Equine Piroplasmosis

Equine piroplasmosis (EP) is a disease of Equidae (horses, donkeys, mules, and zebras) caused by protozoan parasites which invade the red blood cells, causing their destruction. Two species or protozoa, Babesia equi and Babesia caballi, are present in 90% of the world inhabited by horses. Only Canada, United States, Australia, Japan, England and Ireland are not considered to be endemic areas

. The disease is blood borne, and is generally transmitted by ticks and other insects, however improper disinfection of hypodermic needle or other instruments could cause mechanical transmission.

B. caballi causes a less severe disease as only about 1% of the red blood cells are infected. Infections may not be apparent, but can persist 1 to 4 years, although they are eventually eliminated. They may be associated with poor appetite, poor performance, and weight loss.

B. equi infects up to 20% of red blood cells, leading to more severe clinical signs with fever, anemia, icterus (jaundice) increased respiratory and heart rates, and enlargement of the spleen. The parasites destroy the red blood cells, giving anemia, and the released hemaglobin may cause icterus and a dark urine. Colic, constipation followed by diarrhea, and swelling of the legs can occur. Foals can be infected in utero, and can be aborted or born anemic and weak. . Animals with B. equi infections become life-long carriers.

The greatest risk for introduction of this disease into Canada or other non-endemic areas is through trading of animals or international equestrian sports, where infected and non-infected animals are in contact.. Many disease free countries have the climate suitable for a foreign tick vector, or have ticks which could act as vectors. Diagnosis is through serological techniques, and the complement fixation test is generally accepted, although both false positive and false negative tests may occur.

Compiled from Waal, D.T. Protozoal Division, Veterinary Research Institute, Onderstepoor, South Africa; Review Series, British Veterinary Journal, 1992.

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Other Links:
Equine Piroplasmosis - Robert N. Oglesby, D.V.M., (The Horse Advisor),

References:

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