New York Confirms First Equine EEE Case of 2012

The New York State Department of Agriculture and Markets (NYSDAM) confirmed Friday (July 27) the first 2012 case of Eastern equine encephalitis (EEE), in a horse living in St. Lawrence County, N.Y.

The 8-year-old gelding had no vaccination history and no history of travel outside the county. The horse started to show signs of the disease July 23 and died later on that day. Samples were sent to the New York State Deptartment of Health's Wadsworth Center to confirm the diagnosis of EEE. The horse tested negative for rabies and West Nile virus. Other horses residing on the affected horse's home premises are not showing any signs of EEE.

Mosquitoes carry the disease from birds to horses. A viral disease, EEE affects the central nervous system and is transmitted to horses by infected mosquitoes. Its fatality rate in horses is 75-95%. The course of EEE can be swift, with death occurring two to three days after onset of clinical signs despite intensive care. Horses that survive might have long-lasting impairments and neurologic problems. Clinical signs of EEE include moderate to high fever, depression, lack of appetite, cranial nerve deficits (facial paralysis, tongue weakness, difficulty swallowing), behavioral changes (aggression, self-mutilation, or drowsiness), gait abnormalities, or severe central nervous system signs, such as head-pressing, circling, blindness, and seizures. Sixty equine EEE cases were confirmed in the United States in 2011, according to USDA Animal and Plant Health Inspection Service equine disease surveillance; New York confirmed 12 EEE cases in horses in 2011.

It's important to remember that horses exhibiting neurologic signs that could or do have EEE, need to be promptly reported by veterinarians to the NYSDAM and the local health department.

Additionally, the NYSDAM urges all horse owners to ask their veterinarian about EEE vaccination recommendations for their horses. The vaccines are effective for six to twelve months, so horses should be revaccinated at least annually; in an area where the disease occurs year round, many veterinarians recommend vaccination every six months. For the vaccine to be effective it must be handled and administered properly, and be given at least two weeks before the horse could be exposed to the virus. Additionally, to stimulate full immunity, horses must be vaccinated twice, about 30 days apart in the first year that the horse is vaccinated.

Other prevention methods include 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.

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