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.Schistosoma mansoni: A species of trematode blood flukes of the family Schistosomatidae. It is common in the Nile delta. The intermediate host is the planorbid snail. This parasite causes schistosomiasis mansoni and intestinal bilharziasis.Snails: Marine, freshwater, or terrestrial mollusks of the class Gastropoda. Most have an enclosing spiral shell, and several genera harbor parasites pathogenic to man.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)Schistosomiasis mansoni: Schistosomiasis caused by Schistosoma mansoni. It is endemic in Africa, the Middle East, South America, and the Caribbean and affects mainly the bowel, spleen, and liver.Schistosoma: A genus of trematode flukes belonging to the family Schistosomatidae. There are over a dozen species. These parasites are found in man and other mammals. Snails are the intermediate hosts.Biomphalaria: A genus of planorbid freshwater snails, species of which are intermediate hosts of Schistosoma mansoni.Schistosoma japonicum: A species of trematode blood flukes belonging to the family Schistosomatidae whose distribution is confined to areas of the Far East. The intermediate host is a snail. It occurs in man and other mammals.Schistosomiasis: Infection with flukes (trematodes) of the genus SCHISTOSOMA. Three species produce the most frequent clinical diseases: SCHISTOSOMA HAEMATOBIUM (endemic in Africa and the Middle East), SCHISTOSOMA MANSONI (in Egypt, northern and southern Africa, some West Indies islands, northern 2/3 of South America), and SCHISTOSOMA JAPONICUM (in Japan, China, the Philippines, Celebes, Thailand, Laos). S. mansoni is often seen in Puerto Ricans living in the United States.Schistosomiasis japonica: Schistosomiasis caused by Schistosoma japonicum. It is endemic in the Far East and affects the bowel, liver, and spleen.Bulinus: A genus of small freshwater snails of the order Pulmonata, found throughout Africa and the Middle East, where it is a vector of SCHISTOSOMA HAEMATOBIUM.Schistosomicides: Agents that act systemically to kill adult schistosomes.Trematode Infections: Infections caused by infestation with worms of the class Trematoda.Skin Diseases, Parasitic: Skin diseases caused by ARTHROPODS; HELMINTHS; or other parasites.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.Cercaria: The free-swimming larval forms of parasites found in an intermediate host.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.DNA, Helminth: Deoxyribonucleic acid that makes up the genetic material of helminths.Larva: Wormlike or grublike stage, following the egg in the life cycle of insects, worms, and other metamorphosing animals.Antibodies, Helminth: Immunoglobulins produced in a response to HELMINTH ANTIGENS.Cardiidae: A family of bivalve MOLLUSKS with heart-shaped shells, commonly known as cockles. Unlike most BIVALVES, cockles are hermaphroditic.Parasite Egg Count: Determination of parasite eggs in feces.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.KuwaitSchistosoma haematobium: A species of trematode blood flukes of the family Schistosomatidae which occurs at different stages in development in veins of the pulmonary and hepatic system and finally the bladder lumen. This parasite causes urinary schistosomiasis.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.Praziquantel: An anthelmintic used in most schistosome and many cestode infestations.Oxamniquine: An anthelmintic with schistosomicidal activity against Schistosoma mansoni, but not against other Schistosoma spp. Oxamniquine causes worms to shift from the mesenteric veins to the liver where the male worms are retained; the female worms return to the mesentery, but can no longer release eggs. (From Martindale, The Extra Pharmacopoeia, 31st ed, p121)Helminth Proteins: Proteins found in any species of helminth.Lymnaea: A genus of dextrally coiled freshwater snails that includes some species of importance as intermediate hosts of parasitic flukes.Niclosamide: An antihelmintic that is active against most tapeworms. (From Martindale, The Extra Pharmacopoeia, 30th ed, p48)Gastropoda: A class in the phylum MOLLUSCA comprised of SNAILS and slugs. The former have coiled external shells and the latter usually lack shells.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.Disease Vectors: Invertebrates or non-human vertebrates which transmit infective organisms from one host to another.Granuloma, Foreign-Body: Histiocytic, inflammatory response to a foreign body. It consists of modified macrophages with multinucleated giant cells, in this case foreign-body giant cells (GIANT CELLS, FOREIGN-BODY), usually surrounded by lymphocytes.Paramphistomatidae: A family of flukes of the class Trematoda found in the intestinal tract and liver of animals and man. Some of the genera are Homalagaster, Gastrodiscus, Paramphistomum, Watsonius, Nilocotyle, Gigantocotyle, Gastrothylax, Macropotrema, Ceylonocotyle, Zygocotyle, Cotylophoron, and Calicophoron.Dithioerythritol: A compound that, along with its isomer, Cleland's reagent (DITHIOTHREITOL), is used for the protection of sulfhydryl groups against oxidation to disulfides and for the reduction of disulfides to sulfhydryl groups.Liver Diseases, Parasitic: Liver diseases caused by infections with PARASITES, such as tapeworms (CESTODA) and flukes (TREMATODA).Vaccines: Suspensions of killed or attenuated microorganisms (bacteria, viruses, fungi, protozoa), antigenic proteins, synthetic constructs, or other bio-molecular derivatives, administered for the prevention, amelioration, or treatment of infectious and other diseases.DEET: A compound used as a topical insect repellent that may cause irritation to eyes and mucous membranes, but not to the skin.Animal Structures: Organs and other anatomical structures of non-human vertebrate and invertebrate animals.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.Host Specificity: The properties of a pathogen that makes it capable of infecting one or more specific hosts. The pathogen can include PARASITES as well as VIRUSES; BACTERIA; FUNGI; or PLANTS.Antigens, CD15: A trisaccharide antigen expressed on glycolipids and many cell-surface glycoproteins. In the blood the antigen is found on the surface of NEUTROPHILS; EOSINOPHILS; and MONOCYTES. In addition, CD15 antigen is a stage-specific embryonic antigen.Insect Repellents: Substances causing insects to turn away from them or reject them as food.TailAnthelmintics: Agents destructive to parasitic worms. They are used therapeutically in the treatment of HELMINTHIASIS in man and animal.Schistosomiasis haematobia: A human disease caused by the infection of parasitic worms SCHISTOSOMA HAEMATOBIUM. It is endemic in AFRICA and parts of the MIDDLE EAST. Tissue damages most often occur in the URINARY TRACT, specifically the URINARY BLADDER.Mechanical Processes: The behaviors of materials under force.Water: A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Granuloma: A relatively small nodular inflammatory lesion containing grouped mononuclear phagocytes, caused by infectious and noninfectious agents.Mice, Inbred CBAVaccines, Attenuated: Live vaccines prepared from microorganisms which have undergone physical adaptation (e.g., by radiation or temperature conditioning) or serial passage in laboratory animal hosts or infected tissue/cell cultures, in order to produce avirulent mutant strains capable of inducing protective immunity.SesquiterpenesSwimming: An activity in which the body is propelled through water by specific movement of the arms and/or the legs. Swimming as propulsion through water by the movement of limbs, tail, or fins of animals is often studied as a form of PHYSICAL EXERTION or endurance.Fresh Water: Water containing no significant amounts of salts, such as water from RIVERS and LAKES.Vaccination: Administration of vaccines to stimulate the host's immune response. This includes any preparation intended for active immunological prophylaxis.Feces: Excrement from the INTESTINES, containing unabsorbed solids, waste products, secretions, and BACTERIA of the DIGESTIVE SYSTEM.Immunization: Deliberate stimulation of the host's immune response. ACTIVE IMMUNIZATION involves administration of ANTIGENS or IMMUNOLOGIC ADJUVANTS. PASSIVE IMMUNIZATION involves administration of IMMUNE SERA or LYMPHOCYTES or their extracts (e.g., transfer factor, immune RNA) or transplantation of immunocompetent cell producing tissue (thymus or bone marrow).Cathepsin B: A lysosomal cysteine proteinase with a specificity similar to that of PAPAIN. The enzyme is present in a variety of tissues and is important in many physiological and pathological processes. In pathology, cathepsin B has been found to be involved in DEMYELINATION; EMPHYSEMA; RHEUMATOID ARTHRITIS, and NEOPLASM INVASIVENESS.Ovum: A mature haploid female germ cell extruded from the OVARY at OVULATION.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.Artemisinins: A group of SESQUITERPENES and their analogs that contain a peroxide group (PEROXIDES) within an oxepin ring (OXEPINS).BrazilSkin: The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.Administration, Topical: The application of drug preparations to the surfaces of the body, especially the skin (ADMINISTRATION, CUTANEOUS) or mucous membranes. This method of treatment is used to avoid systemic side effects when high doses are required at a localized area or as an alternative systemic administration route, to avoid hepatic processing for example.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)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.Polymerase Chain Reaction: In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.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.Methods: A series of steps taken in order to conduct research.Disease Models, Animal: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.Mice, Inbred C57BLMicroscopy, Electron: Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Seawater: The salinated water of OCEANS AND SEAS that provides habitat for marine organisms.Mice, Inbred Strains: Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations, or by parent x offspring matings carried out with certain restrictions. All animals within an inbred strain trace back to a common ancestor in the twentieth generation.Immunoglobulin G: The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of IgG, for example, IgG1, IgG2A, and IgG2B.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Mice, Inbred BALB CHeat-Shock Proteins: Proteins which are synthesized in eukaryotic organisms and bacteria in response to hyperthermia and other environmental stresses. They increase thermal tolerance and perform functions essential to cell survival under these conditions.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.