Schistosomiasis also known as Bilharzia is an acute and chronic disease caused by parasitic worms. Transmission occurs when people suffering from schistosomiasis contaminate freshwater sources with their excreta containing parasite eggs, which hatch in water. The larval forms of the parasite – released by freshwater snails – penetrate the skin during contact with infested water. In the body, the larvae develop into adult worms that can cause progressive damage to organs.