Equine piroplasmosis
Etiologic agent: Babesia spp. parasites

Test codes:
X0005 - Qualitative detection of Babesia equi by polymerase chain reaction
X0006 - Qualitative detection of Babesia caballi by polymerase chain reaction

Equine piroplasmosis is caused by the intracellular, haemoprotozoan parasites Babesia equi (recently reclassified as Theileria equi, Mehlhorn and Schein, 1998) and Babesia caballi, which are transmitted by ticks of several genera including Boophilus, Hyalomma, Dermacentor and Rhipicephalus. The disease is found in many tropical and subtropical areas. Clinical manifestation of the disease is variable and often includes icterus (jaundice), haemoglobinuria and fever. Both chronic and acute infection can occur. Sub-clinical infected animals are of major concern, as they can be carriers of the organism. The geographic movement of presumably healthy horses may aid in the spread of Babesia species. In addition to the fact that sub-clinical babesiosis may negatively affect the animal’s performance, it has been shown that strenuous exercise, such as that experienced in horse racing, can cause sub-clinical infections to become acute (Hailat et al., 1997). Thus there is a real need for the diagnosis of both clinical and sub-clinical infections.

In general, 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 before they are eventually eliminated. They may be associated with poor appetite, poor performance and weight loss. In contrast, B. equi infects up to 20% of red blood cells, leading to more severe clinical signs including fever, anemia, icterus, increased respiratory and heart rates and enlargement of the spleen. The parasites destroy red blood cells, causing anemia, and the released hemoglobin may cause icterus and 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.

Piroplasmosis can be diagnosed by a number of different methods including giemsa-stained blood smear, ELISA and PCR. PCR in particular has been shown to be sensitive, specific and a useful diagnostic tool for detecting the presence of Babesia (Bose et al., 1995). Giemsa-stained blood smear can only detect these parasites when the infected animal is at the acute stage of infection, and cannot identify chronic carriers. ELISA and other serological detection methods such as complement fixation and indirect fluorescent antibody detection suffer from low sensitivity and cross reactivity.

Utilities:

• Confirm the disease causing agent
• Shorten the time required to confirm a clinical diagnosis of Babesia infection.
• Ensure that animal populations are free of Babesia
• Early prevention of spread of this protozoan
• Minimize personnel exposure to this protozoan
• Safety monitoring of biological products that derive from horses

References:
Bose, R., Jorgensen, W.K., Dalgliesh, R.J., Friedhoff, K.T. and de Vos, A.J. (1995) Current state and future trends in the diagnosis of babesiosis. Vet. Parasit. 57:61–74.
Hailat, N.Q., Lafi, S.Q., Al-Darraji, A.M. and Al-Ani, F.K. (1997) Equine babesiosis associated with strenuous exercise: clinical and pathological studies in Jordan. Vet. Parasit. 69:1–8.
Mehlhorn, H. and Schein, E. (1998) Redescription of Babesia equi Laveran, 1901 as Theileria equi. Parasitol. Res. 84: 467–475.

Specimen requirements: 1 ml whole blood in EDTA (purple top) or ACD (yellow top) tube, shipped overnight at room temperature.

For specimen types other than those listed here, please call to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.Turnaround time: 2 business days

Methodology: Qualitative PCR

Normal range: Nondetected