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Brooks County at 'high risk' for Equine Piroplasmosis

In most parts of the world, equine piroplasmosis is endemic, routine, even commonplace. It's a foreign animal disease in the United States.

The Texas Animal Health Commission (TAHC) has announced mandatory testing of equine, including horses, donkeys, mules, ponies and zebras, will get underway in Brooks County next week after the Commission designated the county as "high risk" this week for exposure to Equine Piroplasmosis (EP), or Piro for short.

The initiative follows comprehensive testing of all equine in Kleberg County last year over concerns of a developing Piro outbreak when a number of horses tested positive for the disease. In the spring of 2013, over 800 animals on more than 300 premises in Kleberg County had been tested. Over two dozen equine tested positive and were treated for Piro.

Kenedy and Kleberg counties were listed as high risk areas during last year's spring outbreak, but concerns have now moved to Brooks County after at least one tick species known to vector the disease, Amblyomma cajennense, was discovered within the county and because Brooks County borders Kleberg County.

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In most parts of the world, equine piroplasmosis is endemic, routine, even commonplace. In the United States, however, this foreign animal disease is reportable and subject to regulatory action to mitigate disease spread. It is a parasitic disease of all equids, caused by Theileria equi and/or Babesia caballi.

In a recent discovery, the cayenne tick was identified as one of the vectors of equine piroplasmosis in horses and was instrumental in the spread of the disease during a 2009 Texas outbreak, according to USDA-APHIS researchers. Only two U.S. tick species—Dermacentor variabilis and Rhipicephalus (Boophilus) microplus—had previously been known to vector the disease until the 2009 Texas outbreak.

The United States was considered free from the disease since 1978, but sporadic cases have occurred in recent years. In October 2009, for example, in Kleberg County, a mare was presented for veterinary care with clinical signs of infection, including poor appetite and weight loss. Subsequent investigation and testing confirmed the original case and identified more than 290 additional infected animals on the ranch.

Another, less severe outbreak occurred in 2011 in South Texas, and again in the 2013 outbreak.

Animal health officials say their efforts to identify the ticks that vector the disease and a comprehensive program of testing equine when infected ticks are discovered in an area represent a front-line defense against another serious outbreak of the disease in Texas.

An informational public meeting will be held on Thursday, November 13, 2014, at 6 p.m. at the Brooks County Courthouse Annex, 408 West Travis Street, in Falfurrias. Brooks County equine owners and veterinarians are encouraged to attend the public meeting. TAHC veterinarians will provide key information regarding the disease and testing during the session.

Severe anemia

Upon introduction to the horse’s body, both T. equi and B. caballi invade the horse’s red blood cells and can cause severe anemia in some infected equine, evidenced by lethargy, reduced performance, and pale mucous membranes. Horses might also develop fever, icterus (jaundice), anorexia, and digestive problems including colic, constipation, or diarrhea. And because these clinical signs can also accompany other diseases, pursuing proper diagnostic testing is crucial.

Veterinarians can detect EP by identifying the parasites on blood smears in clinically ill horses or through serologic testing using the competitive enzyme-linked immunosorbent assay (cELISA) or complement fixation (CF) tests. A third type of serology test, the immunofluorescent antibody (IFA) test, is also available to veterinarians, and scientists have developed polymerase chain reaction (PCR) tests for research purposes.

"Equine Piroplasmosis is considered a foreign animal disease in the U.S.; however, new cases continue to be discovered in South Texas," Dr. Dee Ellis, State Veterinarian, said. "The TAHC is asking for the support of equine owners and veterinarians to make this testing effort a success and help assure the health of the equine population."

 Brooks County equine owners and veterinary practitioners may contact the TAHC Region 5 Office at 1-361-358-3234 with questions or to schedule testing. For more information on Piroplasmosis visit .

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