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Temporal range: Albian to recent 100–0  Ma
Trypanosoma cruzi crithidia.jpeg
Trypanosoma cruzi parasites
Scientific classification

Kent 1880

Doflein 1901

Trypanosomatida is a group of kinetoplastid excavates distinguished by having only a single flagellum. The name is derived from the Greek trypano (borer) and soma (body) because of the corkscrew-like motion of some trypanosomatid species. All members are exclusively parasitic, found primarily in insects. [1] A few genera have life-cycles involving a secondary host, which may be a vertebrate, invertebrate or plant. These include several species that cause major diseases in humans. [2] Trypanosomatida are intracellular parasites.


Medical importance

The three major human diseases caused by trypanosomatids are; African trypanosomiasis (sleeping sickness, caused by Trypanosoma brucei and transmitted by tsetse flies), South American trypanosomiasis (Chagas disease, caused by Trypanosoma cruzi and transmitted by triatomine bugs), and leishmaniasis (a set of trypanosomal diseases caused by various species of Leishmania transmitted by sandflies).


The family is known from fossils of the extinct genus Paleoleishmania preserved in Burmese amber dating to the Albian (100 mya) and Dominican amber from the Burdigalian (20–15 mya) of Hispaniola. [3] The genus Trypanosoma is also represented in Dominican amber in the extinct species Trypanosoma antiquus . [4]


Three genera are dixenous (two hosts in the life cycle) – Leishmania, Phytomonas and Trypanosoma and the remainder are monoxenous (one host in the life cycle). Paratrypanosoma appears to be the first evolving branch in this order. Fifteen genera are recognised in the Trypanosomatidae and there are three subfamilies – Blechomonadinae , Leishmaniinae and Strigomonadinae . The genera in the subfamily Strigomonadinae are characterised by the presence of obligatory intracellular bacteria of the Kinetoplastibacterium genus.

Life cycle

Some trypanosomatids only occupy a single host, while many others are heteroxenous: they live in more than one host species over their life cycle. This heteroxenous life cycle typically includes the intestine of a bloodsucking insect and the blood and/or tissues of a vertebrate. Rarer hosts include other bloodsucking invertebrates, such as leeches, [5] and other organisms such as plants. Different species go through a range of different morphologies at different stages of the life cycle, with most having at least two different morphologies. Typically the promastigote and epimastigote forms are found in insect hosts, trypomastigote forms in the mammalian bloodstream and amastigotes in intracellular environments.


Six main morphologies of trypanosomatids TrypanosomatidMorphologies PlainSVG.svg
Six main morphologies of trypanosomatids

A variety of different morphological forms appear in the life cycles of trypanosomatids, distinguished mainly by the position, length and the cell body attachment of the flagellum. The kinetoplast is found closely associated with the basal body at the base of the flagellum and all species of trypanosomatid have a single nucleus. Most of these morphologies can be found as a life cycle stage in all trypanosomatid genera however certain morphologies are particularly common in a particular genus. The various morphologies were originally named from the genus where the morphology was commonly found, although this terminology is now rarely used because of potential confusion between morphologies and genus. Modern terminology is derived from the Greek; "mastig", meaning whip (referring to the flagellum), and a prefix which indicates the location of the flagellum on the cell. For example, the amastigote (prefix "a-", meaning no flagellum) form is also known as the leishmanial form as all Leishmania have an amastigote life cycle stage.

Other features

Notable characteristics of trypanosomatids are the ability to perform trans-splicing of RNA and possession of glycosomes, where much of their glycolysis is confined to. The acidocalcisome, another organelle, was first identified in trypanosomes. [8]

Related Research Articles

<i>Leishmania</i> Genus of parasitic flagellate protist in the Kinetoplastea class

Leishmania is a genus of trypanosomes that are responsible for the disease leishmaniasis. They are spread by sandflies of the genus Phlebotomus in the Old World, and of the genus Lutzomyia in the New World. At least 93 sandfly species are proven or probable vectors worldwide. Their primary hosts are vertebrates; Leishmania commonly infects hyraxes, canids, rodents, and humans.

Kinetoplastida Flagellated protists belonging to the phylum Euglenozoa

Kinetoplastida is a group of flagellated protists belonging to the phylum Euglenozoa, and characterised by the presence of an organelle with a large massed DNA called kinetoplast. The organisms are commonly referred to as "kinetoplastids" or "kinetoplasts" The group includes a number of parasites responsible for serious diseases in humans and other animals, as well as various forms found in soil and aquatic environments. Their distinguishing feature, the presence of a kinetoplast, is an unusual DNA-containing granule located within the single mitochondrion associated with the base of the cell's flagellum. The kinetoplast contains many copies of the mitochondrial genome.

<i>Trypanosoma</i> Genus of parasitic flagellate protist in the Kinetoplastea class

Trypanosoma is a genus of kinetoplastids, a monophyletic group of unicellular parasitic flagellate protozoa. Trypanosoma is part of the phylum Sarcomastigophora. The name is derived from the Greek trypano- (borer) and soma (body) because of their corkscrew-like motion. Most trypanosomes are heteroxenous and most are transmitted via a vector. The majority of species are transmitted by blood-feeding invertebrates, but there are different mechanisms among the varying species. Some, such as Trypanosoma equiperdum, are spread by direct contact. In an invertebrate host they are generally found in the intestine, but normally occupy the bloodstream or an intracellular environment in the vertebrate host.

<i>Trypanosoma brucei</i> Species of parasite

Trypanosoma brucei is a species of parasitic kinetoplastid belonging to the genus Trypanosoma. This parasite is the cause of vector-borne diseases of vertebrate animals, including humans, carried by species of tsetse fly in sub-Saharan Africa. In humans T. brucei causes African trypanosomiasis, or sleeping sickness. In animals it causes animal trypanosomiasis, also called nagana in cattle and horses. T. brucei has traditionally been grouped into three subspecies: T. b. brucei, T. b. gambiense and T. b. rhodesiense. The first is a parasite of non-human vertebrates, while the latter two are known to be parasites of humans. Only rarely can the T. b. brucei infect a human.

<i>Trypanosoma evansi</i> Species of protist

Trypanosoma evansi is a species of excavate trypanosome in the genus Trypanosoma that causes one form of surra in animals. It has been proposed that T. evansi is—like T. equiperdum—a derivative of T. brucei. Due to this loss of part of the mitochondrial (kinetoplast) DNA T. evansi is not capable of infecting the invertebrate vector and establishing the subsequent life-stages. Due to its mechanical transmission T. evansi is not restricted to transmission via the tsetse fly but shows a very broad vector specificity including the genera Tabanus, Stomoxys, Haematopota, Chrysops and Lyperosia. It rarely causes disease in humans, indeed, it has only been recorded in cases where the patient lacks a normal component of human serum, Apolipoprotein L1. T. evansi is very common in India and Iran and causes acute disease in camels and horses, and chronic disease in cattle and buffalo. In Pakistan, it has been found to be the most prevalent trypanosome species in donkeys.

Crithidia fasciculata is a species of parasitic excavates. C. fasciculata, like other species of Crithidia have a single host life cycle with insect host, in the case of C. fasciculata this is the mosquito. C. fasciculata have low host species specificity and can infect many species of mosquito.

<i>Leishmania major</i>

Leishmania major is a species of parasites found in the genus Leishmania, and is associated with the disease zoonotic cutaneous leishmaniasis. L. major is an intracellular pathogen which infects the macrophages and dendritic cells of the immune system. Though Leishmania species are found on every continent aside from Antarctica, Leishmania major is found only in the Eastern Hemisphere, specifically in Northern Africa, the Middle East, Northwestern China, and Northwestern India.

<i>Leishmania donovani</i> Species of intracellular parasite

Leishmania donovani is a species of intracellular parasites belonging to the genus Leishmania, a group of haemoflagellate kinetoplastids that cause the disease leishmaniasis. It is a human blood parasite responsible for visceral leishmaniasis or kala-azar, the most severe form of leishmaniasis. It infects the mononuclear phagocyte system including spleen, liver and bone marrow. Infection is transmitted by species of sandfly belonging to the genus Phlebotomus in Old World and Lutzomyia in New World. The species complex it represents is prevalent throughout tropical and temperate regions including Africa, China, India, Nepal, southern Europe, Russia and South America. The species complex is responsible for thousands of deaths every year and has spread to 88 countries, with 350 million people at constant risk of infection and 0.5 million new cases in a year.

<i>Leishmania mexicana</i>

Leishmania mexicana belongs to the Leishmania genus and is the causal agent of cutaneous leishmaniasis in Mexico and central America.

<i>Trypanosoma antiquus</i> Extinct species in the kinetoplast class

Trypanosoma antiquus is an extinct species of kinetoplastid, a monophyletic group of unicellular parasitic flagellate protozoa.

Trypanosome may refer to:

<i>Paleoleishmania</i> Extinct genus of parasitic flagellate protist in the Kinetoplastea class

Paleoleishmania is an extinct genus of kinetoplastids, a monophyletic group of unicellular parasitic flagellate protozoa. At present it is placed in the family Trypanosomatidae. The genus contains two species, Paleoleishmania neotropicum and the type species Paleoleishmania proterus.

Trypanosoma irwini is a blood parasite of koalas. First discovered in 2009 by Linda M. McInnes and her peers, it was named in honor of Steve Irwin, "The Crocodile Hunter". The study done by McInnes et al. was the first to describe a Trypanosoma species from koalas.

<i>Angomonas deanei</i> Species of parasitic flagellate protist in the Kinetoplastea class

Angomonas deanei is a flagellated trypanosomatid protozoan. As an obligate parasite, it infects the gastrointestinal tract of insects, and is in turn a host to symbiotic bacteria. The bacterial endosymbiont maintains a permanent mutualistic relationship with the protozoan such that it is no longer able to reproduce and survive on its own. The symbiosis, subsequently also discovered in varying degrees in other protists such as Strigomonas culicis, Novymonas esmeraldas, Diplonema japonicumand Diplonema aggregatum are considered as good models for the understanding of the evolution of eukaryotes from prokaryotes, and on the origin of cell organelles.

Phytomonas is a genus of trypanosomatids that infect plant species. Initially described using existing genera in the family Trypanosomatidae, such as Trypanosoma or Leishmania, the nomenclature of Phytomonas was proposed in 1909 in light of their distinct hosts and morphology. When the term was originally coined, no strict criterion was followed, and the term was adopted by the scientific community to describe flagellate protozoa in plants as a matter of convenience. Members of the taxon are globally distributed and have been discovered in members of over 24 plant families. Of these 24, the two main families that are infected by Phytomonas are Euphorbiaceae and Asclepiadiacae. These protists have been found in hosts between 50° latitude North and South, and thus they can be found on all continents save for Antarctica.

<i>Blastocrithidia</i> Genus of parasitic flagellate protist in the Kinetoplastea class

Blastocrithidia is a genus of parasitic flagellate protist belonging to the family Trypanosomatidae. It is a monoxenous parasite of heteropteran insects, mainly inhabiting their hindgut and glands.

Wallaceina is a genus of parasitic flagellate protist belonging to the family Trypanosomatidae. This generic name is a replacement name for ProteomonasPodlipaev, Frolov et Kolesnikov, 1990 because the latter Proteomonas was already attributed to a cryptomonad. Wallaceina is a taxonomic patronym honoring the protistologist Franklin G. Wallace, a pioneer in the modern taxonomy of trypanosomatids.

<i>Leptomonas</i> Genus of parasitic flagellate protist in the Kinetoplastea class

Leptomonas is a genus of parasitic flagellate protist belonging to family Trypanosomatidae and subfamily Leishmaniinae sensu Maslov & Lukeš 2012. It is a monoxenous parasite of mainly Hemiptera, Diptera, and Siphonaptera insects.

<i>Strigomonas culicis</i> Species of parasitic flagellate protist in the Kinetoplastea class

Strigomonas culicis is a protist and member of flagellated trypanosomatids. It is an obligate parasite in the gastrointestinal tract of mosquito, and is in turn a host to symbiotic bacteria. It maintains strict mutualistic relationship with the bacteria as a sort of cell organelle (endosymbiont) so that it cannot lead an independent life without the bacteria. This and other symbiont-harbouring trypanosomatids such as Angomonas deanei are considered as "excellent models for the study of cell evolution because the host protozoan co-evolves with an intracellular bacterium in a mutualistic relationship", and "the origin of new organelles".

Novymonas esmeraldas is a protist and member of flagellated trypanosomatids. It is an obligate parasite in the gastrointestinal tract of a bug, and is in turn a host to symbiotic bacteria. It maintains strict mutualistic relationship with the bacteria as a sort of cell organelle (endosymbiont) so that it cannot lead an independent life without the bacteria. Its discovery in 2016 suggests that it is a good model in the evolution of prokaryotes into eukaryotes by symbiogenesis. The endosymbiotic bacterium was identified as member of the genus Pandoraea.


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