Nematoda: A class of unsegmented helminths with fundamental bilateral symmetry and secondary triradiate symmetry of the oral and esophageal structures. Many species are parasites.Dracunculoidea: A superfamily of nematodes of the suborder CAMALLANINA. Its organisms possess a poorly developed buccal cavity and a rudimentary esophagus and intestine.Spirurida Infections: Infections with nematodes of the order SPIRURIDA.Strongylida: An order of nematodes of the subclass SECERNENTEA. Characteristics include an H-shaped excretory system with two subventral glands.Ascaridida Infections: Infections with nematodes of the order ASCARIDIDA.Ascaridoidea: A superfamily of polymyarian nematode worms. An important characteristic of this group is the presence of three prominent lips around the mouth of the organism.Oxyuroidea: A superfamily of parasitic nematodes consisting of several genera. ENTEROBIUS, which occurs in humans, and Oxyuris, which occurs in horses, are two of the most common. Other genera are: Skrjabinema, Passalurus, Dermatoxys, and Probstmayria.Air Sacs: Thin-walled sacs or spaces which function as a part of the respiratory system in birds, fishes, insects, and mammals.AnguillaSpiruroidea: A superfamily of parasitic nematodes which requires one or two intermediate arthropod hosts before finally being eaten by the final host. Its organisms occur rarely in man.Ascaridida: An order of nematodes of the subclass SECERNENTEA. Its organisms possess two or three pairs of dorsolateral caudal papillae.Oxyuriasis: Infection with nematodes of the superfamily OXYUROIDEA.Helminthiasis, Animal: Infestation of animals with parasitic worms of the helminth class. The infestation may be experimental or veterinary.Anisakis: A genus of nematodes of the superfamily ASCARIDOIDEA. Its organisms are found in the stomachs of marine animals and birds. Human infection occurs by ingestion of raw fish that contain larvae.Nematode Infections: Infections by nematodes, general or unspecified.Angiostrongylus cantonensis: A species of parasitic nematodes distributed throughout the Pacific islands that infests the lungs of domestic rats. Human infection, caused by consumption of raw slugs and land snails, results in eosinophilic meningitis.Metastrongyloidea: A superfamily of nematodes of the order STRONGYLIDA. Characteristics include a fluid-filled outer layer of cuticle and a reduced mouth and bursa.Tylenchida: An order of nematodes consisting of many species which are plant parasites. Female worms lay eggs that hatch either in soil or in the host plant.Anisakiasis: Infection with roundworms of the genus ANISAKIS. Human infection results from the consumption of fish harboring roundworm larvae. The worms may cause acute NAUSEA; VOMITING; or penetrate into the wall of the DIGESTIVE TRACT where they give rise to EOSINOPHILIC GRANULOMA in the STOMACH; INTESTINES; or the OMENTUM.Paleopathology: The study of disease in prehistoric times as revealed in bones, mummies, and archaeologic artifacts.Atelidae: A family of New World Monkeys in the infraorder PLATYRRHINI, comprising two subfamilies: ALOUATTINAE and ATELINAE.DNA, Helminth: Deoxyribonucleic acid that makes up the genetic material of helminths.Rhabditida: An order of nematodes of the subclass SECERNENTEA. Its organisms are characterized by an annulated or smooth cuticle and the absence of caudal glands.Genome, Helminth: The genetic complement of a helminth (HELMINTHS) as represented in its DNA.Oesophagostomum: A genus of nematodes of the superfamily STRONGYLOIDEA, parasitic in the intestines of animals. The adults are usually free in the intestinal lumen; the larvae encyst in the wall.Mansonelliasis: Infection with nematodes of the genus MANSONELLA. Symptoms include pruritus, headache, and articular swelling.Setariasis: Infection with nematodes of the genus Setaria. This condition is usually seen in cattle and equines and is of little pathogenic significance, although migration of the worm to the eye may lead to blindness.Setaria Nematode: A genus of parasitic nematodes found in the peritoneal cavity of wild or domestic cattle or equines.Cestoda: A subclass of segmented worms comprising the tapeworms.Mermithoidea: A superfamily of nematodes of the order ENOPLIDA. Characteristics include a reduced alimentary tract and the presence of a trophosome. Its organisms can be present in the human intestine through ingestion of unwashed or contaminated raw vegetables.Murinae: A subfamily in the family MURIDAE, comprising the Old World MICE and RATS.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).Enoplida Infections: Infections with nematodes of the order ENOPLIDA.Rivers: Large natural streams of FRESH WATER formed by converging tributaries and which empty into a body of water (lake or ocean).Mansonella: A genus of parasitic nematodes whose organisms are distributed in Central and South America. Characteristics include a smooth cuticle and an enlarged anterior end.Ascaridia: A genus of nematode worms in the superfamily Heterakoidea. A. galli and A. lineata are important intestinal parasites of domestic fowl.Trichostrongyloidea: A superfamily of nematodes. Most are intestinal parasites of ruminants and accidentally in humans. This superfamily includes seven genera: DICTYOCAULUS; HAEMONCHUS; Cooperia, OSTERTAGIA; Nematodirus, TRICHOSTRONGYLUS; and Hyostrongylus.Tardigrada: A phylum of microscopic ecdysozoan invertebrates, closely related to ARTHROPODS. Members exhibit anabiosis and cryptobiosis, dormant states where metabolic activity is reduced or absent, thus making them tolerant to extreme environmental conditions. They are distributed worldwide and most are semi-aquatic.Oesophagostomiasis: Infection of the intestinal tract with worms of the genus OESOPHAGOSTOMUM. This condition occurs mainly in animals other than man.Strongylida Infections: Infections with nematodes of the order STRONGYLIDA.Filarioidea: A superfamily of nematodes of the suborder SPIRURINA. Its organisms possess a filiform body and a mouth surrounded by papillae.ArgentinaMuscle, Striated: One of two types of muscle in the body, characterized by the array of bands observed under microscope. Striated muscles can be divided into two subtypes: the CARDIAC MUSCLE and the SKELETAL MUSCLE.Trichostrongylus: A genus of parasitic nematodes found in the digestive tract of herbivorous animals. They cause incidental infections in humans from the following species: Trichostrongylus colubriformis, T. orientalis, T. axei, and T. probolurus.Heligmosomatoidea: A superfamily of parasitic nematodes which were formerly considered a part of TRICHOSTRONGYLOIDEA. It includes the following genera: Heligmosomum, NEMATOSPIROIDES, and NIPPOSTRONGYLUS. The hosts are rodents.Rodent Diseases: Diseases of rodents of the order RODENTIA. This term includes diseases of Sciuridae (squirrels), Geomyidae (gophers), Heteromyidae (pouched mice), Castoridae (beavers), Cricetidae (rats and mice), Muridae (Old World rats and mice), Erethizontidae (porcupines), and Caviidae (guinea pigs).Fishes: A group of cold-blooded, aquatic vertebrates having gills, fins, a cartilaginous or bony endoskeleton, and elongated bodies covered with scales.Gnathostoma: A genus of parasitic nematodes that occurs in mammals including man. Infection in humans is either by larvae penetrating the skin or by ingestion of uncooked fish.Larva: Wormlike or grublike stage, following the egg in the life cycle of insects, worms, and other metamorphosing animals.BrazilTrichinella spiralis: A parasite of carnivorous mammals that causes TRICHINELLOSIS. It is especially common in rats and in swine fed uncooked garbage. Human infection is initiated by the consumption of raw or insufficiently cooked pork or other meat containing the encysted larvae.Antinematodal Agents: Substances used in the treatment or control of nematode infestations. They are used also in veterinary practice.Parasites: Invertebrate organisms that live on or in another organism (the host), and benefit at the expense of the other. Traditionally excluded from definition of parasites are pathogenic BACTERIA; FUNGI; VIRUSES; and PLANTS; though they may live parasitically.Ascaris suum: A species of parasitic nematode usually found in domestic pigs and a few other animals. Human infection can also occur, presumably as result of handling pig manure, and can lead to intestinal obstruction.Cyprinidae: A family of freshwater fish comprising the minnows or CARPS.Caenorhabditis: A genus of small free-living nematodes. Two species, CAENORHABDITIS ELEGANS and C. briggsae are much used in studies of genetics, development, aging, muscle chemistry, and neuroanatomy.Invertebrates: Animals that have no spinal column.Nematospiroides dubius: A species of intestinal nematode parasites which occur most commonly in mice. Infection is by ingesting larvae. This particular species is used extensively in immunological research.Genome, Mitochondrial: The genetic complement of MITOCHONDRIA as represented in their DNA.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Crustacea: A large subphylum of mostly marine ARTHROPODS containing over 42,000 species. They include familiar arthropods such as lobsters (NEPHROPIDAE), crabs (BRACHYURA), shrimp (PENAEIDAE), and barnacles (THORACICA).Fresh Water: Water containing no significant amounts of salts, such as water from RIVERS and LAKES.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.Microscopy, Electron, Scanning: Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.Helminth Proteins: Proteins found in any species of helminth.DNA, Ribosomal Spacer: The intergenic DNA segments that are between the ribosomal RNA genes (internal transcribed spacers) and between the tandemly repeated units of rDNA (external transcribed spacers and nontranscribed spacers).Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Biological Evolution: The process of cumulative change over successive generations through which organisms acquire their distinguishing morphological and physiological characteristics.Species Specificity: The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Evolution, Molecular: The process of cumulative change at the level of DNA; RNA; and PROTEINS, over successive generations.Seasons: Divisions of the year according to some regularly recurrent phenomena usually astronomical or climatic. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)