The threat of schistosomiasis,which affects 800 milli on people, with 200 milli on infected [1] and a global burden of 3.3 million disability-adjusted life years (DALYs) [2], remains unchanged despite large-scale,long-term repeated treatments using the highly effective drug praziquantel. However,humans in endemic areas acquire at least partial protection naturally [3] and injection of mice with irradiated schistosome cercariae (the in fective parasite stage) consistently induces >80% protection against infection [4], supporting the idea that it should be possible to stimulate protective responses through immunization. A vaccination programme integrated with chemotherapy [5] could lower host para site loads and aid the move toward transmission control