Difference between revisions of "Louping Ill"

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== Introduction  ==
  
====Hosts====
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This is a viral disease affecting sheep, grouse, hares, deer, elk, small rodents, ticks and humans; therefore the disease is zoonotic. The reservoir host for this disease is hard ticks (''[[Ixodes spp.|Ixodes ricinus]]'') and this is transmitted to the host by saliva when the tick bites. Therefore, spread mirrors seasonal tick activity.
*Sheep
 
*Grouse
 
*Hares
 
*Deer elk
 
*Small rodents
 
*Ticks (eg. ''Ixodes ricinus'')
 
*Man
 
  
====Pathogenesis====
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The virus replicates in [[macrophages]] causing pyrexia and then recovery. The second phase of the virus replication occurs in Purkinje cells of the cerebellum and motor nuclei of the brain stem.
*First phase:
 
**Pyrexia with virus in '''macrophages'''
 
**Recovery
 
*Second phase:
 
**Second replication in '''Purkinje cells''' of the cerebellum and '''motor nuclei''' of the brain stem
 
**Trembling, torticollis, and irregular gait
 
**In grouse: starvation
 
**In man: flu-like symptoms can be followed by coma, but recovery normal
 
  
====Epidemiology====
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== Clinical Signs ==
*Reservoir host: '''Ticks (''Ixodes ricinus'')'''
 
**Passed to host by '''saliva'''
 
**Virus can be spread '''between ticks''' when co-feeding on small rodents
 
*Spread mirrors seasonal tick activity
 
  
====Diagnosis====
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Signs in sheep include trembling, torticollis, and irregular gait. In grouse, the disease causes them to die of starvation. In humans, signs are flu-like and can be followed by a coma and rarely death. Usually however, recovery is normal.
*Clinical signs
 
*PM: virus isolation and histopathology of brain tissue
 
  
====Control====
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*Sheep dipping in '''acaracides''' (vector control)
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== Diagnosis  ==
*'''Inactivated vaccines''' in late pregnancy can '''boost maternal antibody'''
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**Lambs inoculated >4 months of age
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Diagnosis is by presence of clinical signs, plus knowledge of tick season. Definitive diagnosis can be achieved by virus isolation and histopathology of brain tissue.
*Human vaccination where at risk
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[[Category:Flaviviruses]][[Category:Sheep Viruses]][[Category:Poultry]][[Category:Zoonoses]][[Category:Rodents]]
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[[Category:To_Do_-_Clinical/Viruses]]
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== Control  ==
[[Category:Neurological Diseases - Sheep]]
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This can be achieved by dipping sheep in '''acaracides''' to control the vector, the tick. '''Inactivated [[vaccines]]''' in late pregnancy can be used to '''boost maternal antibody'''. Lambs are usually inoculated when over 4 months of age. A vaccine is available in humans for those at risk of the disease.
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== References ==
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Bridger, J and Russell, P (2007) '''Virology Study Book''', ''Royal Veterinary College''
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Radostits, O.M, Arundel, J.H, and Gay, C.C. (2000) '''Veterinary Medicine: a textbook of the diseases of cattle, sheep, pigs, goats and horses''' ''Elsevier Health Sciences''
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[[Category:Flaviviruses]] [[Category:Sheep_Viruses]] [[Category:Avian_Viruses]] [[Category:Zoonoses]] [[Category:Rodents]] [[Category:Expert_Review - Farm Animal]] [[Category:Neurological_Diseases_-_Sheep]]

Latest revision as of 16:59, 30 July 2012


Introduction

This is a viral disease affecting sheep, grouse, hares, deer, elk, small rodents, ticks and humans; therefore the disease is zoonotic. The reservoir host for this disease is hard ticks (Ixodes ricinus) and this is transmitted to the host by saliva when the tick bites. Therefore, spread mirrors seasonal tick activity.

The virus replicates in macrophages causing pyrexia and then recovery. The second phase of the virus replication occurs in Purkinje cells of the cerebellum and motor nuclei of the brain stem.

Clinical Signs

Signs in sheep include trembling, torticollis, and irregular gait. In grouse, the disease causes them to die of starvation. In humans, signs are flu-like and can be followed by a coma and rarely death. Usually however, recovery is normal.


Diagnosis

Diagnosis is by presence of clinical signs, plus knowledge of tick season. Definitive diagnosis can be achieved by virus isolation and histopathology of brain tissue.


Control

This can be achieved by dipping sheep in acaracides to control the vector, the tick. Inactivated vaccines in late pregnancy can be used to boost maternal antibody. Lambs are usually inoculated when over 4 months of age. A vaccine is available in humans for those at risk of the disease.


References

Bridger, J and Russell, P (2007) Virology Study Book, Royal Veterinary College

Radostits, O.M, Arundel, J.H, and Gay, C.C. (2000) Veterinary Medicine: a textbook of the diseases of cattle, sheep, pigs, goats and horses Elsevier Health Sciences




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