CHEYENNE, Wyo. — Local mosquitoes are infected with the West Nile Virus, and people should take precautions to prevent bites, said officials from the City of Cheyenne and Cheyenne-Laramie County Public Health Department.
West Nile Virus is a disease that can cause West Nile encephalitis, which is an infection of the brain. People can contract the virus if they get bitten by a mosquito infected with it. Mosquitoes become infected when they feed on birds infected with the virus, according to the CDC. The CDC clarifies that the virus is not spread through coughing, sneezing or touching; by touching live animals; from handling live or dead infected birds; or eating infected animals, including birds.
Most infections are mild and symptoms include fever, headache, body aches and occasionally a skin rash and swollen lymph glands. The county’s public health department states that less than 1% of infections are severe and symptoms may include headache, high fever, neck stiffness, disorientation, muscle weakness and tremors. Individuals over the age of 50 and those with compromised immune systems have the highest risk of severe disease. There is no vaccine for the virus, and people exhibiting severe symptoms should seek medical attention immediately.
West Nile has been detected in every county in Wyoming. The Wyoming Department of Health reports that Laramie County has witnessed one human case and two animal cases between 2014 and 2023. The risk of being infected increases during the summertime, between July and September.
This year, Cheyenne’s Weed and Pest Division is seeing an “elevated” number of infected mosquitoes, according to Steven Trowbridge, the manager for the division. The division recorded an average of 36 infected adult mosquitoes caught per night in the city’s insect traps. That average is higher than the 2.6 average for 2022 and the 11.4 average for 2021. The collection period for each year is between May 2 and Aug. 2.
“Right now, [the infected mosquitoes] are in basically every corner of the city,” he said.
Trowbridge said residents can expect mosquito breeding season to continue in the upcoming months.
“We expect activity to last into August and September, at the very least,” he said.
The Cheyenne-Laramie County Public Health department offers the following protection tips to residents:
- Wear protective clothing, such as lightweight long pants and long-sleeve shirts
- Make sure doors and windows in the home are tight-fitting
- Repair or replace any screens with holes or tears
- Limit outside activity during times of high mosquito activity, such as the feeding times of dusk and dawn
- Apply insect repellant. Studies conducted by the CDC find that insect repellant with DEET (N, N-diethyl-m-toluamide) are the most effective.
| Percent of DEET in Repellant | Average Time of Protection |
| 23.8% DEET | Five hours |
| 20% DEET | Four hours |
| 6.65% DEET | Two hours |
The department also recommends the following actions to eliminate mosquito breeding areas:
- Drain all standing water on residents’ property, no matter how small the amount
- Fill small puddles with dirt or landscape
- Fill in tree rot holes and hollow stumps
- Change the water in bird baths or wading pools. Empty flowerpot saucers at least once a week
- Seal cisterns, septic tanks and water barrels
- Keep roof gutters clear and draining freely
- Remove items that could collect water, such as old tires, buckets and empty cans
- Drill drainage holes in tire swings and outdoor containers, such as garbage cans
- Turn over wheelbarrows or keep them where they will not collect water
- Do not over-water lawns or gardens
