South Carolina state veterinary officials are urging horse owners in that state to vaccinate their animals following the discovery of the first South Carolina case of Eastern Equine encephalitis (EEE) in 2017.

The case was identified July 21 in a horse from Dillon County, said Boyd Parr, DVM, state veterinarian and director of Clemson University Livestock-Poultry Health. The affected horse was not known to have been vaccinated and did not survive.

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. The disease can kill 90% of exposed unvaccinated horses. Horses that survive might have long-lasting impairments and neurologic problems.

A simple vaccine can minimize the risk to horses and other equine species from EEE