October 5, 2015
Feed bags blamed for swine virus that entered US in 2013
Flexible intermediate bulk containers, or FIBC, a kind of tote bag used to transport bulk materials including pig feed, may have brought the porcine epidemic diarrhea virus (PEDv) to the US in 2013, an investigative group formed by the US Department of Agriculture said in its report released recently.
The Root Cause Group (RCG), formed in 2014, concluded that the use of FIBC was the most likely transporter of the virus, which killed some 8 million piglets across the country.
The study noted that several farm investigations and an early case-control study suggested feed or feed delivery as the source of the PEDv outbreak, adding that the association of the epidemic to feed is explained by the contaminated-FIBC scenario, as in the initially infected herds, the feeds were not traced to common feed manufacturers, products or ingredients.
"In this (contaminated-FIBC) scenario, the FIBCs may be contaminated in the origin country by transport in contaminated trucks, by exposure to irrigation or flood waters containing organic fertilizer (i.e., pig manure), by organically grown soybeans, by birds, or via various other products and uses", the report explained.
It added, "Upon arrival in the United States, a contaminated FIBC may be reused for many purposes including transport of bulk feed or ingredients. 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.
Feed contamination
"Once a contaminated FIBC or its contents are delivered to a local mill that manufactures pig rations, the FIBC or its contents would contaminate feed or ingredients destined for delivery to the farm".
Another possible scenario, the investigative group said, would involve products that have been contaminated before shipment and whose waste or scrap material is carried in FIBCs, thus contaminating the bags. The FIBCs could then be reused to transport and deliver swine feed and ingredients.
The researchers considered other scenarios but dismissed them as they lacked supporting evidence or offered no apparent association of the outbreaks to feed and near simultaneous appearance of the disease in different locations.
Follow-up tests also showed that the FIBC scenario was plausible based on the survival of PEDv on FIBC material treated with the cultured PED virus. The virus remained stable for 10 weeks in4 degrees centigrade or minus 80 degrees centigrade temperature. Viable virus was also detected after five weeks but not six weeks at room temperature.
The report recommended that FIBCs be not reused or there should be sanitary management prior to reusing the bags to prevent PEDv.
"Further study is necessary to identify cleaning and disinfection procedures that might be appropriate, but the answer could be as simple as not reusing the bags or yet to be determined disinfection procedures such as dry heat prior to reusing the containers", the study recommended.-Rick Alberto