What is Sleeping Sickness?

Sleeping sickness or human African trypanosomiasis (HAT) is endemic in 37 African countries and around 13 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 first new treatment for sleeping sickness in 25 years.


65 million people at risk
13 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 37 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 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.

DNDi aims to deliver:

  • A safe, effective, and orally administered drug to replace current first-line HAT treatments, and to improve and simplify current case management.
  • The ideal goal is to develop two drugs that are effective against both stage 1 and 2 HAT and both subspecies of the parasite.

If successful, this would represent a fundamental shift in disease management, as it would remove the need both for a risky and painful lumbar puncture test to confirm the disease stage, and for hospitalization, as treatment would no longer rely on administering a drug intravenously.

Fact sheet

DNDi Human African Trypanosomiasis Fact Sheet


Sleeping Sickness: The last steps towards innovative oral therapies