Most at risk for Shiga toxin-producing E. coli infections are those younger than 5, older than 65 and with weakened immune systems.
With the growing and harvesting season over there, according to the FDA, people may eat romaine lettuce that has been hydroponically or greenhouse grown, or has been harvested from the winter growing desert regions of the United States, and is labeled such.
Health officials say improved detection may make outbreaks seem more frequent.
It's not yet known how romaine got contaminated in the latest outbreak. At least two irrigation canals in the Yuma growing region pass by a large feedlot in Wellington, Ariz., though officials never pinpointed the feedlot as the source of the contamination. As no contaminated product has been found in the marketplace and the source of the contamination has not been identified, there have been no product recalls in Canada or the U.S associated with this outbreak. Steps include expanding buffer zones between cattle lots and produce fields. Twenty-five of those experiencing symptoms were interviewed, and 22 reported having eaten Romaine lettuce in the days leading up to the onset of their illness. That bacteria came from a tainted drainage canal near an Arizona lettuce farm, investigators said. But he said such treatment raises concerns about soil and human health. Travis Forgues of the milk producer Organic Valley noted consolidation in the dairy industry is leading to bigger livestock operations that produce massive volumes of manure.
Leafy greens were also blamed for an E. coli outbreak past year.More news: UEFA European Champions qualifying draw
"The timing and type of warning in this incident demonstrated the importance of food safety and the speed at which the industry responds", Droke said. "If the dish contains (uncooked) romaine lettuce, it should be sent back or thrown out", she says.
The FDA said the E. coli O157:H7 strain causing the outbreak is similar to an outbreak of E. coli O157:H7 in the fall of 2017.
The produce industry says the failure to prevent the Yuma outbreak could also reflect the limitations of testing water for generic E. coli.
Food safety experts are not happy about the discrepancy. Most E. coli strains are harmless and indeed part of a healthy gut.
Whole-genome sequencing is making it easier to detect outbreaks, which is pressuring the produce industry.
The FDA is continuing tracebacks of romaine lettuce from locations where impacted consumers purchased or consumed romaine lettuce before they became ill in order to identify specific locations that are the likely source of the outbreak and to determine the factors that resulted in contamination. An industry group said people can expect to start seeing labels as early as this week. The FDA recently hired a former Walmart executive who used blockchain technology to improve traceability in the retailer's supply chain.