Salmonella Standards: FSIS Turns its Focus to Pork
The USDA Food Safety and Inspection Service (FSIS) is taking a closer look at Salmonella performance standards for livestock as part of a comprehensive approach to reduce human illness by Salmonella by 25%.
Last October, FSIS announced it would be mobilizing a stronger and more comprehensive effort to reduce Salmonella illnesses associated with poultry products. Now, it's turning to raw pork products. FSIS published its concerns in a study, “Temporal Changes in the Proportion of Salmonella Outbreaks Associated with Twelve Broad Commodity Classes in the United States,” in Epidemiology & Infection.
In the study, authors examined changes in the proportion of foodborne Salmonella outbreaks attributed to 12 commodity groups between 1998 and 2017. Pork demonstrated a significant increasing trend between 1998 and 2017, the authors said. The estimated proportion of Salmonella outbreaks attributable to pork increased from 4% to 18%—while the proportion of outbreaks for other commodity groups remained unchanged or steady during the 20-year study period.
“Amongst meat and poultry commodities, the consistent and significant increase in the proportion of pork-associated outbreaks is of concern,” authors Michael S. Williams and Eric D. Ebel said in the paper. “Pork ranks as the third most frequently consumed meat commodity in the United States, yet only the chicken and the fruits–nuts commodities are responsible for a larger average proportion of outbreaks in the later years of the dataset. This suggests that the risk of illness per serving from pork may have increased and is high relative to the other meat and poultry commodities.”
FSIS plans to use the study's results, in addition to public comments on the proposed performance standards for Salmonella on pork products, to inform the development of new policies targeted to reduce Salmonella illnesses linked to pork.
Pigs and Poultry Can’t Be Compared
In June, NPPC submitted comments to FSIS regarding the proposed performance standards. In the comments, NPPC noted its appreciation for the efforts FSIS has made with other commodities prior to publishing proposed performance standards.
“The differences in the epidemiology of Salmonella in poultry, the differing production practices between poultry and pork, and indeed the much longer lifespan of pigs versus poultry make a comparison between poultry and pork production problematic,” wrote Andrew Bailey, NPPC Science and Technology Legal Counsel.
Here are four of his key points about the challenges of comparing poultry to pork.
- The epidemiology of Salmonella in swine/pork is complex.
The organism exists not only in the swine GI tract and contaminated skin but may invade lymph nodes, thus requiring a complex, multiple hurdle approach to control that may not be simply achieved through hygienic dressing and sanitation practices, Bailey wrote. A focus on the post-harvest environment is likely to be most effective. However, despite numerous research studies, there are no consistent preharvest interventions for Salmonella control.
- Scientific studies have failed to identify interventions that consistently affect within-herd Salmonella prevalence.
Many of the studies are contradictory on the effect of presumed best management practices at the farm, Bailey wrote. While hygiene and other biosecurity recommendations may be helpful, they are not specific to Salmonella control, and even when done properly, Salmonella has been shown to still exist at the farm level.
- Processes in the abattoir such as carcass decontamination are the most effective means of reducing human health risk.
On-farm Salmonella status very often does not correlate with Salmonella findings or levels at the abattoir, studies show. During the process of being transported from the farm to the abattoir, pigs are exposed to many different stressors. Lairage pens have been shown to be a major source of Salmonella infection for pigs entering the abattoir, immediately prior to harvest and processing. Negative pigs entering lairage become rapidly infected, and Salmonella can be found in cecal contents and tissues within a short time, Bailey wrote.
- Pork processing plants should have access like FSIS granted poultry plants to experiment with new or existing pathogen control and measurement strategies.
The ability of poultry establishments to experiment with new or existing pathogen control and measurement strategies, with data analysis by FSIS to determine if it supports changes to FSIS’s existing Salmonella control strategies, should also be available to pork establishments. These Pilot Projects will be especially important given that on-farm controls are less consistently effective in pork production than poultry, thus giving increased importance to the need to look at multiple hurdles in the post-harvest environment.
Limitations of the Study
Consumption and surveillance are both increasing in the U.S., which makes the FSIS study less certain that what was seen from 1998 to 2017 was a significant increase, NPPC explained.
“A risk assessment is only as good as the data that informs the assessment,” NPPC said in its comments to FSIS. “The data FSIS had to conduct this risk assessment were developed by multiple agencies, not collected for the express purpose of this risk assessment, and the methods and even the years of available data were not consistent. Thus, the risk assessment model is faulty.”
The limitations of the data utilized in this model limit its usefulness, Bailey wrote. NPPC recommended that FSIS use updated data to inform the public health risk from pork products prior to taking additional action on performance standards that may not provide a public health benefit and the impact of which will be difficult to measure.
Industry Commitment
The National Pork Board is committed to funding research that that can be used to inform best practices in the food safety space, says Dr. Heather Fowler, director of producer and public health at the National Pork Board.
“Over the past few years, we’ve partnered with the North American Meat Institute (NAMI) and its research foundation to fund innovative research that addresses food safety topics such as the factors driving Salmonella transmission in pigs, with an eye for prevention. We greatly value this partnership and recognize that it’s through these collaborative efforts that we best serve the pork industry,” Fowler says.
The Swine Health Information Center is also finding ways to keep the industry informed of emerging pathogens like Salmonella I 4, [5],12:i:-, an emerging serotype in swine, that has become one of the most identified serotypes in pigs, pork and humans worldwide. Check out the Swine Health Information Center's fact sheet.
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