Two cases of eastern equine encephalitis confirmed in Texas

Contacts: Kate Bradley,

Blair Fannin, 979-845-2259,

Dr. Terry Hensley,  979-862-3202,

COLLEGE STATION – Eastern equine encephalitis has been confirmed in two East Texas horses from separate facilities by the Texas A&M Veterinary Medical Diagnostic Laboratory in College Station, according to agency officials.

The horses were in Newton and Orange counties. The Orange County case is approximately 10 miles from an eastern equine encephalitis, which occurred in 2014.

As a reportable zoonotic disease, the Texas Department of State Health Services and the Texas Animal Health Commission were made aware of the positive test results. Human infection with eastern equine encephalitis, commonly known as EEE, is relatively infrequent in the U.S.

Of the neurologic diseases that affect horses, eastern equine encephalitis has the highest mortality rate, according to animal health experts. Both horses displayed classic signs: flaccid or droopy lips, dullness, muscle fasciculation, ataxia and head pressing. One of the horses displayed blindness.

“Highly effective vaccines are available for EEE, western equine encephalitis and West Nile virus,” said Dr. Terry Hensley, Texas A&M Veterinary Medical Diagnostic Laboratory assistant agency director and Texas A&M AgriLife Extension Service veterinarian.

“These equine neurologic diseases are preventable with proper vaccination. This is why it is so important to keep your horse current on their vaccinations.

“According to the attending veterinarians in these two cases, both horses were unvaccinated. On the Gulf Coast and especially with all the rain we have had, if you choose to vaccinate for any disease, do so for these neurologic diseases.”

If it is has been more than six months since your horse has been vaccinate, Hensley said, consult with your veterinarian about a booster.

Eastern equine encephalitis is a viral disease that normally cycles between wild birds and mosquitoes. As the virus infection rate increases in birds it is more likely to be transmitted by an infected mosquito that bites horses and humans. The virus abruptly attacks the central nervous system. The virus cannot be transmitted from horse to horse, or from a horse to a human. Horses and humans are considered “dead-end” hosts, which means if infected they cannot transmit the virus back to feeding mosquitoes, Hensley said.

Symptoms for neurologic diseases can be similar, so serologic samples were sent to the lab for neurologic testing. Hensley said it is hard to diagnose a neurologic case with only clinical symptoms. The veterinarians requested a variety of tests: Equine Herpesvirus-1, eastern equine encephalitis, West Nile virus, western equine encephalitis and venezuelan equine encephalitis. Eastern equine encephalitis was confirmed positive for both horses, and all other tests were negative.

For more information on the Texas A&M Veterinary Medical Diagnostic Laboratory’s equine neurologic disease testing, visit, or contact the agency headquarters at 1-888-646-5623.



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