Porcine Epidemic Diarrhea virus (PEDv) made a surprise appearance in the United States in spring 2013. Caused by a distant (viral) cousin of Transmissible Gastroenteritis (TGE), the disease presents similarly with rapid dehydration resulting in a high percentage of deaths in young piglets. Vaccination against TGE does not confer any cross-protection against PEDv and no natural immunity existed in U.S. herds. The virus is transmitted by the fecal-oral route and spreads easily in manure and by manure-contaminated objects (fomites) such as trailers, equipment, boots, and clothing. Natural immunity develops over two to four weeks such that infected sows produce protective antibodies in their colostrum.
During the first half of February 2014, Iowa, Minnesota, Illinois, North Carolina, Ohio, and Indiana accounted for the sources of the most new positive test results reported through the National Animal Health Laboratory Network. Since June 2013 the number of states affected has climbed from 14 to 25 as of February 2014. The total number of pig farms identified with PED since April 2013 is over 3,500 as of late February 2014. The numbers of swine farms testing positive for PEDv increased more rapidly beginning in November 2013 with over 950 new farms testing positive in January 2014.
From when the outbreak was first detected in April through June 2013, only Colorado, Kansas, South Dakota, Illinois, Missouri, Michigan, Minnesota, Iowa, Oklahoma, Indiana, Ohio, Pennsylvania, New York, North Carolina reported positives. While case reports were already geographically extensive, most were from Iowa and Oklahoma. The disease has since been reported from herds in California, Wyoming, Nebraska, Texas, Wisconsin, Maryland, Kentucky, Tennessee, and South Carolina.
Age classes testing positive include suckling (< one month old or still on sow), nursery (one month up to 3 months), grower/finisher pigs (3 months up to 8 months) and sows and boars (8 months of age and older).
Early on, information about location of disease was difficult to track because PED is not reportable in the United States. Voluntary reporting by laboratories in the National Animal Health Laboratory Network began in June 2013 with additional information being reported since November 2013.
Dr. Sagar Goyar at the University of Minnesota has conducted research on the environmental survival of the virus. The PED virus can survive at least seven days and was still viable at the end of the study after 28 days in slurry at low temperatures and in wet feed. Also, PEDv survived one or two weeks in fresh manure, drinking water and dry feed.
Strict biosecurity especially involving trailers, markets and buying stations is required to stop the spread of the virus. The February 26 Pork Checkoff Update includes links to biosecurity resources and how to create and maintain a line of separation between farm personnel and everyone else.
A note on the data: Data reported above are based on data covering testing through February 23, 2014, reported by the USDA APHIS VS NVSL National Animal Health Laboratory Network (NAHLN).Veterinary diagnostic laboratories that have voluntarily reported PEDV testing data to NAHLN include: University of Georgia – Athens, University of Illinois, Iowa State University, Kansas State University, University of Minnesota, Nebraska Veterinary Diagnostic Center, Ohio Department of Agriculture, Purdue University, Michigan State University-- Diagnostic Center for Population and Animal Health, and South Dakota State University. This data does not include testing conducted at private diagnostic laboratories, at the NVSL, or for research purposes.
PEDv in Swine - to 2013
PED is a production-related disease. PED may appear clinically to be the same as transmissible gastroenteritis (TGE) with acute diarrhea. There is no treatment for PED. An emphasis should be made on prevention and control.
Producers will need to work with their herd veterinarian if any TGE-like symptoms appear. As well, strict biosecurity protocols must be in place and practiced.
Laboratory testing is the only way to diagnose PEDv.
Prior to July 2013 PED had not been diagnosed in the United States. However, the virus was then confirmed in about 200 hog facilities in Arkansas, Colorado, Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, North Carolina, New York, Ohio, Oklahoma, Pennsylvania and South Dakota, according to the American Association of Swine Veterinarians. According to the Iowa Pork Industry Center, an industry advocate, the ability to test for the disease is limited. It is believed to be transmitted by infected food or feces, and can be contained by quarantining infected animals and washing down trucks and production facilities..
Agriculture Department officials pulled together an agricultural epidemiologic survey of swine veterinarians, to try to determine how the virus was introduced into the nation's pork production chain and see how it spread. Swine veterinarians across the U.S. collected samples from pork farms that had reported possible cases and sent them in for testing at National Veterinary Service Laboratories and other sites.
Some veterinarians also sent in samples of animal feed for testing, to see whether the virus was spread that way, according to Dr. Keith Roehr, Colorado's state veterinarian.