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Agricultural Review

NCDA&CS urges owners to have equine vaccinated for EEE and West Nile Virus

Frequent periods of wet weather over the past few months could make for a potentially dangerous summer and fall for North Carolina equine. The weather, coupled with a mild winter, means the state could experience a heavier-than-normal mosquito season, which increases the risk of mosquito-borne diseases in horses and donkeys, including diseases that mosquitoes can spread to humans.

“The best way to protect both humans and animals is to reduce the breeding grounds for mosquitoes and reduce exposure,” said Agriculture Commissioner Steve Troxler. “Equine owners can also vaccinate their animals against two diseases that are now endemic in North Carolina − West Nile virus and Eastern Equine Encephalomyelitis.”

Horse owners should talk with their veterinarians to immediately start the vaccination protocol. 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 important to vaccinate as early in the mosquito season as possible. State Veterinarian Dr. David Marshall recommends a booster shot of each vaccine be given every six months in Eastern North Carolina because of the extended active mosquito season.

North Carolina has had no reported cases of EEE or WNV in the past two years, but other Southern states are seeing cases this year. In Florida, there have been 45 reported cases of EEE in horses, and all have been fatal. There have also been eight reported cases in Georgia.

State officials think a number of factors contributed to a two-year decline in the number of cases in North Carolina, including an increased number of vaccinations, increased natural immunity among healthy horses and favorable weather conditions. However, Marshall cautions equine owners against letting their guard down based on a decline in cases the past few years, especially considering the cases in Florida and Georgia this year.

“The best way to prevent these possibly fatal diseases is to vaccinate horses against them. The cost of prevention easily outweighs the cost of treating a sick animal,” Marshall said. “I encourage horse owners to continue to take measures to protect their animals despite the perception that the threat may have lessened.”
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, also known as “equine sleeping sickness,” 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 horses can transmit the virus to other horses, birds or people through contact.
Mosquitoes can breed in any puddle that lasts for more than four days, so removing any source of standing water can reduce the chance of exposing animals to WNV or EEE.

Keeping horses in stalls at night, using insect screens and fans and turning off lights after dusk can also help reduce exposure to mosquitoes. Insect repellants can be effective if used according to manufacturers’ instructions.

NCDA&CS Public Affairs Division, Andrea Ashby, Director
Mailing Address:1001 Mail Service Center, Raleigh NC 27699-1001
Physical Address: 2 West Edenton Street, Raleigh NC 27601
Phone: (919) 707-3001; FAX: (919) 733-5047

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