Difference between revisions of "Transmissible Gastroenteritis Virus"

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Also known as: '''''TGEV — TGE — Epidemic Diarrhoea'''''
 
  
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== Introduction ==
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Also known as: TGEV
  
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TGEV is an enteric [[:Category:Coronaviridae|coronavirus]], of which there is only one serotype. It is now rare in Europe, due to a respiratory coronavirus variant which is now prevalent and is thought to provide immunity to TGEV.
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====Antigenicity====
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*Single serotype
  
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Pigs are particularly susceptible to a number of specific enteric viruses, especially coronaviruses. These may produces outbreaks on a whole farm basis in all ages of pigs. TGEV produces an explosive diarrhoeic disease, which spreads through the farm rapidly. There is a malabsorptive diarrhoea, which affects neonates and can be fatal depending on age and immune status of the piglet. In very young pigs, the virus can reach 100% mortality, whereas in pigs over 5 weeks of age it is rarely fatal.
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====Hosts====
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*Pigs
  
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There is severe villus stunting present in the intestines, which is similar in pathological appearance to [[Rotaviruses|rotavirus]]. The lamina propria is congested and oedemetous. These changes are in contrast to coliform infections, which show much more normal villi. Many gram-negative bacteria can be seen adhering to the villi wall if a gram stain is used and this can contribute to the disease. Secondary bacterial infection make clinical signs more severe.
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====Pathogenesis====
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*Malabsorptive diarrhoea
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*All ages susceptible but effects vary on age:
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**Less than 2 weeks of age: typically fatal
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**Over 5 weeks of age: recovery and immunity
  
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The virus is highly contagious and is spread by orofaecal transmission. The infection can occur in two forms, firstly, epizootic, where an explosive infection occurs following introduction to a non-immune herd. Enzootic infection occurs when a herd is persistently affected.
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====Epidemiology====
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*Largely replaced by a respiratory variant in Europe
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*Highly contagious spread by '''orofecal''' transmission
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*Two forms of infection can occur:
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**'''Epizootic''': Explosive infection
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***Introduction to a non-immune herd spreads quickly
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**'''Enzootic''': Persistent infection
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***Immune sows provide passive immunity but piglets will suffer mild symptoms post-weaning
  
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Immune sows provide passive immunity but piglets will suffer mild symptoms post-weaning.
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====Diagnosis====
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*Fluorescent microscopy on SI sections
  
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== Signalment ==
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====Control====
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Explosive infection:
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*Separate sows 2 weeks from farrowing
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*Exposure of flock will serve to immunise
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*No effective vaccines exist
  
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Pigs only. It can affect other species but is not a disease problem in these. All ages are susceptible but younger pigs are more severely affected. In pigs less than 2 weeks of age the disease is usually fatal. In pigs older than around 5 weeks, pigs will usually recover.
 
  
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== Clinical Signs ==
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* Caused by a [[Coronaviridae|coronavirus]].
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* Known as Epidemic diarrhoea or TGE.
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* Produces an explosive diarrhoeic disease, which spreads through the farm rapidly.
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* Epidemiologically, the disease is easy to recognise, since all ages of pigs scour.
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** This is the means of diagnosis. 
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* Consequences of disease differ with the age of the animal.
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** In very young animals, mortality may be up to 100%.
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** In animals 1-3 weeks old, mortality is around 50%.
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** Over 3 weeks of aged, mortality is 25%.
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** Older pigs tend to recover from the disease.
  
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Signs include very severe malabsorptive diarrhoea, depression, lethargy, weakness, dehydration and death.
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=====Pathology=====
  
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== Diagnosis ==
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* Villi are shortened and more rounded, with a degree of fusion.
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* Epithelial cells over the villi are flattened.
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* The lamnia propria is congested and oedemetous.
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* These changes are in contrast to coliform infections, which show much more normal villi.
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** Many gram-negative bacteria can be seen adhering to the villi wall if a gram stain is used.
  
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Diagnosis is best performed by fluorescent microscopy on small intestinal sections.
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[[Category:Coronaviridae]][[Category:Pig]]
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== Treatment and Control ==
 
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In an epizootic outbreak, where immune sows are not present in the herd, it is important to separate sows that are due to farrow down within two weeks immediately from the rest of the herd if this is not already the case. Then, the herd should be immunised by exposing them to infected stock. Disease will only be mild in older pigs, so immunising them in this way reduces the risk of the fatal form of the disease in piglets.
 
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There is no effective vaccine.
 
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== References ==
 
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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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Jackson, G.G. and Cockcroft, P.D. (2007) '''Handbook of Pig Medicine''', ''Saunders Elsevier''
 
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Straw, B.E. and Taylor, D.J. (2006) '''Disease of Swine''', ''Wiley-Blackwell''
 
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{{review}}
 
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{{OpenPages}}
 
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[[Category:Coronaviridae]] [[Category:Pig_Viruses]] [[Category:Intestinal_Diseases_-_Pig]] [[Category:Enteritis,_Catarrhal]] [[Category:Enteritis,_Viral]] [[Category:Expert_Review - Farm Animal]]
 

Revision as of 13:44, 21 May 2010


 This article is still under construction.


Also known as: TGEV

Antigenicity

  • Single serotype

Hosts

  • Pigs

Pathogenesis

  • Malabsorptive diarrhoea
  • All ages susceptible but effects vary on age:
    • Less than 2 weeks of age: typically fatal
    • Over 5 weeks of age: recovery and immunity

Epidemiology

  • Largely replaced by a respiratory variant in Europe
  • Highly contagious spread by orofecal transmission
  • Two forms of infection can occur:
    • Epizootic: Explosive infection
      • Introduction to a non-immune herd spreads quickly
    • Enzootic: Persistent infection
      • Immune sows provide passive immunity but piglets will suffer mild symptoms post-weaning

Diagnosis

  • Fluorescent microscopy on SI sections

Control

Explosive infection:

  • Separate sows 2 weeks from farrowing
  • Exposure of flock will serve to immunise
  • No effective vaccines exist


  • Caused by a coronavirus.
  • Known as Epidemic diarrhoea or TGE.
  • Produces an explosive diarrhoeic disease, which spreads through the farm rapidly.
  • Epidemiologically, the disease is easy to recognise, since all ages of pigs scour.
    • This is the means of diagnosis.
  • Consequences of disease differ with the age of the animal.
    • In very young animals, mortality may be up to 100%.
    • In animals 1-3 weeks old, mortality is around 50%.
    • Over 3 weeks of aged, mortality is 25%.
    • Older pigs tend to recover from the disease.
Pathology
  • Villi are shortened and more rounded, with a degree of fusion.
  • Epithelial cells over the villi are flattened.
  • The lamnia propria is congested and oedemetous.
  • These changes are in contrast to coliform infections, which show much more normal villi.
    • Many gram-negative bacteria can be seen adhering to the villi wall if a gram stain is used.
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