Porcine Epizootic Diarrhoea (PED)

Porzine Epizootische Diarrhoe (PED)

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Coronavirus

Porcine Epizootic Diarrhoea (PED) or Epizootic Viral Diarrhoea (EVD) is a diarrhoea illness in pigs caused by coronaviruses which can be associated with a high rate of mortality especially amongst young piglets. Since 2013 there have been reports of PED outbreaks of epidemic proportions in North America. Acute outbreaks had been reported in Germany in 2014 and in Austria, the virus was detected on a farm with fattening pigs of German origin.

Information on PED (January 2015)

More information
Coronavirus

Porcine Epizootic Diarrhoea (PED) or Epizootic Viral Diarrhoea (EVD) is a diarrhoea illness in pigs caused by coronaviruses which can be associated with a high rate of mortality especially amongst young piglets. Since 2013 there have been reports of PED outbreaks of epidemic proportions in North America. Acute outbreaks had been reported in Germany in 2014 and in Austria, the virus was detected on a farm with fattening pigs of German origin.

Information on PED (January 2015)

More information

Prevalence

Diarrhoea illnesses with symptoms similar to those of PED were first observed in 1971 in England in fattening pigs and spread thereafter into several European countries. Reports in this regard are available from Belgium (1978), the Czech Republic (1993), Hungary (1996), as well as from Germany, France, The Netherlands and Switzerland. From then on in Europe there were barely any - and if so only isolated - outbreaks of the disease. In a study conducted in Austria by Möstl et al. (1990) no evidence of the existence of PED in the Austrian pig population could be found.
In Italy, in the period from 2005 – 2006 the infection was found in 63 herds. From the year 2000 continuing to the present day, there have been reported outbreaks of PED in Korea, China, Thailand and other Asiatic countries. Since 2010 the outbreaks in these countries associated with high numbers of deaths amongst the piglet population have increased dramatically. 2013 saw the first cases of PED in the US federal states of Iowa and Minnesota. Within a short period of time, further outbreaks were registered throughout the whole of the United States, in Canada, Mexico and in the countries of Central America. These outbreaks are associated with major economic losses which on the one hand are due to the illnesses and deaths amongst pigs and on the other, the resultant restrictions on trade.

As part of the molecular-genetic study of the virus a new variety of the PED Virus (PEDV) was discovered in in America and Asia, which is apparently more virulent than the virus that was originally isolated during the 1980s in Europe. Additionally, in the course of the genetic analyses, a new Coronavirus (Delta Coronavirus) was detected that is possibly also contributing to the outbreaks of illness.

Germany:
Most recently several acute outbreaks were reported in Germany initially amongst fattening pigs but now also among suckling pigs. In these cases the mortality amongst the fattening pigs was low but in the unweaned piglets it was up to 70%. All available sequencing to date from the acute cases arising in Germany indicate a high level of genetic correspondence with the weaker pathogenic variety of the strains occurring in the USA.

Austria:
Shortly before Christmas 2014 on a farm with fattening pigs of German origin, PEDV was also established in Austria in a diarrhoea sample at AGES - IVET in Mödling. A sequencing analysis yielded a 100% match in the S1 gene compared with the strains found in Germany. The affected animals showed decreased appetite and diarrhoea for 2-3 days. There were no fatalities.

Symptoms

The clinical manifestation of the disease symptoms and their development depend greatly on the age of the affected animals and the immunity status of the herd and are described as follows:

If, until the point the virus was introduced, the animals within a herd had no kind of contact whatsoever with the virus (a so-called naive or fully susceptible herd) the following symptoms manifest themselves in suckling pigs (1-28 days old): Close to 100% of the animals fall ill with vomiting: the piglets have acute, watery diarrhoea. As a result of the great loss of fluids and the resulting acidosis, 50-80% of the piglet population may die. If the animals are already somewhat older, considerably fewer animals will die (1-3%). Symptoms of diarrhoea and loss of appetite can be observed in pigs of all ages, including breeding sows. If the herd has survived the acute stage of the disease (the co-called endemic stage), the animals almost return to normal in their actions with only the more occasional case of diarrhoea amongst older or weaned piglets (3 - 6 weeks).

Prevention

Since the virus is primarily transferred via infected pigs, faeces or items contaminated with excrement (liquid manure, shoes, transport vehicles), care should be taken to maintain stricter biosafety and/or hygiene measures such as the cleaning and disinfection of contaminated livestock accommodation, items and methods of transport. The central focus here of course are precautionary measures, especially when shipping animals from affected stables or regions into non-affected countries and regions. In Asia and America vaccines already exist, the effectiveness of which is the subject of controversial debate.

Diagnosis

Diagnosis

Due to the clinical symptoms within a herd, it is only possible to make a suspected diagnosis, which then has to be confirmed by means of appropriate laboratory testing. Using modern, molecular biological methods (PCR) fast and reliable diagnosis is possible to clarify suspected cases.

The following sample materials are suitable for the purpose of diagnosis:

  • Faeces from acutely ill living animals
  • or intestinal content and intestinal tissue (small intestine, large intestine) from deceased animals

The faecal sample should be kept cool (4 °C) having been taken where possible within the first 24 hours of the diarrhoea occurring. Since intestinal tissue becomes subject to autolysis relatively quickly, the organ samples or deceased animals should be brought or sent refrigerated and as quickly as possible to the laboratory. 

Differential diagnosis

Various other diarrhoea pathogens have to be ruled out by means of differential diagnosis:

  • Bacterial infections caused by:  Escherichia coli, Clostridium perfringens, Salmonella
  • Viral infections caused by: the Transmissible Gastroenteritis virus (TGE), Rotavirus, Porcine Circovirus type 2 (PCV-2), the Classical (European) Swine Fever virus (CSF) and African Swine Fever (ASF)
  • Parasitic infection: Coccidia

See also RELATED CONTENT / Pathogens: Transmissible Gastroenteritis of Pigs (TGE), Salmonella, European and African Swine Fever.

 

 

Laboratory

Laboratory

Testing for the PED virus and other coronaviruses takes place at the AGES Institutes for Veterinary Disease Control in Mödling and Linz.
Samples and/or deceased piglets are to be sent directly to the AGES Institute in Mödling or Linz or they may also be handed in at the AGES branches in Graz or Innsbruck.

Information on the Investigating Bodies

See also RANGE OF SERVICES: Testing package / Suckling pig diarrhoea: Focussing on bacteria and viruses.

Links/Literature

Related Links

EFSA: http://www.efsa.europa.eu/en/efsajournal/pub/3877.htm

American Association of Swine Veterinarians: https://www.aasv.org/aasv%20website/Resources/Diseases/PorcineEpidemicDiarrhea.php

see also DOWNLOADS

Literature:

Chen, Q.; Li G, Stasko J, Thomas JT, Stensland WR, Pillatzki AE, Gauger PC, Schwartz KJ, Madson D, Yoon KJ, Stevenson GW, Burrough ER, Harmon KM, Main RG, Zhang J (2014): Isolation and characterization of porcine epidemic diarrhea viruses associated with the 2013 disease outbreak in US swine. J. Clin. Microbiol. 52(1):234-243.

Dea, S.; Vaillancourt, J.; Elazhary, Y.; Martineau, G.P. (1985): An outbreak of diarrhea in piglets caused by a coronavirus antigenically distinct from Transmissible Gastroenteritis Virus. Can vet. J. 26:108-

Hanke, D., Jenckel, M, Petrov, A., Ritzmann, M., Stadler, J., Akimin, V., Blome, S., Pohlmann, A., Schirrmeier, H., Beer, M., Höper, D. (2015): Comparison of Porcine Epidemic Diarrhea Viruses from Germany and the United States, 2014. Emerg. Infect. Dis. 21(3), DOI: 10.3201/eid2103.

Harris. H. (2014): PEDv awakened a sleeping giant in North America. Pig progress 30 (3): 28-29.

Li, W.; Li, H.; Liu, Y.; Pan, Y.; Deng, F.; Song, Y., Tang, X.; He, Q. (2012): New variants of Porcine Epidemic Diarrhea Virus, China 2011. Emerg. Infect. Dis. 18(8):1350-1353.

Lowe, J.; Gauger, Ph.; Harmon, K.; Zhang, J.; Connor, J.; Yeske, P.; Loula, T.; Levis, I.; Dufresne, L.; Main, R. (2014): Role of Transportation in Spread of Porcine Epidemic Diarrhea Virus infection, United States. Emerg. Inf. Dis. 20(5):872-874.

Martelli, P.; Lavazza, A.; Nigrelli, A.D.; Merialdi, G.; Alborali, L.G.; Paensert, M.B. (2008): Epidemic of diarrhea caused by porcine epidemic diarrhea virus in Italy. Vet. Record 162:307-310.

Marthaler, D.; Raymond, L.; Jiang, Y.; Collins, J.; Rossow, K.; Rovira,A. (2014): Rapid detection, Complete Genome Sequencing, and Phylogenetic Analysis of Porcine Deltacoronavirus. CDC 20(8):1-5.

Möstl, K.; Callebaut, P.; Horvath, E.; Pensaert, M. (1989): Erhebungen über Porcine Coronaviren in Österreich, I. Teil: TEGV und das TEGV-verwandte respiratorische Coronavirus der Schweine. Wien, Tierärztl. Mschr. 76:395-400.

Möstl, K.; Horvath, E.; Bürki, F. (1990): Erhebungen über Porcine Coronaviren in Österreich, II. Teil: Porcine Epidemic Diarrhea-Virus (PEDV) der Schweine. Wien, Tierärztl. Mschr. 77:10-18.

Pan, Y.; Tian, X.; Li, W.; Zhou, Q.; Wang, D.; Bi, Y.; Chen, F.; Song, Y. (2012): Isolation and characterization of a variant porcine epidemic diarrhea virus in China. Virology Journal 9:195-204.

Shibata, I.; Tsuda, T.; Mori, M.; Ono, M.; Sueyoshi, M.; Uruno, K. (2000): Isolation of porcine epidemic diarrhea virus in porcine cell cultures and experimental infection of pigs of different ages. Vet. Microbiol. 72:173-182.

Song, D.; Park, B. (2012): Porcine epidemic diarrhea virus: a comprehensive review of molecular epidemiology, diagnosis, and vaccines. Virus genes 44:167-175.


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