''Porcine epidemic diarrhea virus'' (PED virus or PEDV) is a

coronavirus Coronaviruses are a group of related RNA viruses that cause diseases in mammals and birds. In humans and birds, they cause respiratory tract infections that can range from mild to lethal. Mild illnesses in humans include some cases of the com ...

that infects the cells lining the small intestine of a

pig The pig (''Sus domesticus''), often called swine, hog, or domestic pig when distinguishing from other members of the genus '' Sus'', is an omnivorous, domesticated, even-toed, hoofed mammal. It is variously considered a subspecies of ''Sus s ...

, causing porcine epidemic diarrhoea, a condition of severe

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...

and

dehydration In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...

. Older hogs mostly get sick and lose weight after being infected, whereas newborn piglets usually die within five days of contracting the virus. PEDV cannot be transmitted to humans, nor contaminate the human food supply. It was first discovered in

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, but has become increasingly problematic in

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n countries, such as

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China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

, the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

, and

Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...

. It has also spread to North America: it was discovered in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

on May 5, 2013 in

Indiana Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th s ...

, and in

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in the winter of 2014. In January 2014, a new variant strain of PEDV with three deletions, one insertion, and several mutations in S (spike) 1 region was identified in Ohio by the Animal Disease Diagnostic Lab of Ohio Department of Agriculture. PEDV has a substantial economic burden given that it is highly infectious, resulting in significant

morbidity A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...

and

mortality Mortality is the state of being mortal, or susceptible to death; the opposite of immortality. Mortality may also refer to: * Fish mortality, a parameter used in fisheries population dynamics to account for the loss of fish in a fish stock throug ...

in piglets. Morbidity and mortality rates were lower for vaccinated herds than for nonvaccinated herds, which suggests the emergence of a new PEDV field strain(s) for which the current vaccine, based on the CV777 strain, was partially protective. Consumers are likely to feel the effects of the viral disease in the form of higher prices for pork products.

Evolution

A Bayesian study of 138 genomes showed that the virus has six subtypes.Jang J, Yoon SH, Lee W, Yu J, Yoon J, Shim S, Kim H (2018) Time-calibrated phylogenomics of the porcine epidemic diarrhea virus: genome-wide insights into the spatio-temporal dynamics. Genes Genomics 40(8):825-834. doi: 10.1007/s13258-018-0686-0 Groups 1 and 2 originated in North America and groups 3–5 originated in Asia. The evolution rate of the genome was estimated to be 3.38 × 10⁻⁴ substitutions/site/year similar to other RNA viruses. The most recent common ancestor of the extant strains evolved ~1943.

Clinical Signs

PED is an acute disease with an incubation period of 1-4 days. The virus causes diarrhea and vomiting resulting in severe dehydration. In neonates the mortality can be up to 100% in virulent strains. Older pigs generally recover in 7-10 days. Piglets when sick often lie in groups or lie on the mother's belly because they are cold

Transmission

PED is transmitted by fecal-oral transmission and the infectious dose is low. Pre-weaned piglets shed large amounts of virus in their feces resulting in rapid spread and high mortality rates. Older animals do not shed as much virus in their feces as piglets. It can also be spread via contaminated fomites. A study showed that when aerosolized virus particles can spread up to 10 miles from the source of infection.

Necropsy findings

Post-mortem findings in suckling animals include empty stomach contents with little milk curd. The intestines are thin walled and distended, filled with a watery content. Diagnosis of PED is confirmed using PCR from feces or intestines of affected animals, or by immunohistochemistry on formalin-fixed tissue.

References

External links

New Variants of Porcine Epidemic Diarrhea Virus, China, 2011
from the U.S. Centers for Disease Control
Dr. Lisa Becton, U.S. National Pork Board, PEDV - Research Update
from June 4, 2014 World Pork Expo
Dr. Liz Wagstrom, U.S. National Pork Producers Council, PEDV - Next Steps
from June 4, 2014 World Pork Expo
Dr. Harry Snelson, American Association of Swine Veterinarians, PEDV - Lessons Learned
from June 4, 2014 World Pork Expo
Porcine Epidemic Diarrhea Virus Status List
from the U.S. National Pork Board
Porcine Epidemic Diarrhea Virus Emergence in the US: Status Report, Diagnostics, & Observations
Dr. Rodger Main, Iowa State University, Veterinary Diagnostic Lab, from the 2014 Iowa Pork Congress, January 22–23, Des Moines, IA, USA.
Porcine Epidemic Diarrhea Virus Update
Dr. Darin Madson, Iowa State University, Veterinary Diagnostic Lab, from the 2013 Swine Health Seminar, August 16–18, 2013
What’s at stake for Canada as pig virus spreads
{{Taxonbar, from=Q16023751 Alphacoronaviruses Swine diseases