The Virginia Department of Agriculture and Consumer Services announced the fifth and sixth cases of Eastern Equine Encephalitis in horses this year. Both horses were from Suffolk, a male Paint and an Arabian filly. Both horses were euthanized. Neither had up-to-date vaccinations.
In the Tidewater area, veterinarians usually recommend a six-month vaccination interval because mosquitoes are present almost all year long, from early spring to late fall. Virginia had four earlier cases of EEE this year, two others from Suffolk, one from Chesapeake and one from Prince George County.
EEE is a mosquito-borne illness that 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 ten days for signs of the disease to appear.
“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. Charles Broaddus, State Veterinarian. “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 people and their horses.
Last year, Virginia had three reported cases of EEE, one from Suffolk and two from Chesapeake. The disease has a high mortality rate, 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, and vaccinated horses that contract the virus are much more likely to survive than unvaccinated animals.
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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