The Fasciola hepatica, commonly known as the liver fluke, is a parasitic flatworm of the class Trematoda, phylum Platyhelminthes that infects the hepatic bile ducts of sheep and cattle, sometimes also humans, causing fascioliasis. Its intermediate host is a snail, such as Limnea truncatula, in which the parasite can reproduce asexually. The snails are induced by the parasite to vomit the parasites, which are then consumed by ants. Infertile parasites then modify the behavior of the ant, so that they remain at the tips of grass stalks, where they are consumed by ruminants.

In the United Kingdom, Fasciola hepatica is an occasional cause of disease in ruminants - this is most common between March and December. Cattle and sheep are infected when they consume the infectious stage of the parasite from low-lying, marshy pasture. The effects of liver fluke are referred to as fascioliasis, and include anaemia, weight loss and sub-mandibular oedema. Diarrhoea is only an occasional consequence of liver fluke. Liver fluke is diagnosed by yellow-white eggs in the faeces.

A serious consequence of the liver damage caused by fascioliasis is that latent Clostridium novyi spores can be activated by the low oxygen conditions in the damaged tracts the parasite forms in the liver - this can lead to "black disease", caused by Clostridium novyi type B or immune-mediated haemolytic anaemia (IMHA) leading to haemoglobinuria caused by Clostridium novyi type D.

Parasites | Flatworms

فاشيولا كبدية | Großer Leberegel | Douve du foie | Motylica wątrobowa