DiscussionSchistosomiasis (or Bilharzia), is a serious disease of humans and animals caused by schistosome parasitic worms, inflicting suffering on poor rural communities in many parts of the developing world, with the greatest burden within sub-Saharan Africa. Schistosomes are transmitted through eggs passed in stool or urine, depending on the parasite species, which then infect snails in freshwater. The mammalian definitive host, be it human, livestock and/or wildlife, becomes infected when entering freshwater containing infected snail intermediate hosts. Anthropogenic change, through natural phenomena or human interventions such as dam constructions, changes in agricultural practices or drug treatments, impact the dynamics and distribution of this disease, with subsequent effects upon human and animal health. Such changes can increase opportunities for schistosome species of both humans and animals to be found in the same geographical area and in the same host type. Furthermore, human and animal schistosomes can pair to produce viable zoonotic hybrid infections, which can subsequently infect both humans and their animals. Focusing within Niger and Senegal, we are performing research to elucidate for the first time how common these hybrid schistosomes are in humans and animals, what harm they might do to their hosts, how easily they might spread, how they respond to drug treatment, and ultimately how we can control and prevent them.