectious Disease Epidemiology Unit

Conducts surveillance for infectious diseases and investigates clusters and outbreaks

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West Nile virus (WNV) is most commonly transmitted to humans by mosquitoes. WNV has been detected in every county in Wyoming, so it is important to reduce your risk of being infected with WNV by using insect repellent and wearing protective clothing to prevent mosquito bites. There are no medications to treat or vaccines to prevent WNV infection. Fortunately, most people infected with WNV will have no symptoms. About 1 in 5 people who are infected will develop a fever with other symptoms. Less than 1% of infected people develop a serious, sometimes fatal, neurologic illness.


Although mosquitoes are most active at dusk or dawn, some bite during the day. Mosquitoes will bite if you enter an area where they are resting, such as high grass or heavy underbrush. While it is not necessary to limit outdoor activity (unless there is evidence of mosquito-borne disease in the area), you can and should reduce your risk of being bitten by mosquitoes.
Common sense steps you can take to minimize the probability of infection include remembering the

5 D’s of West Nile Virus prevention:

1. DAWN &
2. DUSK – When possible, avoid spending time outside at dawn and dusk.
3. DRESS– Wear shoes, socks, long pants, and a long-sleeved shirt when outdoors for long periods of time or when mosquitoes are most active. Clothing should be light colored and made of tightly woven materials to keep mosquitoes away from the skin.
4. DRAIN – Reduce the amount of standing water in or near your property by draining and/or removing it. Mosquitoes may lay eggs in areas with standing water.
5. DEET – For additional protection from mosquitoes, use an insect repellent containing DEET (N,N-diethyl-m-toluamide) or picaridin (KBR 3023). Other insect repellents such as oil of lemon eucalyptus and IR3535 are also registered by the EPA but may be less effective than products containing DEET. It is important to follow the product guidelines when using insect repellent.

Mosquito Control

To report areas with specific mosquito control problems, contact your local Weed and Pest District.
Wyoming Weed and Pest Council

Protect Your Home Poster

West Nile Virus Brochure

West Nile Virus Brochure - Spanish Version

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