A miracidium is a larval stage of a liver fluke. The liver fluke is a parasitic flatworm that infects the liver of various mammals, including humans. The life cycle of the liver fluke involves several stages, including the miracidium, which is released from the eggs of the fluke and infects a snail intermediate host. After undergoing several more developmental stages in the snail, the fluke is released as a cercariae, which can infect the final host, such as a cow or a human, by penetrating the skin or being ingested.