The Virginia Department of Agriculture and Consumer Services announced on Friday the second case of Eastern Equine Encephalitis in a Virginia horse this year. The horse, a three-year-old Tennessee Walker mare, was from Chesapeake and had only been purchased by the owner three weeks ago. Its vaccination history is unknown.
The horse exhibited signs August 13 and was euthanized August 14 due to the severity of the illness. VDACS received confirmation from the National Veterinary Services Laboratory in Ames, Iowa on August 21. Both cases of EEE this year have been in horses from Chesapeake.
“One of the reasons most veterinarians recommend a six-month vaccination schedule in Tidewater Virginia is because of the prevalence of mosquitos in the area,” said Dr. Richard Wilkes, State Veterinarian. Wilkes explained thatEEE, a mosquito-borne illness, causes inflammation or swelling of the brain and spinal cord and is also called “sleeping sickness.” Symptoms include impaired vision, aimless wandering, head pressing, circling, inability to swallow, irregular staggering gait, paralysis, convulsions and death. Once a horse has been bitten by an infected mosquito, it may take three to 10 days for signs of the disease to appear.
Last year Virginia had one reported case of EEE, in a horse from Suffolk. The disease has a mortality rate of 80 to 90 percent, so prevention is a key part of equine health. Vaccination and mosquito control/ avoidance are the central elements of prevention.
Available vaccines are generally effective in drastically reducing the incidence of both EEE and West Nile Virus (WNV) in horses. VDACS announced the first Virginia horse to test positive for WNV August 14.
For the vaccine to be effective it must be handled and administered properly and be given at least two weeks before the horse is exposed to the virus. Additionally, to stimulate full immunity, horses must be vaccinated twice, about 30 days apart, the first year of vaccination. The vaccines are effective for six to 12 months, so horses should be revaccinated at least annually. In addition to vaccination, horse owners should avoid mosquito infested areas and take measures to reduce the local mosquito population to minimize the chances of mosquitos biting their horses.
For more information, horse owners should contact VDACS’ Office of the State Veterinarian at 804.692.0601 or consult their local veterinarian.
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