What is Sleeping Sickness?

Sleeping sickness or Human African Trypanosomiasis (HAT) is endemic in 36 African countries and around 13 million people are at medium to high risk of being infected. HAT 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 first new treatment for HAT in 25 years.



In 2015, there were less than 3,000 new cases
13.1 million people at 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 7 most affected countries represent 97% of all reported cases (see map). The Democratic Republic of Congo accounted for 89% of all reported cases in 2013. 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.


Fact sheet

DNDi Human African Trypanosomiasis Fact Sheet




WHO Fact Sheets, 2016
Distribution of HAT worldwide, WHO 2013