Common Liver Fluke – Life Cycle

Common Liver Fluke (Fasciola hepatica) belong among the internal parasites of mammals and has a complicated life cycle that includes two host species. Adults live in the bile ducts of cattle, sheep and wild game. Only rarely they can be found in human. The fluke eggs are released with the feces of these host species. When eggs get into the water, small ciliate larvae (miracidium) hatches from them. Miracidium penetrates freshwater snails which are Common Liver Fluke´s first temporary hosts. Once inside the snails, the miracidium changes to a sporocyst that in turn asexually produces a greater number of redia. In the same fashion, redia produces cercariae that have movable „tail“ that enables them to exit their temporary host and to swim freely in the water until they find something to hold on, e.g. grass. They attach to it and encyst to create a metacercaria. The metacercaria is covered by hard outer protective layer and is, therefore, able to survive without water. The life cycle is completed when a final host eats infected grass with the metacercaria on it.