Pig virus can spread through packing plants

By Greg Cima
Published on August 21, 2013
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A virus that infected U.S. pigs for the first time can spread through livestock trailers contaminated at packing plants, according to recent test results.

Analysis of environmental samples taken from about 700 livestock trailers at seven packing plants during June revealed that about 17 percent of trailers were contaminated on arrival with the virus that causes porcine epidemic diarrhea, and another 11 percent of trailers were contaminated while at the facilities, according to a preliminary abstract provided in a newsletter from the American Association of Swine Veterinarians.

“These data suggest that harvest plants and similar livestock collection points serve as an effective method of contaminating fomites with PEDV and could play an important role in expanding the outbreak of PEDV in the U.S.,” the AASV announced in July.

Officials at the Iowa State University Veterinary Diagnostic Laboratory captured this image of the PED coronavirus in diarrheic feces by means of negative-stain electron microscopy. The bar represents 100 nm. (Reprinted with permission from Stevenson GW, Hoang H, Schwartz KJ, et al. Emergence of porcine epidemic diarrhea virus in the United States: clinical signs, lesions, and viral genomic sequences.J Vet Diagn Invest 2013; in press. Copyright ©2013, American Association of Veterinary Laboratory Diagnosticians Inc.) (Courtesy of SAGE Publications)​

Dr. James F. Lowe, the author of the abstract and a clinical instructor at the University of Illinois College of Veterinary Medicine, said the source of the contamination was not yet known, but he and other researchers were examining data on interactions among people and vehicles at packing plants.

“We’re in the process now of looking at some preliminary data to say ‘Why is that happening?’” he said.

Factors examined include distances the trailer drivers walked into the plants, the order in which trucks were unloaded, and the methods used to unload pigs, Dr. Lowe said. He noted that the National Pork Board was coordinating meetings among packers and veterinarians to discuss actions that could be taken at plants to reduce the impact of the virus.

The NPB announced in July it would spend a total of $800,000 on research, education, and coordination efforts related to PED, up from $450,000 announced in June.

PED is caused by a coronavirus that was first discovered in the U.S. in April. The disease has clinical signs similar to those for transmissible gastroenteritis, and outbreaks have caused the most deaths among the youngest pigs.

The AASV also reported in August that the virus had been identified in pigs on about 400 farms in 16 states. A previous report also had indicated it was identified in 16 states, but the latest report indicates that, contrary to the earlier report, no infections had been found in Arkansas, but an infection was found in Tennessee since the previous report.

The AASV newsletter sent July 17 states that veterinary diagnostic laboratories and the National Animal Health Laboratory Network are trying to provide accurate and useful reports, and the reports are more useful if submissions identify where the samples were taken, not the location of a corporate headquarters or the veterinarian’s office.