African trypanosomiasis

African trypanosomiasis is an insect-borne parasitic infection caused by protozoan parasites of the species Trypanosoma brucei. The disease exists in two epidemiologically distinct forms: Trypanosoma brucei gambiense, which is primarily transmitted between humans and accounts for over 92% of reported cases, and Trypanosoma brucei rhodesiense, which is zoonotic with animals including cattle and wildlife serving as reservoirs. The condition is also termed human African trypanosomiasis (HAT) or African sleeping sickness.

The disease progresses through two stages with distinct clinical manifestations. The initial hemolymphatic stage occurs one to three weeks following the infectious bite and presents with non-specific symptoms including intermittent fever, severe headaches, joint pains, itching, weakness, malaise, and fatigue; lymphadenopathy and hepatosplenomegaly may also be observed. A trypanosomal ulcer may develop at the bite site within two days, particularly in T. b. rhodesiense infection. The second neurological stage begins when parasites cross the blood-brain barrier, manifesting as confusion, poor coordination, numbness, and sleep disturbances. Progression to the neurological phase typically occurs within 21-60 days for T. b. rhodesiense and 300-500 days for T. b. gambiense infection, though the two stages often overlap clinically.

African trypanosomiasis is restricted to rural areas of sub-Saharan Africa where tsetse flies are endemic. The disease burden is concentrated in regions with limited healthcare infrastructure, and case detection has historically been challenging due to the non-specific nature of early symptoms. Trypanosoma brucei gambiense causes the vast majority of reported cases, while T. b. rhodesiense accounts for a smaller proportion but typically follows a more acute clinical course. Occupational exposure among farmers, fishermen, and hunters increases infection risk in endemic zones.

Transmission occurs through the bite of infected tsetse flies (Glossina species), which serve as the biological vector. For T. b. gambiense, human-to-human transmission via the vector maintains the epidemic cycle, whereas T. b. rhodesiense involves zoonotic transmission from animal reservoirs including domestic livestock and wildlife. Both forms are most commonly acquired in rural agricultural or forested areas where tsetse fly habitats overlap with human activity.

Individuals living in or traveling to rural areas of sub-Saharan Africa where tsetse flies are endemic face elevated risk of infection. Occupational groups with prolonged outdoor exposure in these regions—including farmers, fishermen, hunters, and herders—experience heightened exposure to infected vectors. Persons from non-endemic areas may present with more pronounced early manifestations such as trypanosomal ulceration at the bite site.

Prevention strategies center on vector control measures to reduce tsetse fly populations and personal protection against bites in endemic areas. Public-health programs emphasize active screening of at-risk populations using serological blood tests to identify cases early, particularly for T. b. gambiense infection. Early detection before neurological involvement significantly improves treatment outcomes, as therapeutic options are more limited and toxic once the central nervous system is affected.

Surveillance for African trypanosomiasis requires consideration of the disease's focal endemicity and the non-specific nature of early symptoms, which may delay diagnosis and underreport cases. The distinction between the two parasite species has implications for both case management and outbreak investigation, as T. b. rhodesiense cases may signal zoonotic exposure requiring veterinary investigation. Monitoring should account for seasonal and environmental factors influencing tsetse fly distribution, and surveillance systems should incorporate both passive clinical reporting and active community-based screening in known endemic foci.

1. 1 Wikidata. African trypanosomiasis.
2. 2 Wikipedia. African trypanosomiasis - Wikipedia.

ICD-10

B56

ICD-11

1F52

Total cases

0

Peak month

—

Coverage

0 reporting countries · —