Surra (Trypanosomiasis)
Etiologic agent: Trypanosoma evansi

Test codes:
X0008 - Ultrasensitive qualitative detection of Trypanosoma evansi by real time polymerase chain reaction

Surra is an animal disease occurring in Africa, Asia and Latin America, caused by Trypanosoma evansi. T. evansi belongs to the subgenus Trypanozoon, together with T. equiperdum and T. brucei. The parasite infects various host species and is transmitted by biting flies such as Tabanidae and Stomoxys species, as well as by vampire bats including Desmodus rotondus (Hoare, 1972). Camels and horses are very susceptible to the infection and death can occur within weeks or months. T. evansi infections of cattle and buffalo usually lead to pronounced immunosuppression, resulting in increased susceptibility to other opportunistic diseases such as Pasteurella and anthrax (Stephen, 1986).

Diagnosis of T. evansi infection usually starts with clinical symptoms or the detection of antibodies to T. evansi. Conclusive evidence of T. evansi infection, however, relies on detection of the parasite in the blood or tissue fluids of infected animals. Unfortunately, parasitological techniques cannot always detect ongoing infections as the level of parasitemia is often low and fluctuating, particularly during the chronic stage of the disease (Nantulya, 1990).

Molecular detection of T. evansi using the polymerase chain reaction is a highly sensitive and specific alternative to parasitological tests.

Utilities:

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

References:
Hoare, C.A. (1972) The trypanosomes of mammals. Oxford, Blackwell Scientific Publications 1972, 1-749.
Nantulya, V.M. (1990) Trypanosomiasis in domestic animals: the problems of diagnosis.
Rev Sci Tech 1990, 9:357-367.
Stephen, L.E. (1986) Trypanosomiasis. A veterinary perspective (Edited by: StephenLE). Oxford, Pergamon Press 1986.

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

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 real time PCR

Normal range: Nondetected