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African trypanosomiasis: Clinical manifestations, diagnosis, and treatment

Sanjeev Krishna, MA, BMChB, DPhil, FRCP, ScD, FMedSci
August Stich, MD, MSc, DTMH
Section Editor
Peter F Weller, MD, MACP
Deputy Editor
Elinor L Baron, MD, DTMH


Human African trypanosomiasis (HAT), also known as sleeping sickness, is caused by protozoan parasites [1,2]. There are two forms of the disease: an acute form occurring mainly in East Africa and caused by Trypanosoma brucei rhodesiense and a more chronic form occurring mainly in West and Central Africa caused by Trypanosoma brucei gambiense (table 1) [3]. These two species have identical morphologic appearances, and both are transmitted by tsetse flies of the genus Glossina. However, the clinical infections differ in presentation, management, and prognosis.

The clinical manifestations, diagnosis, and treatment of African trypanosomiasis will be reviewed here. The epidemiology, life cycle, and prevention of African trypanosomiasis are discussed separately. (See "African trypanosomiasis: Epidemiology, pathogenesis, and prevention".)


Human African trypanosomiasis (HAT) is characterized by an early stage, known as the hemolymphatic stage, during which trypanosomes circulate in the blood or lymphatics, and a late stage, in which there is involvement of the central nervous system (CNS). T. b. gambiense causes a slowly progressive infection, and an oligosymptomatic phase can last for months or years. In contrast, T. b. rhodesiense presents as a rapidly progressive infection (often with signs of septicemia), can cause early myocarditis and CNS involvement, and is usually detectable within weeks of infection. Both infections are considered fatal without treatment, although rare instances of asymptomatic infection or resolution of T. b. gambiense without treatment have been documented [4] and are associated with proinflammatory cytokine responses [5]. Outside endemic areas, clinical features among returning travelers may differ from clinical features among immigrants (table 2) [6].

Data on African trypanosomiasis and human immunodeficiency virus (HIV) infection are limited [7]; some studies suggest a higher speed of clinical progression and a higher rate of side effects during treatment among HIV-infected patients.

Early infection (stage I) — Early symptoms of HAT infection include intermittent headache, fevers, malaise, and arthralgia. These symptoms may correspond with successive waves of parasitemia and antibody production. Hepatomegaly and particularly splenomegaly may be observed, and generalized lymphadenopathy may also be present. Other nonspecific symptoms may be present including pruritus, rash, weight loss, and facial swelling. Neuroendocrine disturbances leading to amenorrhea in women or impotence in men may also occur. The duration of this phase is approximately three years in T. b. gambiense infection [8]. In contrast, T. b. rhodesiense presents as an acute illness with poor demarcation between stages, leading to death within months.

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Literature review current through: Nov 2017. | This topic last updated: Nov 27, 2017.
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