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| | + | Also known as: '''''Equine viral encephalomyelitis — Equine viral encephalitides — Equine viral encephalomyelitides''''' |
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| − | ====Description==== | + | ==Introduction== |
| − | Viraemia during the acute phase of EEE and WEE. Incubation period of 1-3weeks after experimental infection with EEE or WEE. Incubtion often shorter with EEE. CNS replication within a week
| + | Viral diseases affecting the central nervous system (CNS) of equidae causing encephalitis or meningoencephalitis. Most commonly involves [[Equine Togaviral Encephalitis]]. |
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| − | ====Epidemiology==== | + | ==Aetiology== |
| − | Transfer via '''vector''': mostly through '''[[Culicidae|mosquito salivary transfer]]'''
| + | Infection with any of the following viruses can cause CNS disease in horses: |
| − | Disease amplification occurs during the viraemic phase which lasts until nervous signs develop.
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| − | ====Signalment====
| + | Family Bornaviridae, Genus ''Bornavirus'' |
| | + | *Borna Disease Virus |
| | + | Family Bunyaviridae, Genus ''Bunyamweravirus'' |
| | + | *Cache Valley Virus |
| | + | Family Bunyaviridae, Genus ''Orthobunyavirus'' |
| | + | *California Encephalitis viruses <ref>Bertone, J.J (2010) Viral Encephalitis in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) '''Equine Internal Medicine''' (Third Edition), ''Saunders'', Chapter 12.</ref> |
| | + | **Snowshoe Hare Virus |
| | + | **Jamestown Canyon Virus |
| | + | *Main Drain Virus |
| | + | Family [[:Category:Flaviviridae|Flaviviridae]], Genus [[:Category:Flaviviruses|''Flavivirus'']] |
| | + | *[[Japanese Encephalitis Virus]] |
| | + | *Kunjin Virus |
| | + | *[[Louping Ill|Louping Ill Virus]] |
| | + | *Murray Valley Virus |
| | + | *Powassan virus |
| | + | *St. Louis Encephalitis Virus |
| | + | *[[West Nile Virus|West Nile Virus (WNV) **]] |
| | + | Family [[:Category:Paramyxoviridae|Paramyxoviridae]], Genus ''Henipavirus'' |
| | + | *[[Nipah Virus]] |
| | + | Family [[:Category:Rhabdoviridae|Rhabdoviridae]], Genus ''Lyssavirus'' |
| | + | *[[Rabies]] Virus |
| | + | Family [[:Category:Reoviridae|Reoviridae]], Genus ''Orbivirus'' |
| | + | *Equine Encephalosis Virus |
| | + | [[:Category:Togaviridae|Family Togaviridae]], Genus [[Equine Encephalitis Virus|''Alphavirus'']] |
| | + | *Aura Virus |
| | + | *Eastern Equine Encephalitis Virus (EEV) ** |
| | + | *Western EEV ** |
| | + | *Venezuelan EEV ** |
| | + | *Highlands J Virus |
| | + | *Getah Virus |
| | + | *Semliki Forest Virus |
| | + | *Ross River Virus |
| | + | *Una Virus |
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| − | ====Diagnosis====
| + | Other viruses implicated in equine encephalitis: |
| − | Clinical signs. Virus isolation can be performed from blood or spinal fluid
| + | *Maguari Virus<ref>Calisher, C.H, Monath, T.P, Sabattini, M.S, Mitchell, C.J, Lazuick, J.S, Tesh, R.B, Cropp, C.B (1987) A newly recognised vesiculovirus, Calchaqui virus, and subtypes of Melao and Maguari viruses from Argentina, with serologic evidence for infections of humans and horses, ''Am J Trop Med Hyg'', 36:114-119. In: Bertone, J.J (2010) Viral Encephalitis in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) '''Equine Internal Medicine''' (Third Edition), ''Saunders'', Chapter 12.</ref> |
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| − | ====Clinical Signs==== | + | ==Legislation== |
| − | Worse in unvaccinated animals. Acute signs of EEE and WEE are nonspecific, last up to 5 days and include:
| + | Diseases caused by some of the viruses listed above (**) are subject to The Infectious Diseases of Horses Order 1987. "''The Order, which revoked and replaced earlier legislation, makes these diseases compulsorily notifiable: it gives an inspector powers to declare an infected place where disease is suspected; to carry out a veterinary inquiry, prohibits the movement of horses carcases and other things onto or off the premises and requires cleansing and disinfection''". Council Directive 90/426 describes all cases of equine encephalomyelitis (regardless of cause) as compulsorily notifiable to the EU.<ref>http://www.defra.gov.uk/foodfarm/farmanimal/diseases/atoz/viralenceph/index.htm</ref> |
| − | *mild to severe pyrexia
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| − | *anorexia
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| − | *stiffness
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| − | Early signs transient and often missed:
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| − | *pyrexia
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| − | *mild depression
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| − | Disease progression occurs more frequently with EEE than WEE:
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| − | *fever may rise and fall sporadically
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| − | Cerebral signs often occur a few days post-infection (but can occur at any time. In the acute phase the following may be noted:
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| − | *propulsive walking
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| − | *depression
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| − | *somnolence
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| − | *hyperaesthesia
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| − | *agression
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| − | *excitability
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| − | *frenzy in response to sensory stimulation
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| − | *conscious proprioceptive deficits
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| − | With progression, worsening cerebral cortical and cranial nerve dysfunction may result in:
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| − | *head pressing
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| − | *propulsive walking
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| − | *blindness
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| − | *circling
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| − | *head tilt
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| − | *facial and appendicular muscle fasciculations
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| − | *paralysis of pharynx, larynx and tongue
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| − | *recumbency for 1-7 days followed by death
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| − | VEE may have similar or different clinical presentations to WEE and EEE, which may relate to a persistently hightitre viraemia with VEE and differences in strain pathogenicity:
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| − | *pyrexia peaks early and remains high throuhgout the disease course
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| − | *mild fever and leukopenia associated experimentally with endemic strains
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| − | *severe pyrexia and leukopenia associated with epidemic strains
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| − | *diarrhoea, severe depression recumbency and death may precede neurological signs
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| − | *neurological signs around 4 days post-infection
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| − | *other associated signs: abortion, oral ulceration, pulmonary haemorrhage, epistaxis
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| | + | {{Learning |
| | + | |full text = [http://www.cabi.org/cabdirect/FullTextPDF/2005/20053177514.pdf ''' Update on viral encephalitis, encephalomyelitis and myeloencephalopathy.''' Traub-Dargatz, J.; Eastern States Veterinary Association, Gainesville, USA, Proceedings of the North American Veterinary Conference. Large animal. Volume 19, Orlando, Florida, USA, 8-12 January, 2005, 2005, pp 274-278, 10 ref.] |
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| − | *Paralysis of the lips
| + | ==References== |
| − | *Drooping eyelids
| + | <references/> |
| − | *Incoordination
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| − | ====Laboratory Tests====
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| − | ====Biopsy====
| + | {{review}} |
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| − | ====Pathology====
| + | {{OpenPages}} |
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| − | ====Treatment====
| + | [[Category:Expert_Review]] |
| − | | + | [[Category:Neurological Diseases - Horse]] |
| − | ====Prognosis====
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| − | Often '''fatal''', comatose animals rarely survive. Survivors exhibit functional improvement over weeks to months.
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| − | ====Control====
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| − | Annual '''vaccination'''. Vector control. Human vaccination recommended for vets in endemic areas
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| − | ====References====
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| − | '''[[Venezuelan Equine Encephalomyelitis (VEE) - Donkey|VEE in Donkeys]]'''
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| − | [[Category:Togaviridae]] | |
| − | [[Category:Horse]] | |
| − | [[Category:To_Do_-_Viruses]]
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| − | [[Category:To_Do_-_Nina]]
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