|
''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. ''T. annulata'' causes tropical theileriosis and ''T. parva'' causes East Coast fever. ''Theileria'' are transmitted by ticks. The genomes of ''T. annulata'' and ''T. parva'' have been sequenced and published. ''Theileria equi'' is a known cause of equine piroplasmosis. Vaccines against ''Theileria'' are in development.〔 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.〔(【引用サイトリンク】title=Cattle disease vaccine launched 30 years after invention ) SciDev.net (7 May 2010).〕 ==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.〔 *(Theileria ) reviewed and published by WikiVet, accessed 11 October 2011.〕 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Theileria」の詳細全文を読む スポンサード リンク
|