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Difference between revisions of "Equine Viral Encephalitis"
 
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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==
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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==
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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:
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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:
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Clinical signs.  Virus 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'', 36:114-119.  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====
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==Legislation==
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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>
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*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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*Paralysis of the lips
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{{Learning
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*Drooping eyelids
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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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*Incoordination
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}}
  
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====Laboratory Tests====
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==References==
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<references/>
  
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====Biopsy====
 
  
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====Pathology====
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{{review}}
  
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====Treatment====
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{{OpenPages}}
  
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====Prognosis====
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[[Category:Expert_Review]]
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Often '''fatal'''
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[[Category:Neurological Diseases - Horse]]
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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]]
 

Latest revision as of 15:25, 6 July 2012


Also known as: Equine viral encephalomyelitis — Equine viral encephalitides — Equine viral encephalomyelitides

Introduction

Viral diseases affecting the central nervous system (CNS) of equidae causing encephalitis or meningoencephalitis. Most commonly involves Equine Togaviral Encephalitis.

Aetiology

Infection with any of the following viruses can cause CNS disease in horses:

Family Bornaviridae, Genus Bornavirus

  • Borna Disease Virus

Family Bunyaviridae, Genus Bunyamweravirus

  • Cache Valley Virus

Family Bunyaviridae, Genus Orthobunyavirus

  • California Encephalitis viruses [1]
    • Snowshoe Hare Virus
    • Jamestown Canyon Virus
  • Main Drain Virus

Family Flaviviridae, Genus Flavivirus

Family Paramyxoviridae, Genus Henipavirus

Family Rhabdoviridae, Genus Lyssavirus

Family Reoviridae, Genus Orbivirus

  • Equine Encephalosis Virus

Family Togaviridae, Genus 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

Other viruses implicated in equine encephalitis:

  • Maguari Virus[2]

Legislation

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.[3]


Equine Viral Encephalitis Learning Resources
CABICABI logo.jpg
Full Text Articles
Full text articles available from CAB Abstract
(CABI log in required) 		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.


References

  1. ↑ 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.
  2. ↑ 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.
  3. ↑ http://www.defra.gov.uk/foodfarm/farmanimal/diseases/atoz/viralenceph/index.htm


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