Difference between revisions of "Theileria"

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{{OpenPagesTop}}
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[[Image:Theileria parva life cycle.jpg|thumb|right|150px|''Theileria parva'' Life Cycle Diagram - Dennis Jacobs & Mark Fox RVC]]
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{{Taxobox
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[[Image:Lymph node smear East Coast Fever.jpg|thumb|right|150px|Lymph node smear of a cow with East Coast Fever - Drs. Elizabeth Howerth and Bruce LeRoy, Department of Pathology, UGA College of Veterinary Medicine]]
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|name              = ''Theileria'' spp
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[[Image:H and E stain brain East Coast Fever.jpg|thumb|right|150px|H and E stain of brain and meningal vessels of a cow with East Coast Fever - Drs. Elizabeth Howerth and Bruce LeRoy, Department of Pathology, UGA College of Veterinary Medicine]]
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|kingdom            = Protista
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[[Image:Theileria cervi.jpg|thumb|right|150px|''Theileria cervi'' (deer) - Drs. Elizabeth Howerth and Bruce LeRoy, Department of Pathology, UGA College of Veterinary Medicine]]#
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|sub-kingdom        =
 
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|phylum            = [[:Category:Protozoa|Protozoa]]
 
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|super-class        =
 
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|class              =
 
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|sub-class          =
 
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|super-order        =
 
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|order              = Piroplasmorida
 
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|sub-order          =
 
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|super-family      =
 
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|family            = Theileriidae
 
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|sub-family        =
 
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|genus              = Theileria
 
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|species            = ''Theileria parva'' and others
 
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}}
 
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==Introduction==
 
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[[Image:Theileria parva life cycle.jpg|thumb|right|300px|''Theileria parva'' Life Cycle Diagram - Dennis Jacobs & Mark Fox RVC]]
 
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[[File:Theileria_lifecycle.gif|thumb|200px|right|''Theileria'' Lifecycle]]
 
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''Theileria'' species are a group of '''[[Protozoa | protozoan]]''' pathogens causing severe '''lymphatic proliferative disease''' in cattle.
 
  
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'''''T. parva''''' is the species of most veterinary importance, affecting cattle in Central and Eastern Africa and is the cause of [[East Coast Fever | East Coast Fever]].
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*Main species of veterinary importance is ''Theileria parva''
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**Causes '''East Coast Fever'''
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***Severe, proliferative lymphatic disease of cattle
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***Central and Eastern Africa
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***Transmitted by [[Hard Ticks - Overseas|''Rhipicephalus appendiculatus'']]
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***[[Ticks#Disease Transmission|Trans-stadial]] transmission
  
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Other species cause significant economic losses in the Mediterranean, Middle East and Northern Africa.
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*Other ''Theileria'' species cause production losses in cattle and sheep in the Middle East, Mediterranean and in Northern Africa
  
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==Lifecycle==
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'''Life Cycle'''
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''Theileria'' are transmitted via the [[Haemaphysalis spp.|''Haemaphysalis'']] and [[Rhipicephalus spp.|''Rhipicephalus'']] species of '''[[Ticks|tick]] vectors'''.
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*Incubation phase lasts 1 week
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'''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.
 
  
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Schizonts then '''disseminate''' through the '''[[:Category:Primary Lymphoid Tissue | lymphoid tissues]]''' before differentiating into '''merozoites'''.
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*Lymphoblast proliferation
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**Local [[Lymph Nodes - Anatomy & Physiology|lymph node]] first infected then spreads through body
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**Occurs in week two
  
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The merozoites enter the '''[[Erythrocytes | erythrocytes]]''' and form '''piroplasms''' which are '''infective to ticks''' and capable of sexual reproduction.
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*Lymphoid depletion
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**[[Lymphocytes|Lymphocytes]] killed
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**Decreases lymphopoiesis
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**Occurs in week 3
  
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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.
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*Total incubation period takes about 18 days
  
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Transmission in the tick is then '''[[Ticks#Disease Transmission|trans-stadial]]'''.
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'''Diagnosis'''
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*Clinical signs
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**Pyrexia
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**Enlarged local [[Lymph Nodes - Anatomy & Physiology|lymph node]]
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***Usually parotid [[Lymph Nodes - Anatomy & Physiology|lymph node]] as [[Hard Ticks - Overseas|''Rhipicephalus appendiculatus'']] feeds in the ear
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**Loss of condition
  
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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.
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*Examine Giemsa stained smears of:
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**Local [[Lymph Nodes - Anatomy & Physiology|lymph node]] aspirated for schizonts
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**Blood smears for piroplasms in red blood cells
  
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For more information on ticks as vectors, see [[Tick Disease Transmission]].
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*Post-mortem
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**Pulmonary oedema
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**Gut mucosal haemorrhages
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**[[Lymph Nodes - Anatomy & Physiology|Lymph node]] and [[Spleen - Anatomy & Physiology|splenic]] cellular atrophy
  
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==Pathogenesis==
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'''Control'''
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[[Lymphocytes - Introduction|Lymphocytes]] are '''killed''' by invading protozoa and later in disease, '''lymphopoeisis''' is reduced and prevented.
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*Integrated control of both the [[Tick Control|tick vector]] and disease
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**[[Vaccines - WikiBlood|Vaccination]] and [[Ectoparasiticides]]
  
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==Diseases==
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*Current [[Vaccines - WikiBlood|vaccination]] is live unattentuated
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<big><b>[[Theileriosis - Cattle |Bovine Theileriosis]]
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**Contains frozen stabilate of ground up tick gut containing infective sporozoites
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**Long lasting oxytetracycline administered at the same time to slow down schizogony giving the immune response time to develop[[Category:Piroplasmida]]
  
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[[East Coast Fever]]
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[[Category:To_Do_-_Parasites]]
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[[Babesiosis - Horse|Equine Babesiosis]]</b></big>
 
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==''Theileria parva''==
 
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''T. parva'' is primarily a parasite of '''African buffalo''' and the cause of '''[[Theileriosis - Cattle | Bovine Theileriosis]]''' and '''[[East Coast Fever]]'''. It may be transmitted by a wide range of [[Ticks |tick]] hosts although ''Rhipicephalus appeniculatus'' is the most importnat in the field.
 
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The protozoa form '''rod shaped''' piroplasms within host [[Erythrocytes | erythrocytes]].
 
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Sheep and mice can also be infected.
 
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==''Theileria annulata''==
 
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Also Known As: '''''T. dispar''
 
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''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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==''Theileria equi''==
 
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''Theileria equi'' (formerly ''Babesia equi'') and ''Babesia caballi'' cause [[Babesiosis - Horse|babesiosis in horses]].
 
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{{Learning
 
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|flashcards = [[Piroplasmida_Flashcards|Piroplasmida Flashcards]]
 
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}}
 
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==References==
 
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<references/>
 
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{{CABI source
 
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|datasheet = [http://www.cabi.org/ahpc/?compid=3&dsid=96673&loadmodule=datasheet&page=2144&site=160 Theileria]
 
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|date = 4/06/2011
 
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}}
 
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<br><br><br>
 
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{{Nick Lyons
 
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|date = July 8, 2012}}
 
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==Webinars==
 
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<rss max="10" highlight="none">https://www.thewebinarvet.com/parasitology/webinars/feed</rss>
 
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[[Category:Piroplasmida]]
 
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[[Category:CABI Expert Review]][[Category:CABI AHPC Pages]]
 
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[[Category:Nick Lyons reviewed]]
 

Revision as of 12:08, 2 August 2010

Theileria parva Life Cycle Diagram - Dennis Jacobs & Mark Fox RVC
File:Lymph node smear East Coast Fever.jpg
Lymph node smear of a cow with East Coast Fever - Drs. Elizabeth Howerth and Bruce LeRoy, Department of Pathology, UGA College of Veterinary Medicine
File:H and E stain brain East Coast Fever.jpg
H and E stain of brain and meningal vessels of a cow with East Coast Fever - Drs. Elizabeth Howerth and Bruce LeRoy, Department of Pathology, UGA College of Veterinary Medicine
Theileria cervi (deer) - Drs. Elizabeth Howerth and Bruce LeRoy, Department of Pathology, UGA College of Veterinary Medicine

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  • Main species of veterinary importance is Theileria parva
  • Other Theileria species cause production losses in cattle and sheep in the Middle East, Mediterranean and in Northern Africa

Life Cycle

  • Incubation phase lasts 1 week
  • Lymphoblast proliferation
    • Local lymph node first infected then spreads through body
    • Occurs in week two
  • Lymphoid depletion
    • Lymphocytes killed
    • Decreases lymphopoiesis
    • Occurs in week 3
  • Total incubation period takes about 18 days

Diagnosis

  • Examine Giemsa stained smears of:
    • Local lymph node aspirated for schizonts
    • Blood smears for piroplasms in red blood cells
  • Post-mortem

Control

  • Current vaccination is live unattentuated
    • Contains frozen stabilate of ground up tick gut containing infective sporozoites
    • Long lasting oxytetracycline administered at the same time to slow down schizogony giving the immune response time to develop
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