The U.S. Department of Agriculture’s (USDA’s) Animal and Plant Health Inspection Service (APHIS) has linked a 2013-2014 outbreak of porcine epidemic diarrhea virus (PEDv) that killed more than 7 million piglets to Flexible Intermediate Bulk Containers (FIBCs), the reusable tote bags used to transport and store pig feed. According to an APHIS report, which seeks to explain why PEDv occurred in the United States but not Canada or the European Union, the bags were most likely contaminated in their origin country before distribution to feed mill customers across the Midwest, where they contaminated “feed or ingredients destined for delivery to the farm.”

“Several of the farm investigations as well as an early case-control study suggested feed or feed delivery as the source of the outbreak; however, there were no common feed manufacturers, products, or ingredients in the initially infected herds,” states the report, which notes that the PEDv strain found in the United States matched a similar strain from China. “In addition to meeting the investigation criteria, the contaminated FIBC scenario explains the apparent anomalous association of the epidemic to feed.”