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.
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.
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.
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.
The genome of T. orientalis has been sequenced.
Theileria can be transmitted to cattle through tick bites, including the brown ear tick Rhipicephalus spp.
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- Theileria annulata sequencing project
- Theileria parva sequencing project
- Tropical theileriosis - Wellcome Trust project