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[[Category:To Do - CABI]]
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Also Known As: '''''Bovine Theileriosis — [[Theileria]] — [[East Coast Fever]] — Egyptian Fever — Tropical Theileriosis — Mediterranean Coast Fever'''''
Caused By: [[Theileria|'''''Theileria parva''''' — '''''Theileria annulata''''']]
==Introduction==
[[File:T_parva.gif|thumb|200px|right|''Theileria'' sp. inside erythrocytes of host]]
Theileriosis is a disease of mammals and birds caused by a [[protozoa | '''protozoal''']] pathogen which resides within the [[Lymphocytes - Introduction |lymphocytes]] and [[Macrophages|macrophages]].
[[Theileria|''T. parva'' and ''T. annulata'']] in cattle and ''T. lestoguardi'' in sheep are the most economically important in domestic ruminants.
''[[Theileria]]'' species are closely related to ''[[Babesia]]'' parasites.
==Signalment==
Buffalo, both domestic and wild, appear less susceptible to theileriosis.
'''Native animals''' also appear to have a higher degree of '''innate tolerance''' in endemic areas than those that are imported, even if of the same breed.
'''Friesians''' appear particularly susceptible to infection with ''[[Theileria]]'' species.
[[Parturition Endocrine Control - Anatomy & Physiology |Parturition]], [[Lactation - Anatomy & Physiology |lactation]] and stress can make an animal vulnerable to theileriosis, as they can to any disease.
Age linked tolerance may make younger calves more tolerant of disease than adults in some areas.
==Distribution==
Distribution of disease depends on the presence of [[Ticks|tick]] vectors and thus is primarily in '''tropical regions'''. Various species of tick are implicated.
The distribution of theileriosis is increasing all the time.
==Transmission==
[[File:Theileria_lifecycle.gif|thumb|200px|right|Theileria Lifecycle]]
''[[Theileria]]'' species first invade the local '''[[Lymph Nodes - Anatomy & Physiology|lymph nodes]]''' of the hosts before forming schizonts and disseminating through the '''lymphoid tissues'''.
'''Asexual''' reproduction in the '''host''' is followed by '''sexual reproduction''' within the '''tick''' vector. The parasite is then transmitted through the '''salivary glands''' of the tick into the mammalian host during bloodfeeding.
For more information on ticks as vectors, see ''[[Theileria]]'' and [[Tick Disease Transmission]].
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.
==Clinical Signs==
[[File:Theileriosis_diarrhoea.jpg|thumb|200px|right|Bloody diarrhoea often seen in Theileriosis cases]]
'''Marked pyrexia''', '''[[Lymph Nodes - Anatomy & Physiology |lymph node enlargement]]''', '''dyspnoea''', '''epistaxis''', '''emaciation''', [[Diarrhoea |'''diarrhoea''']] and other GI signs.
'''Ocular signs''' and masses may develop.
Pruritus and '''skin lesions/plaques''' are also seen.
Neurological and reproductive signs may develop in chronic or endemic disease.
The degree of pyrexia, pathogen load and host susceptibility will determine the severity of clinical signs at presentation.
==Diagnosis==
Detection of parasite stages in thin '''blood smears''' with Giemsa staining. '''Schizonts''' should be looked for in thin smears from '''lymph node''' or '''liver''' biopsies.
On '''post-mortem examination''', blood is watery and carcasses are [[Icterus|icteric]] and gelatinised. Numerous petechiae may be present within the mucous membranes, gut mucosae and heart. The [[Liver - Anatomy & Physiology |liver]] is often pale and friable and the [[Gall Bladder - Anatomy & Physiology |gall bladder]] distended with dark green bile. Ulcers are often evident in the [[Abomasum - Anatomy & Physiology |abomasum]] of ruminants and are surrounded by haemorrhagic zones. Urine is dark brown due to the presence of [[Bilirubin |bilirubin]]. [[Pulmonary Oedema|Pulmonary oedema]] may be present.
Indirect Fluorescent Antibody Tests (IFAT) and [[ELISA testing |ELISAs]] are also available and are useful for identifying carrier animals.
Sporozoites can also be detected within the '''salivary glands''' of ticks by staining with methyl-green pyronin and more recently with '''PCR'''.
==Treatment==
'''Buparvaquone''' and '''Halofuginone''' chemotherapeutics and/or '''Tetracyclines''' are the treatments of choice.
==Control==
Control of '''tick vectors''' and use of '''tick resistant''' host species such as zebu cattle in endemic areas is effective but expensive.
Care should be taken when intensively dipping with [[Ectoparasiticides |ectoparasiticides]] to control ticks as upsurges in other tick borne diseases are not uncommon when programmes are interrupted.
'''Endemic stability''' can be encouraged by breeding indigenous or known carrier animals, although these are often still infective for ticks so '''separation''' from adult susceptible animals is essential to prevent further spread of disease.
'''Vaccines''' are available involving '''attenuated schizont-infected cells''' and are the mainstay of tropical theleriosis in endemic countries with highly susceptible cattle breeds.
{{Learning
|flashcards = [[Theileriosis - Cattle Flashcards]]
}}
==References==
<references/>
{{CABI source
|datasheet = [http://www.cabi.org/ahpc/?compid=3&dsid=62110&loadmodule=datasheet&page=2144&site=160 bovine theilerioses]
|date = 3 June 2011
}}
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