The road to interruption of transmission of Gambiense Human African trypanosomiasis in the Democratic Republic of the Congo, an analysis of 25 years of routine data

IntroductionHuman African Trypanosomiasis (HAT) has caused hundreds of thousands of deaths in the Democratic Republic of the Congo (DRC) as recently as the 1990s. Since then annual incidence has reduced by 98% but the disease is known for its tendency of resurgence. We outlined areas at risk, HAT foci, and assessed trends in HAT infection within these foci. MethodsWe applied methodology developed by WHO to outline areas at risk by period and compared surface areas from 2000-2024. Combining risk areas identified we outlined HAT foci. Within each of these foci we assessed annual numbers of HAT cases and infection rates. ResultsAreas at risk have greatly reduced over the past 25 years, 67% for areas at low risk or above ([≥] 1 per 100,000), 97% for areas at moderate to high risk ([≥] 1 per 10,000). We outlined 15 HAT foci, all of which had been at moderate to high risk at some point in the 25-year period assessed. Three main foci account for over 80% of the total case load. Of those, the focus in the former province of Equateur rapidly declined in the early years of our analysis, while the foci in Kasai and Kwilu started to decline later. Currently 91% of all cases reported are within one of the foci outlined, most (77%) are clustered in the Kwilu focus. DiscussionGreat progress has been made on the road to interruption of HAT transmission in DRC. The epidemic is now concentrated mainly in a few foci. Given these results, the advent of a new single dose oral drug, acoziborole, makes it possible to consider interruption of transmission provided current efforts are sustained. Given the tendency of resurgence it is however imperative to put in place post-elimination surveillance in all foci.