Digenea is a class of trematodes in the Platyhelminthes phylum, consisting of parasitic flatworms with a syncytial tegument and, usually, two suckers, one ventral and one oral. Adults commonly live within the digestive tract, but occur throughout the organ systems of all classes of vertebrates. Once thought to be related to the Monogenea, it is now recognised that they are closest to the Aspidogastrea and that the Monogenea are more closely allied with the Cestoda. Around 6,000 species have been described to date.
Clonorchiasis is an infectious disease caused by the Chinese liver fluke and two related species. Clonorchiasis is a known risk factor for the development of cholangiocarcinoma, a neoplasm of the biliary system.
Opisthorchis viverrini, common name Southeast Asian liver fluke, is a food-borne trematode parasite from the family Opisthorchiidae that infects the bile duct. People are infected after eating raw or undercooked fish. Infection with the parasite is called opisthorchiasis. O. viverrini infection also increases the risk of cholangiocarcinoma, a cancer of the bile ducts.
The thorny-headed worm family Polymorphidae contains endoparasites which as adults feed mainly in fish and aquatic birds. When this taxon was erected by Meyer in 1931, a subfamily Polymorphinae was established in it. As the Polymorphidae as presently understood would then be monotypic, with no basal genera outside the Polymorphinae, the proposed subfamily is redundant for the time being and therefore most modern treatments simply omit it. Polymorphus minutus is an economically significant parasite in goose and duck farming.
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few significant parasites of humans.
Psilostomatidae is a family of trematodes in the order Plagiorchiida. They parasitise aquatic vertebrates as definitive hosts.
Opisthorchis is a genus of flukes in the family Opisthorchiidae.
Heterophyidae is a family of intestinal trematodes in the order Plagiorchiida.
Bucephalidae is a family of trematodes that parasitize fish. They lack suckers, having instead a muscular organ called a "rhynchus" at the front end which they use to attach to their hosts. The characteristics of the rhynchus are used to help define the genera of the family. It is one of the largest digenean families, with 25 genera containing hundreds of described species. Bucephalids are cosmopolitan, having been recorded all over the world. They are parasites of fish from freshwater, marine, and brackish water habitat types.
Opecoelidae is a family of trematodes. It is the largest digenean family with over 90 genera and nearly 900 species, almost solely found in marine and freshwater teleost fishes. It was considered by Bray et al. to belong in the superfamily Opecoeloidea Ozaki, 1925 or the Brachycladioidea Odhner, 1905.
Telorchiidae is a family of trematode parasites.
Coitocaecum is a genus of trematodes in the family Opecoelidae. It has been synonymised to Ozakia Wisniewski, 1934, Paradactylostomum Zhukov, 1972 nec Toman, 1992, and Pseudocoitocaecum Bilqees, 1972.
Caudotestis is a genus of trematodes in the family Opecoelidae.
Echinostomatidae is a family of trematodes in the order Plagiorchiida, first described in 1899.
Cryptogonimidae is a family of trematodes belonging to the order Plagiorchiida.
Derogenidae is a family of trematodes belonging to the order Plagiorchiida.
Hemiuridae is a family of trematodes belonging to the order Plagiorchiida containing 514 described species.
Prosthogonimus is a genus of trematodes belonging to the family Prosthogonimidae.
Halipegus is a genus of trematode in the family Derogenidae.
Echinostomatinae is a subfamily of trematodes in the order Plagiorchiida, first described in 1899.
