Tuesday, August 27, 2013

Eastern Equine Encephalomyelitis continues to be an issue in 2013: are your horses protected?

2012 was a fairly bad year for Eastern Equine Encephalomyelitis (EEE) in the US.  209 cases were reported to the USDA-APHIS Veterinary Service.  This was a marked increase compared to the 60 cases reported in 2011, but still not quite as high as the 2 previous years.  (For a breakdown of the historical cases of EEE in the US for the last 10 years please visit:  http://www.aphis.usda.gov/vs/nahss/equine/ee/2012_eastern_equine_encephalitis_final.pdf ).

As of August 13, there have been 55 reported veterinary cases of EEE in the US.  Florida leads the way with 25 cases, and Georgia is second with 10.  Alabama, Arkansas, Louisiana, Massachusetts, Mississippi, New Jersey, North Carolina, Texas and Maryland are also reporting cases.

EEE is a blood-borne disease transmitted by mosquitos that can affect most mammals, but is seen primarily in horses and humans.  Horses are considered “dead end” hosts of the disease meaning they cannot transmit the disease directly to other mammals.  Humans and horses are infected when a mosquito carrying the virus bites them.   August and September are the months when EEE and other mosquito transmitted disease are most commonly diagnosed.  Horse owners should be extra vigilante with regard to mosquito control at this time of year.  Additionally, horses should be vaccinated before this “mosquito season” begins to ensure full protection against the virus’s carried by them.

Clinical signs of EEE and other mosquito-transmitted encephalitic diseases include:  fever, depression, loss of appetite, ataxia, altered behavior, disturbed mentation. If your horse displays any of these clinical signs you should contact your veterinarian immediately.

Some methods for mosquito control and to try to protect horses from exposure to these deadly viruses include:  making sure there are no nearby puddles or areas where water can accumulate such as in old tires, or disused water troughs, bird baths or water fountains; be sure to bring horses indoors during the times of the day when mosquito activity is highest; utilize an insect repellant that is effective against mosquitos.

Highly effective vaccines are available for EEE and the related viral diseases Western Equine Encephalomyelitis (WEE) and Venezuelan Equine Encephalomyelitis (VEE).  These vaccines are generally available in combination with tetanus toxoid and should be boostered yearly, prior to the onset of mosquito season.  Horses should also be vaccinated yearly for West Niles Virus, another mosquito-borne disease.  EEE and WEE along with rabies and tetanus have been determined by the American Association of Equine Practitioners to be the core vaccines for horses.  (A core vaccine is one that is considered essential for all horses regardless of age, breed or use).  Depending on your geographical area VEE may also be considered essential. Keeping your horse up-to-date on these critical vaccines is the best way of ensuring protection against these deadly mosquito-associated viruses. As always, check with your veterinarian for the best vaccination plan for your horse.

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