Oncomelania are parasite hosts. The source of infection is viable eggs in the patient's feces. Oncomelania are the only intermediate host of schistosomiasis, so they are not a source of infection. Oncomelania snails are molluscs, divided into male and female, amphibious on land and water, and are composed of two parts: the snail shell and the soft body. The front part of the soft body is the head, neck, feet and mantle, and the rear part is the internal organs; those with longitudinal ribs on the surface are called "Ribbed shell snails" have a shell length of about 10 mm and a width of about 4 mm. They live in lakes, swamps or water network areas; those with smooth shell surfaces are "light shelled snails", which are slightly smaller than ribbed shell snails, with a length and width of 6 mm respectively. and 3 mm, more common in hilly areas.