Theileria
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Theileria
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Theileria annulata |
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Theileria is a genus of parasitic protozoan that belongs to the phylum Apicomplexa and is closely related to Plasmodium. Two Theileria species, T. annulata and T. parva, are important cattle parasites.[1] T. annulata causes tropical theileriosis and T. parva causes East Coast fever. Theileria are transmitted by ticks.[2] The genomes of T. annulata and T. parva have been sequenced and published.[3][4]
Theileria equi is a known cause of equine piroplasmosis.[5]
Vaccines against Theileria are in development.[1][6] In May 2010, it was reported that a vaccine to protect cattle against East Coast fever had been approved and registered by the governments of Kenya, Malawi and Tanzania.[7]
Contents
Description
Species in this genus undergo exoerythrocytic merogony in the lymphocytes, histiocytes, erythroblasts and other cells of the internal organs.
This is followed by invasion of the erythrocytes by the merozoites, which may or may not reproduce.
When merogony does occur no more than four daughter cells are produced.
The frequent occurrence of elongate bacillary or "bayonet" forms within the erythrocyte is considered as characteristic of this genus.
The organism is transmitted by various tick species including Rhipicephalus, Dermacentor and Haemaphysalis. The organism reproduces in the tick as it progresses through its life stages.[8]
Both T annulata and T parva induce transformation of infected cells of lymphocyte or macrophage/monocyte lineages. T orientalis does not induce uncontrolled proliferation of infected leukocytes and instead multiplies predominantly within infected erythrocytes.
Genomics
The genome of T. orientalis has been sequenced.[9]
Evolution
The genus is thought to have first appeared in ruminants during the Miocene.
Transmission
Theileria can be transmitted to cattle through tick bites, including the brown ear tick Rhipicephalus spp.
Important species
Theileria parva
The cause of bovine Theileriosis and East Coast fever.[8]
Theileria annulata
Also the cause of bovine Theileriosis.[8]
Theileria equi
Causing equine piroplasmosis.[8]
References
- ↑ 1.0 1.1 Lua error in package.lua at line 80: module 'strict' not found.
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- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found. SciDev.net (7 May 2010).
- ↑ 8.0 8.1 8.2 8.3 *Theileria reviewed and published by WikiVet, accessed 11 October 2011.
- ↑ Hayashida K, Hara Y, Abe T, Yamasaki C, Toyoda A, Kosuge T, Suzuki Y, Sato Y, Kawashima S, Katayama T, Wakaguri H, Inoue N, Homma K, Tada-Umezaki M, Yagi Y, Fujii Y, Habara T, Kanehisa M, Watanabe H, Ito K, Gojobori T, Sugawara H, Imanishi T, Weir W, Gardner M, Pain A, Shiels B, Hattori M, Nene V, Sugimoto C (2012) Comparative genome analysis of three eukaryotic parasites with differing abilities to transform leukocytes reveals key mediators of theileria-induced leukocyte transformation. MBio 3(5). pii: e00204-12. doi: 10.1128/mBio.00204-12
