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.Disease Vectors: Invertebrates or non-human vertebrates which transmit infective organisms from one host to another.Molluscacides: Agents destructive to snails and other mollusks.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.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.Snails: Marine, freshwater, or terrestrial mollusks of the class Gastropoda. Most have an enclosing spiral shell, and several genera harbor parasites pathogenic to man.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.Hemocytes: Any blood or formed element especially in invertebrates.Hemolymph: The blood/lymphlike nutrient fluid of some invertebrates.Cercaria: The free-swimming larval forms of parasites found in an intermediate host.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.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.Euphorbia: A large plant genus of the family EUPHORBIACEAE, order Euphorbiales, subclass Rosidae. They have a milky sap and a female flower consisting of a single pistil, surrounded by numerous male flowers of one stamen each. Euphorbia hirta is rarely called milkweed but that name is normally used for ASCLEPIAS.Population Density: Number of individuals in a population relative to space.BrazilSchistosoma: 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.Niclosamide: An antihelmintic that is active against most tapeworms. (From Martindale, The Extra Pharmacopoeia, 30th ed, p48)Silver Staining: The use of silver, usually silver nitrate, as a reagent for producing contrast or coloration in tissue specimens.Latex: A milky, product excreted from the latex canals of a variety of plant species that contain cauotchouc. Latex is composed of 25-35% caoutchouc, 60-75% water, 2% protein, 2% resin, 1.5% sugar & 1% ash. RUBBER is made by the removal of water from latex.(From Concise Encyclopedia Biochemistry and Molecular Biology, 3rd ed). Hevein proteins are responsible for LATEX HYPERSENSITIVITY. Latexes are used as inert vehicles to carry antibodies or antigens in LATEX FIXATION TESTS.Oocysts: Zygote-containing cysts of sporozoan protozoa. Further development in an oocyst produces small individual infective organisms called SPOROZOITES. Then, depending on the genus, the entire oocyst is called a sporocyst or the oocyst contains multiple sporocysts encapsulating the sporozoites.Egypt: A country in northern Africa, bordering the Mediterranean Sea, between Libya and the Gaza Strip, and the Red Sea north of Sudan, and includes the Asian Sinai Peninsula Its capital is Cairo.Biological Phenomena: Biological processes, properties, and characteristics of the whole organism in human, animal, microorganisms, and plants, and of the biosphere.Guadeloupe: The name of two islands of the West Indies, separated by a narrow channel. Their capital is Basse-Terre. They were discovered by Columbus in 1493, occupied by the French in 1635, held by the British at various times between 1759 and 1813, transferred to Sweden in 1813, and restored to France in 1816. Its status was changed from colony to a French overseas department in 1946. Columbus named it in honor of the monastery of Santa Maria de Guadalupe in Spain. (From Webster's New Geographical Dictionary, 1988, p470 & Room, Brewer's Dictionary of Names, 1992, p221)Competitive Behavior: The direct struggle between individuals for environmental necessities or for a common goal.Angiostrongylus: A genus of parasitic nematodes of the superfamily METASTRONGYLOIDEA. Two species, ANGIOSTRONGYLUS CANTONENSIS and A. vasorum, infest the lungs of rats and dogs, respectively. A. cantonensis is transmissible to man where it causes frequently fatal infection of the central nervous system.Lakes: Inland bodies of still or slowly moving FRESH WATER or salt water, larger than a pond, and supplied by RIVERS and streams.Saint Lucia: An independent state in the West Indies. Its capital is Castries. It was probably discovered by Columbus in 1502 and first settled by the English in 1605. Contended for by the French and English in the 17th century, it was regarded as neutral in 1748 but changed hands many times in the wars of the 19th century. It became a self-governing state in association with Great Britain in 1967 and achieved independence in 1979. Columbus named it for the day on which he discovered it, the feast of St. Lucy, a Sicilian virgin martyr. (From Webster's New Geographical Dictionary, 1988, p1051 & Room, Brewer's Dictionary of Names, 1992, p477)Echinostomiasis: Infection by flukes of the genus Echinostoma.Pest Control, Biological: Use of naturally-occuring or genetically-engineered organisms to reduce or eliminate populations of pests.Lethal Dose 50: The dose amount of poisonous or toxic substance or dose of ionizing radiation required to kill 50% of the tested population.ArgentinaPiperaceae: A family of flowering plants in the order Piperales best known for the black pepper widely used in SPICES, and for KAVA and Betel used for neuroactive properties.DNA, Helminth: Deoxyribonucleic acid that makes up the genetic material of helminths.Fresh Water: Water containing no significant amounts of salts, such as water from RIVERS and LAKES.Dalbergia: A plant genus of the family FABACEAE. Members of this genus can cause CONTACT DERMATITIS.Parasite Egg Count: Determination of parasite eggs in feces.Pest Control: The reduction or regulation of the population of noxious, destructive, or dangerous plants, insects, or other animals. This includes control of plants that serve as habitats or food sources for animal pests.Schistosomicides: Agents that act systemically to kill adult schistosomes.Martinique: An island in the Lesser Antilles, one of the Windward Islands. Its capital is Fort-de-France. It was discovered by Columbus in 1502 and from its settlement in 1635 by the French it passed into and out of Dutch and British hands. It was made a French overseas department in 1946. One account of the name tells of native women on the shore calling "Madinina" as Columbus approached the island. The meaning was never discovered but was entered on early charts as Martinique, influenced by the name of St. Martin. (From Webster's New Geographical Dictionary, 1988, p734 & Room, Brewer's Dictionary of Names, 1992, p339)Tilapia: A freshwater fish used as an experimental organism and for food. This genus of the family Cichlidae (CICHLIDS) inhabits Central and South America (one species extends north into Texas), West Indies, Africa, Madagascar, Syria, and coastal India.Cuba: An island in the Greater Antilles in the West Indies, south of Florida. With the adjacent islands it forms the Republic of Cuba. Its capital is Havana. It was discovered by Columbus on his first voyage in 1492 and conquered by Spain in 1511. It has a varied history under Spain, Great Britain, and the United States but has been independent since 1902. The name Cuba is said to be an Indian name of unknown origin but the language that gave the name is extinct, so the etymology is a conjecture. (From Webster's New Geographical Dictionary, 1988, p302 & Room, Brewer's Dictionary of Names, 1992, p132)Random Amplified Polymorphic DNA Technique: Technique that utilizes low-stringency polymerase chain reaction (PCR) amplification with single primers of arbitrary sequence to generate strain-specific arrays of anonymous DNA fragments. RAPD technique may be used to determine taxonomic identity, assess kinship relationships, analyze mixed genome samples, and create specific probes.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).Plant Extracts: Concentrated pharmaceutical preparations of plants obtained by removing active constituents with a suitable solvent, which is evaporated away, and adjusting the residue to a prescribed standard.Ecology: The branch of science concerned with the interrelationship of organisms and their ENVIRONMENT, especially as manifested by natural cycles and rhythms, community development and structure, interactions between different kinds of organisms, geographic distributions, and population alterations. (Webster's, 3d ed)Polymorphism, Restriction Fragment Length: Variation occurring within a species in the presence or length of DNA fragment generated by a specific endonuclease at a specific site in the genome. Such variations are generated by mutations that create or abolish recognition sites for these enzymes or change the length of the fragment.Schistosoma 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.Larva: Wormlike or grublike stage, following the egg in the life cycle of insects, worms, and other metamorphosing animals.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.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.Disease 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.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)Predatory Behavior: Instinctual behavior pattern in which food is obtained by killing and consuming other species.Genetic Markers: A phenotypically recognizable genetic trait which can be used to identify a genetic locus, a linkage group, or a recombination event.Genetic Variation: Genotypic differences observed among individuals in a population.Environment: The external elements and conditions which surround, influence, and affect the life and development of an organism or population.Biomphalaria: A genus of planorbid freshwater snails, species of which are intermediate hosts of Schistosoma mansoni.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.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.Reproduction: The total process by which organisms produce offspring. (Stedman, 25th ed)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)Immunity, Innate: The capacity of a normal organism to remain unaffected by microorganisms and their toxins. It results from the presence of naturally occurring ANTI-INFECTIVE AGENTS, constitutional factors such as BODY TEMPERATURE and immediate acting immune cells such as NATURAL KILLER CELLS.DNA, Ribosomal: DNA sequences encoding RIBOSOMAL RNA and the segments of DNA separating the individual ribosomal RNA genes, referred to as RIBOSOMAL SPACER DNA.DNA, Mitochondrial: Double-stranded DNA of MITOCHONDRIA. In eukaryotes, the mitochondrial GENOME is circular and codes for ribosomal RNAs, transfer RNAs, and about 10 proteins.Electrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.Time Factors: Elements of limited time intervals, contributing to particular results or situations.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.