African sleeping sickness (human African trypanosomiasis)
African sleeping sickness (human African trypanosomiasis) is a tsetse fly-transmitted infection with Trypanosoma brucei that progresses from a hemolymphatic stage of recurring fever and lymphadenopathy, driven by antigenic variation, to a meningoencephalitic stage of somnolence and coma. Staging by CSF examination determines whether therapy uses a bloodborne-stage agent (suramin, pentamidine) or a CNS-penetrating regimen (melarsoprol or nifurtimox-eflornithine).
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What this article covers
- Overview
A tsetse fly-transmitted protozoal infection with two clinical stages: African sleeping sickness is caused by the hemoflagellate protozoan Trypanosoma brucei, transmitted by the bite of a tsetse fly…
- Epidemiology
Transmitted by the tsetse fly across sub-Saharan Africa: human African trypanosomiasis occurs in regions where the tsetse fly vector is endemic, with exposure classically associated with a painful tsetse fly bite.
- Risk factors
Residence in or travel to a tsetse fly-endemic region of sub-Saharan Africa: the fundamental exposure risk, since the tsetse fly bite is the necessary route of transmission.
- Pathophysiology
Inoculation occurs via a painful tsetse fly bite: the trypanosome is introduced into the skin and bloodstream at the bite site.
- Clinical features
Recurring fever, the hallmark of the hemolymphatic stage: episodic fever driven by cycles of antigenic variation, rather than a single sustained febrile course, is the earliest and most characteristic systemic sign.
- Differential diagnosis
Malaria: Malaria causes overlapping recurring fever and systemic illness in a traveler from an endemic tropical region; discriminated by a positive blood smear or antigen test for Plasmodium species and the absence of trypomastigotes.
- Diagnosis
The disease is confirmed by direct microscopic identification of the organism: motile trypomastigotes seen on a Giemsa-stained peripheral blood smear (or on lymph node aspirate or CSF), which is the clinching diagnostic finding.
- Management
First, confirm the parasitologic diagnosis and stage the disease with CSF examination before selecting therapy, as above, because the two stages require different drugs.
- Complications
Progression to coma and death if untreated or inadequately staged: the natural history of untreated infection is progression from recurring fever and lymphadenopathy through somnolence to coma.
- Prognosis
Favorable with early diagnosis and stage-appropriate treatment: disease identified and treated in the hemolymphatic stage, before CNS invasion, has a substantially better prognosis and can be managed…
- Prevention
Avoid tsetse fly bites when traveling in or residing in an endemic region of sub-Saharan Africa: wearing protective clothing and using insect precautions reduces the risk of the bite that transmits…
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