Liver Fluke (Fasciola hepatica)

additional information on the generation cycle of Fasciola hepatica.

The larger liver fluke's intermediate host, however, is a water snail, Galba truncatula, a pond snail (Lymnaeidae).

Picture left: Galba truncatula, the larger liver fluke's intermediate host. Source: Orbis Field Guide "Life in Creek and Pond".

The liver fluke's larva hatched from their eggs in the water they infect pond snails (Galba truncatula). This snail has got a yellow-brown shell, the whorls of which are set against each other like stairs.

Inside the snails the miracidia live on nutritients from the snail's blood and reproduce parthenogenetically. Having reached a sufficient number, they leave the snail through its skin and in the water change into the next larval generation, the cercaries. Those produce endurence stages (cystes) on plants standing near the water. In this stage they can endure several weeks even if they fall dry.

Mammals grazing near the mentioned water may be infected by the cercaries, as soon as the cystes' walls are digested. From the terminal host's digestive tract the cercaries move into the liver where they change into adult liver flukes. Those reproduce sexually and afterwards lay eggs. The host animal excretes the eggs into the water, where the miracidia can hatch, the generation cycle is closed.

The larger liver fluke especially is distributed where cattle graze on meadows near the water. Pond snails due to their partly amphibious way of living can survive their home water falling dry remaining dug in the mud.