ABSTRACT
The present review is on two groups of haemoflagellates that cause disease in economically important animals, cryptobiosis in salmonids in North America, while mammalian trypanosomiasis is in livestock in Africa. Although the causative agents, Cryptobia and Trypanosoma, of both diseases are closely related (Order Kinetoplastida) there are some very significant differences between the two diseases they cause. There are both haematozoic and non-haematozoic Cryptobia. At least three species of haematozoic Cryptobia are known to cause disease in freshwater and marine fishes, and they are Cryptobia (Trypanoplasma) salmositica in salmonids, C (T.) bullocki in flatfishes, and C (T.) borreli in cyprinids. These parasites are normally transmitted indirectly by bloodsucking leeches; however C salmositica can also be transmitted directly between fish in the absence of blood sucking leeches (Woo, 1994; Woo and Poynton, 1995). There are also numerous species of Glossina-transmitted trypanosomes that infect livestock in tropical Africa, but these pathogens are not just confined to Africa. In areas where tsetse flies are not present, these haemoflagellates (e.g. Trypanosoma vivax in South America, Trypanosoma evansi in South East Asia) are transmitted mechanically, usually as a result of interrupted feeding, by other blood-feeding flies (Hoare, 1972).
