Advocacy in Action: The role of government and industry in limiting feed-borne pathogens (Sep ’18)

Our experience with porcine epidemic diarrhea (PED) and research conducted by Dr Scott Dee have highlighted the potential risk feed and feed ingredients pose regarding pathogen introduction and transmission. The National Pork Board and Swine Health Information Center recently convened a meeting to discuss this issue. Participants included veterinarians, producers, feed and ingredient representatives, researchers, and government representatives from the US Department of Agriculture (USDA) and Food and Drug Administration (FDA). The objective of the meeting was to review current research and government policies and regulations and make recommendations to reduce the risk of feed and feed ingredients for pathogen transmission.

Regarding government policy, the FDA and the USDA share regulatory responsibility for feed and feed ingredients. The FDA has oversight over feed and feed ingredients moving interstate whereas the Animal Health Protection Act gives USDA regulatory authority over imported animal feed.

When evaluating the safety of feed ingredients, the FDA relies on information provided by the ingredient industry. In addition, ingredients may be classified as Generally Recognized as Safe (GRAS) if an expert panel of reviewers determines that, based on their experience and a review of any available scientific literature, an ingredient should be safe when used as intended and in the intended species. Interestingly, ingredient companies can self-declare ingredients to be GRAS without an FDA review.

The FDA representatives present indicated that the agency does not have the resources to limit or uniformly enforce GRAS status. From a monitoring standpoint, the FDA relies largely on consumer complaints and reports of illnesses attributed to animal feed. Active surveillance of feed and feed ingredients is rare.

The recently enacted Food Safety Modernization Act may provide some additional safeguards including the establishment of preventive controls for animal feed and the development of facility-specific feed safety plans. These new regulations place responsibility for the control of identified hazards on the importer of the feed or ingredient. Facilities will identify reasonably foreseeable hazards and develop plans to prevent those hazards.

In addition, the Foreign Supplier Verification program requires the importer to identify and control potential hazards. Examples of hazards commonly applied to swine feed include bacteria, mycotoxins, drug carryover, nutrient deficiencies or toxicities, and chemical and physical hazards.

Regulatory authority within USDA generally falls to the Animal and Plant Health Inspection Service (APHIS). When considering the safety of imported products, APHIS reviews the disease status of the country of origin and recommendations from the World Organization for Animal Health and the World Trade Organization. In addition, APHIS considers the potential implications on US international trade. Restriction on product importation requires a risk assessment identifying a defined pathway for the introduction of a pathogen and the ability of the pathogen to cause disease. The importation of non-animal origin products is usually not restricted by APHIS based on animal health concerns. Representatives from USDA highlighted the importance of considering the potential impact on international trade and possible restrictions that could be imposed on exports if the United States enact restrictions on imports.

It has been suggested that imported feed and ingredients should be sampled for foreign animal diseases. The USDA has been reluctant to do this because if a sample were found to be positive, it could jeopardize the United States’ negative disease status and thus impact international trade.

The researchers participating in the meeting noted that we now have experimental evidence that certain viruses of concern could survive transportation to the United States. There are also plausible pathways by which feed and feed ingredients could become contaminated in the country of origin and during post-processing abroad or in the United States. Research conducted at Kansas State University also implicates feed mills as a likely source of pathogen contamination during the feed manufacturing process. It is feasible that imported feed and ingredients could be a route of introduction of a foreign pathogen into the United States and that feed could serve as a vector for disease transmission to domestic herds.

The group discussed and prioritized the following list of next steps to address gaps and establish additional protections:

1. Test and verify product safety prior to shipment from a foreign country using blockchain testing and traceability, Preventive Controls for Animal Food program, or some other program.
2. Actively monitor imported feed components for foreign animal diseases or other transboundary pathogens at ports of entry or before shipping from source countries. The monitoring should be conducted at a foreign facility prior to shipment to avoid trade implications of a positive finding in the United States.
3. Determine the minimum and median infective dose of classical swine fever, pseudorabies virus, and foot-and-mouth disease in feed assuming normal feeding behavior. This research has already been completed for African swine fever.
4. Implement active domestic monitoring in feed mills to measure the incidence of pathogens in these facilities.
5. Validation of environmental sampling tools (ie, Swiffers, sponges, paint rollers, etc).
6. Demonstrate the detectability of other viruses via environmental sampling.
7. Validate the use of dust samples compared to feed samples for detection of pathogens.
8. Enterobacteriaceae are used as an indicator organism for fecal contamination of feed. Similarly, determine if rotavirus or some other enteric virus could be an indicator of fecal contamination with other viruses.

The goal should be to prevent the introduction of foreign and transboundary diseases into the United States. It is evident, however, that we cannot rely on government to fully protect the US swine industry. We have likely imported several devastating diseases into the United States over the last few decades (porcine reproductive and respiratory syndrome, porcine circovirus, PED, etc) and our biosecurity measures have not been successful in preventing the spread of those pathogens within the domestic herd. The safeguards currently in place to guard against pathogen importation and dissemination are vulnerable and government is limited in what they can do to provide additional assurances of protection. Thus, it falls to the swine industry to take additional measures to protect the US herd.

Harry Snelson, DVM
Director of Communications