Piroplasmosis Table Topic (AAEP 2012)

Piroplasmosis Table Topic (AAEP 2012)

Attendees discussed the different methods of disease transmission, including tick-borne transmission and iatrogenic/needle transmission, among other topics.

Photo: Photos.com

It was evident from the table topic attendance at the 2012 American Association of Equine Practitioners' convention, held Dec. 1-5 in Anaheim, Calif., that equine piroplasmosis (EP) caused by the blood parasites Theileria equi (formerly Babesia equi) and Babesia caballi is still interesting and relevant to many practitioners.

During a T. equi outbreak on a south Texas ranch in October 2009, 413 out of 2,500 horses tested during the investigation of the outbreak were found to be infected. Subsequent testing and enhanced surveillance testing of more than 200,000 horses throughout the United States since 2009 has identified an additional 189 EP-infected horses (179 T.equi-infected, 10 B. caballi-infected) that were all unrelated to the Texas ranch outbreak. These positive horses have been found in only two high-risk groups in the U.S: horses imported prior to August 2005 (when a less sensitive diagnostic test was the official import test for EP) and racehorses, mostly Quarter Horses connected with unsanctioned horse racing.

In addition to information shared on the history of EP in the U.S., table topic attendees addressed both regulatory and practical topics. They discussed the different methods of disease transmission, including tick-borne transmission seen on the Texas ranch, iatrogenic/needle transmission identified in the racehorse cases, and even the occasional vertical transmission cases from mare to foal.

Also discussed were exciting results of the EP treatment research program through which more than 170 EP-infected horses, including all remaining positive horses on the Texas ranch, have been treated and now proved cleared of the piroplasma organism. Along with successful clearance of the organism, veterinarians also documented antibody seroconversion (formation of antibodies against the organism) post-treatment that they previously thought unlikely or impossible in treated horses. Attendees described treatment's side effects as well as potential interactions between treatment drugs and non-steroidal anti-inflammatories (NSAIDs) that could affect organism clearance.

Overall, the collaborative working relationships formed between state and federal regulatory officials, researchers, and many equine industry partners were highlighted as the most important factor that has lead to winning the battle against EP in the United States.

This table topic was moderated by Ben Espy, DVM, Dipl. ACT, veterinarian for King Ranch, in Kingsville, Texas, and Angela Pelzel, DVM, a Western region epidemiologist with the USDA Animal and Plant Health Inspection Service.

About the Author

Benjamin Espy, DVM, Dipl. ACT

Benjamin Espy, DVM, Dipl. ACT (boarded in equine reproduction), has practiced veterinary medicine in Texas and Kentucky. He has been licensed to practice acupuncture for nine years and is on numerous AAEP committees and task forces. Espy serves on the alternative therapy committee for the Texas Veterinary Medical Association, and he's an animal treatment consultant for the Professional Rodeo Cowboys Association.

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