Summary

• Infection by extracellular protozoan parasites, transmitted through the bite of an infected tsetse fly (Glossina).
• Two forms of the disease exist, caused by 2 different subspecies of Trypanosoma brucei: T b gambiense occurs in central and west Africa and causes the chronic disease form; T b rhodesiense occurs in east and southern Africa and causes the acute form.
• Two disease stages can be distinguished: the first or early stage (haemolymphatic), in which parasites are located in the blood, lymph, and peripheral organs; and the second, late, or advanced stage (meningoencephalitic), in which parasites have crossed the blood-brain barrier and invaded the central nervous system. Signs and symptoms vary according to the disease stage.
• In T b gambiense-endemic regions, the card agglutination test for trypanosomiasis is used for population screening.
• Definite diagnosis is based on microscopic evidence of the trypanosome in body fluids. Disease staging is based on CSF examination.
• Treatment depends on parasite subspecies and disease stage, but all drugs can have severe side effects and are complex to use. The disease is fatal without treatment.