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Porcine Epidemic Diarrhoea (PED)

Porcine epidemic diarrhoea is caused by a coronavirus somewhat similar to that which causes TGE. This virus is widespread in Europe. The virus damages the villi in the gut thus reducing the absorptive surface, with loss of fluid and dehydration. After introduction of the virus into a susceptible breeding herd, a strong immunity develops over two to three weeks. The colostral immunity then protects the piglets. The virus usually disappears spontaneously from breeding herds particularly small ones (< 300 sows).

Acute outbreaks of diarrhoea occur when the virus is first introduced into a susceptible population. In such cases up to 100% of sows may be affected, showing a mild to very watery diarrhoea. Two clinical pictures are recognised: PED Type I only affects growing pigs whereas PED Type II affects all ages including sucking pigs and mature sows. The incubation period is approximately 2 days and diarrhoea lasts for 7 to 14 days. In sucking pigs the disease can be mild or severe with mortalities up to 40%.

In large breeding herds, particularly if kept extensively, not all the females may become infected first time round and there may be recrudescence. This only occurs in piglets suckling from sows with no maternal antibodies and is therefore sporadic.


  • This can vary from very mild "cow pat" faeces through to a watery diarrhoea.
  • Loose faeces.
  • Diarrhoea.
  • Dehydration.
  • Mortality may be high.
Weaners & Growers
  • Acute watery diarrhoea with no blood or mucus.
  • Mortality is usually low but morbidity can be high.
  • When the virus is first introduced on to the farm there is a rapid spread of diarrhoea across all breeding and growing pigs with almost 100% morbidity (pigs affected) within 5 to 10 days. The incubation period is 2 to 4 days.
  • Vomiting.

Causes / Contributing factors

  • The immunological status of the herd i.e. no immunity.
  • Disease may be perpetuated as susceptible pigs enter the finishing herd.
  • Disease normally only seen when virus first enters the herd.


This is based on the history, clinical signs and examination of faeces samples for evidence of porcine epidemic diarrhoea virus by ELISA tests or electron microscopy. Post-mortem examination of dead pigs and laboratory tests on the small intestine may be necessary to confirm the diagnosis.

PED must be differentiated from TGE by laboratory tests.


Clinical signs of PED closely resemble a Transmissible Gastro Enteritis (TGE) and Swine delta corona virus (SDCoV) outbreaks. While PED and TGE are caused by similar coronaviruses, cross immunity is not provided with infection of either virus.

All three coronaviruses cause similar clinical symptoms early in the disease, making it impossible to identify without testing which specific virus is at the root of the infection on the farm. Laboratory testing is needed to identify the pathogen. Diagnostic tools used include PCR, ELISA, immunohistochemistry (IHC) and histopathology.

Biosecurity is key in controlling swine coronaviruses as they spread indirectly through air, dust, feed, transport and people. Environmental testing with molecular tools helps audit the success of biosecurity measures, such as disinfecting transport trailers and barn facilities, and it enables producers to quickly get information about the actual situation on the farm.

A PCR test is available for environmental and feed samples to simultaneous screen for all three swine coronaviruses:

  • Porcine epidemic diarrhea virus (PEDV)
  • Transmissible gastroenteritis virus (TGEV)
  • Swine delta corona virus (SDCoV)

For more information about PCR diagnostic solutions for PEDV, click here.

Further Reading

Click on the links below to find out more about this disease, including treatment, management control and prevention information. The top link is the main article on this disease.