Health economic evaluation of strategies to eliminate gambiense human African trypanosomiasis in the Mandoul disease focus of Chad

Human African trypanosomiasis, caused by the gambiense subspecies of Trypanosoma brucei (gHAT), is a deadly parasitic disease transmitted by tsetse. Partners from around the world have stepped up efforts to eliminate the disease, and the Chadian government have had a particular focus on the previously high-prevalence setting of Mandoul. In this study, we evaluate the economic efficiency of the intensified strategies that were put in place from 2014 aimed at interrupting transmission of gHAT, and we make recommendations on the best way forward based on both epidemiological projections and cost-effectiveness. In our analysis we use a dynamic transmission model fit to epidemiological data from Mandoul to evaluate the cost-effectiveness of combinations of active screening, improved passive screening (defined as an expansion of the number of health posts capable of screening for gHAT), and vector control activities (the deployment of Tiny Targets). For cost-effectiveness analyses, our primary outcome is disease burden, denominated in disability-adjusted life-years (DALYs), and costs, denominated in 2020 US$. Although active and passive screening have enabled more rapid diagnosis and accessible treatment in Mandoul, the addition of vector control provided good value-for-money (at less than $750/DALY averted) and substantially increased the probability of reaching the 2030 elimination target for gHAT as set by the World Health Organization. Our transmission modelling and economic evaluations suggests that the gains have been made could be maintained by robust passive screening, and the inclusion of active screening and vector control strategies could be considered for other foci in the country with active transmission. Our analysis speaks to comparative efficiency, and it does not take into account all possible considerations; for instance, any cessation of on-going active screening should first consider that strong surveillance activities will be critical to verify elimination of transmission and to protect against the possible importation of infection from neighbouring endemic foci. Author summary In a drive to eliminate human African trypanosomiasis (gHAT or sleeping sickness) from Chad following a peak in 2002, the National Sleeping Sickness Control programme and their partners focused on making substantial changes to interventions within the high prevalence setting of Mandoul. These included the use of vector control starting in 2014 and improved screening in health facilities starting in 2015. To explore whether these interventions were an efficient use of resources we carried out a retrospective analysis using a dynamic transmission model fit to epidemiological data from Mandoul combined with a cost model. Our analysis indicated that active and passive screening have enabled more rapid diagnosis and accessible treatment in Mandoul compared to less ambitious interventions, and furthermore the addition of vector control provided good value-for-money and substantially increased the probability of reaching the 2030 elimination of transmission target for gHAT set by the World Health Organization. Looking forwards, our prospective analysis also considers the health economics of future strategies and, as part of this, concludes that the scaleback of vertical interventions appears cost-effective if passive screening remains robust in Mandoul. This could therefore enable shifting of resources to tackle other remaining foci in Chad. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was supported by the Bill and Melinda Gates Foundation (www.gatesfoundation.org) through the Human African Trypanosomiasis Modelling and Economic Predictions for Policy (HAT-MEPP) project \[OPP1177824 and INV-005121\] (MA, CH, SAS, REC, PEB, XWS, EHC, KSR, and FT) and the Trypa-NO! project \[INV-008412 and INV-001785\] (PRB, AP, AS, PS and IT). The funders of the study had no role in study design, data collection, data analysis, data interpretation, or writing of the report. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. 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