Eastern Equine Encephalitis

Two Horses in East Texas Die from Eastern Equine Encephalitis (EEE);  
Vaccinate Your Horses and Protect Against Mosquito Exposure!

Two horses, one in Jasper County and the other in Newton County, in East Texas have died from Eastern Equine Encephalitis (EEE).   Humans also are susceptible to EEE, which causes inflammation of the brain.  The disease is spread by mosquitoes, and measures should be taken to prevent human and animal exposure to the biting pests.

"As part of their routine health care, horses in all parts of the state should be vaccinated to protect against dangerous mosquito-borne diseases, including West Nile Virus, and Eastern and Western Equine Encephalitis (EEE and WEE)," said Dr. Bob Hillman, Texas' state veterinarian and head of the Texas Animal Health Commission (TAHC), the state's livestock and poultry health regulatory agency. 

"It takes a week to 10 days after vaccination for the animal to develop protective antibodies, and booster shots must be administered as directed by the vaccine manufacturer to maintain the highest level of protection," he said.  "As effective as vaccines are, however, they are not foolproof, and rare instances of disease can occur.  Therefore, it is essential that you protect yourself and your horses against mosquito exposure with a repellent containing DEET."

Dr. Hillman also said other preventive measures should include draining stagnant water, where mosquitoes can breed, and using approved products that kill mosquito larvae in desired water sources, such as troughs, ponds and fountains.  Avoid being outside at night or at dawn, when mosquitoes are most active, wear long sleeves when possible, and consider sheltering horses at night.

"Contact your veterinarian immediately, if your horse acts erratically, is confused, staggers or collapses. These are clinical signs of an encephalitic­or brain inflammation-- condition, and a blood test is needed to confirm the diagnosis. With appropriate supportive care, about half of infected horses may survive.  An infected horse will not spread the West Nile Virus, EEE or WEE to humans," said Dr. Hillman.  Although they are not regulatory diseases, these mosquito-spread infections are reportable to the TAHC, due to their potential to cause human illness.  In 2009, a horse in Washington County, also in East Texas, has been confirmed to have West Nile Virus. 

EEE also has been reported in July in horses in Florida, Louisiana, Missouri and Virginia.

Texas Animal Health Commission
Box l2966 * Austin, Texas 78711 * (800) 550-8242 * FAX (512) 719-0719
Bob Hillman, DVM * Executive Director
For info, contact Carla Everett, information officer, at 1-800-550-8242, ext. 710, or ceverett@tahc.state.tx.us