WASHINGTON, D.C. — The USDA’s Animal and Plant Health Inspection Service (APHIS) said the deadly porcine epidemic diarrhea virus (PEDv), which killed more than 8 million piglets in 2013-14, nearly matches the DNA of a virus found in China – and was likely carried into the United States on reusable tote bags used in international trade.
According to APHIS’ Sept. 30 Root Cause Investigation Report, there are "potential scenarios for how the swine enteric coronavirus disease (SECD) viruses entered the U.S." Investigators examined 17 potential root cause scenarios, "looking to see if they meet all four criteria needed to bring the virus from an overseas location to U.S. pig farms, as well as if there was evidence to support the scenario.
"While the investigation did not uncover definite proof for any route of entry, a small number of scenarios were deemed plausible," the report said.
It stated the scenario that best fit the criteria for virus entry was a virus spread through the reuse of contaminated flexible intermediate bulk containers (FIBC), which are commonly used to transport many types of material, including sand for flood control, soybeans, pet treats or almost any kind of bulk material – and designed to be reused.
"It is not a common practice to clean and disinfect these FIBCs between uses in the United States," the report added. "Evidence collected as part of the investigation suggests that the FIBCs could be potentially contaminated in their origin country and, upon arrival in the United States, are likely being reused.
"If a contaminated FIBC was used to transport bulk feed or ingredients to the swine feed mill networks, a small bit of contaminated material could have been mixed into feed destined for many locations and spread the virus onto farms."
The Associated Press reported the USDA said flexible intermediate bulk containers, which are woven plastic bags, were used to ship up to 3,000 pounds of goods. In fact, APHIS investigators said these containers could have been contaminated with "compost, fertilizer or water from a farm in China that had been affected by the virus," Reuters added.
"The most probable route of dissemination is in the context of recycled food or feed products through distribution companies who generally service a large network of feed mill customers across the Midwest and beyond," the report said.
Harry Snelson, director of communications at the American Assoc. of Swine Veterinarians in Perry, Iowa, said shortly after the outbreak here, his group joined U.S. pork producers in asking the USDA to conduct an analysis of the possible routes of introduction "and this is their conclusion based on the analysis they conducted …
"Whether or not the virus actually was transported to the U.S. on contaminated totes is just speculation at this point," he explained. "It does, however, give us additional insight into other aspects of ingredient access and utilization that we need to consider when establishing mitigations, to prevent future exposure of our animals to global pathogens."
The report said APHIS completed follow-up testing in an attempt to provide evidence for this scenario, which the agency stated further supports the hypothesis that PEDv could easily remain stable through the time needed to travel to the United States and infect pigs.
It added the first cases of novel SECD were confirmed in the U.S. in April 2013, when SECD viruses were also quickly spreading to many swine premises throughout the country, "killing 7 million piglets within the first year and causing tremendous hardship for many American pork producers."
"The APHIS, the states and the swine industry have worked jointly to slow the spread of these diseases, including enhancing biosecurity practices," the report said. "The APHIS also issued a federal order on June 5, 2014, requiring the reporting of SECD cases to assist with tracking and understanding these viruses. The number of new cases has dropped dramatically in the past year."
Ron Birkenholz, communications director at the Iowa Pork Producers Assoc. in Clive, said while the pork industry appreciates the work the USDA did on possible scenarios, its investigation was inconclusive and a pathway into the country still could be open for entry of other diseases.
"Pork producers remain concerned about the gap in the nation’s system for protecting animal health," he said.
Snelson said PEDv has highlighted the need to understand the source of on-farm inputs and their potential to carry and transmit pathogens. "We need to understand vulnerabilities at the national level and at the farm level, and the industry has to take responsibility for its own protection," he explained.
Lisa Becton, DVM, director of swine health information and research for the pork checkoff in Des Moines, encourages pork producers to work with their veterinarians to design and evaluate herd health plans: "If something looks wrong on your farm, contact your veterinarian and animal health officials immediately."
