Parasite Load: Measure of the number of the PARASITES present in a host organism.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.Leishmaniasis, Visceral: A chronic disease caused by LEISHMANIA DONOVANI and transmitted by the bite of several sandflies of the genera Phlebotomus and Lutzomyia. It is commonly characterized by fever, chills, vomiting, anemia, hepatosplenomegaly, leukopenia, hypergammaglobulinemia, emaciation, and an earth-gray color of the skin. The disease is classified into three main types according to geographic distribution: Indian, Mediterranean (or infantile), and African.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.Leishmania infantum: A parasitic hemoflagellate of the subgenus Leishmania leishmania that infects man and animals and causes visceral leishmaniasis (LEISHMANIASIS, VISCERAL). Human infections are confined almost entirely to children. This parasite is commonly seen in dogs, other Canidae, and porcupines with humans considered only an accidental host. Transmission is by Phlebotomus sandflies.Leishmaniasis, Cutaneous: An endemic disease that is characterized by the development of single or multiple localized lesions on exposed areas of skin that typically ulcerate. The disease has been divided into Old and New World forms. Old World leishmaniasis is separated into three distinct types according to epidemiology and clinical manifestations and is caused by species of the L. tropica and L. aethiopica complexes as well as by species of the L. major genus. New World leishmaniasis, also called American leishmaniasis, occurs in South and Central America and is caused by species of the L. mexicana or L. braziliensis complexes.Parasitic Diseases, Animal: Infections or infestations with parasitic organisms. The infestation may be experimental or veterinary.Antiprotozoal Agents: Substances that are destructive to protozoans.Leishmania major: A parasitic hemoflagellate of the subgenus Leishmania leishmania that infects man and animals and causes cutaneous leishmaniasis (LEISHMANIASIS, CUTANEOUS) of the Old World. Transmission is by Phlebotomus sandflies.Parasite Egg Count: Determination of parasite eggs in feces.Leishmania: A genus of flagellate protozoa comprising several species that are pathogenic for humans. Organisms of this genus have an amastigote and a promastigote stage in their life cycles. As a result of enzymatic studies this single genus has been divided into two subgenera: Leishmania leishmania and Leishmania viannia. Species within the Leishmania leishmania subgenus include: L. aethiopica, L. arabica, L. donovani, L. enrietti, L. gerbilli, L. hertigi, L. infantum, L. major, L. mexicana, and L. tropica. The following species are those that compose the Leishmania viannia subgenus: L. braziliensis, L. guyanensis, L. lainsoni, L. naiffi, and L. shawi.Leishmaniasis Vaccines: Vaccines or candidate vaccines used to prevent infection with LEISHMANIA.Leishmaniasis: A disease caused by any of a number of species of protozoa in the genus LEISHMANIA. There are four major clinical types of this infection: cutaneous (Old and New World) (LEISHMANIASIS, CUTANEOUS), diffuse cutaneous (LEISHMANIASIS, DIFFUSE CUTANEOUS), mucocutaneous (LEISHMANIASIS, MUCOCUTANEOUS), and visceral (LEISHMANIASIS, VISCERAL).Leishmania donovani: A parasitic hemoflagellate of the subgenus Leishmania leishmania that infects man and animals and causes visceral leishmaniasis (LEISHMANIASIS, VISCERAL). The sandfly genera Phlebotomus and Lutzomyia are the vectors.DNA, Protozoan: Deoxyribonucleic acid that makes up the genetic material of protozoa.Platyhelminths: A phylum of acoelomate, bilaterally symmetrical flatworms, without a definite anus. It includes three classes: Cestoda, Turbellaria, and Trematoda.Trypanosoma cruzi: The agent of South American trypanosomiasis or CHAGAS DISEASE. Its vertebrate hosts are man and various domestic and wild animals. Insects of several species are vectors.Parasitemia: The presence of parasites (especially malarial parasites) in the blood. (Dorland, 27th ed)Chagas Disease: Infection with the protozoan parasite TRYPANOSOMA CRUZI, a form of TRYPANOSOMIASIS endemic in Central and South America. It is named after the Brazilian physician Carlos Chagas, who discovered the parasite. Infection by the parasite (positive serologic result only) is distinguished from the clinical manifestations that develop years later, such as destruction of PARASYMPATHETIC GANGLIA; CHAGAS CARDIOMYOPATHY; and dysfunction of the ESOPHAGUS or COLON.Protozoan Proteins: Proteins found in any species of protozoan.Hawks: Common name for many members of the FALCONIFORMES order, family Accipitridae, generally smaller than EAGLES, and containing short, rounded wings and a long tail.Ectoparasitic Infestations: Infestations by PARASITES which live on, or burrow into, the surface of their host's EPIDERMIS. Most ectoparasites are ARTHROPODS.Sulfadimethoxine: A sulfanilamide that is used as an anti-infective agent.Toxoplasma: A genus of protozoa parasitic to birds and mammals. T. gondii is one of the most common infectious pathogenic animal parasites of man.Plasmodium falciparum: A species of protozoa that is the causal agent of falciparum malaria (MALARIA, FALCIPARUM). It is most prevalent in the tropics and subtropics.Mice, Inbred BALB CAntibodies, Protozoan: Immunoglobulins produced in a response to PROTOZOAN ANTIGENS.Leishmania braziliensis: A parasitic hemoflagellate of the subgenus Leishmania viannia that infects man and animals. It causes cutaneous (LEISHMANIASIS, CUTANEOUS), diffuse cutaneous (LEISHMANIASIS, DIFFUSE CUTANEOUS), and mucocutaneous leishmaniasis (LEISHMANIASIS, MUCOCUTANEOUS) depending on the subspecies of this organism. The sandfly, Lutzomyia, is the vector. The Leishmania braziliensis complex includes the subspecies braziliensis and peruviana. Uta, a form of cutaneous leishmaniasis in the New World, is caused by the subspecies peruviana.Malaria: A protozoan disease caused in humans by four species of the PLASMODIUM genus: PLASMODIUM FALCIPARUM; PLASMODIUM VIVAX; PLASMODIUM OVALE; and PLASMODIUM MALARIAE; and transmitted by the bite of an infected female mosquito of the genus ANOPHELES. Malaria is endemic in parts of Asia, Africa, Central and South America, Oceania, and certain Caribbean islands. It is characterized by extreme exhaustion associated with paroxysms of high FEVER; SWEATING; shaking CHILLS; and ANEMIA. Malaria in ANIMALS is caused by other species of plasmodia.Leishmania mexicana: A parasitic hemoflagellate of the subgenus Leishmania leishmania that infects man and animals including rodents. The Leishmania mexicana complex causes both cutaneous (LEISHMANIASIS, CUTANEOUS) and diffuse cutaneous leishmaniasis (LEISHMANIASIS, DIFFUSE CUTANEOUS) and includes the subspecies amazonensis, garnhami, mexicana, pifanoi, and venezuelensis. L. m. mexicana causes chiclero ulcer, a form of cutaneous leishmaniasis (LEISHMANIASIS, CUTANEOUS) in the New World. The sandfly, Lutzomyia, appears to be the vector.Protozoan Vaccines: Suspensions of attenuated or killed protozoa administered for the prevention or treatment of infectious protozoan disease.Antigens, Protozoan: Any part or derivative of any protozoan that elicits immunity; malaria (Plasmodium) and trypanosome antigens are presently the most frequently encountered.Parasitology: The study of parasites and PARASITIC DISEASES.DNA, Kinetoplast: DNA of kinetoplasts which are specialized MITOCHONDRIA of trypanosomes and related parasitic protozoa within the order KINETOPLASTIDA. Kinetoplast DNA consists of a complex network of numerous catenated rings of two classes; the first being a large number of small DNA duplex rings, called minicircles, approximately 2000 base pairs in length, and the second being several dozen much larger rings, called maxicircles, approximately 37 kb in length.Dog Diseases: Diseases of the domestic dog (Canis familiaris). This term does not include diseases of wild dogs, WOLVES; FOXES; and other Canidae for which the heading CARNIVORA is used.Meglumine: 1-Deoxy-1-(methylamino)-D-glucitol. A derivative of sorbitol in which the hydroxyl group in position 1 is replaced by a methylamino group. Often used in conjunction with iodinated organic compounds as contrast medium.Malaria, Falciparum: Malaria caused by PLASMODIUM FALCIPARUM. This is the severest form of malaria and is associated with the highest levels of parasites in the blood. This disease is characterized by irregularly recurring febrile paroxysms that in extreme cases occur with acute cerebral, renal, or gastrointestinal manifestations.Chagas Cardiomyopathy: A disease of the CARDIAC MUSCLE developed subsequent to the initial protozoan infection by TRYPANOSOMA CRUZI. After infection, less than 10% develop acute illness such as MYOCARDITIS (mostly in children). The disease then enters a latent phase without clinical symptoms until about 20 years later. Myocardial symptoms of advanced CHAGAS DISEASE include conduction defects (HEART BLOCK) and CARDIOMEGALY.Poecilia: A genus of livebearing cyprinodont fish comprising the guppy and molly. Some species are virtually all female and depend on sperm from other species to stimulate egg development. Poecilia is used in carcinogenicity studies as well as neurologic and physiologic research.Toxoplasmosis, Animal: Acquired infection of non-human animals by organisms of the genus TOXOPLASMA.Cryptosporidiosis: Intestinal infection with organisms of the genus CRYPTOSPORIDIUM. It occurs in both animals and humans. Symptoms include severe DIARRHEA.Psychodidae: Small, hairy, moth-like flies which are of considerable public health importance as vectors of certain pathogenic organisms. Important disease-related genera are PHLEBOTOMUS, Lutzomyia, and Sergentomyia.Spleen: An encapsulated lymphatic organ through which venous blood filters.LizardsFish Diseases: Diseases of freshwater, marine, hatchery or aquarium fish. This term includes diseases of both teleosts (true fish) and elasmobranchs (sharks, rays and skates).Blood: The body fluid that circulates in the vascular system (BLOOD VESSELS). Whole blood includes PLASMA and BLOOD CELLS.Feces: Excrement from the INTESTINES, containing unabsorbed solids, waste products, secretions, and BACTERIA of the DIGESTIVE SYSTEM.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.Apicomplexa: A phylum of unicellular parasitic EUKARYOTES characterized by the presence of complex apical organelles generally consisting of a conoid that aids in penetrating host cells, rhoptries that possibly secrete a proteolytic enzyme, and subpellicular microtubules that may be related to motility.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.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.Mice, Inbred C57BLSkin: The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.Plasmodium berghei: A protozoan parasite of rodents transmitted by the mosquito Anopheles dureni.Antimalarials: Agents used in the treatment of malaria. They are usually classified on the basis of their action against plasmodia at different stages in their life cycle in the human. (From AMA, Drug Evaluations Annual, 1992, p1585)Parasitic Diseases: Infections or infestations with parasitic organisms. They are often contracted through contact with an intermediate vector, but may occur as the result of direct exposure.Interferon-gamma: The major interferon produced by mitogenically or antigenically stimulated LYMPHOCYTES. It is structurally different from TYPE I INTERFERON and its major activity is immunoregulation. It has been implicated in the expression of CLASS II HISTOCOMPATIBILITY ANTIGENS in cells that do not normally produce them, leading to AUTOIMMUNE DISEASES.Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Cytokines: Non-antibody proteins secreted by inflammatory leukocytes and some non-leukocytic cells, that act as intercellular mediators. They differ from classical hormones in that they are produced by a number of tissue or cell types rather than by specialized glands. They generally act locally in a paracrine or autocrine rather than endocrine manner.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.BrazilTrematoda: 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.Disease Susceptibility: A constitution or condition of the body which makes the tissues react in special ways to certain extrinsic stimuli and thus tends to make the individual more than usually susceptible to certain diseases.Erythrocytes: Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.Genes, Protozoan: The functional hereditary units of protozoa.Real-Time Polymerase Chain Reaction: Methods used for detecting the amplified DNA products from the polymerase chain reaction as they accumulate instead of at the end of the reaction.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.Cestoda: A subclass of segmented worms comprising the tapeworms.Protozoan Infections: Infections with unicellular organisms formerly members of the subkingdom Protozoa.Interleukin-10: A cytokine produced by a variety of cell types, including T-LYMPHOCYTES; MONOCYTES; DENDRITIC CELLS; and EPITHELIAL CELLS that exerts a variety of effects on immunoregulation and INFLAMMATION. Interleukin-10 combines with itself to form a homodimeric molecule that is the biologically active form of the protein.Protozoan Infections, Animal: Infections with unicellular organisms formerly members of the subkingdom Protozoa. The infections may be experimental or veterinary.Macrophages: The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood MONOCYTES. Main types are PERITONEAL MACROPHAGES; ALVEOLAR MACROPHAGES; HISTIOCYTES; KUPFFER CELLS of the liver; and OSTEOCLASTS. They may further differentiate within chronic inflammatory lesions to EPITHELIOID CELLS or may fuse to form FOREIGN BODY GIANT CELLS or LANGHANS GIANT CELLS. (from The Dictionary of Cell Biology, Lackie and Dow, 3rd ed.)Haemosporida: An order of heteroxenous protozoa in which the macrogamete and microgamont develop independently. A conoid is usually absent.Genome, Protozoan: The complete genetic complement contained in a set of CHROMOSOMES in a protozoan.Sensitivity and Specificity: Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)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.Helminthiasis, Animal: Infestation of animals with parasitic worms of the helminth class. The infestation may be experimental or veterinary.Genetic Load: The relative amount by which the average fitness of a POPULATION is lowered, due to the presence of GENES that decrease survival, compared to the GENOTYPE with maximum or optimal fitness. (From Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)Immunoglobulin G: The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of IgG, for example, IgG1, IgG2A, and IgG2B.Parasitic Sensitivity Tests: Tests that demonstrate the relative effectiveness of chemotherapeutic agents against specific parasites.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.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Sporozoites: The product of meiotic division of zygotes in parasitic protozoa comprising haploid cells. These infective cells invade the host and undergo asexual reproduction producing MEROZOITES (or other forms) and ultimately gametocytes.Drug Resistance: Diminished or failed response of an organism, disease or tissue to the intended effectiveness of a chemical or drug. It should be differentiated from DRUG TOLERANCE which is the progressive diminution of the susceptibility of a human or animal to the effects of a drug, as a result of continued administration.Nematode Infections: Infections by nematodes, general or unspecified.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.Th1 Cells: Subset of helper-inducer T-lymphocytes which synthesize and secrete interleukin-2, gamma-interferon, and interleukin-12. Due to their ability to kill antigen-presenting cells and their lymphokine-mediated effector activity, Th1 cells are associated with vigorous delayed-type hypersensitivity reactions.Plasmodium yoelii: A species of PLASMODIUM causing malaria in rodents.Trematode Infections: Infections caused by infestation with worms of the class Trematoda.Plasmodium vivax: A protozoan parasite that causes vivax malaria (MALARIA, VIVAX). This species is found almost everywhere malaria is endemic and is the only one that has a range extending into the temperate regions.Chloroquine: The prototypical antimalarial agent with a mechanism that is not well understood. It has also been used to treat rheumatoid arthritis, systemic lupus erythematosus, and in the systemic therapy of amebic liver abscesses.Trophozoites: Cells or feeding stage in the life cycle of sporozoan protozoa. In the malarial parasite, the trophozoite develops from the MEROZOITE and then splits into the SCHIZONT. Trophozoites that are left over from cell division can go on to form gametocytes.Trypanosoma brucei brucei: A hemoflagellate subspecies of parasitic protozoa that causes nagana in domestic and game animals in Africa. It apparently does not infect humans. It is transmitted by bites of tsetse flies (Glossina).Mice, Knockout: Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.Anopheles: A genus of mosquitoes (CULICIDAE) that are known vectors of MALARIA.Acanthocephala: A phylum of parasitic worms, closely related to tapeworms and containing two genera: Moniliformis, which sometimes infects man, and Macracanthorhynchus, which infects swine.Cricetinae: A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.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.Schizonts: Multinucleate cells or a stage in the development of sporozoan protozoa. It is exemplified by the life cycle of PLASMODIUM FALCIPARUM in the MALARIA infection cycle.Merozoites: Uninuclear cells or a stage in the life cycle of sporozoan protozoa. Merozoites, released from ruptured multinucleate SCHIZONTS, enter the blood stream and infect the ERYTHROCYTES.Bacterial Load: Measurable quantity of bacteria in an object, organism, or organism compartment.Trypanosoma: A genus of flagellate protozoans found in the blood and lymph of vertebrates and invertebrates, both hosts being required to complete the life cycle.Microsporidia: A phylum of fungi comprising minute intracellular PARASITES with FUNGAL SPORES of unicellular origin. It has two classes: Rudimicrosporea and MICROSPOREA.Giardia lamblia: A species of parasitic EUKARYOTES that attaches itself to the intestinal mucosa and feeds on mucous secretions. The organism is roughly pear-shaped and motility is somewhat erratic, with a slow oscillation about the long axis.RNA, Protozoan: Ribonucleic acid in protozoa having regulatory and catalytic roles as well as involvement in protein synthesis.Cestode Infections: Infections with true tapeworms of the helminth subclass CESTODA.Coccidiosis: Protozoan infection found in animals and man. It is caused by several different genera of COCCIDIA.Eukaryota: One of the three domains of life (the others being BACTERIA and ARCHAEA), also called Eukarya. These are organisms whose cells are enclosed in membranes and possess a nucleus. They comprise almost all multicellular and many unicellular organisms, and are traditionally divided into groups (sometimes called kingdoms) including ANIMALS; PLANTS; FUNGI; and various algae and other taxa that were previously part of the old kingdom Protista.Artemisinins: A group of SESQUITERPENES and their analogs that contain a peroxide group (PEROXIDES) within an oxepin ring (OXEPINS).Entamoeba histolytica: A species of parasitic protozoa causing ENTAMOEBIASIS and amebic dysentery (DYSENTERY, AMEBIC). Characteristics include a single nucleus containing a small central karyosome and peripheral chromatin that is finely and regularly beaded.Toxoplasmosis: The acquired form of infection by Toxoplasma gondii in animals and man.Malaria Vaccines: Vaccines made from antigens arising from any of the four strains of Plasmodium which cause malaria in humans, or from P. berghei which causes malaria in rodents.Insect Vectors: Insects that transmit infective organisms from one host to another or from an inanimate reservoir to an animate host.Nematoda: A class of unsegmented helminths with fundamental bilateral symmetry and secondary triradiate symmetry of the oral and esophageal structures. Many species are parasites.Eimeria: A genus of protozoan parasites of the subclass COCCIDIA. Various species are parasitic in the epithelial cells of the liver and intestines of man and other animals.