Several flukes, trematode parasitic flatworms, cause human disease, fascioliasis. They include Fasciola hepatica and Opisthorchis species. The adult worms live in the biliary tract and have a complex life cycle involving freshwater snails, a free-living stage, and freshwater fish. Humans and fish-eating mammals are infected when they eat raw fish or plants that are contaminated by infective metacercaria, such as watercress or water chestnut.
Subjects: Public Health and Epidemiology.