Fluke's Life Cycle
A human being can pick up this parasitic organism by eating raw or undercooked fish, usually a carp or a trout, which contains larvae of the parasite. The immature fluke enter man's liver, living there and causing extensive damage and producing eggs, which leave the body with the feces. If some of the fecal material reaches a body of fresh water, such as a lake, the fluke egges hatch into larvae as some of them infect snails, reaching its liver, where they reproduce asexually into another larval stage called cercaria. A single infected snail may release as many as 200,000 cercarial larvae. This second larval stage leaves the snail and burrows into through the scales and skin of a fish. The cercarial larvae form cysts in the fish muscles. The cycle starts all over again when a human being consume raw fish. Thus, all three hosts (snail, fish, and man) are needed to complete a reproducing cycle of the fluke.
Below, schematic view of a parasitic fluke's life cycle
Below, a macrophotography of an adult flukeworm