Sleeping sickness or African trypanosomiasis is a parasitic disease in humans. Caused by protozoa of the genus Trypanosoma brucei and transmitted by the tsetse fly, the disease is endemic in certain regions of Sub-Saharan Africa, covering about 36 countries and 60 million people. It is estimated that 300,000 - 500,000 people are infected, and about 40,000 die every year. A related disease in cattle, called nagana, is responsible for the death of several million heads of cattle each year.

The early stages of the disease are treated with either suramin or pentamidine. Advanced cases are treated with melarsoprol, or in unresponsive cases, with eflornithine. These drugs, especially melarsoprol, are far from ideal and the treatment regimen is often difficult to enforce. It is for these reasons that new and better drug are urgently needed.