Schistosomiasis, or snail fever, is a parasitic disease, caused by schistosomes, which leads to long-term ill-health and affects millions of people, predominantly across Africa and Asia. In order to reduce the impact of this disease, we have to better understand the complicated life cycle of the parasite and all the creatures that carry and transmit it. This is why we wanted to see whether small mammals (like rats and mice) spread the form of schistosomiasis that affects humans. We trapped 420 rodents in Senegal, West Africa, and tested them for the presence of the parasite. We found that the animals were carrying two separate species of Schistosoma, as well as a hybrid form – the offspring of different types of schistosomes, some affecting humans and some affecting animals. Our data suggest that rodents play an important role in spreading schistosomes in West Africa.