Federal officials say the e-coli outbreak that led to the deaths of five people and sickened hundreds more is over. But the U.S. Food and Drug administration now says bacteria that contaminated romaine lettuce grown near Yuma, Arizona has been found in local irrigation canals.
The news has local food researchers scratching their heads, while the search for the original source of the contamination continues.
Illnesses were first reported in March. The most recent numbers from the Centers for Disease Control and Prevention say 96 people were hospitalized, including 27 with a rare type of severe kidney failure. Deaths were reported in Arkansas, California, and New York. Two people died in Minnesota.
The outbreak was initially tied to bagged romaine salad but the illness of several inmates at a prison in Alaska was linked to whole-head lettuce.
Most of the country’s winter lettuce and other leafy greens are grown in Yuma, so contaminated romaine lettuce should be off store shelves by now. The CDC says the latest reported illness started on June 6 and that the outbreak is now over.
Despite tracing the outbreak to the Yuma region, no individual farm, field, processing facility, or distributor has been linked to the outbreak. But the FDA now says bacteria taken from irrigation canals in the Yuma area matches the strain that caused the outbreak.
Dr. Paul Rivadeneira is a food safety researcher with the University of Arizona Cooperative Extension. Rivadeneira works with local growers, helping them inspect fields and devise strategies to prevent contamination. She says farmers are devastated that their livelihoods are linked to five deaths and the illness of so many others. But the FDA’s statement that matching bacteria was found in local canals is, she says, surprising.
Rivadeneira says growers test canal water regularly. Samples taken before the outbreak were clean and news now that samples taken more recently match the E-coli strain linked to tainted romaine lettuce leads to more questions. For example, fecal matter contaminated with E-coli tends to disperse and dilute in water. So how did a waterborne contamination spread to so many people? And why weren’t more crops affected?
“It is just pretty shocking that it would potentially contaminate so many fields. And then also that it’s only contaminating romaine. We had a lot of different crops growing, so why only romaine?”
Rivadeneira warns that finding the original source of the contamination is still a high priority. She says growers are already taking orders for the new season and they need to be able to plan their fall planting with confidence in their food safety practices and their water delivery systems.
The CDC says the 2018 E-coli outbreak was the largest in more than ten years. In 2006 more than 200 people were sickened and five died from contaminated baby spinach grown in the Salinas, California region.