Susan Kerr, DVM
September 25, 2013
Porcine epidemic diarrhea virus (PED) can sweep quickly through a pig herd, and there are currently no vaccines approved for the disease in the U.S. - Photo courtesy Ingram Publishing/Thinkstock (HobbyFarsms.com)
Courtesy Ingram Publishing/Thinkstock

The porcine epidemic diarrhea virus was confirmed for the first time in the U.S. in May 2013, though it’s been present in European and Asian herds for several years. (It has also been identified in Canadian herds.) According to the National Pork Board, PED was confirmed in almost 350 sites in 15 states as of July 2013. The disease is a concern because American swine have no immunity to the virus, which is believed to be transmitted by infected food or feces. The virus can be contained by quarantining infected animals, washing down trucks and production facilities, and using a strong biosecurity program.

The PED virus is a coronavirus, the same family as the transmissible gastroenteritis virus. Signs of both diseases are the same, but there is no cross-protection between them. Signs include vomiting, diarrhea, depression, poor appetite, dehydration and death; these signs are most pronounced in young pigs.

The disease is most often transmitted through fecal-oral contact, but transmission through aerosolization, aka inhaling or consuming vaporized liquids and solids that contain pathogenic particles, is also possible. Affected animals can shed the virus for more than a week. Porcine epidemic diarrhea virus is specific to swine; it does not affect other species, including humans, and humans cannot contract the disease by consuming pork products.

The incubation period for PED can be as short as 12 hours or as long as four days. It can quickly sweep through an entire population on premises. Animals are sick for two to three days; those that live develop active immunity, but this immunity might not be lifelong. Sows that have been exposed to the virus will pass on passive protection to their piglets, which will help protect them during the most susceptible phase of life. The older a pig is when it encounters the virus for the first time, the greater the likelihood of survival.

Although fatality rates vary, they can be very high for young pigs—80 to 100 percent. Animals that survive PED infection might have lower finishing weights than their uninfected counterparts.

If you suspect PED in your herd, contact your Veterinarian or county extension agent immediately. The disease can only be definitively diagnosed through laboratory testing, and several other viruses, bacteria and parasites can cause similar signs. Work with your veterinarian to ensure samples are submitted properly and securely.

No PED vaccine currently exists for use in the U.S. A PED vaccine is used in some other countries, but the vaccine strain might not be that effective against the disease—a handful of vaccines have been licensed in Asia, but infection rates have been on the rise there in the past several years. As such, your best prevention is to implement stringent biosecurity practices on your farm, including but not limited to quarantining new additions and recent returns from shows and exhibitions; quarantining symptomatic animals; utilizing separate supplies, equipment and work attire when caring for animals showing signs of any illness; and maintaining clean and appropriate facilities to minimize the risk of spreading disease from animal to animal.

About the Authors: Susan Kerr, DVM, PhD, is a WSU Northwest Regional Livestock and Dairy Extension Specialist. Dr. Lyle G. McNeal is a livestock specialist in the Department of Animal, Dairy and Veterinary Sciences at Utah State University.

This article originally appeared in the October/November 2013 issue of Hobby Farms.



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