NASHVILLE

July 18, 2003

State animal health officials on alert for the return of West Nile virus (WNV) are also on the lookout for the re-emergence of another mosquito-borne disease in the Southeast – eastern equine encephalitis (EEE).

“Outbreaks of viral encephalitis in horses is a seasonal occurrence due to the prevalence of mosquitoes this time of year,” said Ron Wilson, state veterinarian with the Tennessee Department of Agriculture. “Horse owners should be aware of symptoms of viral encephalitis and consult their local veterinarian should their horse develop any of the signs associated with this group of diseases.”

Florida, Georgia, North Carolina and South Carolina have seen several horse cases of EEE this season. Tennessee’s only horse case to date this year was confirmed this week in Anderson County.

Wilson says the disease warrants close monitoring because of the high mortality rate in horses. Mosquitoes feeding on infected birds and later transmitting the virus to susceptible horses generally cause outbreaks. The disease is relatively sporadic in Tennessee with only a handful of horses having contracted the disease in recent years.

There have been no cases of equine WNV reported in Tennessee this year, but Wilson says the spread of WNV has heightened awareness and concern for other nervous system diseases in horses. Many of the signs of EEE overlap with those described for WNV in horses and include: · Decreased alertness · Blindness or impaired vision · Aimless wandering or circling · Head pressing · Inability to swallow · Weakness, paralysis or convulsions

“Definitive diagnosis is important in tracking the spread of viral infections,” said Wilson. “It requires a commitment on the part of horse owners working with their local veterinarian and verifying test results through laboratory analysis.”

A vaccine is available to protect against EEE and its variant, western equine encephalitis. An approved vaccine for equine WNV is also available. Horse owners are encouraged to review their records and consult with their veterinarian regarding immunization for these diseases.

The Department of Agriculture’s Kord Animal Disease Laboratory in Nashville provides diagnostic services for livestock owners and private veterinarians. For more information about EEE or other viral diseases in horses, contact the State Veterinarian’s office and laboratory at (615) 837-5120.