The human blood fluke, Schistosoma mansoni, harbours bacteria throughout the parasite's life cycle.

Symbiotic relationships between invertebrates and bacteria have been extensively described; nevertheless, studies of microbial communities inhabiting parasitic worms remain scarce. Exploring the microbiota associated with helminths responsible for major infectious diseases will inform on parasite biology, host-pathogen interactions, and disease pathophysiology. We investigated the presence of microorganisms inhabiting tissues of the human parasite Schistosoma mansoni. In situ hybridisation using a pan-bacterial 16S rRNA gene probe revealed bacteria colonising key developmental stages that were successfully removed after antibiotic treatment of live parasites. Understanding the composition and function of S. mansoni-associated microbiota may lead to the development of novel microbiome-targeted control strategies.