A new paper published in Frontiers in Nutrition describes U.S. regulatory agencies’ roles in two recent, high-profile foodborne illness outbreak investigations—the Boar’s Head listeriosis outbreak and the McDonald’s Escherichia coli outbreak—and highlights the shortcomings and strengths in how the outbreaks were managed. The paper was authored by Grishma Prabhukhot, Ph.D.

Boar’s Head Listeriosis Outbreak

In July 2024, more than 7 million pounds of Boar’s Head ready-to-eat (RTE) deli meats were recalled following a multi-state Listeria monocytogenes outbreak that resulted in ten deaths. Although the recall was announced on July 26, sample collection occurred between May 29 and July 12, indicating a nearly two-month delay in outbreak recognition. This lag highlights challenges in timely detection and response.

U.S. Department of Agriculture Food Safety and Inspection Service (USDA-FSIS) inspection reports revealed recurring food safety lapses at the company’s Virginia production plant. Serious violations were not followed up with strong enforcement actions, signaling insufficient oversight by both company management and federal and state agencies; USDA was contracting inspections of the facility to Virginia state inspectors through a Talmadge-Aiken agreement.

Following the investigation, USDA shared plans to review the Listeria Rule and strengthen regulatory oversight, making several immediate changes and announcing areas for future work. Key areas for improvement include sampling practices, inspector training, oversight of Talmadge-Aiken plants, and potential policy updates.

McDonald’s E. coli Outbreak

A 2024–2025 E. coli O157:H7 linked to onions served at McDonald’s restaurants highlighted persistent challenges in outbreak response, even for companies with advanced food safety systems. The outbreak spanned 14 states, causing more than 100 illnesses, four cases of hemolytic uremic syndrome (HUS), and one death.

Traceback pointed to slivered onions supplied by a Taylor Farms facility, but whole genome sequencing (WGS) conducted by the U.S. Food and Drug Administration (FDA) and the Colorado Department of Public Health showed that the strain of E. coli found on Taylor Farms onions did not match the outbreak strain, causing uncertainty about the contamination pathway. Still, FDA and the U.S. Centers for Disease Control and Prevention (CDC) named Taylor Farms onions the “likely source of contamination.” This illustrates how advanced molecular surveillance can identify multiple E. coli strains in the production environment, while persistent constraints in traceback records, sampling frames, and environmental data leave uncertainty about the exact contamination pathway.

Rapid interagency coordination enabled a large-scale voluntary recall by Taylor Farms, but neither the source of contamination or a grower were definitively confirmed. An FDA Form 483 inspection report issued after the recall documented sanitation deficiencies, hygiene lapses, and inadequate verification records at Taylor Farms’ Colorado facility; however, this should be interpreted as an opinion and not as a proven causal explanation for this specific event.

The outbreak illustrates systemic constraints: FDA relies on industry to implement preventive controls and voluntary recalls, while resource limitations restrict inspection frequency. From a policy standpoint, more frequent, risk-based audits could reduce future risks, although such measures would require statutory changes and additional resources.

Ultimately, the incident reinforces that modernized screening and sampling approaches are only verification tools with inherent limitations, and that traceback is reactive not preventive, emphasizing the need for stronger preventive measures and systemic improvements in outbreak response.

Takeaways and Recommendations

Based on the gaps revealed by the Boar’s Head and McDonald’s outbreaks, the author suggests several steps and policy actions that could improve U.S. foodborne illness outbreak response.

• FDA and industry could establish lot-level digital traceability targets for high-risk and high-volume commodities and a standardized system that can rapidly integrate electronic data from different firms and systems
• The development of training modules and targeted technical assistance for small- and medium-sized suppliers that support large national brands, with an emphasis on implementing robust digital traceability systems
• Clearer expectations around audits and intensified inspections.

Additionally, FDA Coordinated Outbreak Response and Evaluation (CORE) Network data shows that, in 2020–2025, a food vehicle of illness was identified for 56 percent of outbreaks, while 44 percent remained unsolved—indicating limited progress over time in enhancing traceability and source attribution. This trend also highlights the challenges in outbreak investigation surveillance systems and the complex nature of investigations involving multiple responsible regulatory agencies. Overall, the data underscores the continued need for improved harmonization and efficiency in outbreak investigation frameworks.

The Boar’s Head and McDonald’s incidents revealed that, on one hand, WGS, centralized recall-tracking networks, and multi-agency coordination enabled relatively rapid detection, case linking, and multistate communication. However, there were still delays in recognizing patterns seen in earlier outbreaks. This suggests that, while U.S. outbreak responses have evolved toward more sophisticated tools and frameworks, structural issues in traceability, supplier oversight, and outbreak attribution continue to limit the full benefits of these advances.