An active blood parasite that is present in practically all domestic animals in Africa, the West Indies, and parts of Central and South America. In Africa, the insect vector is the tsetse fly. In other countries, infection is by mechanical means indicating that the parasites have been introduced to these countries and have been able to maintain themselves in spite of the lack of a suitable intermediate host. It is a cause of nagana, the severity of which depends on the species affected.
