US outbreak of E. coli from romaine lettuce declared over

The U.S. Food and Drug Administration, along with the U.S. Centres for Disease Control and Prevention and state and local partners previously reported that public health experts were tracking three separate outbreaks linked to romaine lettuce caused by three different strains of E. coli O157:H7. The FDA’s traceback investigation identified a common grower between the outbreaks in Salinas, California, based on supply chain information. It should be noted that romaine from this grower does not explain all of the illnesses seen in these outbreaks.

The FDA has lifted the consumer advisory to avoid romaine lettuce from Salinas, as the growing season for the region is over, and there is no need for consumers to avoid it, or other products from Salinas, California. The FDA and CDC have been tracking two multi-state romaine lettuce outbreaks; federal health officials have now declared both multi-state outbreaks over. One of the outbreaks sickened 167 people in 27 states, while the other outbreak, linked to Fresh Express salad kits, sickened 10 people in five states. A third outbreak in Washington State that sickened 11 people has also been declared over.

The last reported illness onset for all the outbreaks was 21 December 2019. Based on this, it appears that the advisory issued on 22 November 2019 to not eat romaine lettuce from Salinas prevented illnesses and contained this outbreak, as it prompted the removal of romaine from Salinas from the marketplace, and warned consumers to throw away romaine from that region. The FDA traceback investigation required investigators to go through hundreds of supply chain records to find a commonality to a single grower with multiple fields. This was further narrowed down to at least 10 fields in the lower Salinas Valley.

Investigators from the FDA, CDC, the California Department of Food and Agriculture and the California Department of Public Health visited these fields, taking samples from water, soil and compost. While sample results came back negative for all three outbreak strains of E. coli O157:H7, investigators did find a strain of E. coli that was unrelated to any illnesses in a soil sample taken near a run-off point in a buffer zone between a field where a product was harvested and where cattle would graze. This requires further examination as the investigation continues, but does not explain the illnesses seen in these outbreaks.

The investigation into the source or sources of contamination is ongoing, and is important as it will enable romaine growers to implement measures to prevent future contamination and illnesses. The FDA will conduct an additional root-cause investigation to determine how contamination could have occurred and what controls are needed to prevent future outbreaks. Once over, the FDA will issue a report so growers can implement best practices to protect consumers from contaminated product.

While millions of servings of leafy greens are consumed safely every day, the repeat nature of these outbreaks linked to romaine lettuce remains a concern. The FDA will continue sampling to monitor for pathogens in romaine lettuce, while everyone across the romaine supply chain must take every measure to understand why and how these outbreaks keep happening. Preventive measures must also be implemented by all stakeholders, including growers, processes, distributors and retailers, to further protect consumers.

The FDA will continue to work with fellow regulators and the food industry to identify and address causes of outbreaks, and keep consumers aware of potential risks. As part of the FDA’s New Era of Smarter Food Safety Initiative, advances in technology will be used to track and trace products through the supply chain. While the FDA places an emphasis on prevention, prompt responses to outbreaks when they occur are also a priority. The FDA will launch a New Era of Smarter Food Safety Blueprint in early 2020, to help consumers get information faster, enabling people to better protect themselves and their families.

Image credit: ©stock.adobe.com/au/Victor Moussa