Captain Obvious: Nearby cow shit can cause E. coli Outbreaks in leafy greens

By Bill Marler on May 21, 2020

This is not meant as a criticism of my friends at the FDA or the good people at LGMA – California and Arizona – or at Western Growers, United Fresh or PMA. But seriously, since leafy green E. coli O157:H7outbreaks spiked in the early 2000’s, is anyone surprised by the following conclusion by the FDA (only that it was not said out loud sooner).

Also, the has long reported that tracebacks on all three outbreaks have identified a common grower in Salinas. However, that grower has remained unnamed – so much for transparency.

FDA considers adjacent or nearby land use for cattle grazing as the most likely contributing factor associated with these three outbreaks. While the agency could not confirm a definitive source or route(s) of contamination of the romaine fields, the Agency considers indirect transmission of fecal material from adjacent and nearby lands from water run-off, wind, animals or vehicles to the romaine fields, or to the agricultural water sources used to grow the romaine, as possible routes of contamination.

According to a report by the FDA released today, in November and December 2019 there were three E. coli O157:H7 foodborne illness outbreaks. One outbreak sickened 167 and was in part linked to Ready Pac Bistro® Chicken Caesar Salad and Fresh Express Leafy Green Romaine. The romaine lettuce came from the Salinas growing region. The second outbreak sickened 11 and was linked in part to the Evergreen’s restaurant chain and was again linked to romaine lettuce from the Salinas growing region. The third outbreak sickened 10 and was linked to Fresh Express Sunflower Crisp Chopped Salad Kits from romaine lettuce grown in the Salinas growing region.

During the course of these investigations, the FDA determined that:

Each of these three outbreaks was caused by distinctly different strains of coli O157:H7 as determined by whole genome sequencing (WGS) analysis;
Outbreak 1 strain of coli O157:H7 was found in two different brands of fresh-cut salads containing romaine lettuce in 2019;
Traceback investigations of multiple illness sub-clusters and supply chain information identified a common grower with multiple ranches/fields, which supplied romaine lettuce during the timeframe of interest to multiple business entities associated with Outbreaks 1, 2 and 3;
The Outbreak 1 strain of coli O157:H7 was detected in a fecal-soil composite sample taken from a cattle grate on public land less than two miles upslope from a produce farm with multiple fields tied to the outbreaks by the traceback investigations.
Other STEC strains, while not linked to outbreaks 1,2, or 3, were found in closer proximity to where romaine lettuce crops were grown, including two samples from a border area of a farm immediately next to cattle grazing land in the hills above leafy greens fields and two samples from on-farm water drainage basins.

See picture above right – cows on hillside, leafy greens below. People say what about shit and hillsides?

The FDA has made the following recommendation (not mandates):

In light of the findings of these investigations, FDA recommends that growers of leafy greens:

Emphasize/Redouble efforts around Prevention
Assess growing operations to ensure implementation of appropriate science and risk-based preventive measures, including applicable provisions of the FSMA Produce Safety Rule and GAPs.
Adjacent Land Use – Assess and mitigate risks associated with adjacent and nearby land uses, including grazing lands and animal operations regardless of size. Prevent contamination from uphill adjacent cattle grazing lands, such as by produce farms increasing buffer zones if fields are adjacent to cattle grazing lands (based on assessment); and adding physical barriers such as berms, diversion ditches and vegetative strips
Agricultural Water – Ensure that all agricultural water is safe and of adequate sanitary quality for its intended use. Assess and mitigate risks related to land uses near or adjacent to agricultural water sources that may contaminate agricultural water. Ensure that any agricultural water treatment is validated, verified, and in accordance with all applicable Federal, State, Local, and other regulations
Improve Traceability
Increase digitization, interoperability and standardization of traceability records, which would expedite traceback and prevent further illnesses.
Broader, more consistent implementation of voluntary source labeling on packaging or point of sale signs, or by other means to help consumers and retailers more readily identify product during an outbreak or recall.
Improve Root Cause Analysis
Perform a root cause analysis when a foodborne pathogen is identified in the growing environment, in agricultural inputs (e.g., agricultural water or soil amendments), in raw agricultural commodities or in fresh-cut ready-to-eat produce.