Trypanosoma evansi is a protozoal pathogen closely related to African trypanosomes which causes the disease ‘Surra’ in ruminants, horses and camels. Dogs are highly susceptible to T. evansi infection and they often exhibit severe clinical signs than can lead to death.
|Parasite: Trypanosoma evansi|
|Common name: ‘surra’|
|Hosts: Ruminants, horses, camels, dogs, cats|
|Location in host: free in bloodstream|
|Distribution: Asia, Latin America, North Africa|
|Transmission route: biting insects (tabanids and stomoxes), iatrogenic, oral transmission.|
The disease spread from North Africa towards the Middle East, Turkey, India, southern Russia, across all South-East Asia, down to Indonesia and the Philippines and into Latin America.
T.evansi infection in dogs includes fever, anorexia, lethargy, lymphadenomegaly, hepatosplenomegaly, edema, ascites, petechial hemorrhages, uveitis, oculonasal discharge, corneal edema reminiscent of blue eye caused by canine adenovirus infection, and neurological signs associated with meningoencephalitis.
The diagnosis of T. evansi trypanosomiasis involves detection of trypomastigote forms of the parasite by cytology of blood, body fluids or tissues by microscopy (Fig 1). Dogs may have anemia, leukocytosis or leukopenia and thrombocytopenia. Serum biochemistry abnormalities include increased activities or liver enzymes, azotemia, hypoalbuminemia and hyperglobulinemia.
PCR with sequencing are useful for detection of low parasitemias and for species determination. ELISA, IFA and the card agglutination trypanosomiasis test (CATT) are available for the detection of antibodies against T. evansi.
T.evansi infection in dogs can be treated with off-label use of diminazene aceturate at 5mg/kg IM or suramin (70 mg IV in 100 mL 0.9% NaCl TID every third day till resolution of parasitaemia)1, with variable responses noted.
Disallowing consumption of raw meat and eliminating dog contact with vectors by using topical repellants and insecticides such as collars and spot-on formulations (e.g. permethrin, flumethrin, deltamethrin).
 Defontis M, Rochartz J, Engelmann N, Bauer N, Schwierk C, Buscher VM, Moritz A. Canine Trypanosoma evansi infection introduced into Germany. Vet Clin Pathol. (2012), 41(3), 369-74.