Selective primary health care: strategies for control of disease in the developing world. VIII. African trypanosomiasis.

African trypanosomiasis in humans is caused by trypanosomes, parasitic protozoa that inhabit the blood and tissue spaces. Humans are infected by the bite of the tsetse (Glossina species), which itself acquires the parasites from human or animal hosts. The vector and the disease are confined to sub-saharan Africa where the disease occurs in endemic foci from which epidemics arise. Two forms of African trypanosomiasis in humans are recognized and both are fatal if left untreated. Control strategy is dependent on the capacity of the public health services to diagnose and treat cases, and the maintenance of surveillance is essential if epidemics are to be prevented. In epidemics this strategy should be extended to include vector-control measures to break transmission of the disease while cases continue to be diagnosed and treated. Eradication of the vector is not feasible nor can animal reservoirs be eliminated. National authorities must thus maintain surveillance to reduce the human reservoir of infection in order for low levels of endemicity, particularly in areas where epidemics have occurred in the past, to be retained.