Priority knowledge gaps for schistosomiasis research and development in the World Health Organization Africa Region

Abstract

Schistosomiasis, also known as bilharzia, is a widespread neglected tropical disease (NTD) in Africa, with more significant research and development (R&D) challenges and gaps compared to other preventive chemotherapy NTDs (PC-NTDs) like onchocerciasis, lymphatic filariasis, and trachoma. In response to this challenge, some global initiatives have advocated for bridging this gap, focusing on coordinated engagement with research donors. In this opinion article we highlight key R&D priorities for combating schistosomiasis in the WHO Africa region. These include defining morbidity indicators, expanding prevention, and developing innovative diagnostics, treatments, and public health strategies like test-and-treat. We emphasize integrating efforts with broader health campaigns, assessing zoonotic transmission through One Health, and using environmental surveillance tools like xenomonitoring and eDNA. We stress the need to study climate and environmental impacts on transmission, zoonotic transmission, schistosome hybridization, and snail ecology, advancing snail control, and developing vaccines, while calling for new treatments beyond praziquantel, addressing drug resistance, and improving access for children and remote populations. Further, operational research should refine hotspot interventions, enhance water, sanitation and hygiene integration, and address socio-cultural barriers. Lastly, sustainable funding and global collaboration are vital to achieve 2030 NTD Roadmap goals.

Keywords: Diagnostic tools; Intermediate snail hosts; Mass Drug Administration; Morbidity indicators; Neglected tropical diseases; One Health approach; Preventive chemotherapy; Schistosomiasis; Water, sanitation and hygiene; Zoonotic transmission.

Fig. 1

Phases of schistosomiasis control and elimination programmes. *To be conducted in selected areas (with suspected high transmission of schistosomiasis infection) after at least 2 years of PC, however, there is need to clearly define hotspots currently defined as “an area that demonstrates a < 1/3 reduction in prevalence of Schistosoma spp. infection between an initial survey (with prevalence ≥ 10%) and a follow up survey conducted after at least 2 years of preventive chemotherapy with effective (≥ 75%) treatment coverage” [42]. **After a country has been validated for EPHP, post-validation surveillance is recommended. However, surveillance is also recommended in any implementation unit that has reduced the frequency of PC distribution or achieved the EPHP target. EPHP elimination as public health problem, PC preventive chemotherapy