Spring In Wyoming: Mosquito Threat And Rise In West Nile Virus Cases

Spring has officially arrived in the Cowboy State and with it, the return of many insects and pests carrying diseases that could impact the health of livestock and Wyomingites alike.

Warmer weather accompanied by an increase in standing water due to melting ice and snow has created ideal breeding conditions for mosquitoes across the state. While many species of mosquito can be nothing more than an itchy nuisance, some species, like the Culex tarsalis mosquito, can spread West Nile Virus (WNV), a virus that can be fatal in serious cases.

Wyoming Weed and Pest says Wyoming saw a sharp increase in the number of reported WNV cases last year. According to the Wyoming Department of Health, just three human cases of West Nile were reported in 2022. However, 27 human cases occurred in 2023, an average of 4.8 cases per 100,000 people, which far exceeded the national average of 0.7. Four fatalities were also reported, the first WNV-related deaths in Wyoming since 2018.

Humans are not the only ones at risk of catching WNV. Animals, particularly horses, are also at risk of exposure with nearly 50 instances of equine-related WNV cases last year, an alarming increase from just a single case the year prior.

Weed and Pest predicts the trend will continue this year.

Following what was considered the worst outbreak of West Nile in 10 years, the Wyoming Weed and Pest Council is advising folks to prepare themselves for mosquito season and is offering tips that can help protect your family and cut down the number of mosquitoes that carry the virus.

Per the Wyoming Weed and Pest Council: "Take time to minimize standing water sources on or near your property. It could be buckets, old tires, or anywhere that puddles form. According to Songer, “it could be as small as a water bottle cap or as large as a cattail swamp area.” Also minimize stagnation of irrigation waters by avoiding over-irrigating on saturated soils and by draining pastures of excess water. Ensure irrigation structures are in good working order and remove any blockages in ditches and culverts. Keep water from collecting in low-lying areas Protect yourself from exposure to bites. Mosquito-proof or long sleeve clothing can be effective at keeping the bugs at bay, as can treating boots, pants, and socks with EPA-approved repellant. If you are unsure of what repellent to use, the EPA has a useful guide on their website to help you choose.

"Be sure to protect infants and children by covering their arms and legs. If using repellent, make sure the ingredients are suitable for children and apply using your hands, avoiding eyes, mouths, cuts, and the child’s hands. If using sunscreen, apply before spraying repellent.

"For horse owners, be sure to get your horses vaccinated for WNV in the spring. Ensure the horses are turned in at dusk and dawn which are the times when mosquitos are most active. Fans and sprays are also effective deterrents.

"Be on the lookout for the symptoms of West Nile Virus. According to the CDC, most people do not experience any symptoms. However, some people may experience a fever, headaches, joint pains, vomiting, diarrhea, or rashes. If you think you or a family member have contracted West Nile Virus, contact your doctor. Contact the WWPC if you or an animal on your property is diagnosed to help guide surveillance and treatment efforts.

“West Nile Virus has the potential to spread quickly among livestock and among the human population of Wyoming,” said Mikenna Smith, president the Wyoming Mosquito Management Association and member of the Wyoming Weed and Pest Council. “The good news is that by taking necessary steps to protect ourselves, the virus can be mitigated before it even starts.”