Innovative Approaches to Salmonella Regulation in Poultry

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In the autumn of 2021, the U.S. Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS) unveiled a robust strategy to curtail Salmonella-related illnesses linked to poultry products. USDA Deputy Under Secretary Sandra Eskin, who leads this initiative, stated, “Our current policies have proven ineffective in advancing our public health goal. It’s time to reevaluate our approach.”

In the ensuing period, the USDA has actively sought input from stakeholders on Salmonella control and measurement strategies, including pilot programs in poultry slaughter and processing facilities. A pivotal aspect of their strategy is the promotion of preharvest controls to diminish Salmonella contamination before it enters the processing plant. Data from these pilot projects will help assess whether an alternative approach can reduce Salmonella-related illnesses in consumers.

Current USDA performance standards for raw poultry do not differentiate between Salmonella subtypes that vary significantly in their potential to cause human illness, nor do they account for the varying risks posed by different levels of Salmonella contamination. In fact, these standards treat all Salmonella equally, regardless of the contamination level. Some Salmonella serovars may have mutations or genomic features that reduce their virulence, making them less likely to cause human disease. Yet, the existing prevalence-based performance standards for raw poultry do not reflect these distinctions.

USPOULTRY and its Foundation have supported a research project that aims to conduct a formal risk assessment for Salmonella in raw poultry. This assessment will evaluate various interventions and potential standards to assess their impact on public health. The U.S. poultry industry will be actively involved through an industry advisory council, ensuring that the findings guide the development of future Salmonella control approaches in poultry and that the industry plays an active role in shaping Salmonella regulations.

Principal Investigator Matthew Stasiewicz, along with collaborators, postulates that most cases of Salmonella-related illnesses from poultry consumption are linked to products with relatively high contamination levels. Thus, interventions focused on identifying and controlling higher contamination levels and higher-risk serotypes are expected to yield more targeted effects than prevalence-based interventions.

Objectives

The researchers will test their hypotheses through two objectives:

  1. Build a comprehensive quantitative microbial risk assessment (QMRA) for Salmonella subtypes in poultry products, incorporating different production strategies. This will enable an evaluation of the public health impact of various interventions, performance standards, and regulations.
  2. Use the QMRA to assess the probable impact on foodborne diseases of interventions, performance standards, and regulations that target Salmonella levels and specific strains.

Novelty

This study employs a QMRA for Salmonella in poultry that emphasizes the importance of controlling higher levels of contamination for public health rather than overall pathogen prevalence. Moreover, this QMRA integrates serotype-specific virulence parameters to assess the public health impact of interventions. Historically, QMRA efforts have not effectively addressed serovar-specific virulence due to data limitations and a lack of tools for industry application. However, this project is made possible by existing data sets that inform the model and the development of analytical tools for the routine generation of monitoring data, thereby supporting improved management strategies based on serovar-specific risk.

Procedures

The research team will construct a computer model of Salmonella prevalence, levels, and serotypes in production and processing. This model will draw upon public FSIS data and the work of co-principal investigator Nikki Shariat, who employs the novel CRISPR-SeroSeq tool to identify multiple Salmonella serovars within a single food sample. Subsequently, the researchers will assign differing relative risks to the serovars present in poultry using tools developed by co-principal investigator Martin Wiedmann and collaborator Tim Johnson, which combine whole genomic sequence analysis with laboratory data to differentiate high-risk and low-risk strains. Finally, principal investigator Stasiewicz will lead the effort to use the model to assess the impact on the risk of illness of alternative management strategies that target high-risk serovars, discount low-risk serovars, or employ a combination of both strategies.

Impact

This project will directly assess the potential public health benefits of a risk-based approach to Salmonella control, with direct industry input into potential interventions. It will provide the scientific foundation for selecting the most effective strategies to mitigate the public health impact of Salmonella.

Source: US Poultry & Egg Association