trypanosoma trypanosoma trypanosoma is a genus of kinetoplastids (class trypanosomatidae), 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 (requiring more than one obligatory host to complete life cycle) 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. this article is about the genus. for the humans-specifics pathogens, see trypanosoma brucei and trypanosoma cruzi. trypanosoma trypanosoma sp. among red blood cells. scientific classification domain: eukaryota phylum: euglenozoa class: kinetoplastea order: trypanosomatida family: trypanosomatidae genus: trypanosomagruby, 1843 subgenera aneza özdikmen 2009 duttonella (chalmers 1918) hoare 1964 herpetosoma doflein 1901 megatrypanum hoare 1964 nannomonas hoare 1964 pycnomonas hoare 1964 schizotrypanum (chagas 1909) trypanozoon (lühe 1906) hoare 1964 synonyms castellanella chalmers 1918 non pacheco & rodrigues 1930 duttonella chalmers 1918 haematomonas mitrophanow 1883 schizotrypanum chagas 1909 trypanozoon lühe 1906 trypanosomes infect a variety of hosts and cause various diseases, including the fatal human diseases sleeping sickness, caused by trypanosoma brucei, and chagas disease, caused by trypanosoma cruzi. the mitochondrial genome of the trypanosoma, as well as of other kinetoplastids, known as the kinetoplast, is made up of a highly complex series of catenated circles and minicircles and requires a cohort of proteins for organisation during cell division. history in 1841, gabriel valentin found flagellates that today are included in trypanoplasma in the blood of trout. the genus (t. sanguinis) was named by gruby in 1843, after parasites in the blood of frogs. in 1903, david bruce identified the protozoan parasite and the tsetse fly vector of african trypanosomiasis. taxonomy the monophyly of the genus trypanosoma is not supported by a number of different methods. rather, the american and african trypanosomes constitute distinct clades, implying that the major human disease agents t. cruzi (cause of chagas’ disease) and t. brucei (cause of african sleeping sickness) are not closely related to each other. phylogenetic analyses suggest an ancient split into a branch containing all salivarian trypanosomes and a branch containing all non-salivarian lineages. the latter branch splits into a clade containing bird, reptilian and stercorarian trypanosomes infecting mammals and a clade with a branch of fish trypanosomes and a branch of reptilian or amphibian lineages. salivarians are trypanosomes of the subgenera of duttonella, trypanozoon, pycnomonas and nannomonas. these trypanosomes are passed to the recipient in the saliva of the tsetse fly (glossina spp.). antigenic variation is a characteristic shared by the salivaria, which has been particularly well-studied in t. brucei. the trypanozoon subgenus contains the species trypanosoma brucei, t. rhodesiense and t. equiperdum. the subgenus duttonella contains the species t. vivax. nannomonas contains t. congolense. stercorians are trypanosomes passed to the recipient in the feces of insects from the subfamily triatominae (most importantly triatoma infestans). this group includes trypanosoma cruzi, t. lewisi, t. melophagium, t. nabiasi, t. rangeli, t. theileri, t. theodori. the subgenus herpetosoma contains the species t. lewisi. the subgenus schizotrypanum contains t. cruzi and a number of bat trypanosomes. the bat species include trypanosoma cruzi marinkellei, trypanosoma dionisii, trypanosoma erneyi, trypanosoma livingstonei and trypanosoma wauwau. other related species include trypanosoma conorhini and trypanosoma rangeli. evolution the ancestor of modern trypanosomes absorbed a green alga around one billion years ago and co-opted some of its genetic material. this has resulted in modern trypanosomes such as t. brucei containing essential genes for the breakdown of sugars that are most closely related to plants. this difference may be used as the target of therapies. the relationships between the species have not been worked out to date. it has been suggested that t. evansi arose from a clone of t. equiperdum which lost its maxicircles. it has also been proposed that t. evansi should be classified as a subspecies of t. brucei. it has been shown that t. equiperdum has emerged at least once in eastern africa and t. evansi at two independent occasions in western africa. selected species species of trypanosoma include the following: t. ambystomae. in amphibians t. antiquus, extinct (fossil in miocene amber) t. avium, which infects birds and blackflies t. bennetti, which infects birds and biting midges t. boissoni, in elasmobranch t. brucei, which causes sleeping sickness in humans and nagana in cattle t. cruzi, which causes chagas disease in humans trypanosoma culicavium, which infects birds and mosquitoes t. congolense, which causes nagana in ruminant livestock, horses and a wide range of wildlife t. equinum, in south american horses, transmitted via tabanidae, t. equiperdum, which causes dourine or covering sickness in horses and other equidae, it can be spread through coitus. t. evansi, which causes one form of the disease surra in certain animals including camels (a single case report of human infection in 2005 in india was successfully treated with suramin) t. everetti, in birds t. hosei, in amphibians t. irwini, in koalas t. lewisi, in rats t. melophagium, in sheep, transmitted via melophagus ovinus t. parroti, in amphibians t. percae, in the species perca fluviatilis t. phedinae t. rangeli, believed to be nonpathogenic to humans t. rotatorium, in amphibians t. rugosae, in amphibians t. sergenti, in amphibians t. simiae, which causes nagana in pigs. its main reservoirs are warthogs and bush pigs t. sinipercae, in fishes t. suis, which causes a different form of surra t. theileri, a large trypanosome infecting ruminants and transmitted by a variety of vectors including tabanids and mosquitoes t. thomasbancrofti, an avian trypanosome with culicine mosquito vector t. triglae, in marine teleosts t. tungarae, in frogs t. vivax, which causes the disease nagana, mainly in west africa, although it has spread to south america hosts, life cycle and morphologies