Trypanosoma

A genus of asexual digenetic protozoan flagellates (family Trypanosomatidae) that have a spindle-shaped body with an undulating membrane on one side, a single anterior flagellum, and a kinetoplast; they are parasitic in the blood plasma of many vertebrates (only a few being pathogenic) and as a rule have an intermediate host, a bloodsucking invertebrate, such as a leech, tick, or insect; pathogenic species cause trypanosomiasis in humans and a number of other diseases in domestic animals. [G. trypanon, an auger, + soma, body]

- T. avium a species that occurs in owls, crows, and other birds; various bloodsucking arthropods are the vectors, including mosquitoes, black flies, and hippoboscids; this species was reported under a large number of names now considered to be physiologic strains of the species.

- T. brucei a protozoan species now divided into three subspecies: T. brucei brucei, T. brucei rhodesiense, and T. brucei gambiense.

- T. brucei brucei a protozoan subspecies causing nagana in Africa; it produces fatal disease in camels, acute disease in equines, dogs, and cats, and chronic disease in swine, cattle, sheep, and goats; it is transmitted primarily by tsetse flies of the genus Glossina. In wild African ungulates the infection is widespread but rarely fatal.

- T. brucei gambiense a protozoan subspecies causing Gambian trypanosomiasis in humans; transmitted by tsetse flies, especially Glossina palpalis. SYN: T. gambiense, T. hominis, T. ugandense.

- T. brucei rhodesiense a protozoan subspecies causing Rhodesian trypanosomiasis; it is transmitted by tsetse flies, especially Glossina morsitans in humans; various game animals can act as reservoir hosts. SYN: T. rhodesiense.

- T. cruzi a species that causes South American trypanosomiasis and is endemic in Mexico and various countries of Central and South America; transmission and infection are common only where the triatomine bug vector defecates while taking blood, as the bug feces contains the infective agents that are scratched into the skin or brought in contact with mucosal surfaces. Trypomastigotes are found in the blood, and amastigotes occur intracellularly in clusters or colonies in the tissues; heart muscle fibers and cells of many other organs are attacked, the organisms not being restricted to macrophages as in visceral leishmaniasis; humans, dogs, cats, house rats, armadillos, bats, certain monkeys, and opossums are the usual vertebrate hosts; vectors are members of the family Triatominae. Also known as Schizotrypanum cruzi, a distinct generic designation widely used in the endemic regions. SYN: T. escomelis, T. triatomae.

- T. dimorphon an African species found in horses, cattle, sheep, goats, pigs, and dogs, formerly thought to be the same as T. congolense but now recognized as a distinct and more pathogenic species in cattle, sheep, and dogs; it is spread by tsetse flies across central Africa.

- T. escomelis SYN: T. cruzi.

- T. gambiense SYN: T. brucei gambiense.

- T. hominis SYN: T. brucei gambiense.

- T. ignotum old name for T. simiae.

- T. lewisi species that is a worldwide nonpathogenic parasite in the blood of rats widely used for laboratory study; it is transmitted by the rat flea, Nosopsyllus fasciatus.

- T. melophagium a nonpathogenic species (related to T. theileri) found in sheep throughout the world, and probably in goats as well; the vector is Melophagus ovinus.

- T. rangeli a species that parasitizes a wide variety of mammals, including humans, in South America and is transmitted by the triatomid bugs Rhodnius prolixus and Tiratoma dimidiata, and probably others; it is apparently nonpathogenic but may be pathogenic in the bug host.

- T. rhodesiense SYN: T. brucei rhodesiense.

- T. theileri a large, relatively nonpathogenic species found in African antelopes and in cattle in many parts of the world; the parasites are spread by bloodsucking tabanid horseflies.

- T. triatomae SYN: T. cruzi.

- T. ugandense SYN: T. brucei gambiense.

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try·pano·so·ma tri-.pan-ə-'sō-mə n

1) cap the type genus of the family Trypanosomatidae comprising kinetoplastid flagellates that as adults are elongated and somewhat spindle-shaped, have a posteriorly arising flagellum which passes forward at the margin of an undulating membrane and emerges near the anterior end of the body as a short free flagellum, and are parasitic in the blood or rarely the tissues of vertebrates, that following development in the digestive tract of a blood-sucking invertebrate and usu. an insect pass ultimately to the mouthparts or salivary structures where they may be transmitted into a new vertebrate host bitten by the invertebrate host, and that are responsible for various serious diseases (as Chagas' disease, dourine, nagana, sleeping sickness, and surra) of humans and domestic animals

2) pl -mas or -ma·ta -mət-ə TRYPANOSOME

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n.

a genus of parasitic protozoans that move by means of a long trailing flagellum and a thin wavy membrane, which project from the body surface. Trypanosomes undergo part of their development in the blood of a vertebrate host. The remaining stages occur in invertebrate hosts, which then transmit the parasites back to the vertebrates. T. rhodesiense and T. gambiense, which are transmitted through the bite of tsetse flies, cause sleeping sickness in Africa. T. cruzi, carried by reduviid bugs, causes Chagas' disease in South America.

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Try·pano·so·ma (tri-pan″o-soґmə) [Gr. trypanon borer + sōma body] a genus of hemoflagellate protozoa of the order Kinetoplastida, phylum Euglenozoa, parasitic in invertebrates and vertebrates (see trypanosomiasis). Most are digenetic, with a cycle of multiplicative and developmental stages in the blood of vertebrates and in the gut of invertebrates (leeches and arthropods). Trypomastigote and epimastigote stages occur in most life cycles; amastigote and promastigote stages are less common. In some systems of classification, the genus is divided into two groups according to where parasites develop in the digestive system of the vector: the salivaria include the subgenera Duttonella, Nannomonas, and Trypanozoon; and the stercoraria include the subgenera Megatrypanum, Herpetosoma, and Schizotrypanum. Another system classifies the genus into four groups based on biological similarities: (1) the lewisi group includes T. cruzi, T. lewisi, and various nonpathogenic species; (2) the vivax group includes T. vivax and T. uniforme; (3) the congolense group includes T. congolense, T. dimorphon, and T. simiae; and (4) the brucei group includes T. brucei, T. gambiense, T. rhodesiense, T. evansi, T. equinum, and T. equiperdum.