Stool survey and egg isolation
All stools samples collected from participants were weighed, and single slides prepared as previously described (Katz et al., 1972). On the following day, the slides were read, and the number of schistosome eggs per gram and the presence of other helminths were recorded. Stools positive for S . mansoni were homogenized in a blender with 200 mL of 2% saline solution and then processed through a series of metal sieves and nylon filter bags (300 µm - 55 µm mesh pore size, FSI, Michigan City, Indiana, USA) and gravity sedimentation to concentrate the eggs (Dresden and Payne, 1981). The bottom 5 mL of sediment was collected and then kept frozen at -20 °C for DNA extraction. In accordance with Brazilian Ministry of Health guidelines (Ministério da Saúde do Brasil, 2014), participants with one or more egg-positive stools samples were given a one-time dose of praziquantel (60 mg/kg for children 4 to 15 years old and 50 mg/kg for adults), and 4–6 weeks later three follow-up stool examinations were performed on those treated. For other helminthiases a single dose of albendazole was provided (FigureS1).