Human African trypanosomiasis – a neglected disease

Sleeping sickness or human African trypanosomiasis is a widespread tropical disease in sub-Saharan Africa. It is caused by trypanosomes or parasites that are transmitted through the bite of an infected tsetse fly. Two forms of sleeping sickness exist. Uganda is the only country unfortunate to be affected by both; they are caused by two sub-species of the Trypanosoma brucei parasite.

The West African sleeping sickness

This form of the disease is caused by Trypanosoma brucei gambiense, which is found in Central and Western Africa and represents more than 90 % of reported cases of sleeping sickness. It causes a chronic infection and it can takes months or even years before the infected person shows symptoms of the disease. When symptoms do emerge, the patient is often already in an advanced stage of the disease when the central nervous system is affected. Because it is chronic, it is difficult to diagnose in the field. Moreover, low levels of trypanosomes in circulating blood make it difficult to detect the presence of parasites in blood smears, requiring sophisticated means of detecting trypanosomes.

The East African sleeping sickness

Caused by Trypanosoma brucei rhodensiense, it is the acute form of the disease but has a much more limited range (less than 10 % of reported cases of sleeping sickness). Found in Southern and Eastern Africa, infections emerge in the first few weeks following transmission and are far more virulent and faster developing. More than 95% of T.b. rhodensiense cases are reported from Uganda, Tanzania, Malawi, and Zambia.

Some statistics

• 66 million people at risk in 37 countries
• 30,000-50,000 new cases reported per year
• an estimated 300,000-500,000 people are currently affected by the disease
• 48,000 deaths per year
• 1,5 million DALYs* per year

*DALY (Disability Adjusted Life Year) is a measure of societal impact, ie the sum of years of potential life lost due to premature mortality and the years of productive life lost due to disability.