EEE in south carolina

The South Carolina State Veterinarian’s Office has received confirmation of the state’s first case of Eastern equine encephalitis (EEE) in a horse for 2018, the Equine Disease Communication Center (EDCC) reported Aug. 8.

“The 5-year-old mare, which was located in Chesterfield County and had no vaccination history, died,” the EDCC said.

EEE 101

A viral disease, EEE affects the central nervous system and is transmitted to equids by infected mosquitoes. Clinical signs in horses 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; and
  • Severe central nervous system signs, such as head-pressing, circling, blindness, and seizures.

The disease can progress rapidly, with death occurring two to three days after onset of clinical signs despite intensive care in some cases. Fatality rates can reach 75-80%. Equids that survive might have long-lasting impairments and neurologic problems.

Studies have shown that vaccines are a very effective EEE prevention tool. Horses vaccinated in past years will need an annual booster shot; in areas with a prolonged mosquito season, veterinarians might recommend two boosters annually—one in the spring and another in the fall. Horses unvaccinated in previous years or those with an unknown vaccination history should receive the initial two-shot vaccination series within a three- to six-week period.

In addition to vaccinations, owners should work to reduce the mosquito populations and possible breeding areas and horses’ exposure by:

  • Removing stagnant water sources;
  • Dumping, cleaning, and refilling water buckets and troughs regularly;
  • Keeping animals inside during the bugs’ feeding times (typically early in the morning and evening); and
  • Applying mosquito repellents approved for equine use.