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Analyses of the Contributing Factors Associated With Foodborne Outbreaks in School Settings (2000–2010)

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PDF Icon JEH 2015 (465.00 KB)

State-reported school foodborne outbreaks account for about 3.8% (n = 464) of all outbreaks and 8.2% (n = 20,667) of all illnesses reported to the Centers for Disease Control and Prevention’s Foodborne
Disease Outbreak Surveillance System. Of 464 school foodborne outbreaks, 122 (26%) outbreaks, 7,603 illnesses, and 301 reported food safety errors met the criteria for inclusion in the analyses. The purpose of the authors’ study was to examine the role of contributing factors in school foodborne outbreaks. Contamination factors accounted for the greatest proportion (49.2%) of outbreaks involving some level of food handling interaction by a school food service worker, followed by proliferation (34.9%) and survival factors (15.9%). Over 56% of all illnesses were associated with norovirus and food service worker practices. The results of these analyses highlight the importance of effective food safety education programs that focus on the role of contributing factors and prevention of foodborne disease from food safety errors.


Contributing Factors and Foodborne Disease

The health burden posed by foodborne disease is significant. The Centers for Disease Control and Prevention (CDC) estimate that viral, bacterial, and parasitic foodborne disease strikes about 48 million individuals resulting in 128,000 hospitalizations and 3,000 deaths on an annual basis (Painter et al., 2013; Scallan et al., 2011). Foodborne disease surveillance reports highlight the significant health burden particularly among children, who are one of the most vulnerable segments of the population to the effects of foodborne disease (Centers for Disease Control and Prevention [CDC], 2012a; McCabe-Sellers & Beatte, 2004).

According to foodborne surveillance data, contributing factors play a significant role in foodborne disease in school settings (Daniels et al., 2002). Contributing factors are defined as “food safety practices and behaviors that most likely contributed to a foodborne illness outbreak (Bryan, Guzewich, & Todd, 1997).” Contributing factors associated with foodborne outbreaks fall into three broad categories with associated subcategories of food safety errors: 

  • contamination (C1 to C15), i.e., food safety practices that contribute to the introduction of pathogens into food (e.g., bare-hand or gloved-hand contact with food by an infected food worker);
  • proliferation (P1 to P12), i.e., improper food preparation practices that allow pathogens to proliferate while food is being prepared (e.g., improper temperature control during hot or cold holding); and
  • survival (S1 to S5), i.e., failure of processes intended to eliminate or inhibit the survival of a microbial contaminant (e.g., insufficient time/temperature control during cooking, reheating, or freezing) (CDC, 2012b, 2013a; Gould, Walsh et al., 2013).

Contributing factors are typically identified during the environmental health assessment phase of a foodborne outbreak investigation, which is initiated at the start of an outbreak investigation (Todd, Guzewich, & Bryan, 1997). Identification of contributing factors can be both challenging and complex. The value of an environmental health assessment relies heavily on the quality, completeness, and accuracy of epidemiological information from the outbreak investigation (CDC, 2012c; Council to Improve Foodborne Outbreak Response [CIFOR], 2009). Environmental health assessments are not conducted for all outbreaks, however, which is one major obstacle in identification of contributing factors.

The U.S. Department of Agriculture Food and Nutrition Service administers the National School Lunch Program (NSLP) and the School Breakfast Program (SBP) through state education, health, or agriculture agencies. As of fiscal year 2012, the NLSP and the SBP served over 101,000 (93%) schools throughout the U.S. with 32 million lunches and 12 million breakfasts daily (U.S. Department of Agriculture Food and Nutrition Service, 2013). The potential for foodborne outbreaks to occur in a closed setting such as schools and to affect a large segment of the school-aged population is significant (Daniels et al., 2002). Based on this potential, preventing foodborne disease is a major goal. The purpose of our study was to examine the role of contributing factors and the spread of foodborne disease in school foodborne outbreaks.


Page updated: November 30, 2021