An elimination investment case (EIC) for human African trypanosomiasis (HAT) Trypanosoma brucei (T.b.) gambiense ("sleeping sickness")

Abstract

Discoveries related to the peculiar disease of African trypanosomiasis have occurred throughout the centuries. ‘Sleeping Sickness’, the short name for human African trypanosomiasis (HAT), is derived from changes in the sleep-wake pattern seen in HAT patients as the presence of the trypanosoma parasite in the brain causes a slow neurological breakdown. Although major epidemics have been recorded over the past centuries, the number of cases have declined rapidly over the last decade placing HAT in the position of reaching elimination. In 2011, the World Health Organization (WHO) set a range of targets for eradication, elimination, or control of 17 neglected tropical diseases, but it still remains unclear how achievable many of these goals are, and what are the best ways forward. The Swiss Tropical and Public Health Institute (Swiss TPH) was supported to develop EICs for onchocerciasis, lymphatic filariasis (LF), and human African trypanosomiasis (HAT). Unlike filarial parasites that respond well to preventative chemotherapy oral treatments, trypanosoma parasites involve a more complex diagnostic and treatment paradigm. For this reason, a unique approach was taken to developing an EIC for HAT T.b. gambiense. Evidence was collected systematically to address the initial questions posed by the Ernst Struggmann Forum “Eradication Investment Case” (EIC) framework. From this information, potential strategies using current available tools and potential technologies were hypothesized that could be simulated through prospective modelling exercises to evaluate various outcomes. A dynamical model was also developed to simulate HAT T.b. gambiense transmission, and to forecast the impact of current and emerging innovations on the key concerns of the EIC: elimination, costs, health impact, cost-effectiveness, and number of cases. Modelling was also done to simulate household surveys to evaluate the impact of elimination on poverty. In addition a discrete event simulation model evaluated the possibility of integration comparing old and new strategies, while a social justice assessment was undertaken to ascertain which strategies would lead to ethical compromises within potential elimination programs. The EIC results provide various options for stakeholders moving towards HAT elimination, but substantial funds will be required. In addition, trade-offs between cost-effectiveness, social justice and elimination targets in the next few decades will need to be made. Integration is feasible with new technologies and will provide more flexibility to capacity in high risk foci areas, but further exploration of this methods use within an EIC still needs to be explored. The multiple components of the EIC appear suitable for MCDA and this is also a methodological option to consider for future decision making within EICs. Overall, the EIC has proven to be a useful approach that is both technically feasible and informative for deliberations within a disease under review for elimination. It is now recommended that funders use the results to move forward with elimination campaigns.