First Case of Eastern Equine Encephalitis in 2010 Confirmed

The Virginia Department of Agriculture and Consumer Services (VDACS) has confirmed the first case of Eastern Equine Encephalitis (EEE) in a horse this year. The horse, an 18-month-old mustang female from Suffolk, was euthanized July 26 because of the severity of her symptoms – extreme weakness and ataxia, the inability to coordinate voluntary muscle movements, unsteady movements and staggering gait. The horse received an initial vaccination and a booster in the fall of 2009, as well as a booster in May of 2010.

Many states are experiencing an unusually high level of EEE infection this year but this is the first reported case in Virginia. Last year the state had eight cases, most of them in the Tidewater area. The disease has a mortality rate of around 80 percent, so prevention is a key part of equine health. Generally, EEE is transmitted by mosquitoes. Prevention methods include vaccination, destroying standing water breeding sites for mosquitoes, using insect repellents and removing animals from mosquito-infested areas during peak biting times, usually dusk to dawn.

In an April 2010 press release, Dr. Richard Wilkes, VDACS’ State Veterinarian, encouraged horse owners to work with their veterinarians to plan a vaccination schedule that would protect their horses from EEE and West Nile Virus. Available vaccines are generally effective in drastically reducing the incidence of both EEE and WNV in horses. 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 twelve months, so horses should be re-vaccinated at least annually.  In an area where the disease occurs frequently, such as southeast and Tidewater Virginia, most veterinarians recommend vaccination every six months.

For more information, please contact the Office of the State Veterinarian at 804.692.0601 or consult your local veterinarian.