Reported West Nile virus cases in the state at a more than decade high


September 12, 2023 — The Wyoming Department of Health (WDH) is reporting the state has seen more West Nile virus activity this season than in over a decade. To date, 20 West Nile virus cases have been reported statewide, none of them in Sweetwater County.

In neighboring Fremont County, one case did lead to the death of an older adult woman. Cases have been reported in Campbell, Goshen, Laramie, Natrona, Park, Platte, Sheridan, and Washakie counties.

“This is clearly Wyoming’s most active West Nile virus season in at least a decade, and it does not appear to be over yet,” said Courtney Tillman, an epidemiologist with WDH. “It remains important to avoid mosquito bites to help prevent illness with this virus, which can sometimes be quite serious.”

Tillman noted many people who have likely been ill with WNV this year have not been tested and do not realize what has caused their symptoms. “It’s been estimated that for every confirmed neuroinvasive case, there may be roughly 30 fever cases. Many, if not most, of these cases have not been identified with testing,” Tillman said.

According to the WDH, symptoms include fever, headache, body aches, skin rash, and diarrhea. A very small number of individuals develop West Nile neuroinvasive disease with symptoms such as severe headache, fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, and paralysis.

The WDH notes that mosquito pools and animals from around the state continue to test positive for the West Nile virus.

The WDH “5 D’s” of West Nile virus prevention include:

1) DAWN and 2) DUSK – Mosquitos prefer to feed at dawn or dusk, so avoid spending time outside during these times.
3) DRESS – Wear shoes, socks, long pants, and a long-sleeved shirt outdoors. Clothing should be light-colored and made of tightly woven materials.
4) DRAIN – Mosquitos breed in shallow, stagnant water. Reduce the amount of standing water by draining and/or removing.
5) DEET – Use an insect repellent containing DEET (N, N-diethyl-m-toluamide). When using DEET, be sure to read and follow label instructions. Picaridin (KBR 3023) or oil of lemon eucalyptus can also be effective.

Information from WDH about the West Nile virus can be found at