Animation of Schistosoma sp. parasites swimming in fresh water. Schistosoma parasites are the cause of the disease schistosomiasis, or bilharzia. At this stage the parasite is called a cercaria. These cercariae live in fresh water and swim freely in search of human skin. When they contact skin they swiftly burrow into it, entering the bloodstream and migrating to the liver. They mature in the liver before moving to the veins of the intestine, where they release eggs that are passed with faeces. The eggs hatch in water and the resulting miracidia infect water snails, in which they develop into the free_swimming cercariae seen here, completing the life cycle. Schistosomiasis is a prevalent chronic tropical disease that damages organs and impairs growth.