NY Confirms First Case of Eastern Equine Encephalitis in Horse

The New York State Department of Agriculture and Markets (NYSDAM) confirms 2011’s first case of Eastern Equine Encephalitis, also known as EEE, in an Oneida County, NY horse. The 9-year-old mare had lived at her current home for several years and had no recent travel history. The horse was unvaccinated. There is one other horse on the same premises that is not showing any signs of EEE, and which has since been vaccinated. Typical symptoms of encephalitis in equines include staggering, circling, depression, loss of appetite and sometimes fever or blindness. There is no cure for this disease, which has a high mortality rate in horses. Humans cannot become infected by handling an infected horse, nor can a horse acquire the virus from another infected horse; however, the presence of an infected horse in the area indicates that mosquitoes carrying EEE are present and pose a threat to both humans and horses.

Commissioner of Agriculture and Markets, Darrel J. Aubertine, reminds horse owners that West Nile Virus causes neurologic symptoms similar to those of EEE and is also spread by mosquitoes. Commissioner Aubertine urges all horse owners to discuss vaccination against both diseases with their veterinarian. State Veterinarian David Smith adds that any horse exhibiting neurologic problems should always be handled with great caution. The risk of physical injury to handlers is greater when horses are unsteady on their feet, and also rabies needs to be ruled out as a cause of the symptoms. Vaccines currently available drastically reduce the incidence of EEE in horses and are effective for six to twelve months, so horses should be re-vaccinated at least annually. In an area where the disease occurs frequently, most veterinarians recommend vaccination every six months. For the vaccine to be effective, it must be handled and administered properly and ideally 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, in the first year of vaccination. While it’s best to have horses vaccinated well before potential exposure, vaccinating horses now will still provide protective benefits for this year’s mosquito season.

Other preventive measures include destroying standing-water breeding sites for mosquitoes, using insect repellents, and removing animals from mosquito-infested areas during peak biting times, normally dusk to dawn. Humans should reduce contact with mosquitoes; wearing protective clothing and insect repellents and avoiding the outdoors during dawn and dusk are among the means of avoiding mosquito bites. For more information on humans and EEE, visit www.health.state.ny.us/diseases/communicable/eastern_equine_encephalitis/fact_sheet.htm.

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