Public health challenge of hybridization in urogenital schistosomiasis: New insights and one health perspectives from Malawi.

Abstract

The emergence of hybrid schistosomes resulting from interspecies mating between human and animal Schistosoma species is set to reshape the epidemiology of urogenital schistosomiasis in Malawi. Findings from the hybridization in urogenital schistosomiasis (HUGS) study in Malawi confirm the occurrence and circulation of S. haematobium × S. mattheei in humans, livestock and snails, from exemplar studies in Nsanje and Mangochi districts. Introgressed schistosomes complicate traditional diagnosis with atypical egg morphologies that defy standard microscopic identification, challenge current preventive chemotherapy strategies and raise concerns about long-term performance of mass drug administration considering zoonotic transmission inputs. With the recent completion of the multidisciplinary 4-year HUGS investigation, analysis of data reveals expanded infection risk among adults engaged in water-dependent occupations and highlights shared water bodies as key sites for human-animal-snail contact and hybrid emergence. This new One Health perspective introduces climate-driven ecological shifts, poor livestock management and lack of vector control strategies as circumstances that promote hybrid dispersal and environmental persistence. There is an urgent need to revise national schistosomiasis control strategies in Malawi, with incorporation of appropriate One Health dimensions. Looking ahead, better inclusion of hybrid schistosome surveillance into public health frameworks with intervention target indicators is needed to safeguard disease control gains and prevent future resurgence. This article is part of the Royal Society Science+ meeting issue 'Parasite evolution and impact in action: exploring the importance and control of hybrid schistosomes in Africa and beyond'.