JACKSON, Wyo. — The Wyoming Department of Health (WDH) is warning folks that Wyoming is entering mosquito season and these insects can carry diseases like West Nile virus (WNV).
“Even if you don’t get bitten by mosquitoes often, one bite can still put you at risk of WNV infection,” said Courtney Tillman, epidemiologist at the WDH. “It’s important that we all take steps to prevent mosquito bites and WNV infection.”
WNV is spread by mosquitos who pick up the organism while feeding on infected birds and then pass it on to humans or other animals. Most cases of WNV infection are asymptomatic, but people with symptoms can experience fever, headache, body aches, skin rash and swollen lymph nodes. In rare cases, severe illness or death can occur, particularly in those over the age of 55 or with chronic health conditions.
Wyoming has been outpacing the rest of the U.S. in infection rates over the past several years, per WDH.
The best way to prevent infection with the virus is to avoid getting bitten by a mosquito in the first place. Here are some tips to prevent mosquito bites:
- When spending time outdoors, use insect repellents approved by the Environmental Protection Agency that contain DEET, picaridin, Oil of Lemon Eucalyptus, or IR3535. Always follow label instructions.
- Wear loose-fitting long-sleeved shirts and pants while outdoors.
- Avoid outdoor activities during dawn and dusk, when mosquitoes that spread WNV are most active.
- Use tightly fitted screens on windows to keep mosquitoes out.
- Remove standing water around the home to prevent mosquitoes from breeding.
- Use larvicides, such as Bacillus thuringiensis israelensis, in water that does not drain, including ornamental ponds and water features. Always follow product instructions.
West Nile virus was first found in Wyoming in 2002. A major spike was observed in 2023 with 72 reported cases including four deaths among Wyoming residents. In 2025, two Wyoming residents died, per WDH data.
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