Risk assessment of Escherichia coli O157:H7 along the farm-to-fork fresh-cut romaine lettuce supply chain

Outbreaks of Escherichia coli O157:H7 (ECO157) in romaine lettuce remain an ongoing public health concern. Quantitative microbial risk assessment (QMRA) models are key tools for identifying control measures to mitigate foodborne diseases. Here, we introduce a comprehensive QMRA framework along the farm-to-fork fresh-cut romaine lettuce chain, including a novel preharvest difference equation model, to predict annual ECO157 illness cases in the United States and evaluate control strategies. We demonstrated the importance of managing irrigation-related contamination at preharvest to control illness cases. Wildlife intrusions pose lower health risk, followed by runoffs and biological soil amendments of animal origin. When preharvest contamination persists and combines with time-temperature abuses at postharvest, the predicted ECO157 illness cases rise considerably. We showed a broad range of interventions targeting both preharvest and postharvest stages can effectively improve the microbial safety of fresh-cut romaine. The comprehensive practices and interventions explored in this study will aid decision-makers in establishing/enhancing food safety best management practices.