On 18 December 2020 the Interagency Food Safety Analytics Collaboration (IFSAC) announced the release of its 2018 annual report on the sources of foodborne illness involving the pathogens Salmonella, Escherichia coli (E. coli) O157, Listeria monocytogenes, and campylobacter. The report is significant in that it may guide future food safety oversight priorities for the U.S. Food and Drug Administration (FDA) and U.S. Department of Agriculture (USDA).

The IFSAC is an interagency group created by Centers for Disease Control and Prevention (CDC), FDA, and the USDA Food Safety and Inspection Service (FSIS) that collects and analyses foodborne-illness outbreak data for certain pathogens and specific foods that are responsible for foodborne illness in the United States.

To compile its most recent annual report, “Foodborne illness source attribution estimates for 2018 for Salmonella, Escherichia coli O157, Listeria monocytogenes, and Campylobacter using multi-year surveillance data, United States,”¹ IFSAC used the data from 1,459 outbreaks that (1) occurred between 1998 and 2018, (2) that were suspected or confirmed to be caused by one of the four listed pathogens, and (3) in which the implicated food could be assigned to a single food category.²

While the report provides a detailed accounting of IFSAC’s methodology and limitations, some of the key takeaways include:

• Salmonella illnesses were linked to multiple food categories (chicken, seeded vegetables, pork, fruits, other produce (such as nuts), eggs, and turkey), which, IFSAC stated, suggests that interventions designed to reduce illnesses from these pathogens need to “target a variety of food categories.”
• The majority of E. coli O157 illnesses were attributed to two food categories: vegetable row crops (e.g., leafy greens) and beef. IFSAC concluded that this indicated that “interventions focusing on those two categories may be most effective in reducing illness.”
• The majority of Listeria monocytogenes illnesses were attributed to two food categories: dairy and fruits. However, IFSAC noted that the rarity of Listeria outbreaks and the “wide credibility intervals” make these estimates less reliable than those for the other pathogens.
• Campylobacter illnesses were attributed across multiple food categories, and most frequently linked to chicken (often through chicken liver products). The report did not include an attribution percentage for dairy because, the IFSAC explained, most foodborne campylobacter outbreaks were associated with unpasteurized milk, which is not widely consumed.

The IFSAC notes that these attribution estimates allow FDA, USDA, and CDC to take a “consistent approach to identifying food safety priorities.” Additionally, the estimates inform agency efforts to “prioritize food safety initiatives, interventions, and policies for reducing foodborne illness.”

Next steps

We will continue to monitor developments related to foodborne outbreaks and food safety. 

References

1 The Interagency Food Safety Analytics Collaboration, Foodborne illness source attribution estimates for 2018 for Salmonella, Escherichia coli O157, Listeria monocytogenes, and Campylobacter using multi-year surveillance data, United States (December 2020) https://www.cdc.gov/foodsafety/ifsac/pdf/P19-2018-report-TriAgency-508.pdf.

2 According the report, IFSAC classifies foods into 17 categories that “closely align with the U.S. food regulatory agencies’ classification needs.” IFSAC Food Categorization Scheme (February 2015) https://www.cdc.gov/foodsafety/ifsac/projects/food-categorization-scheme.html.

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