A genus of protozoan parasites in the family Theileriidae. They are transmitted by ticks, multiply in leukocytes and then invade erythrocytes.
- T. annulata (syn. T. dispar) — found in cattle and water buffalo, transmitted by Hyalomma spp. ticks and causes a clinical disease similar to east coast fever.
- T. buffali — found in cattle and buffalo in Australia and transmitted by Haemaphysalis longicornis and H. bancrofti. Similar to T. mutans. Only sporadic cases of clinical disease and is seen mostly in splenectomized calves.
- T. camalensis — found in camels, transmission thought to be by Hyalomma spp. ticks.
- T. cervi — nonpathogenic, found in splenectomized deer.
- T. dispar — see Theileria annulata (above).
- T. hirci — found in sheep and goats. Transmitting vector uncertain but probably the tick Rhipicephalus bursa. Causes a disease similar to east coast fever in cattle.
- T. lawrenci — found in cattle, buffalo and water buffalo. Transmitted by the tick Rhipicephalus appendiculatus; causes fatal corridor disease.
- T. mutans — found in cattle, transmitted by ticks including Rhipicephalus and Haemaphysalis spp. and causes a benign bovine theileriasis.
- T. orientalis — usually benign but can cause severe anemia in imported cattle.
- T. ornithorhynci — found in platypus.
- T. ovis — found in sheep and goats, transmitted by ticks of the genera Rhipicephalus, Dermacentor, Haemaphysalis and Ornithodoros spp. It causes a mild form of theileriasis.
- T. parva — found in cattle, African buffalo and Indian water buffalo; transmitted by Rhipicephalus appendiculatus and possibly other ticks. It causes the widespread and serious disease east coast fever.
- T. sergenti — doubtful identity; mostly benign in cattle.
- T. tarandi — found in reindeer, transmitted by Ixodes persulcatus and causes an acute disease.
- T. taurotragi — mildly pathogenic; found in cattle in Africa, Asia.
- T. velifera — mildly pathogenic; found in cattle.
