Report of the Thirteenth Meeting of the OIE Ad hoc Group on Non Tsetse-Transmitted Animal Trypanosomoses

There is increasing interest in many parts of the world in trypanosomoses other than those transmitted by tsetse flies, as shown by numerous research projects and field studies. The refinement of techniques for studying the behaviour of trypanosomes (techniques of molecular biology) in axenic culture or in the parasitised host has led to progress in diagnosis and immunology, and a rational approach to chemotherapy and chemoprophylaxis of these infections. Field trials of enzyme-linked immunosorbent assays in Africa, Asia and South America have shown that these tests may now be regarded as reliable in demonstrating antibodies or antigens for Trypanosoma evansi infection in buffalo, cattle and camels, and for mono-infection with T. equiperdum in equines. However, it is not yet possible to differentiate reliably between infections with T. evansi and T. equiperdum in equines. The card agglutination trypanosomosis test (CATT) has been adapted to T. evansi infection and can also be recommended. Immunosuppression induced by T. evansi infection inhibits the immune response to vaccination against Pasteurella haemolytica. In areas freed from tsetse flies (Cameroon, Central African Republic, Zambia) it has been observed that Trypanosoma vivax can be transmitted mechanically by other biting insects, which are at present being identified. Research on trypanocides has led to the toxic factor for Trypanosoma brucei or T. equiperdum present in human or simian serum being localised to the high density lipoprotein of serum lipoproteins. Various derivatives are being tested under laboratory conditions, and the efficacy of some (e.g. ronidazole) is being checked at present, while others are ready to pass to the development stage (e.g. IMOL 881). Melarsomine, already available commercially (as Cymelarsan) for the treatment of T. evansi infection in camels, is being studied for possible use in other species of animals.