Mud snails (Galba truncatula) releasing cercariae, larvae of the liver fluke (Fasciola hepatica). The snail is the intermediate host for the liver fluke, and is infected by its free-swimming miracidium stage. Cercaria larvae (white) then emerge from the snail and form cysts known as metacercariae on nearby vegetation. The metacercariae are ingested by a ruminant, or sometimes by humans eating uncooked foods such as watercress. Immature flukes emerge and migrate into the bile ducts where they reach maturity and pass eggs into the host's faeces which contaminate water. The eggs hatch to release miracidia, which infect snails, thus continuing the fluke's life cycle. Fascioliasis is a liver disease caused by liver fluke infection, with symptoms including digestive problems, fever, pain, anaemia and jaundice. Footage filmed at Ridgeway Research, Gloucestershire, United Kingdom.