Transmissible Gastroenteritis Virus

Also known as: TGEV, TGE

• 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.

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.