COLUMBIA — South Carolina’s state veterinarian announced Monday that the state’s first case this year of Eastern Equine Encephalitis (EEE) has been confirmed in Chesterfield County.
The infected horse, a year-old Appaloosa colt, had not been vaccinated and did not survive.
“This is a clarion call for vaccinations against diseases like EEE and West Nile Virus (WNV),” said Boyd Parr, South Carolina state veterinarian and director of Clemson University Livestock Poultry Health, a state agency responsible for protecting the health of animals and consumers through control of disease and inspection of meat and poultry products. Horse owners should check with their veterinarian to be sure their horses’ vaccinations are up to date.”
The EEE and WNV viruses are mosquito-borne and fast-acting. Symptoms of EEE in horses usually develop from two to five days after exposure. The symptoms include stumbling, circling, head pressing, depression or apprehension, weakness of legs, partial paralysis, the inability to stand, muscle twitching or death.
“These diseases have a very high mortality rate in infected, unvaccinated horses – between 30 and 40 percent for West Nile and 90 percent for EEE,” said Sean Eastman, veterinarian and director of field services for the Livestock Poultry Health Animal Health Programs. “Although not directly communicable from horses to people, both EEE and WNV have a human health significance, and cases can be prevented through effective vaccination and mosquito management strategies.”
Clemson Veterinary Diagnostic Center currently provides testing for EEE and WNV at no charge thanks to an agreement with the S.C. Department of Health and Environmental Control (DHEC). The current agreement expires July 31, but DHEC is exploring its options for continuing this surveillance program after July.
Widespread vaccination last year held the number of S.C. cases to only one of EEE – also in Chesterfield County – and four of West Nile. In contrast, in 2013 the Palmetto State led the nation in cases of the disease with 49 EEE-infected horses, all unvaccinated. Of those, 48 died.
In addition to EEE and WNV, other neurologic diseases, including rabies and EHV-1, can infect horses. Any livestock that display neurologic symptoms — stumbling, circling, head pressing, depression or apprehension — must be reported to the state veterinarian at 803-788-2260 within 48 hours, according to state law.
A list of reportable diseases, along with other resources, is published on the LPH website at
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