romaine lettuce

Update on Romaine Lettuce E. coli Outbreaks and Investigation

Dan Cooper Industry News Release, Leafy Vegetables, Top Posts

romaine lettuce
Photo credit: The Toidi /

Illnesses subsiding, FDA continues to aggressively investigate source and route of contamination to prevent future outbreaks

(FDA) — The U.S. Food and Drug Administration (FDA) is providing an update on its investigation of an outbreak of E. coli O157:H7 illnesses linked to romaine lettuce. The FDA takes its responsibility of protecting the public from unsafe food very seriously and is committed to providing the public with more information as it becomes available.

Outbreaks Reported

Early on, based on test results provided by the Maryland Department of Health, The FDA investigation pointed to farms in Salinas, California, as potential sources of contaminated romaine lettuce based on the initial, limited number of reported illnesses. The FDA, in partnership with the California Department of Public Health and the California Department of Food and Agriculture, rapidly mobilized in November to concurrently deploy inspection teams to the farms identified through the initial traceback investigation. The on-site investigations at these farms included collecting a wide-variety of samples for lab testing, including water, soil, soil amendments, scat and swab samples. While the majority of these samples tested negative for the outbreak strain, final results are pending and the Wisconsin Department of Health Services recently reported that it had isolated E. coli O157:H7 from a particular bag of pre-washed, chopped romaine lettuce.

The FDA has also been tracking two additional and separate outbreaks of E. coli O157:H7.

Earlier this week, the FDA, U.S. Centers for Disease Control and Prevention (CDC), and the Canadian Food Inspection Agency announced an outbreak linked to Fresh Express Sunflower Crisp Chopped Salad Kits. To date, the CDC reported eight confirmed cases in the United States across three states associated with this cluster of illnesses.The Public Health Agency of Canada External Link Disclaimer also reports 24 cases in six Canadian provinces.

Concurrently, the FDA has been working with health officials in Washington State regarding an outbreak of E. coli O157:H7 associated with romaine consumption at a local restaurant chain. Washington State officials reported 10 confirmed and three probable cases in this outbreak with all reports of exposure in early to mid-November.

It should be noted that these are currently being considered as three separate outbreaks caused by three different strains of E. coli O157:H7. 


Traceback Convergence

Because of the expansive nature of these outbreaks, the FDA investigation remains a complicated work in progress, and it is too soon to draw definitive conclusions. The FDA, CDC and state partners have identified a common grower between each of the outbreaks, which is a notable development.

This finding reinforces earlier traceback results. It’s still too early to conclusively determine whether other sources may have also been involved in the outbreaks. However, progress is being made, and the FDA is actively investigating other traceback leads identified to determine if it can triangulate a more precise location of the contamination. FDA will provide updates to the public as further information becomes available.

Issues Critical to the Investigation

While the outbreak investigation remains a high priority for the agency, the progress made to this point is only possible due to three major factors. The first is the ability for federal agencies and the states to detect and link cases of foodborne illness through new DNA-fingerprinting capabilities referred to as whole genome sequencing. This technology allows FDA to make connections earlier and to help prevent additional illnesses, ultimately saving lives. Second, strong federal and state coordination on matters of public health are critical in this work. In both isolating the outbreak strain in food samples and assisting in providing traceback records, state partners’ work is exemplary and has proven critical to this investigation, and FDA continues to work to strengthen these vital public health partnerships. Finally, the voluntary adoption of labeling best practices by many and technology-enabled traceability used by some in the industry help to target consumer advice to a defined growing region – compared to last year’s advisory which was to avoid romaine lettuce nationwide regardless of where it was grown.  

The Challenges with Traceback 

While progress has been made, conducting traceback investigations into many segments of the produce industry remains challenging, as it involves digging into past records to work backward from case-patients to the point of purchase of the product, and then through the supply chain to the source from where it was grown. Traceback investigations are resource and time-intensive, and largely done the same way FDA has been conducting them for years. Since it is common for people who become ill from a leafy green like romaine lettuce to eat the food frequently, a solid traceback investigation requires specific details about all the food exposures a person had prior to becoming sick. This means the critical elements of a successful traceback – identifying which exposures most likely led to illnesses, and which to trace back to – is complex.

None of this work can begin until an illness is reported. Once the initial evidence is laid out, a traceback investigation includes investigating retail establishments, suppliers and distributors working back to the farm or farms that may have grown the lettuce that ended up in consumers’ meals and homes. It’s a labor-intensive task requiring collecting and evaluating thousands of records while also trying to accurately document how the contaminated lettuce moved through the food supply chain to grocery stores, restaurants and other locations where it was sold or served.

With the current outbreak investigations, the FDA worked quickly with romaine producers, distributors, retailers and foodservice companies to request that they promptly and voluntarily withdraw the product from the market in an attempt to contain these outbreaks. FDA has also conducted a sampling assignment to monitor romaine lettuce and will continue to do this through 2020. With technology and assignments like that just mentioned, the FDA is more forward-leaning than ever and will continue to get better at identifying potential outbreaks – and solving them. 

Preventive Measures More Important Than Ever

While FDA understands that millions of servings of fresh leafy greens are served safely every day to consumers, given the repeat nature of these outbreaks linked to leafy greens – and more specifically to romaine lettuce – it’s critical that everyone across the romaine supply chain do everything possible to fully understand why and how these outbreaks keep happening and continue to aggressively implement preventive measures to further protect consumers. The FDA’s continuing investigation of these outbreaks for products past their best-by dates, and even in fallow fields, is one of the efforts to find out how this contamination occurred so that the romaine growers can make interventions that will prevent future contamination and illnesses.

As an agency, FDA remains laser-focused on prevention. Food safety is not a competitive issue, so everyone involved in the farm-to-table supply chain of fresh leafy greens (growers, distributors, retailers and foodservice companies) must work collaboratively, with a sense of urgency, and do everything possible to fully understand how and why these outbreaks continue to occur. Moreover, they must aggressively implement additional preventive measures to address any shortcomings identified to further protect consumers.

A New Era of Smarter Food Safety

While public health agencies have gotten better at detecting foodborne illnesses, the ability to trace back to the source of contaminated foods that may have caused the illnesses has lagged, due in part to the lack of modernized food traceability capabilities. 

Under the FDA’s New Era of Smarter Food Safety initiative, the agency plans to use advances in technology to improve its ability to track and trace products through the supply chain. FDA will be launching a New Era of Smarter Food Safety blueprint in early 2020 that will outline how it will advance work in this area.

This will help consumers get information more quickly, enabling people to better protect themselves and their families. FDA looks forward to continuing its work with growers, processors, distributors and retailers in shared efforts to protect consumers, and FDA will continue to provide updated information as it becomes available.

Source: U.S. Food and Drug Administration

Share this Post