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 comm ...

that infects the cells lining the small intestine of a

pig The pig (''Sus domesticus''), also called swine (: swine) or hog, is an omnivorous, domesticated, even-toed, hoofed mammal. It is named the domestic pig when distinguishing it from other members of the genus '' Sus''. Some authorities cons ...

, causing porcine epidemic diarrhoea, a condition of severe

diarrhea Diarrhea (American English), also spelled diarrhoea or diarrhœa (British English), is the condition of having at least three loose, liquid, or watery bowel movements in a day. It often lasts for a few days and can result in dehydration d ...

and

dehydration In physiology, dehydration is a lack of total body water that disrupts metabolic processes. It occurs when free water loss exceeds intake, often resulting from excessive sweating, health conditions, or inadequate consumption of water. Mild deh ...

. 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

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

, but has become increasingly problematic in

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

n countries, such as

Korea Korea is a peninsular region in East Asia consisting of the Korean Peninsula, Jeju Island, and smaller islands. Since the end of World War II in 1945, it has been politically Division of Korea, divided at or near the 38th parallel north, 3 ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

, the

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, and

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

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

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

on May 5, 2013 in

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, 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 adversely affects the structure or function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical conditions that are asso ...

and mortality 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