Metacercariae: Encysted cercaria which house the intermediate stages of trematode parasites in tissues of an intermediate host.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.Trematode Infections: Infections caused by infestation with worms of the class Trematoda.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.Paragonimus: A genus of lung flukes of the family Troglotrematidae infecting humans and animals. This genus consists of several species one of which is PARAGONIMUS WESTERMANI, a common lung fluke in humans.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).Echinostomiasis: Infection by flukes of the genus Echinostoma.Paragonimiasis: Infection with TREMATODA of the genus PARAGONIMUS.Osmeriformes: An order of fish including smelts, galaxiids, and salamanderfish.Echinostoma: A genus of intestinal flukes of the family Echinostomatidae which consists of many species. They occur in man and other vertebrates. The intermediate hosts are frequently mollusks.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.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)Echinostomatidae: A family of flukes (TREMATODA) characterized by a collar of spines at their anterior end. The body is elongated and is covered with spines, and the two suckers are usually close together. (Noble et al., Parasitology: the Biology of Animal Parasites, 6th ed, p183)Korea: Former kingdom, located on Korea Peninsula between Sea of Japan and Yellow Sea on east coast of Asia. In 1948, the kingdom ceased and two independent countries were formed, divided by the 38th parallel.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).LaosFishes: A group of cold-blooded, aquatic vertebrates having gills, fins, a cartilaginous or bony endoskeleton, and elongated bodies covered with scales.Fresh Water: Water containing no significant amounts of salts, such as water from RIVERS and LAKES.Brachyura: An infraorder of chiefly marine, largely carnivorous CRUSTACEA, in the order DECAPODA, including the genera Cancer, Uca, and Callinectes.Paragonimus westermani: A species of lung fluke infecting humans and other animals, and found chiefly in Asia and the Far East.Host-Parasite Interactions: The relationship between an invertebrate and another organism (the host), one of which lives at the expense of the other. Traditionally excluded from definition of parasites are pathogenic BACTERIA; FUNGI; VIRUSES; and PLANTS; though they may live parasitically.Cyprinidae: A family of freshwater fish comprising the minnows or CARPS.Life Cycle Stages: The continuous sequence of changes undergone by living organisms during the post-embryonic developmental process, such as metamorphosis in insects and amphibians. This includes the developmental stages of apicomplexans such as the malarial parasite, PLASMODIUM FALCIPARUM.Fascioliasis: Liver disease caused by infections with parasitic flukes of the genus FASCIOLA, such as FASCIOLA HEPATICA.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.Intestinal Diseases, Parasitic: Infections of the INTESTINES with PARASITES, commonly involving PARASITIC WORMS. Infections with roundworms (NEMATODE INFECTIONS) and tapeworms (CESTODE INFECTIONS) are also known as HELMINTHIASIS.Snails: Marine, freshwater, or terrestrial mollusks of the class Gastropoda. Most have an enclosing spiral shell, and several genera harbor parasites pathogenic to man.Ostreidae: A family of marine mollusks in the class BIVALVIA, commonly known as oysters. They have a rough irregular shell closed by a single adductor muscle.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.Eye Infections, Parasitic: Mild to severe infections of the eye and its adjacent structures (adnexa) by adult or larval protozoan or metazoan parasites.Perciformes: The most diversified of all fish orders and the largest vertebrate order. It includes many of the commonly known fish such as porgies, croakers, sunfishes, dolphin fish, mackerels, TUNA, etc.Aquaculture: Cultivation of natural faunal resources of water. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Helminthiasis, Animal: Infestation of animals with parasitic worms of the helminth class. The infestation may be experimental or veterinary.Rivers: Large natural streams of FRESH WATER formed by converging tributaries and which empty into a body of water (lake or ocean).Metamorphosis, Biological: Profound physical changes during maturation of living organisms from the immature forms to the adult forms, such as from TADPOLES to frogs; caterpillars to BUTTERFLIES.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.Parasite Egg Count: Determination of parasite eggs in feces.Smegmamorpha: Group of fish under the superorder Acanthopterygii, separate from the PERCIFORMES, which includes swamp eels, mullets, sticklebacks, seahorses, spiny eels, rainbowfishes, and KILLIFISHES. The name is derived from the six taxa which comprise the group. (From http://www.nanfa.org/articles/Elassoma/elassoma.htm, 8/4/2000)Cichlids: Common name for perch-like fish of the family Cichlidae, belonging to the suborder Labroidei, order PERCIFORMES.AnguillaParasite Load: Measure of the number of the PARASITES present in a host organism.Flatfishes: Common name for the order Pleuronectiformes. A very distinctive group in that during development they become asymmetrical, i.e., one eye migrates to lie adjacent to the other. They swim on the eyeless side. FLOUNDER, sole, and turbot, along with several others, are included in this order.Larva: Wormlike or grublike stage, following the egg in the life cycle of insects, worms, and other metamorphosing animals.Refrigeration: The mechanical process of cooling.Astacoidea: A superfamily of various freshwater CRUSTACEA, in the infraorder Astacidea, comprising the crayfish. Common genera include Astacus and Procambarus. Crayfish resemble lobsters, but are usually much smaller.Bivalvia: A class in the phylum MOLLUSCA comprised of mussels; clams; OYSTERS; COCKLES; and SCALLOPS. They are characterized by a bilaterally symmetrical hinged shell and a muscular foot used for burrowing and anchoring.Liver Diseases, Parasitic: Liver diseases caused by infections with PARASITES, such as tapeworms (CESTODA) and flukes (TREMATODA).VietnamPrevalence: The total number of cases of a given disease in a specified population at a designated time. It is differentiated from INCIDENCE, which refers to the number of new cases in the population at a given time.Antibodies, Helminth: Immunoglobulins produced in a response to HELMINTH ANTIGENS.CambodiaDisease Reservoirs: Animate or inanimate sources which normally harbor disease-causing organisms and thus serve as potential sources of disease outbreaks. Reservoirs are distinguished from vectors (DISEASE VECTORS) and carriers, which are agents of disease transmission rather than continuing sources of potential disease outbreaks.Zoonoses: Diseases of non-human animals that may be transmitted to HUMANS or may be transmitted from humans to non-human animals.Microscopy: The use of instrumentation and techniques for visualizing material and details that cannot be seen by the unaided eye. It is usually done by enlarging images, transmitted by light or electron beams, with optical or magnetic lenses that magnify the entire image field. With scanning microscopy, images are generated by collecting output from the specimen in a point-by-point fashion, on a magnified scale, as it is scanned by a narrow beam of light or electrons, a laser, a conductive probe, or a topographical probe.Parasitology: The study of parasites and PARASITIC DISEASES.Thailand: Formerly known as Siam, this is a Southeast Asian nation at the center of the Indochina peninsula. Bangkok is the capital city.