Epidemiology and evolution of zoonotic schistosomiasis in a changing world – Schistosome Hybrids: Epidemiology, Evolution and Prevention (ZELS SHEEP)




Modji Ende12

Schistosoma spp. are the causative agents of schistosomiasis, a chronic and debilitating helminthic disease of humans and animals mainly prevalent across much of the developing world. Schistosomiasis infects >240 million people with >750 million at risk of infection, >90% of which are within sub Saharan Africa (SSA). Schistosomiasis is also of substantial veterinary importance, with millions of livestock infected worldwide and wild animals as significant zoonotic reservoir hosts. Recent environmental and anthropogenic changes, such as such as dam constructions, altered agricultural practices and/or mass drug administration programs, are exacerbating opportunities for mixing and subsequent hybridization between human and animal schistosomes, which is likely to have a substantial impact on the epidemiology, evolution and clinical outcomes of the disease, with further challenges and constraints for effective control. Working within a One Health framework, the aim of our ZELS project is to understand the complex dynamics of zoonotic hybrid schistosomiasis transmission in two West African countries, Senegal and Niger. Extensive parasite sampling in humans, livestock, wildlife and snail intermediate hosts and the application of novel molecular and diagnostic tools, as well as mathematical modeling and socio-economic surveys, are being used to elucidate the epidemiology of novel zoonotic hybrid schistosomes and its impact on host spectrum, PZQ efficacy, host morbidity and ultimately transmission potential. By so doing, we will inform and contribute to sustainable control and development strategies for those living in areas being impacted by environmental change.


Our research contributes to the major push to control and eliminate schistosomiasis as a public health problem as set by the WHO NTD roadmap and the London Declaration of the NTD coalition, which pledge to contribute towards the control or elimination of schistosomiasis by the end of the decade. It is essential to discover fully the extent of schistosome zoonotic infections as this may influence progress in reducing transmission in many regions of West Africa in addition to Niger and Senegal. In collaboration with our African partner institutions, this research also develops, optimizes and applies methodologies for improved diagnostics and genetic analyses of zoonotic hybrid schistosomes in SSA. The results produced are fed directly back into policy, including international WHO guidelines and national control programmes, in order to improve human and livestock health, welfare and hence livelihoods the poorest countries in the world.

Our objective is a better understanding of the evolution, ecology and transmission dynamics of this potentially emerging disease threat, of paramount important to the health of humans and their livestock, particularly amongst the poorest of the poor. More generally this research will enhance our understanding of a wide spectrum of multi-host parasitic diseases of humans and animals, and in particular the role of evolution of host ranges and introgressions within major taxonomic groups, in our rapidly changing world.



The outcomes of this study could substantially contribute to change international policy on disease control and knowledge, modifying attitudes and practice of those inflicted with the threat of this disease. Pressure will be placed for the implementation of modified praziquantel treatment regimes for people and animals living in zoonotic high transmission zones with the application of a One Health framework for schistosomiasis control. A full appreciation of the interactions taking place between schistosomes of humans and animals will provide decision-makers and health services at both national and community levels with improved tools to targeted interventions.


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