Speakers - 2026

Title: Optimising delivery of interventions for control and elimination of schistosomiasis in senegal: A modelling study

Abstract

Background: Senegal aims to achieve control and elimination of schistosomiasis by 2030, primarily through mass drug administration. However, challenges exist due to discrepancies between available resources and the actual needs for effective intervention, which vary based on the target population, treatment coverage, frequency and prevalence levels. This study uses a schistosomiasis transmission model to identify optimal treatment strategies for achieving control and elimination in Senegal.

Methods: An individual-based stochastic transmission model was calibrated with Senegal-specific demographic and prevalence data from 2003 to 2024. The model simulated the time required to achieve morbidity control (prevalence below 10% in school-aged children (SAC)), and elimination of public health problem (EPHP, prevalence under 1% in heavy intensity of infection in SAC). The current national strategy was compared with several optimized strategies differing in treatment frequency and coverage among preschool-aged children (PSAC), SAC and adults. An economic assessment was conducted using routine program data from the Ministry of Health’s perspective. The optimal treatment strategy was selected based on the shortest time to achieve control and/or elimination, with minimum cost and the least coverage of the target population.

Results: Model projections indicated that the current treatment strategy is unlikely to achieve EPHP within 17 years across all prevalence settings. In moderate-prevalence areas, morbidity control could be achieved within 1 to 13 years, but EPHP would require 10 to beyond 17 years. In high-prevalence settings, both control and EPHP would require beyond 17 years, while in low-prevalence areas, EPHP would take beyond 17 years. The optimal strategy following WHO guidelines, which targets individuals ages 2 years and above at 75% coverage, achieved the shortest timelines across all settings. In low-prevalence areas, annual treatment achieved EPHP within 6 years at USD 8.5M. In moderate-prevalence settings, annual treatment achieved control within 1 to 6 years and EPHP within 7 to 13 years at costs up to USD 17.8M. In high-prevalence areas, biannual treatment achieved control within 4 years at USD 11.5M and EPHP within 6 years at USD 17.0M. The financial cost per individual decreased from USD 1.61 for SAC-only treatment to USD 0.3 when all age groups were targeted.

Conclusion: The findings suggest that Senegal's current strategy requires optimization to meet national and global elimination goals. Expanding treatment to include PSAC and adults, along with increasing treatment frequency to biannual in high-prevalence areas, accelerates progress toward morbidity control and elimination while reducing implementation costs. This highlights the potential for national scale-up and long-term success.