An Updated Scheme for Categorizing Foods Implicated in Foodborne Disease Outbreaks: A Tri-Agency Collaboration

Abstract

Background: Foodborne disease data collected during outbreak investigations are used to estimate the percentage of foodborne illnesses attributable to specific food categories. Current food categories do not reflect whether or how the food has been processed and exclude many multiple-ingredient foods.

Materials and methods: Representatives from three federal agencies worked collaboratively in the Interagency Food Safety Analytics Collaboration (IFSAC) to develop a hierarchical scheme for categorizing foods implicated in outbreaks, which accounts for the type of processing and provides more specific food categories for regulatory purposes. IFSAC also developed standard assumptions for assigning foods to specific food categories, including some multiple-ingredient foods. The number and percentage of outbreaks assignable to each level of the hierarchy were summarized.

Results: The IFSAC scheme is a five-level hierarchy for categorizing implicated foods with increasingly specific subcategories at each level, resulting in a total of 234 food categories. Subcategories allow distinguishing features of implicated foods to be reported, such as pasteurized versus unpasteurized fluid milk, shell eggs versus liquid egg products, ready-to-eat versus raw meats, and five different varieties of fruit categories. Twenty-four aggregate food categories contained a sufficient number of outbreaks for source attribution analyses. Among 9791 outbreaks reported from 1998 to 2014 with an identified food vehicle, 4607 (47%) were assignable to food categories using this scheme. Among these, 4218 (92%) were assigned to one of the 24 aggregate food categories, and 840 (18%) were assigned to the most specific category possible.

Conclusions: Updates to the food categorization scheme and new methods for assigning implicated foods to specific food categories can help increase the number of outbreaks attributed to a single food category. The increased specificity of food categories in this scheme may help improve source attribution analyses, eventually leading to improved foodborne illness source attribution estimates and enhanced food safety and regulatory efforts.

Keywords: IFSAC; food categorization; foodborne; outbreak.

IFSAC food glossary with examples of foods for each food category. Foods are assigned to one of four food groups: aquatic animals, land animals, plants, and other. Food groups include increasingly specific food categories.

FIG. 1.

Decision Rules for Assigning Outbreaks to Food Categories. *If multiple contaminated ingredients or multiple implicated foods are assigned to different subcategories within the same overarching category, then the outbreak is assigned to the highest common category (e.g., if implicated foods are assigned to Melons and Tropical Fruit, then the outbreak is assigned to Fruits).

FIG. 2.

IFSAC Food Categorization Scheme. (A) Aquatic Animal and Land Animal Categories. (B) Oils–Sugars, Fruits, and Vegetable Categories. (C) Grains–Beans and Nuts–Seeds Categories. Green boxes show current analytical food categories, that is, categories which contain a sufficient number of outbreaks to facilitate appropriate outbreak summary analyses and correspond to the Painter et al. (2009) categories in most instances. **All levels include an “Other” category in which to place foods. Some of these “Other” categories are explicitly included in the new scheme because of their regulatory importance. IFSAC, Interagency Food Safety Analytics Collaboration.

FIG. 2.

IFSAC Food Categorization Scheme. (A) Aquatic Animal and Land Animal Categories. (B) Oils–Sugars, Fruits, and Vegetable Categories. (C) Grains–Beans and Nuts–Seeds Categories. Green boxes show current analytical food categories, that is, categories which contain a sufficient number of outbreaks to facilitate appropriate outbreak summary analyses and correspond to the Painter et al. (2009) categories in most instances. **All levels include an “Other” category in which to place foods. Some of these “Other” categories are explicitly included in the new scheme because of their regulatory importance. IFSAC, Interagency Food Safety Analytics Collaboration.

FIG. 2.

IFSAC Food Categorization Scheme. (A) Aquatic Animal and Land Animal Categories. (B) Oils–Sugars, Fruits, and Vegetable Categories. (C) Grains–Beans and Nuts–Seeds Categories. Green boxes show current analytical food categories, that is, categories which contain a sufficient number of outbreaks to facilitate appropriate outbreak summary analyses and correspond to the Painter et al. (2009) categories in most instances. **All levels include an “Other” category in which to place foods. Some of these “Other” categories are explicitly included in the new scheme because of their regulatory importance. IFSAC, Interagency Food Safety Analytics Collaboration.