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Also Known As – TBEV – Spanish sheep encephalomyelitis – Exotic encephalitis – Turkish sheep encephalomyelitis
==Introduction==
Tickborne encephalitis is caused by a '''[[Flaviviridae|Flavivirus]]''' which may be due to any one of a '''large complex''' of [[Viruses|viral]] pathogens. They affect a '''wide range of hosts''' including ruminants, birds, rodents, carnivores and horses, but '''clinical disease is most commonly observed in dogs''' with most other infections remaining subclinical.
These diseases can also be '''zoonotic'''. Ruminants and dogs are thought to be the main source of infection for humans.<ref> Anon (1999) '''Flaviviridae'''. In: Murphy, F. A., Gibbs, E. P. J., Horzinek, M. C., Studdert, M. J. eds. '''Veterinary Virology'''. ''San Diego, USA: Academic Press'', 556-569</ref>
==Distribution==
'''Hanzalova Virus, Hypr Virus, Kumlinge Virus and Neudoerfl Virus''' are all found in Europe.
'''[[Louping Ill|Louping Ill Virus]], Central European Encephalitis Virus, Omsk Haemorhhagic Fever Virus, Russian Spring-Summer encephalitis virus, Absettariv Virus, Karshi Virus, Langat Virus, Negishi Virus, Royal Farm Virus and Sofyn Virus''' are all found in the Far East.
'''Carey Island Virus''' is only found on the Malaysian island of the same name and '''Phnom Penh Bat Virus''' in Cambodia.
'''Kyasanur Forest Disease Virus''' is found in India and the Middle-East.
'''Powassan Virus''' is restricted to North America.
The viruses are all spread by '''[[Ticks|tick]] vectors'''. For more information on the role of ticks in disease transmission, see [[Tick Disease Transmission|here]]. '''''[[Ixodes spp.]], [[Dermacentor spp.]]''''' and ''Haemaphysalis'' spp. are all implicated. Transmission is trans-stadial.
==Signalment==
A host of species can be affected with ruminants and dogs being the main species for clinical signs to manifest in.
Disease outbreaks tend to occur during the '''Summer months''' when the ticks are most active.
==Clinical Signs==
===Dogs===
'''Dogs''' exhibit '''neurological signs including tremors, stupor, tetraparesis, bunny hopping, seizures, blindness, delirium, hyperaesthesia aggression, circling, head pressing, dullness and mortalities.'''
===Ruminants===
'''Ruminants''' exhibit '''neurological signs, usually head tilt, facial paralysis, listlessness,blindness, hypermetria, opisthotonus, excess salivation''' and ataxia. They may bunny hop if weakness is severe. Animals are often anorexic and demonstrating discomfort and bruxism.
Respiratory signs can also occur.
===People===
Humans can be infected by ticks or by drinking unpasteurised milk from infected cattle.
TBE results in serious, '''acute central nervous system disease''' which may result in death or permanent/longterm neurological deficits. Onset is usually characterised by '''fever, headache and meningeal irritation''' followed by '''convulsions, colic and diarrhoea.'''
==Diagnosis==
In dogs confirmed with TBE infection, '''lymphohistiocytic meningitis''' is seen with '''neuronal necrosis, glial karyorrhexis and microglial proliferation'''. Perivascular cuffs can be present in all regions of the brain.
Viral antigen is most consistently found in the neuroparenchyma surrounding the '''fourth ventricle''' but also in the cerebellum, mesencephalon, thalamus, hippocampus and neocortex.<ref name="Wessenbock">Weissenböck, H (1999) '''Post-mortem diagnosis of tick-borne encephalitis in dogs'''. Tierärztliche Umschau, 54(5):249-255; 15</ref> CSF can also be used. Virus can be detected by immunohistology.<ref name="Weissenbock" /> '''Antibodies can be detected in serum and CSF by [[ELISA testing|ELISA]].'''
==Treatment==
'''Palliative''' care is the only option once infected. There is no cure for TBE.
==Control==
'''Humans are protected by vaccines''' but they are not commercially available in animals.
'''Reduction of exposure to ticks and tick removal''' is valuable but difficult.
{{Learning
|flashcards = [[Tickborne Encephalitis Virus Flashcards]]
}}
==References==
<references/>
Animal Health & Production Compendium, '''Tickborne Encephalitis Virus datasheet''', accessed 06/07/2011 @ http://www.cabi.org/ahpc/
Animal Health & Production Compendium, '''Tickborne Encephalitis datasheet''', accessed 06/07/2011 @ http://www.cabi.org/ahpc/
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