page_title: Fasciola hepatica
section_title: Parasitic adaptations
hierarchical_section_title: Fasciola hepatica / Parasitic adaptations
caption_attribution_description: Free cercaria in water and cysts attached to the grass
context_page_description: Fasciola hepatica, also known as the common liver fluke or sheep liver fluke, is a parasitic trematode of the class Trematoda, phylum Platyhelminthes. It infects the livers of various mammals, including humans. The disease caused by the fluke is called fasciolosis or fascioliasis, which is a type of helminthiasis and has been classified as a neglected tropical disease. Fasciolosis is currently classified as a plant/food-borne trematode infection, often acquired through eating the parasite's metacercariae encysted on plants. F. hepatica, which is distributed worldwide, has been known as an important parasite of sheep and cattle for decades and causes significant economic losses in these livestock species, up to £23 million in the UK alone. Because of its relatively large size and economic importance, it has been the subject of many scientific investigations and may be the best-known of any trematode species. F. hepatica's closest relative is Fasciola gigantica. These two flukes are sister species; they share many morphological features and can mate with each other.
context_section_description: F. hepatica's tegument protects it from the enzymes of the host's digestive system, whilst still allowing water to pass through. Free-swimming larvae have cilia and the cercariae have a flagellum-like tail to help them swim through the aquatic environment and also allow them to reach the plants on which they form a cyst. To attach within the host, F. hepatica has oral suckers and body spines. Their pharynges also help them to suck onto the tissues within the body, particularly within the bile ducts. The adult fluke's respiration is anaerobic; this is ideal, as no oxygen is available in the liver. F. hepatica is adapted to produce a large number of eggs, which increases its chances of survival, as many eggs are destroyed on release into the environment. Also, F. hepatica is hermaphrodite, thus all flukes can produce eggs, increasing the number of offspring produced by the population.
  The genome for F. hepatica was published in 2015. At 1.3 Gb, its genome is one of the largest known pathogen genomes. The genome contains many polymorphisms, and this represents the potential for the fluke to evolve and rapidly adapt to changes in the environment, such as host availability and drug or vaccine interventions.
caption: The left image shows the free-swimming cercariae, the flagella is clearly visible. The right side of the diagram shows the cysts attached to grass.
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