Both F. hepatica and F. gigantica and their hybrids infect the liver tissue of a wide variety of mammals, including humans, in a condition known as fascioliasis.

[3]Fasciola pass through five phases in their life cycle: egg, miracidium, cercaria, metacercaria, and adult fluke.

When these cysts are ingested along with the aquatic plants by a mammalian host, they mature into adult flukes and migrate to the bile ducts.

[9] A wide variety of mammals can be definitive hosts, where Fasciola reach adulthood and reproduce, including pigs, rodents, ruminants, and humans.

[12][13] Evidence of fascioliasis in humans exists dating back to Egyptian mummies that have been found there are with Fasciola eggs.

[17] This is of particular concern in areas where animal waste is used as fertilizer for the cultivation of watercress, as the full life cycle of Fasciola can sustained while contaminating crops intended for human consumption.