1,433
edits
Changes
Jump to navigation
Jump to search
no edit summary
[[Category:To Do - Steph]]
[[Category:To Do - Steph]]
Also Known As — '''''Bovine Theileriosis''''' — '''''[[Theileria]]''''' — '''''Theileria parva''''' — '''''Theileria annulata'''''
==Introduction==
Theileriosis is a disease of mammals and birds caused by a [[protozoa | '''protozoal''']] pathogen which resides within the [[Lymphocytes – Introduction | lymphocytes]] and [[Macrophages | macrophages]]
''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 and Physiology | lactation]] and stress can make an animal vulnerable to theileriosis, as they can 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 [[Ticks | tick]] are implicated.
The distribution of anaplasmosis is increasing all the time.
==Lifecycle and Transmission==
[[Theileria]] species replicate '''asexually''' in the host [[Primary Lymphoid Tissue | primary]] and [[Secondary Lymphoid Tissue | secondary]] '''lymphoid''' tissues, forming '''schizonts'''.
These then develop into '''piroplasma''' within the [[Erythrocytes | erythrocytes]].
These piroplasms include the gametes which are infective for ticks and capable of '''sexual reproduction'''.
Transmission is then '''trans-stadial'''.
Sexual reproduction of the parasite can only occur within the '''larval''' or '''nymph''' stage of the tick, in which '''sporogony''' can occur. The infective stage is within the '''salivary glands''' of the following stage of the tick.
The nymph or adult can then innoculate a mammalian host with the [[Protozoa | protozoan]].
Because of its dependence upon the tick, transmission of Theileriosis is also affected by environmental and seasonal conditions. These will vary with geographical location.
''Haemaphysalis'', ''Rhipicephalus'' and ''Dermacentor'' [[Ticks | tick]] species are all commonly implicated.
For more information on ticks as vectors, see [[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==
'''Fever''', '''lymph node enlargement''', '''dyspnoea''', '''emaciation''', [[Diarrhoea | '''diarrhoea''']].
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.
Indirect Fluorescent AntibodyTests (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/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 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 but are inefficient and undergoing improvement.
==References==
<references/>
'''Animal Health & Production Compendium''', ''Theileriosis datasheet'', accessed 02/06/2011 @ http://www.cabi.org/ahpc/