WWPC Prepares for Mosquito Season Following Worst Year of West Nile Cases since 2013

Spring has officially arrived in the Cowboy State and with it the return of many insects and pests carrying diseases which 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 which can be fatal in serious cases. 

Coordinating control efforts

This is why the Wyoming Weed and Pest Council (WWPC) is trying to learn as much as possible about the state’s mosquito population before adults begin hatching for the year.

“We’ve been out dipping for mosquito larvae, and we’re finding some pretty significant quantities,” says Brian Songer, assistant supervisor for the Sheridan County Weed and Pest District. “We bring them back to our office and watch their development daily and try to determine when the adults will start hatching.”

WWPC, along with the Sheridan County Weed and Pest District, have developed a partnership with the city of Sheridan and the towns of Dayton and Ranchester to coordinate mosquito control efforts. The program is a critical measure to prevent the spread of diseases typically transmitted through mosquitoes.

“We try to identify the larvae and predict which adult mosquitos are going to emerge,” explains Songer. “By doing this, we can predict when we’ll start seeing adults and whether they are a simple nuisance or carry WNV.”

Wyoming WNV cases

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 WNV 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.

“We are very concerned the trend will continue, and this is why we’ve ramped up our program, trying to get out and predict where the mosquitos are and make our larval treatments more effective,” Songer says.

Tips for minimizing

WNV risk

Following what was considered the worst outbreak of WNV in 10 years, WWPC is advising individuals to prepare themselves for mosquito season and is offering tips which can help protect people and their families, while cutting down the number of mosquitoes carrying the virus.

First, WWPC advises individuals to minimize standing water sources on or near their property. This may include buckets, old tires or anywhere 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.

WWPC also encourages individuals to protect themselves from exposure to mosquito bites. Mosquito-proof or long sleeve clothing can be effective at keeping the bugs at bay, as can treating boots, pants and socks with Environmental Protection Agency (EPA)-approved repellant. 

Songer notes the EPA has a useful guide on their website to help choose which repellents to use.

WWPC notes it is also important 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 hands, avoiding eyes, mouths, cuts and the child’s hands. 

If using sunscreen, apply before spraying repellent.

Additionally, horse owners should be sure to get their 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.

Lastly, be on the lookout for symptoms of WNV. 

According to the Centers for Disease Control and Prevention, most people do not experience any symptoms. However, some people may experience a fever, headaches, joint pains, vomiting, diarrhea or rashes. 

If a person thinks they or a family member have contracted WNV, they should contact a doctor. Contact the WWPC if a person or an animal is diagnosed to help guide surveillance and treatment efforts

“WNV 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 WWPC. “The good news is by taking necessary steps to protect ourselves, the virus can be mitigated before it even starts.”

WWPC is comprised of 23 weed and pest districts in the state of Wyoming. The council works closely with the Wyoming Department of Agriculture and the University of Wyoming to keep current with the latest technology and research available in the ongoing management of noxious weeds and pests. The overall mission is to provide unified support and leadership for integrated management of noxious weeds and pests to protect economic and ecological resources in the state.