WASHINGTON, D.C. — The U.S. Food and Drug Administration this week published a report on the investigation into the Fall 2020 outbreak of Shiga Toxin-Producing E. coli (STEC) O157:H7 illnesses linked to the consumption of leafy greens grown in the California Central Coast. The report describes findings from the investigation, as well as trends that are key to understanding leafy green outbreaks that are linked to the California Central Coast growing region, specifically encompassing the Salinas Valley and Santa Maria growing areas every fall since 2017.
The FDA released their preliminary findings earlier this year that noted this investigation found the outbreak strain in a sample of cattle feces collected on a roadside about a mile upslope from a produce farm. This finding drew their attention once again to the role that cattle grazing on agricultural lands near leafy greens fields could have on increasing the risk of produce contamination, where contamination could be spread by water, wind or other means. In fact, the findings of foodborne illness outbreak investigations since 2013 suggest that a likely contributing factor for contamination of leafy greens has been the proximity of cattle. Cattle have been repeatedly demonstrated to be a persistent source of pathogenic E. coli, including E. coli O157:H7.
Considering this, the FDA is recommending that all growers be aware of and consider adjacent land-use practices, especially as it relates to the presence of livestock, and the interface between farmland, rangeland and other agricultural areas, and conduct appropriate risk assessments and implement risk mitigation strategies, where appropriate. Increasing awareness around adjacent land use is one of the specific goals of the Leafy Greens Action Plan released last March, which the FDA also announced ishas been updated to include new activities for 2021.
During their analysis of outbreaks that have occurred each fall since 2017, the FDA states they have determined there are three key trends in the contamination of leafy greens by E. coli O157:H7 in recent years: a reoccurring strain, reoccurring region and reoccurring issues with activities on adjacent land. The 2020 E. coli O157:H7 outbreak associated with leafy greens represents the latest in a repeated series of outbreaks associated with leafy greens that originated in the Central Coast of California (encompassing Salinas Valley and Santa Maria) growing region.
In the investigation, the FDA recommends that growers of leafy greens in the California Central Coast Growing Region consider this reoccurring E. coli strain a reasonably foreseeable hazard, and specifically of concern in the South Monterey County area of the Salinas Valley. It is important to note that farms covered by the Food Safety Modernization Act (FSMA) Produce Safety Rule are required to implement science and risk-based preventive measures in the rule, which includes practices that prevent the introduction of known or reasonably foreseeable hazards into or onto produce.
The FDA also recommends that the agricultural community in the California Central Coast growing region work to identify where this reoccurring strain of pathogenic E. coli is persisting and the likely routes of leafy green contamination with STEC. Specifically, the FDA has outlined specific recommendations in their investigation report for growers in the California Central Coast leafy greens region. Those recommendations include participation in the California Longitudinal Study and the California Agricultural Neighbors workgroup. When pathogens are identified through microbiological surveys, pre-harvest or post-harvest testing, the agency recommends growers implement industry-led root cause analyses to determine how the contamination likely occurred and then implement appropriate prevention and verification measures.
The FDA issued the Leafy Green Action Plan last year to foster a more urgent and collaborative approach to preventing leafy greens outbreaks caused by STEC. They have also updated their plan for 2021 to include a renewed emphasis on actions to help prevent contamination from adjacent land, to include new actions that build on the accomplishments and learnings from the 2020 plan, and to renew their commitment to actions that were difficult to accomplish in 2020 due to challenges presented by the COVID-19 pandemic.
The FDA states they have made significant progress on their Leafy Greens Action Plan this year by enhancing prevention strategies, improving response activities by the agency and other entities, and identifying and addressing the knowledge gaps that exist around STEC contamination of leafy greens. The FDA launched the California Longitudinal Study, developed an efficacy protocol for the development and registration of antimicrobial treatments for pre-harvest agricultural water and took critical steps to advance traceability of leafy greens. They have also conducted several focused inspections, follow-up investigations and sampling assignments.
The FDA stated that although the agency is keenly focused on taking steps to help mitigate recurring leafy green contamination events, they alone cannot fix this issue. Industry leadership and collaboration among growers, processors, retailers, state partners and the broader agricultural community is critical to reducing foodborne illnesses. FDA affirmed that the safety of leafy greens remains a top priority, and they are committed to working with all stakeholders to address this significant public health issue and further protect consumers.
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