South Carolina’s state veterinarian has confirmed the first case of Eastern equine encephalitis (EEE) in the state in 2015. An unvaccinated horse died from the disease in Barnwell County.

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; fatality rates reach 75-80% among horses. Horses that survive might have long-lasting impairments and neurologic problems.

Vaccinating horses against EEE coupled with mosquito control are the most important ways to minimize an animal’s chances of becoming infected