Interagency Report for 2020 on Foodborne Illness Attributed to Salmonella, E. coli O157, and Listeria monocytogenes

An interagency collaboration of FDA, CDC, and USDA, identified as IFSAC, released their yearly report on foodborne illness source attribution estimates based upon outbreak surveillance data.  The goal of this is to "provide a harmonized analytic approach for estimating foodborne illness source attribution  from outbreak data can provide consistency in the use and interpretation of estimates across public health and  regulatory agencies."

The information provides information on outbreaks caused by Salmonella, E.coli O157 and Listeria monocytogenes.

https://www.cdc.gov/foodsafety/ifsac/pdf/P19-2020-report-TriAgency-508.pdf
Foodborne illness source attribution estimates for 2020 for Salmonella, Escherichia coli O157, and Listeria monocytogenes using multi-year outbreak surveillance data, United States
The Interagency Food Safety Analytics Collaboration (IFSAC)
November 2022

IFSAC derived the estimates for 2020 using the same method used for the previous estimates, with some modifications. The data came from 1,287 foodborne disease outbreaks that occurred from 1998 through 2020 and for which each confirmed or suspected implicated food was assigned to a single food category. The method relies most heavily on the most recent five years of outbreak data (2016 – 2020). Foods are categorized using a scheme IFSAC created to classify foods into 17 categories that closely align with the U.S. food regulatory agencies’ classification needs.

Salmonella illnesses came from a wide variety of foods.
More than 75% of Salmonella illnesses were attributed to seven food categories: Chicken, Fruits, Pork, Seeded Vegetables (such as tomatoes), Other Produce (such as fungi, herbs, nuts, and root vegetables), Beef, and Turkey.
E. coli O157 illnesses were most often linked to Vegetable Row Crops (such as leafy greens) and Beef.
More than 80% of illnesses were linked to these two categories.
Listeria monocytogenes illnesses were most often linked to Dairy products, Fruits, and Vegetable Row Crops.
More than 75% of illnesses were attributed to these three categories, but the rarity of Listeria monocytogenes
outbreaks makes these estimates less reliable than those for other pathogens

Overall Key Results

• The results are based on 960 outbreaks caused or suspected to be caused by Salmonella, 272 by E. coli O157, and 55 by Listeria.
• Estimated Salmonella illnesses were more evenly distributed across food categories than illnesses caused by E. coli O157 and Listeria; most of the illnesses for those pathogens were attributed to one or two food categories.
• The credibility intervals overlap for the Salmonella and Listeria categories with the highest attribution percentages, indicating no statistically significant difference among them.

Salmonella Key Results 

• More than 75% of illnesses were attributed to seven food categories: Chicken, Fruits, Pork, Seeded Vegetables (such as tomatoes), Other Produce (such as fungi, herbs, nuts, and root vegetables), Beef, and Turkey. 
• The credibility intervals for each of the seven food categories that account for 77.5% of all illnesses overlap with some of the others

E. coli O157 Key Results

• More than 80% of E. coli O157 illnesses were attributed to Vegetable Row Crops (such as leafy greens)
• and Beef.
• Vegetable Row Crops had a significantly higher estimated attribution percentage than all other
• categories.
• Beef had a significantly higher estimated attribution percentage than all categories other than Vegetable Row Crops.
• No illnesses were attributed to Eggs or Oils-Sugars.

Listeria monocytogenes Key Results

• More than 75% of illnesses were attributed to Dairy, Fruits, and Vegetable Row Crops.
• More than 90% of illnesses were attributed to non-meat food categories.
• The credibility intervals for the Dairy, Fruits, Vegetable Row Crops, and Other Produce categories were quite wide, partly due to the small total number of outbreaks (55 total). The credibility intervals overlapped each other, and the intervals for the Fruits, Vegetable Row Crops, and Other Produce categories overlapped those for some food categories with much smaller estimated attribution percentages, such as Eggs, Sprouts, Pork, and Fish.
• No illnesses were attributed to Other Meat/Poultry, Game, Other Seafood, Grains-Beans, Oils-Sugars, or Seeded Vegetables.