Difference between revisions of "Theileria"
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{{Taxobox | {{Taxobox | ||
| − | |name = Theileria spp | + | |name = ''Theileria'' spp |
|kingdom = Protista | |kingdom = Protista | ||
|sub-kingdom = | |sub-kingdom = | ||
| − | |phylum =Protozoa | + | |phylum = [[:Category:Protozoa|Protozoa]] |
|super-class = | |super-class = | ||
|class = | |class = | ||
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|sub-family = | |sub-family = | ||
|genus = Theileria | |genus = Theileria | ||
| − | |species = Theileria parva and others | + | |species = ''Theileria parva'' and others |
}} | }} | ||
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==Introduction== | ==Introduction== | ||
| + | [[Image:Theileria parva life cycle.jpg|thumb|right|300px|''Theileria parva'' Life Cycle Diagram - Dennis Jacobs & Mark Fox RVC]] | ||
| + | [[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]] | ||
''Theileria'' species are a group of '''[[Protozoa | protozoan]]''' pathogens causing severe '''lymphatic proliferative disease''' in cattle. | ''Theileria'' species are a group of '''[[Protozoa | protozoan]]''' pathogens causing severe '''lymphatic proliferative disease''' in cattle. | ||
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==Lifecycle== | ==Lifecycle== | ||
| − | + | ''Theileria'' are transmitted via the [[Haemaphysalis spp.|''Haemaphysalis'']] and [[Rhipicephalus spp.|''Rhipicephalus'']] and [[Dermacentor spp.|''Dermacentor'']] species of '''[[Ticks|tick]] vectors'''. | |
| − | ''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. | '''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'''. | + | 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. | 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 | | + | 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]]'''. | Transmission in the tick is then '''[[Ticks#Disease Transmission|trans-stadial]]'''. | ||
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==Diseases== | ==Diseases== | ||
| − | + | <big><b>[[Theileriosis - Cattle |Bovine Theileriosis]] | |
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| − | [[Theileriosis - Cattle | Bovine Theileriosis | ||
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| − | + | [[East Coast Fever]]</b></big> | |
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| − | + | ==''Theileria parva''== | |
| + | Also Known As:''' ''T. mutans'' and ''T. sergenti''. | ||
| − | + | ''T. parva is primarily a parasite of '''African buffalo''' and the cause of '''[[Theileriosis - Cattle | Bovine Theileriosis]]''' and '''[[East Coast Fever]]'''. It is transmitted by a wide range of [[Ticks |tick]] hosts and also the burrowing mite, '''''[[Sarcoptes | Sarcoptes scabei]]'''''. | |
| − | The | + | The protozoa form '''rod shaped''' piroplasms within host [[Erythrocytes | erythrocytes]]. |
| − | + | ''T. parva'' shows extreme antigenic diversity across its geographical distribution, although parasites isolated in different diseases are genetically identical. | |
| − | + | Sheep and mice can also be infected. | |
| − | + | ==''Theileria annulata''== | |
| + | Also Known As: '''''T. dispar'' | ||
| − | + | ''T. annulata'' is also a cause of [[Theileriosis - Cattle |Bovine Theileriosis]]. The parasite infects '''[[Macrophages |macrophages]]''' and '''[[B cells| B Lymphocytes]]''' forming '''round or oval''' piroplasma within host [[Erythrocytes | erythrocytes]]. | |
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| − | + | It also infects sheep and yaks. | |
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==References== | ==References== | ||
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[[Piroplasmida_Flashcards|Piroplasmida Flashcards]] | [[Piroplasmida_Flashcards|Piroplasmida Flashcards]] | ||
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| + | {{review}} | ||
[[Category:Piroplasmida]] | [[Category:Piroplasmida]] | ||
| − | [[Category: | + | [[Category:CABI Expert Review]] |
Revision as of 14:44, 4 June 2011
| Theileria spp | |
|---|---|
| Kingdom | Protista |
| Phylum | Protozoa |
| Order | Piroplasmorida |
| Family | Theileriidae |
| Genus | Theileria |
| Species | Theileria parva and others |
Introduction
Theileria species are a group of 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
Theileria are transmitted via the Haemaphysalis and Rhipicephalus and Dermacentor species of 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 are first infected.
Schizonts then disseminate through the lymphoid tissues before differentiating into merozoites.
The merozoites enter the 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 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 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 are killed by invading protozoa and later in disease, lymphopoeisis is reduced and prevented.
Diseases
Theileria parva
Also Known As: T. mutans and T. sergenti.
T. parva is primarily a parasite of African buffalo and the cause of Bovine Theileriosis and East Coast Fever. It is transmitted by a wide range of tick hosts and also the burrowing mite, Sarcoptes scabei.
The protozoa form rod shaped piroplasms within host erythrocytes.
T. parva shows extreme antigenic diversity across its geographical distribution, although parasites isolated in different diseases are genetically identical.
Sheep and mice can also be infected.
Theileria annulata
Also Known As: T. dispar
T. annulata is also a cause of Bovine Theileriosis. The parasite infects macrophages and B Lymphocytes forming round or oval piroplasma within host erythrocytes.
It also infects sheep and yaks.
References
Animal Health & Production Compendium, Theileria datasheet, accessed 04/06/2011 @ http://www.cabi.org/ahpc/
Test yourself with the Piroplasmida Flashcards
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