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  1. CFSAN Constituent Updates

IFSAC Analysis Improves Understanding of Foodborne Illness Attribution

Constituent Update

June 15, 2016

Scientists from the Interagency Food Safety Analytics Collaboration (IFSAC) recently published “Comparing Characteristics of Sporadic and Outbreak-Associated Foodborne Illnesses, United States, 2004–2011,” a paper in Emerging Infectious Diseases that compared some characteristics of outbreak and sporadic (non-outbreak) human illnesses caused by Salmonella, Escherichia coli (E. coli) O157, Listeria monocytogenes, and Campylobacter.  The analyses help assess the usefulness of outbreak data in estimating which major food categories are linked to foodborne illnesses.

Using data collected by CDC’s Foodborne Diseases Active Surveillance Network (FoodNet), the study compared outbreak illnesses with sporadic illnesses. The results of the analysis provide evidence that:

  • Campylobacter, Listeria monocytogenes, and E. coli O157 outbreak illnesses are not significantly different from sporadic illnesses with respect to patients’ illness severity, gender, and age.
  • Salmonella outbreak illnesses are not significantly different from sporadic illnesses with respect to illness severity and gender.  For age, the percentages of outbreak and sporadic illnesses that occur among older children and adults are also similar.  However, the percentage of outbreak illnesses in the youngest age category (0-3 years) was substantially lower compared with the other age groups.

FoodNet data include only a portion of reported U.S. illnesses (about 15% of the U.S. population); therefore, the number of outbreaks and illnesses available for analysis was limited.  For example, fewer Campylobacter illnesses were associated with outbreaks compared with the other three pathogens, which limits the strength of conclusions about Campylobacter attribution.

This study’s finding that outbreak and sporadic illnesses have similar characteristics indicates that using outbreak data to estimate which foods are most often linked to specific foodborne illnesses is reasonable for most age groups among the pathogens examined in this analysis.  Analyses, such as this study, help us better understand the relationship between sporadic foodborne illnesses and those that are identified as a part of an outbreak.  Such analyses are essential to advancing scientific progress in this field.  IFSAC also developed a research brief on the article.

IFSAC was created in 2011 by three federal agencies—the Centers for Disease Control and Prevention (CDC), the U.S. Food and Drug Administration (FDA), and the Food Safety and Inspection Service (FSIS) of the United States Department of Agriculture (USDA)—to improve coordination of federal food safety analytic efforts and address cross-cutting priorities for food safety data collection, analysis, and use.  IFSAC activities currently focus on foodborne illness source attribution, defined as the process of estimating the most common food sources linked to specific foodborne illnesses.  View More information about IFSAC.

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