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Also known as: '''''Equine viral encephalomyelitis — Equine viral encephalitides — Equine viral encephalomyelitides'''''
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====Description====
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==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
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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====
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==Aetiology==
Transfer via '''vector''': mostly through '''[[Culicidae|mosquito salivary transfer]]'''
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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====
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Family Bornaviridae, Genus ''Bornavirus''
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*Borna Disease Virus
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Family Bunyaviridae, Genus ''Bunyamweravirus''
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*Cache Valley Virus
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Family Bunyaviridae, Genus ''Orthobunyavirus''
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*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>
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**Snowshoe Hare Virus
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**Jamestown Canyon Virus
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*Main Drain Virus
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Family [[:Category:Flaviviridae|Flaviviridae]], Genus [[:Category:Flaviviruses|''Flavivirus'']]
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*[[Japanese Encephalitis Virus]]
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*Kunjin Virus
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*[[Louping Ill|Louping Ill Virus]]
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*Murray Valley Virus
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*Powassan virus
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*St. Louis Encephalitis Virus
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*[[West Nile Virus|West Nile Virus (WNV) **]]
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Family [[:Category:Paramyxoviridae|Paramyxoviridae]], Genus ''Henipavirus''
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*[[Nipah Virus]]
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Family [[:Category:Rhabdoviridae|Rhabdoviridae]], Genus ''Lyssavirus''
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*[[Rabies]] Virus
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Family [[:Category:Reoviridae|Reoviridae]], Genus ''Orbivirus''
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*Equine Encephalosis Virus
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[[:Category:Togaviridae|Family Togaviridae]], Genus [[Equine Encephalitis Virus|''Alphavirus'']]
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*Aura Virus
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*Eastern Equine Encephalitis Virus (EEV) **
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*Western EEV **
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*Venezuelan EEV **
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*Highlands J Virus
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*Getah Virus
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*Semliki Forest Virus
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*Ross River Virus
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*Una Virus
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====Diagnosis====
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Other viruses implicated in equine encephalitis:
Clinical signsVirus isolation can be performed from blood or spinal fluid
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*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'', 36:114-119In: 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====
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==Legislation==
Worse in unvaccinated animals.  Acute signs of EEE and WEE are nonspecific, last up to 5 days and include:
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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 timeIn 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
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|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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}}
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*Paralysis of the lips
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==References==
*Drooping eyelids
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<references/>
*Incoordination
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====Laboratory Tests====
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====Biopsy====
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{{review}}
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====Pathology====
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{{OpenPages}}
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====Treatment====
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[[Category:Expert_Review]]
 
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[[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]]
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[[Category:Horse]]
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[[Category:To_Do_-_Viruses]]
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[[Category:To_Do_-_Nina]]
 
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