WEE Confirmed in Cache County, Utah

Officials at the Utah Department of Agriculture and Food (UDAF) have confirmed that a 30-year-old unvaccinated horse in Cache County is recovering from Western equine encephalomyelitis (WEE).

About Equine Encephalomyelitis

Eastern, Western, and Venezuelan equine encephalomyelitis (EEE, WEE, and VEE) are transmitted by mosquitoes from bird and rodent reservoirs. WEE is typically seen west of the Mississippi River.

Mosquitoes that feed on WEE-infected animals can transmit the virus to humans, horses, and other (host) animals. Infected horses cannot pass WEE onto other horses or humans. WEE’s survival rate ranges from 50-60%.

​Tips for preventing mosquito-borne diseases include:

  • Avoid mosquito bites: Use insect repellent when outdoors, especially from dusk to dawn.
  • Look for EPA-labeled products containing active ingredients such as DEET, picaridin (KBR3023), or oil of lemon eucalyptus (p-menthane 3,8-diol).
  • Apply more repellent, according to label instructions, if mosquitoes start to bite.
  • Mosquito-proof homes: Fix or install window and door screens, and cover or eliminate empty containers with standing water where mosquitoes can lay eggs.
  • Protect your horses: Veterinarians recommend commercially available licensed vaccines against WEE for all horses in the U.S. Horses should be vaccinated at least annually (recommendations vary in high-risk areas). It’s not too late this year to vaccinate your horses.
  • Use approved insect repellents to protect horses.
  • If possible, put horses in stables, stalls, or barns during the prime mosquito exposure hours of dusk and dawn.
  • Eliminate standing water, drain water troughs, and empty buckets at least weekly.
  • Stock water tanks with fish that consume mosquito larvae (contact your local mosquito control for assistance), or use mosquito “dunks” (solid “donuts” of Bacillus thuringiensis israelensis[BTi], which are nontoxic to horses) available at hardware stores.