Four months after telling the country it's, food regulators are pointing to cow feces as the likely culprit in outbreaks of E. coli that sickened 188 people across the country.
"The proximity of cattle to produce fields may have been a contributing factor" in three outbreaks of food-borne illness tied to romaine lettuce, according to a recent report from the U.S. Food and Drug Administration.
The outbreaks in November and December sickened people from 27 states, according to the U.S. Centers for Disease Control and Prevention. Not deaths were reported.
Investigators concluded the illness stemmed from ranches and fields owned by the same grower of romaine lettuce that were located downslope from public land where cattle grazed in the Salinas Valley in California.
E. coli infection usually causes sickness two to eight days later, according to health authorities. Most people get diarrhea and abdominal cramps. However, some cases can be life-threatening, causing kidney failure and seizures.
E. coli bacteria can get into water and soil through multiple routes, including waste from domesticated animals or wild animals, fertilizer and other agricultural products.
The FDA couldn't definitely identify a route of contamination for the three 2019 outbreaks. But the agency said the possibilities included water runoff from the grazing area, wind-blown material, or animals or vehicles tracking it to the fields.
"Agricultural water sources used to grow the romaine" also were possible routes, the report's executive summary said.
Another E. coli outbreak in spring 2018 that sickened more than 200 people and killed five was traced to tainted irrigation water near a cattle lot.
Between 2009 and 2018, federal authorities identified 40 food-borne outbreaks of E. coli in the U.S. "with a confirmed or suspected link to leafy greens," the FDA said.
The sandwich chainfrom its 2,800 restaurants nationwide in an E. coli outbreak that sickened more than a dozen people in five states. An outbreak of intestinal illness linked to eating McDonald's salads contaminated with a cyclospora parasite of the chain's customers in the summer of 2018.
Industry groups tightened safety measures following the 2018 E. coli outbreak, including safer distancing between livestock and growing fields. The FDA this March issued a plan with a number of voluntary recommendations for reducing the risk of contaminating fields. They include increasing buffers between grazing lands and growing fields and adding barriers such as ditches and berms.
The investigation was performed by FDA with the Centers for Disease Control and Prevention, agencies in several states and Canadian health and food inspection agencies.