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  • Updated 04.18.2023
  • Released 07.19.1993
  • Expires For CME 04.18.2026

Sleeping sickness



Sleeping sickness is a prevalent and serious, yet often ignored and understudied, infectious illness. In this article, the author summarizes the key features of this illness and provides information about promising treatment and prevention methods.

Key points

• African sleeping sickness is a devastating but unfortunately forgotten epidemic that affects tens of thousands of sub-Saharan Africans.

• Underdiagnosis remains a major barrier to effective control and diagnosis is usually established by parasite identification, although PCR and other gene tests are being developed.

• The causative agent usually belongs to one of three species of the Trypanosoma genus and is transmitted to humans through a vector, the tsetse fly.

• Effective vaccination does not exist, and most available chemotherapeutic agents have some degree of toxicity although research is ongoing to find an effective, nontoxic alternative.

• Vector control remains an effective yet not often utilized method of prevention.

Historical note and terminology

African sleeping sickness or human African trypanosomiasis (HAT), in French la maladie du sommeil, was described in the last half of the 19th century by European explorers of West Africa who observed patients with enlarged glands and dramatic neurologic symptomatology, often in epidemic settings. Sleeping sickness was an established part of the tribal lore of West Africa, especially in the Congo and Niger basins and the Upper Voltas. Beginning in 1885, the commercial development of the Congo Free State, with soldiers, settlers, and laborers plying the Congo River basin, led to the extensive spread of the disease from "primordial" riverside foci, aided by the clearing of the forests and their replacement with low thicket that favors the tsetse fly (Glossina genus) vector. During the early 1900s, several legendary pioneers of tropical medical science, including D Bruce, A Castellani, JE Dutton, H Koch, A Laveran, P Manson, FW Mott, and E Rouband, elucidated the disease cycle and causative protozoal trypanosomes now known collectively as the Trypanosoma brucei subspecies.

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