A Dunn County horse has tested positive for Eastern equine encephalitis. It’s the state’s first confirmed equine case of the disease this year, according to the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP). The unvaccinated 10-year-old mare was euthanized due to rapidly progressing neurological symptoms.

There have been no active cases in Douglas County this year, said Justin Dahl, veterinarian with Happy Tails Animal Hospital in Superior. In 2019, there were five reported cases statewide, including one in Barron County, according to DATCP. In 2017, the state received a record 24 reported cases each of Eastern equine encephalitis and West Nile virus. Both are mosquito-borne diseases that affect the animal’s nervous system.

The disease is spread by mosquitoes, who pick it up from birds, Dahl said. There is an annual vaccine to prevent Eastern equine encephalitis, and it’s considered a core — or vital — vaccine for horses.

“The reason why we encourage vaccines is because the mortality rate is pretty high, anywhere from 75% to 95% of horses who get it die and they usually die within a couple days of showing symptoms,” Dahl said.

Vaccines for both Eastern equine encephalitis and West Nile virus are very effective in horses, according to Dr. Julie McGwin, DATCP’s equine program manager. West Nile virus is fatal in about 30% to 40% of cases.

“It’s always heartbreaking seeing equines succumb to these diseases knowing that the suffering may have been prevented by vaccination,” she said in a news release.

Horses who get either disease are not contagious. Although humans and other animals can also become infected by both Eastern equine encephalitis and West Nile virus, it does not pass directly between people and horses. The only route of transmission is from a mosquito bite, according to DATCP.

Residents can protect themselves and their horses by reducing the number of mosquitoes in the area. That means eliminating pools of standing water nearby.

“Because that’s of course how we get a lot of mosquitoes, they’re breeding in water,” Dahl said. “So birdbaths, pools, tires that are collecting water, we try to get rid of those.”

Visit the DATCP website for more information.