Difference between revisions of "Rotaviruses"

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== Introduction ==
 
  
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There are 5 distinct antigenic groups of rotaviruses; A to E. A is the most commonly seen and studied and this is further subdivided to G and P types. Rotaviruses are thought to be mostly species specific, but some transmission between species occurs. Group A is present in all mammals, whereas group B and C are only common in pigs. Strains are known to vary in virulence, but they are always confined to the gut.
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====Antigenicity====
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*5 distinct antigenic groups: A to E
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*A is the most commonly seen and studied
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*A is further subdivided to G and P types
  
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The  incubation period of the virus is around 1 - 4 days and the disease is most prevalent in neonates, where is can be very severe and even fatal. The disease occurs in neonates that have had a [[Failure of Passive Transfer|failure of passive transfer]] of colostrum, as rotavirus antibodies are found in colostrum and would provide protection from the disease for some time (species dependent). Transmission is via the faeco-oral route and the virus is highly infectious and will spread rapidly through a group of animals. The young tend to excrete the virus clinically or sub-clinically in their faeces as passive maternal antibodies wane.
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====Hosts====
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*RVs are thought to be mostly species specific, but some transmission between species occurs
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*Group A is present in all mammals
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*Groups B and C are common in pigs but not fully understood
  
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The target tissue of the virus is the '''small intestine enterocyte. '''The villi become stunted and so difficulty digesting food will occur. The virus is confined to the gut, i.e. there is no viraemia.
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====Pathogenesis====
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*Strains vary in virulence but are always confined to the gut
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*Incubation: 1-4 days
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*Target tissue: '''small intestine enteroycte'''
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**Infected enterocytes are shed, villi shorten, and become covered with immature cuboidal epithelium
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**As such, absorption is compromised
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*Results in '''white scour'''
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*NO viremia: confined to GIT
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*Associated symptoms:
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**Weight loss
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**Depression
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**Dehydration
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*Can be fatal if unchecked
  
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== Signalment ==
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====Epidemiology====
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*Occurs in neonates of most species, although the role of RVs in lamb and foal diarrhoea is less certain
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*NOT associated with diarrhoea in dogs and cats
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*Group A RVs are endemic in domestic animals worldwide
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*Orofecal transmission, highly infectious
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*Excreted in feces as maternal antibody wanes (calves: 2 weeks, piglets: post-weaning)
  
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Will affect neonates of most species, but particularly '''pigs '''and '''calves'''. Rotavirus is NOT associated with diarrhoea in dogs and cats.
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====Diagnosis====
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*On feces:
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**ELISA and Latex agglutination
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*On sera:
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**Rising antibody titres are not particularly helpful as most animals show high Ab levels from passive immunity
  
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== Clinical Signs ==
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====Control====
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*Ensure maternal antibody transfer through the reception of colostrum
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*Hygiene and management strategies: all-in/all-out, isolation of sick animals, etc.
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*Fluid therapy where necessary
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*Dam vaccine:
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**Boost and prolong Ab secretion during suckling
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**Primarily for beef suckler herds as dairy calves receive batch milk after 24 hours
  
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The characteristic clinical sign of the disease is ''''white scour'. '''The onset of diarrhoea is acute and can in severe cases lead to sudden death. Other clinical signs include depression, dehydration and weight loss.
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==Vilous atrophy in Enteritis==
  
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== Diagnosis ==
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* Affects young foals and calves.
  
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Signalment and clinical signs are suggestive of the condition.
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====Pathology====
  
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Care should be taken when examining faeces, as rotavirus is usually present in the faeces of clinically normal neonatal animals. [[ELISA testing|ELISA]] and Latex agglutination tests can be performed on faecal samples. Blood tests for serology can be used to show rising antibody titres, but this is not useful as the majority of animals have high levels of rotavirus antibody from maternal antibodies (passive immunity).
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=====Gross=====
  
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== Treatment and Control ==
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* [[Small Intestine - Anatomy & Physiology|small intestine]] distended with yellow fluid.
  
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There is no 'treatment' for this disease although fluids can be given to provide supportive therapy if severe dehydration is present.
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=====Histopathology=====
  
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Control measures include ensuring maternal antibody transfer to rotavirus has occurred by the ingestion of colostrum in the first 24 hours of life. This is the most important method of preventing this disease. Other control mechanisms include general hygiene strategies and management systems e.g. 'all in/ all out' systems and isolation of sick animals.
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* Loss of villus epithelium
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** Replacement with cuboidal or squamous cells
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There is a dam vaccine available in the UK in cattle. It is primarily used for beef suckler herds and is given pre-calving to ensure the dam has enough antibodies in her colostrum and to increase length of protection whilst the calf is suckling. It is not used in dairy herds as the calves are usually fed batch milk after 24 hours. There is no vaccine in the UK for sows.
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* [[:Category:Enteritis, Villus Atrophy|Villus atrophy]].  
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* Relatively mild inflammation.  
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== References ==
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* Coronavirus in young calves results in similar pathological changes.
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[[Category:Reoviridae]]
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Brown, C.M, Bertone, J.J. (2002) '''The 5-Minute Veterinary Consult - Equine''', ''Lippincott, Williams & Wilkins''
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[[Category:Cattle]][[Category:Sheep]][[Category:Horse Viruses]][[Category:Dog]][[Category:Cat]][[Category:Goat]]
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[[Category:Enteritis,_Viral]][[Category:Enteritis, Villus Atrophy]]
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Blood, D.C. and Studdert, V. P. (1999) '''Saunders Comprehensive Veterinary Dictionary''' (2nd Edition),'' Elsevier Science''
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[[Category:To_Do_-_Clinical/Viruses]]
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Bridger, J and Russell, P (2007) '''Virology Study Guide,''''' Royal Veterinary College''
 
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Cowart, R.P. and Casteel, S.W. (2001) '''An Outline of Swine diseases: a handbook,''''' Wiley-Blackwell ''
 
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Divers, T.J. and Peek, S.F. (2008) '''Rebhun's diseases of dairy cattle,''''' Elsevier Health Scieneces''
 
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Taylor, D.J. (2006) '''Pig Diseases''' (Eighth edition), ''St Edmunsdbury Press ltd ''
 
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{{review}}
 
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{{OpenPages}}
 
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[[Category:Reoviridae]]  
 
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[[Category:Cattle_Viruses]] [[Category:Sheep_Viruses]] [[Category:Horse_Viruses]] [[Category:Dog_Viruses]] [[Category:Cat_Viruses]] [[Category:Goat_Viruses]] [[Category:Pig_Viruses]]
 
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[[Category:Intestinal_Diseases_-_Cattle]] [[Category:Intestinal_Diseases_-_Sheep]] [[Category:Small_Intestinal_Diseases_-_Horse]] [[Category:Intestinal_Diseases_-_Dog]] [[Category:Intestinal_Diseases_-_Cat]] [[Category:Intestinal_Diseases_-_Pig]][[Category:Enteritis,_Viral]] [[Category:Enteritis,_Villus_Atrophy]]
 
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[[Category:Expert_Review - Farm Animal]]
 

Revision as of 12:25, 30 July 2010


 This article is still under construction.


Antigenicity

  • 5 distinct antigenic groups: A to E
  • A is the most commonly seen and studied
  • A is further subdivided to G and P types

Hosts

  • RVs are thought to be mostly species specific, but some transmission between species occurs
  • Group A is present in all mammals
  • Groups B and C are common in pigs but not fully understood

Pathogenesis

  • Strains vary in virulence but are always confined to the gut
  • Incubation: 1-4 days
  • Target tissue: small intestine enteroycte
    • Infected enterocytes are shed, villi shorten, and become covered with immature cuboidal epithelium
    • As such, absorption is compromised
  • Results in white scour
  • NO viremia: confined to GIT
  • Associated symptoms:
    • Weight loss
    • Depression
    • Dehydration
  • Can be fatal if unchecked

Epidemiology

  • Occurs in neonates of most species, although the role of RVs in lamb and foal diarrhoea is less certain
  • NOT associated with diarrhoea in dogs and cats
  • Group A RVs are endemic in domestic animals worldwide
  • Orofecal transmission, highly infectious
  • Excreted in feces as maternal antibody wanes (calves: 2 weeks, piglets: post-weaning)

Diagnosis

  • On feces:
    • ELISA and Latex agglutination
  • On sera:
    • Rising antibody titres are not particularly helpful as most animals show high Ab levels from passive immunity

Control

  • Ensure maternal antibody transfer through the reception of colostrum
  • Hygiene and management strategies: all-in/all-out, isolation of sick animals, etc.
  • Fluid therapy where necessary
  • Dam vaccine:
    • Boost and prolong Ab secretion during suckling
    • Primarily for beef suckler herds as dairy calves receive batch milk after 24 hours

Vilous atrophy in Enteritis

  • Affects young foals and calves.

Pathology

Gross
Histopathology
  • Loss of villus epithelium
    • Replacement with cuboidal or squamous cells
  • Villus atrophy.
  • Relatively mild inflammation.
  • Coronavirus in young calves results in similar pathological changes.
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