Information Possibly Outdated
The information presented on this page was originally released on June 28, 1999. It may not be outdated, but please search our site for more current information. If you plan to quote or reference this information in a publication, please check with the Extension specialist or author before proceeding.
Encephalitis Threatens Unvaccinated Horses
MISSISSIPPI STATE -- A viral disease is threatening unvaccinated horses in Mississippi and Louisiana earlier in the summer than normal.
Dr. Fred Lehman, Extension veterinarian with Mississippi State University's College of Veterinary Medicine, said health officials believe emus from a flock in Lincoln County died recently from Eastern Equine Encephalitis. On June 10, the Veterinary Diagnostic Laboratory reported the diagnosis of the virus. Wild birds can carry the virus which is spread through mosquitoes to horses.
"Maintaining current vaccinations is the best way to protect a horse from EEE, which attacks the central nervous system," Lehman said. "There is no effective treatment, and seizures resulting in death usually occur within two to three days of an animal's first symptoms."
Lehman said the state veterinarian's office is working with Extension Service agents, veterinarians and other agencies to help educate horse owners and the public. The virus cannot be transmitted to humans from infected horses, only from mosquitoes.
"There is a remote chance that humans can contract the disease. Although this risk is minimal, about one case every five years, we shouldn't take this threat too lightly," Lehman said. "The State Health Department is encouraging people in south central Mississippi to take steps to avoid mosquito bites."
Lehman said there is no human vaccine available for routine usage, so mosquito avoidance is the best protection in areas where EEE has been diagnosed. People should avoid mosquito-infested areas, use repellents and eliminate water-holding containers that invite mosquito-breeding opportunities.
Properly administered vaccinations for horses are only effective for one year, so annual booster shots are necessary. Newly vaccinated animals require a two-shot series given two to four weeks apart. Begin vaccinations for foals during the summer to ensure protection during the first year of life.
Symptoms of Eastern Equine Encephalitis include unsteadiness, erratic behavior and a marked loss of coordination. Report possible cases in horses to a local veterinarian as soon as possible for diagnosis.
"The disease is fatal in unvaccinated horses. There is no quarantine for EEE, but failure to report a case postpones the mosquito control activities that could protect other horses in the area," Lehman said.
Contact: Dr. Fred Lehman, (601) 325-3432