Human African Trypanosomiasis

Type: Parasitic

Geography: Africa

Cases Per Year: 2,000 to 3,000 in recent years

Fatality Rate: nearly 100% for untreated cases, low with treatment

First Discovered: 1903 by David Bruce in South Africa


Also called “sleeping sickness”, Human African trypanosomiasis is caused by parasites transmitted by infected tsetse flies. It is endemic in 36 sub-Saharan African countries. Rural populations depending on agriculture, fishing, animal husbandry, or hunting are the most exposed to the tsetse fly and therefore to the disease.

Infection occurs in two stages and there are two types of this disease, depending on the parasite involved. In the first stage, the parasites are found in the blood and lymphatic system. In the second stage, the parasites invade the central nervous system.  East African trypanosomiasis progresses to the second phase within a week, while the average duration of West African trypanosomiasis is 3 years. Symptoms common to both types of the disease include fever, severe headaches, irritability, extreme fatigue, swollen lymph nodes, and aching muscles and joints. Progressive confusion, personality changes, disruption to the sleep cycle and other neurologic problems occur during the second stage.

For East African trypanosomiasis, symptoms usually occur 1 to 3 weeks after an infection, while West Africa trypanosomiasis symptoms may be minimal or intermittent during the first few months of infection and take up to a year to become apparent. If not treated, trypanosomiasis can be fatal.

Photo: Trypanosoma evansi – Electron micrograph