Human African Trypanosomiasis, known as sleeping sickness, is a vector-borne parasitic disease. Trypanosoma which are the parasites are protozoa transmitted to humans by tsetse flies. Tsetse flies live in Africa, and they are found in vegetation by rivers and lakes, gallery-forests and vast stretches of wooded savannah.
Sleeping sickness occurs only in sub-Saharan Africa, in regions where tsetse flies are endemic. There are many regions where tsetse flies are found, but sleeping sickness is not. The rural populations that live in such environments and depend on the flies for agriculture, fishing, animal husbandry or hunting are the most exposed - along with their livestock - to the bite of the tsetse fly. Sleeping sickness affects remote and rural areas where health systems are least effective, or non-existent. It spreads with socio-economic problems such as political instability, displacement of populations, war and poverty. .
Human African trypanosomiasis takes two forms, depending on the parasite involved: Trypanosoma brucei gambiense (T.b. gambiense) is found in central and West Africa. A person can be infected for months or even years without obvious symptoms of the disease emerging. When symptoms do emerge, the disease is already at an advanced stage. .
Trypanosoma brucei rhodesiense (T.b. rhodesiense) is found in southern and east Africa. It causes acute infection that emerges after a few weeks. It is more virulent than the other strain and develops more rapidly, which means that it is more quickly detected clinically. .
The disease was first seen in the fourteenth century. A writer named Ibn Khaldoun described in a book he wrote "History of the Berbers" that a Sultan from Mali got a disease that killed him. The description made of the disease has the same symptoms and disorders as this African sleeping sickness (Domergue, 1981).
The distribution of African trypanosomiasis is completely linked to the range of its vector, the tsetse fly.