FDA continues investigation into E. coli outbreak linked to romaine lettuce
The U.S. Food and Drug Administration (FDA) continues to investigate the outbreak of E. coli O157:H7 infections associated with romaine lettuce from the Yuma, Ariz. growing region.
The U.S. Food and Drug Administration (FDA) continues to investigate the outbreak of E. coli O157:H7 infections associated with romaine lettuce from the Yuma, Ariz. growing region. Any contaminated product from the Yuma growing region has already worked its way through the food supply and is no longer available for consumption, but the agency continues to investigate the source of the outbreak in order to prevent similar events in the future.
In a post on FDA’s website, FDA Commissioner Scott Gottlieb offered a progress report on the investigation. “This outbreak of E. coli O157:H7 illnesses is the largest in the United States in more than 10 years,” wrote Gottlieb. As of June 1, it has affected 197 people in 35 states, hospitalized 89 people, and resulted in five deaths. In addition, 26 people have developed hemolytic uremic syndrome (HUS), one of the most serious complications that can occur with E. coli O157:H7 infection.
In the current outbreak, illness has generally been linked to the consumption of chopped romaine lettuce. The lettuce was generally consumed at restaurants or purchased at markets. In one cluster of illnesses at an Alaska correctional facility, the prison received and served whole head romaine lettuce rather than chopped and bagged romaine.
The FDA has released a traceback diagram that focuses on the settings where there were several well-documented clusters of cases. The diagram reveals that based on the information the agency has thus far, there are still no obvious points of convergence along the supply chain. Except for the farm that provided the whole head lettuce to the Alaska correctional facility, the other tracebacks in the diagram show different suppliers, distributors, and/or processors. These pathways lead back to different farms, sometimes many farms, where possibly contaminated lettuce could have been harvested during the timeframe of interest. The only point of commonality in the traceback efforts to date is that all the farms are in the Yuma growing region.
“If the explanation was as simple as a single farm, or a single processor or distributor, we would have already figured that out,” wrote Gottlieb. “The traceback diagram does show us that the contamination with E. coli O157:H7 was unlikely to have happened near the end of the supply chain (such as at a distributor) because there are no common distributors among the places that received and sold or served contaminated lettuce. The contamination likely happened at, or close to, the Yuma growing area.”
The FDA is now working on evaluating several theories about how romaine lettuce grown on multiple farms in the same growing region could have become contaminated around the same time. It’s possible that contamination occurred on multiple farms at once, through some sort of environmental contamination (e.g., irrigation water, air/dust, water used for pesticide application, animal encroachment). Another possibility is that it happened just after the lettuce left the farm.
“Food safety is one of the highest priorities at the FDA,” wrote Gottlieb. “This outbreak is a clear illustration of why that’s the case. It shows the terrible consequences when something goes wrong.”