FDA E. coli outbreak investigation closes; no specific source found

An investigation into a fall 2020 outbreak of E. coli linked to leafy greens found cattle manure with the same strain about a mile from a field in California’s Salinas Valley, but the pathogen was not detected on any leafy greens or farms they were grown on.

The Food and Drug Administration released an update on its investigation on the outbreak on Jan. 27, and a full report will be released later. Forty people became sick in the outbreak, and half of them were hospitalized.

“Although the investigation has been unable to identify a specific type of leafy green at the heart of this outbreak, it is clear that this is yet another outbreak tied to leafy greens,” Frank Yiannas, the FDA’s deputy commissioner for food policy and response said in a news release on the agency’s findings.

Epidemiological and traceback investigations did not determine a specific leafy green, brand or supplier, but the E. coli strain is genetically related to a strain linked to a fall 2019 outbreak from romaine lettuce.

Investigators from the FDA and other agencies visited dozens of farms in the Salinas Valley to collect samples. They also collected samples in adjacent areas, testing animal feces, compost and water, according to the FDA. The cattle manure that yielded the positive test result was found on a roadside, uphill from where “leafy greens or other food identified on the traceback investigation were grown,” according to the FDA release.

“This finding draws our 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,” Yiannas said in the release.

The FDA continues to recommend that growers assess and mitigate risks from areas adjacent to their fields, particularly in the vicinity of cattle operations, he said. That is a specific goal of the FDA’s Leafy Greens Action Plan, released in March, he said.

Yiannas said the FDA’s final report on the outbreak will include recommendations “shaped by these findings.”