A week before Thanksgiving, the Centers for Disease Control and Prevention announced it was investigating an outbreak of E.coli in romaine lettuce, the fourth such outbreak in two years. In early December, a fifth outbreak was discovered, this time linked to E.coli in packaged chopped salad. While Americans rushed to remove salad from their holiday tables, investigators from the Food and Drug Administration still have not determined where the bacteria came from, and why the same strain has repeatedly infected our lettuce supply.
E. coli are deadly bacteria that live in the guts of cows and some wild animals, such as birds and deer. They don’t harm the animals but can spread through the water, soil, and air to infect fresh vegetables. Lettuce growers have taken steps to protect their crops — implementing new rules to sanitize some irrigation water and increase the distance between their fields and large cattle feedlots. But what about the animal farms and feedlots where these bacteria often originate?
The April 2018 outbreak of Shiga toxin-producing E.coli, or STEC — the most common, deadly strain of the bacteria — was the largest outbreak in several decades. Five people died, and at least 240 were sickened after eating romaine. Investigators from the Food and Drug Administration traced the E.coli to an irrigation canal near Wellton, Arizona, that runs adjacent to lettuce fields and a feedlot that can hold 120,000 head of cattle. They don’t know precisely how the bacteria entered the lettuce fields, partly because they were only able to take six samples from the feedlot, months after the outbreak occurred. “Since the sampling was limited, it is not possible to draw statistically valid conclusions regarding the presence or absence of the outbreak strain on this facility,” the FDA’s environmental assessment report states.
Overall, the CDC estimates that 265,000 people annually are sickened by STEC around the country, and 30 people die.
Government inspectors have to ask the owner’s permission to collect samples from…