Opisthorchis: A genus of trematode liver flukes of the family Opisthorchidae. It consists of the following species: O. felineus, O. noverca (Amphimerus noverca), and O. viverrini. The intermediate hosts are snails, fish, and AMPHIBIANS.Opisthorchiasis: Infection with flukes of the genus Opisthorchis.LaosMetacercariae: Encysted cercaria which house the intermediate stages of trematode parasites in tissues of an intermediate host.Thailand: Formerly known as Siam, this is a Southeast Asian nation at the center of the Indochina peninsula. Bangkok is the capital city.Food Parasitology: The presence of parasites in food and food products. For the presence of bacteria, viruses, and fungi in food, FOOD MICROBIOLOGY is available.Clonorchis sinensis: A species of trematode flukes of the family Opisthorchidae. Many authorities consider this genus belonging to Opisthorchis. It is common in China and other Asiatic countries. Snails and fish are the intermediate hosts.Cholangiocarcinoma: A malignant tumor arising from the epithelium of the BILE DUCTS.Trematode Infections: Infections caused by infestation with worms of the class Trematoda.Cyprinidae: A family of freshwater fish comprising the minnows or CARPS.Bile Ducts, Intrahepatic: Passages within the liver for the conveyance of bile. Includes right and left hepatic ducts even though these may join outside the liver to form the common hepatic duct.Bile Duct Neoplasms: Tumors or cancer of the BILE DUCTS.Cathepsin F: A lysosomal papain-related cysteine proteinase that is expressed in a broad variety of cell types.Trematoda: Class of parasitic flukes consisting of three subclasses, Monogenea, Aspidogastrea, and Digenea. The digenetic trematodes are the only ones found in man. They are endoparasites and require two hosts to complete their life cycle.Fasciola hepatica: A species of helminth commonly called the sheep liver fluke. It occurs in the biliary passages, liver, and gallbladder during various stages of development. Snails and aquatic vegetation are the intermediate hosts. Occasionally seen in man, it is most common in sheep and cattle.Clonorchiasis: Infection of the biliary passages with CLONORCHIS SINENSIS, also called Opisthorchis sinensis. It may lead to inflammation of the biliary tract, proliferation of biliary epithelium, progressive portal fibrosis, and sometimes bile duct carcinoma. Extension to the liver may lead to fatty changes and cirrhosis. (From Dorland, 27th ed)Heterophyidae: A family of intestinal flukes of the class Trematoda which occurs in animals and man. Some of the genera are Heterophyes, Metagonimus, Cryptocotyle, Stellantchasmus, and Euryhelmis.Helminth Proteins: Proteins found in any species of helminth.Asia, Southeastern: The geographical area of Asia comprising BORNEO; BRUNEI; CAMBODIA; INDONESIA; LAOS; MALAYSIA; the MEKONG VALLEY; MYANMAR (formerly Burma), the PHILIPPINES; SINGAPORE; THAILAND; and VIETNAM.Cypriniformes: An order of fish with 26 families and over 3,000 species. This order includes the families CYPRINIDAE (minnows and CARPS), Cobitidae (loaches), and Catostomidae (suckers).Helminths: Commonly known as parasitic worms, this group includes the ACANTHOCEPHALA; NEMATODA; and PLATYHELMINTHS. Some authors consider certain species of LEECHES that can become temporarily parasitic as helminths.Cercaria: The free-swimming larval forms of parasites found in an intermediate host.Mesocricetus: A genus of the family Muridae having three species. The present domesticated strains were developed from individuals brought from Syria. They are widely used in biomedical research.Fish Diseases: Diseases of freshwater, marine, hatchery or aquarium fish. This term includes diseases of both teleosts (true fish) and elasmobranchs (sharks, rays and skates).Praziquantel: An anthelmintic used in most schistosome and many cestode infestations.Anthelmintics: Agents destructive to parasitic worms. They are used therapeutically in the treatment of HELMINTHIASIS in man and animal.Antibodies, Helminth: Immunoglobulins produced in a response to HELMINTH ANTIGENS.Antigens, Helminth: Any part or derivative of a helminth that elicits an immune reaction. The most commonly seen helminth antigens are those of the schistosomes.Feces: Excrement from the INTESTINES, containing unabsorbed solids, waste products, secretions, and BACTERIA of the DIGESTIVE SYSTEM.