Source:  NCDA&CS, 6/16/10

Equine owners are reminded that now is the best time to vaccinate horses, donkeys and mules against West Nile Virus and Eastern Equine Encephalomyelitis.

State Veterinarian David Marshall said these diseases are  now endemic in North Carolina, but they are easily preventable.

“We haven’t had a lot of cases of EEE or West Nile the past few years, but the disease cycle ebbs and flows in our state,” Marshall said. “Horse owners should keep upp their guard and continue to vaccinate against these diseases, as well as take other precautions to minimize standing water that would allow mosquitoes to breed.”

In 2009, North Carolina had 23 reported cases of EEE in horses, 21 of which were fatal. It is estimated that for every reported case, three or four cases go unreported. In 2008, there were 13 reported cases. Not only were there more cases in 2009, but cases were reported later in the year and farther west than in previous years. There were no reported cases of WNV in equine the past two years.

Horse owners should talk to their veterinarians to determine the best time to start the vaccination process. Both vaccinations initially require two shots, 30 days apart, for horses that have no prior vaccination history. Neither vaccination fully protects the animal until several weeks after the second shot, so it is best to vaccinate as early in the mosquito season as possible. Marshall recommends a booster shot of each vaccine be given every six months in North Carolina because of the extended active mosquito season.

Symptoms of WNV in horses can include loss of appetite and depression, fever, weakness or paralysis of hind limbs, convulsions, impaired vision or hyperexcitability.

Symptoms of EEE, include impaired vision, aimless wandering, head pressing, circling, inability to swallow, irregular staggering gait, paralysis, convulsions and death. People, horses and birds can become infected from a bite by a mosquito carrying the diseases, but there is no evidence that horses can transmit the virus to other horses, bird or people through direct contact.