The Equine Disease Communication Center (EDCC) reported Oct. 11 that a horse in Allendale County, South Carolina, has tested positive for Eastern equine encephalitis (EEE).

“The case is an unvaccinated 1-year-old Quarter Horse from Allendale County,” the EDCC statement said. “The horse did not survive. This is the first confirmed case in this county this year. The total number of confirmed cases in South Carolina in 2016 is now 15.”

A viral disease, EEE affects the central nervous system and is transmitted to horses by infected mosquitoes. Clinical signs of EEE include moderate to high fever, depression, lack of appetite, cranial nerve deficits (facial paralysis, tongue weakness, difficulty swallowing), behavioral changes (aggression, self-mutilation, or drowsiness), gait abnormalities, or severe central nervous system signs, such as head-pressing, circling, blindness, and seizures. The course of EEE can be swift, with death occurring two to three days after onset of clinical signs despite intensive care. Horses that survive might have long-lasting impairments and neurologic problems.

Horse owners should also consult their private practicing veterinarian to determine an appropriate disease prevention plan for their horses. Vaccines have proven to be a very effective prevention tool. Horses that have been vaccinated in past years will need an annual booster shot. However, if an owner did not vaccinate their animal in previous years, the horse will need the two-shot vaccination series within a three- to six-week period