Alabama Horse Owners Advised to Vaccinate for EEE, WNV

Alabama Agriculture and Industries Commissioner John McMillan announced that since June, several positive cases of Eastern equine encephalitis (EEE) have been found in Alabama in birds and horses.

"We are entering into the time of year that makes us extremely vulnerable to the spread of mosquito-borne viruses and we need to protect our livestock and ourselves," stated McMillan. "I want to encourage horse owners to vaccinate their horses for both EEE and West Nile virus (WNV) as soon as possible."

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.

Clinical signs for WNV include flu-like signs, where the horse seems mildly anorexic and depressed; fine and coarse muscle and skin fasciculations (twitching); hyperesthesia (hypersensitivity to touch and sound); changes in mentation (mentality), when horses look like they are daydreaming or "just not with it"; occasional somnolence (drowsiness); propulsive walking (driving or pushing forward, often without control); and "spinal" signs, including asymmetrical weakness. Some horses show asymmetrical or symmetrical ataxia (incoordination on one or both sides, respectively). Equine mortality rate can be as high as 30-40%. The USDA Animal and Plant Health Inspection Service reported 83 cases of WNV in U.S. horses in 2011.

McMillan and State Veterinarian Tony Frazier, DVM, recommend vaccinating horses every six months against both EEE and WNV. Horse owners are encouraged toensure their animals' vaccinations are up-to-date, or to contact their veterinarian to schedule a vaccination for their horses. The public is also advised to make every effort to reduce human exposure to mosquitoes during this time of year.

The two horses that tested positive for EEE in Alabama were located in Mobile and Washington Counties. Birds that have tested EEE-positive were found in Lee County.

For more information about EEE or WNV, contact Frazier at 334/240-7253. For more information on public health mosquito surveillance and control programs, contact the Alabama Department of Public Health, Division of Epidemiology at 800/677-0939.

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