The Journal of Food Protection published a study of three previous romaine lettuce outbreaks in which Shiga toxin-producing Escherichia coli (STEC) was implicated. The study focused on identifying the source of the outbreaks through traceback investigations.

The U.S. Food and Drug Administration (FDA) traceback investigation experts used a standardized process to initiate, execute, and interpret the results of the traceback investigations. They collaborated with the U.S. Centers for Disease Control and Prevention as well as with state and local health departments. FDA took a look at the demonstrated challenges, limitations, and opportunities for improvement. 

The three outbreaks, which occurred in 2018 and 2019, caused 474 illnesses, 215 hospitalizations, and 5 deaths, which were all linked to the consumption of romaine lettuce from three separate growing regions in Arizona and California. 

According to the study, a few of the challenges encountered included the time it took to initiate a traceback, limited product-identifying information throughout the supply chain, a lack of interoperability in record-keeping systems, and commingling of products from various suppliers. Some initiatives that will help researchers address these challenges include the implementation of technology-enabled traceability systems, testing of these systems, and future regulations to incentivize their adoption.