Human African trypanosomiasis (HAT) is considered a highly promising candidate for elimination within the next decade. This paper argues that the experiential knowledge of frontline health workers will be critical to achieve this goal. Interviews are used to explore the ways in which HAT workers understand, maintain, and adjust their skills amidst global and national challenges. We contrast two cases: South Sudan where HAT expertise is scattered and has been repeatedly rebuilt, and the Democratic Republic of Congo (DRC) where specialised mobile detection teams have pro-actively tested people at risk for almost a century. We describe HAT careers where skills are built through participation in HAT technology trials and screening programmes; in the DRC expertise is also supported through formal rotations in screening teams and HAT referral centres for new health workers. As cases fade, de-skilling is a real threat as awareness of populations and authorities diminishes and previously vertical programmes evolve, re-configuring professional development and career paths and associated opportunities for HAT practice. To avoid repeating the mistakes of the 1960s, when elimination also seemed close at hand, we need to recognise that the 'last mile' of elimination hinges on protecting the fragile expertise of frontline health workers.