News – Sheridan Media
The Sheridan County Weed and Pest Control District is alerting the community to confirmed presence of West Nile virus (WNV) in local mosquito samples. So far, no human, horse, bird, or other animal cases have been reported in Sheridan County.
Routine testing of adult mosquitoes is conducted by Weed and Pest Districts across Wyoming. Two recent mosquito samples from Sheridan County tested positive for the virus. Other counties reporting West Nile virus activity this season include Laramie, Albany, and Natrona.
West Nile virus is transmitted by Culex mosquitoes. Infected mosquitoes can spread the virus to birds, horses, and humans.
Most human infections are asymptomatic or mild, but elderly individuals or those with weakened immune systems are more vulnerable to serious illness.
Symptoms may include headache, body aches, joint pain, vomiting, diarrhea, and rash. Fatigue and weakness can last for weeks or months. Anyone experiencing these symptoms should contact a healthcare provider.
Sheridan County uses adulticide fogging and larvicide treatments to control mosquito populations. Fogging takes place throughout the summer in Sheridan, Ranchester, Dayton, and Clearmont. Larvicide (Bti) is applied to standing water to prevent mosquito larvae from maturing into biting adults.
When WNV is detected, these efforts are increased in areas where Culex mosquitoes are most active.
Sheridan County Weed and Pest Control District Assistant Supervisor Brian Songer recommends utilizing the five Ds of WNV prevention.
Dawn & Dusk – Avoid outdoor activities at these peak mosquito times.
Dress – Wear long sleeves, pants, socks, and shoes; light-colored, tightly woven fabrics offer better protection.
Drain – Eliminate standing water around your home to reduce mosquito breeding grounds.
DEET – Use EPA-registered insect repellents with DEET or picaridin. Alternatives like oil of lemon eucalyptus and IR3535 are available but may be less effective.
Defend – Stay informed and support community mosquito control efforts.
West Nile prevention is a community effort. Mosquitoes can travel up to 2 miles, so everyone plays a role in reducing risk.
Larvicide is available to the public at the Sheridan County Weed and Pest office and local retailers.
For questions about larvicide or county mosquito mitigation, contact: Brian Songer Assistant Supervisor, Sheridan County Weed and Pest Control District (307) 672-3740.
For further information on West Nile Virus, click here, and here.
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Last modified: July 11, 2025