What is Sleeping Sickness?

Sleeping sickness or human African trypanosomiasis (HAT) is endemic in 36 African countries and around 10.8 million people are at medium to high risk of being infected. Sleeping sickness is transmitted by the tsetse fly and is usually fatal without treatment. Up until 2009, existing treatments for stage 2 of the disease were toxic or difficult to administer. In 2009, DNDi and its partners launched the NECT, the first new treatment for sleeping sickness in 25 years. At the end 2018, fexinidazole, the first all-oral treatment developed by DNDi and partners was recommended by the European Medicines Agency.


65 million people at risk
10.8 million people estimated to live in areas at  moderate to very high risk

Usually fatal if left untreated
Displacement of populations, war, and poverty lead to increased transmission, with severe social and economic consequences
Some areas are still not covered by surveillance and control efforts

Large proportions of communities can be affected by human African trypanosomiasis – also known as sleeping sickness – with serious social and economic consequences. Epidemics at the end of the 20th century infected up to 50% of the population in several villages across rural Africa.


Of the 36 countries considered endemic for sleeping sickness, the seven most affected countries represent 98% of all reported cases (see map). The Democratic Republic of Congo accounted for 84% of all reported cases in 2015. Sleeping sickness primarily occurs in the poorest, most rural areas in Africa, where difficulty of diagnosis, political instability, and lack of health surveillance make estimates of disease prevalence difficult to ascertain.


Transmitted by the parasite Trypanosoma brucei (T. b.) to humans by tsetse flies, sleeping sickness is caused by two sub-species of the kinetoplastid protozoan parasite: T. b. gambiense (West and Central Africa), T. b. rhodesiense (East Africa).


Sleeping sickness occurs in two stages:

  • Stage 1 – The haemolymphatic phase – includes non-specific symptoms like headaches and bouts of fever (generally goes undiagnosed without active sleeping sickness surveillance).
  • Stage 2 – The later, neurologic phase – occurs when the parasite crosses the blood-brain barrier (BBB) and can lead to serious sleep cycle disruptions, paralysis, progressive mental deterioration, and, ultimately, results in death without effective treatment.

Patient treatment needs

A safe, effective, and orally administered stage 2 treatment is needed that improves and simplifies current case management. This drug should ideally work in both stages of the disease.

DNDi aims to:

  • Complete the development and register two drugs that are effective against both stages of the disease and both subspecies of the parasite (Trypanosoma brucei gambiense (g-HAT) and Trypanosoma brucei rhodesiense (r-HAT).



Sleeping Sickness factsheet

Disease brief

Newer, better treatments for sleeping sickness
An update on DNDi R&D programmes

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