51 - Human African Trypanosomiasis

Abstract

Human African trypanosomiasis (HAT) is a parasitic disease caused by Trypanosoma brucei gambiense or T.b. rhodesiense, transmitted by tsetse flies (Glossina spp.). HAT has a prominent history as it received major attention by the colonial administrations because it hampered utilization of whole regions. This resulted in a decrease from over 100 000 cases per year around 1900 to 4435 cases by 1964. However, by 1998, the disease had resurged after failure of the public health systems to 40 000 reported plus over 300 000 estimated cases. After significant efforts made by the World Health Organization (WHO) and partners, the number of reported new HAT cases dropped by 97%. The WHO added HAT to its neglected tropical diseases road map in 2012 and targeted its elimination as a public health problem by 2020 and interruption of transmission (zero cases) by 2030. The development of new, simpler, and better-tolerated treatments, improved diagnostics, and vector control tools are at the basis for this positive development: The toxic compound melarsoprol for treatment of second-stage gambiense HAT could be replaced by nifurtimox-eflornithine combination therapy (NECT) and recently by the oral drug fexinidazole, except for very advanced cases. The treatment-related mortality rate consequently dropped from 5% with melarsoprol to around 0.5%. A single-dose oral treatment, acoziborole, has completed Phase III trials and may further revolutionize HAT treatment. Unfortunately, the situation remains far gloomier for rhodesiense HAT, which still has to be treated with the abridged regimen for melarsoprol. In addition to active and passive case finding and treatment of infected individuals, targeted vector control plays a decisive role in the elimination of HAT. It benefited from the recent development of so-called ‘tiny targets’, smaller-size horizontal traps impregnated with insecticide that facilitates distribution and maintenance and maximizes cost-efficiency.