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|species = Theileria parva and others
|species = Theileria parva and others
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==Introduction==
''Theileria'' species are a group of '''[[Protozoa | protozoan]]''' pathogens causing severe '''lymphatic proliferative disease''' in cattle.
'''''T. parva''''' is the species of most veterinary importance, affecting cattle in Central and Eastern Africa.
Other species cause significant economic losses in the Mediterranean, Middle East and Northern Africa.
==Lifecycle==
[[Image:Theileria parva life cycle.jpg|thumb|right|150px|''Theileria parva'' Life Cycle Diagram - Dennis Jacobs & Mark Fox RVC]]
''Theileria'' are transmitted via the ''Haemaphysalis'' and ''Rhipicephalus'' and ''Dermacentor'' species of '''[[Ticks | tick]] vectors'''.
'''Sporozoites''' enter '''mononuclear''' cells of the host and develop into '''trophozoites''' and multinucleate '''schizonts''' by '''asexual''' reproduction. This process stimulates proliferation of the host cells, allowing further multiplication of the parasite. The local '''[[Lymph Nodes - Anatomy & Physiology|lymph nodes]]''' are first infected.
Schizonts then '''disseminate''' through the '''[[Category:Primary Lymphoid Tissue | lymphoid tissues]]''' before differentiating into '''merozoites'''.
The merozoites enter the '''[[Erythrocytes | erythrocytes]]''' and form '''piroplasms''' which are '''infective to ticks''' and capable of sexual reproduction.
Sexual reproduction occurs within the nymph and larval stages of the [[Ticks | tick]] and the final infective stage is present within the '''salivary glands''' and is transmitted to mammalian hosts when bloodfeeding.
Transmission in the tick is then '''[[Ticks#Disease Transmission|trans-stadial]]'''.
In endemic areas, '''endemic stability''' is often reached, in which most or all cattle may be infected and be carriers and most ticks are also infected, but young calves gain solid immunity from their immune dams and therefore rarely show clinical disease. This state however takes time to stabilise and will cause significant economic losses in the process.
For more information on ticks as vectors, see [[Tick Disease Transmission]].
==Pathogenesis==
[[Lymphocytes - Introduction|Lymphocytes]] are '''killed''' by invading protozoa and later in disease, '''lymphopoeisis''' is reduced and prevented.
==Diseases==
[[Image:Lymph node smear East Coast Fever.jpg|thumb|right|200px|Lymph node smear of a cow with East Coast Fever - Drs. Elizabeth Howerth and Bruce LeRoy, Department of Pathology, UGA College of Veterinary Medicine]]
[[Image:H and E stain brain East Coast Fever.jpg|thumb|right|200px|H and E stain of brain and meningeal vessels of a cow with East Coast Fever - Drs. Elizabeth Howerth and Bruce LeRoy, Department of Pathology, UGA College of Veterinary Medicine]]
[[Theileriosis - Cattle | Bovine Theileriosis]]
[[East Coast Fever]]
==Theileria parva==
Also Known As ''T. mutans'' and ''T. sergenti''.
Primarily a parasite of '''African buffalo'''.
Transmitted by a wide range of [[Ticks | tick]] hosts and also the burrowing mite, '''''[[Sarcoptes | Sarcoptes scabei]]'''''.
The cause of '''[[Theileriosis - Cattle | Bovine Theileriosis]]''' and '''[[East Coast Fever]]'''
Forms '''rod shaped''' piroplasms within host [[Erythrocytes | erythrocytes]].
Shows extreme antigenic diversity across its geographical distribution, although parasites isolated in different diseases are genetically identical.
Can also infect sheep and mice.
==Theileria annulata==
Also Known As ''T. dispar''
Also a cause of [[Theileriosis - Cattle | Bovine Theileriosis]]
Infects '''[[Macrophages | macrophages]]''' and '''[[B cells| B Lymphocytes]]'''.
Forms '''round or oval''' piroplasma within host [[Erythrocytes | erythrocytes]].
Also infects sheep and yaks
==References==
<references/>
Animal Health & Production Compendium, '''Theileria datasheet''', accessed 04/06/2011 @ http://www.cabi.org/ahpc/
==Test yourself with the Piroplasmida Flashcards==
[[Piroplasmida_Flashcards|Piroplasmida Flashcards]]
[[Category:Piroplasmida]]
[[Category:To_Do_-_CABI review]]