A 2-year-old Andalusian mixed-breed mare in Grandview in Yakima County has been sickened by West Nile virus, the state Department of Agriculture announced Monday.
The horse is the first infected by the virus this year in Washington, which last year had more equine cases of the disease than any other state.
The virus, spread by mosquitoes that have fed on infected birds, typically begins showing up in horses in late July or early August.
The infected horse was not vaccinated for the disease and was stumbling and had trouble eating, according to the WSDA.
WSDA field veterinarian Thomas Gilliom said Monday that the horse was still alive and may recover.
Gilliom said he expected the virus to sicken horses for several more months. The disease is fatal to horses in about one-third of the cases in which the animal shows signs of illness.
“I’m going to assume we’re going to have quite a few horses infected,” he said. “Sadly, a lot of people seem to not put much stock in vaccinating their horses, for whatever reason.”
WSDA identified 36 horses with the virus in 2015, the most in Washington since 73 horses were sickened in 2009. All cases were in Eastern Washington.
In addition, 24 humans were infected by the virus. No humans have contracted the disease this year, according to the state Department of Health.
Mosquitoes trapped in Adams, Benton, Grant, Franklin and Yakima counties have tested positive this summer for West Nile virus.
“It’s never too late to vaccinate your horse for West Nile virus,” Gilliom said. “We’ve had cooler days, but when hot summer days return, the risks of mosquito bites will increase.”
Besides vaccination, horse owners can protect their animals by limiting exposure to mosquitoes, especially by eliminating standing water.
Veterinarians who learn of potential West Nile virus cases in horses or other animals should contact the State Veterinarian’s Office at (360) 902-1878.
The U.S. Department of Agriculture in 2015 tallied 225 cases of West Nile virus in horses nationwide.