Eastern Equine Encephalitis

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North Carolina has had its first confirmed case of Eastern Equine Encephalitis (EEE) for this year. Eastern Equine Encephalitis (EEE) is a mosquito-borne, viral disease that affects the central nervous system of horses and causes inflammation of the brain. EEE occurs primarily in the eastern part of the United States and Canada. Last year seven cases were reported in North Carolina. Most cases are reported in the late summer and early fall. EEE usually affects equine species (horses, mules, donkeys) but does have the potential to affect pigs, rodents, bats, reptiles, llamas, and amphibians. Birds are reservoirs of the virus and can be infected without signs or symptoms of the disease.

Once bitten by an infected mosquito, it can take anywhere from 3 – 10 days for the horse to start showing clinical signs of EEE. Onset of symptoms can include moderate to high fever, depression, lack of appetite, behavioral changes, gait abnormalities and head-pressing/circling/blindness, or seizures. EEE progresses rapidly, and horses usually die within 2-3 days of showing signs of being infected. There is no cure for EEE; intensive veterinarian care and around-the-clock nursing can help save some infected horses, but because EEE affects the nervous system, the horse will have permanent brain damage. Contact your vet immediately if your horse begins to act unusual or exhibits these symptoms!

In the confirmed N.C. case, an unvaccinated 4-year-old mare contracted the mosquito-borne disease and was euthanized. Vaccination is the best and only prevention method. Veterinarians can vaccinate horses against EEE. Horses will be given two injections about 2 – 4 weeks apart and will follow up with a booster shot every year. Horses should be vaccinated during the spring, before mosquito season, to ensure the horse has time to build immunity.

Mosquitos can also transmit EEE to humans. There is no evidence to suggest that the disease can travel from an infected horse to a human or vice versa. In North Carolina, the incidence of humans contracting EEE is low but should not be treated lightly. Adults older than 50 and children younger than 15 are more susceptible to EEE. Be sure to use mosquito repellent to prevent mosquito bites and control mosquito populations.

Reducing the mosquito population will also help reduce the spread of this disease. Below are tips to help manage mosquito populations:

  • Limit stagnant water; mosquitos breed in standing water.
  • Dump and clean water troughs regularly.
  • Keep animals inside during insect feeding times (morning and evening).
  • Use insect screens and fans.
  • Use mosquito repellent.

For more information, please contact Taylor Chavis, Extension Livestock Agent, at 910-671-3276, by email at Taylor_Chavis@ncsu.edu, or visit our website.

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