This story was originally published by Investigate Midwest.
After a series of outbreaks of E. coli sickened more than 160 people who ate romaine lettuce in late 2019, the U.S. Food and Drug Administration has launched an investigation. Months later, in March 2020, the agency announced its plan to prevent toxic outbreaks of E. coli related to leafy greens.
But in the two years since the FDA announcement, there have been at least four outbreaks of E. coli caused by leafy greens. At least 69 people have fallen ill and 28 have been hospitalized.
Contamination of crops with E. coli is difficult to prevent for a number of reasons, experts have said, but some food safety advocates want the government to adopt stricter regulations, particularly regarding the distance between lettuce fields and concentrated animal feed operations. In April 2021, the FDA first called nearby livestock a “recurring safety issue.”
Jaydee Hanson, director of policy at the Center for Food Safety, advocated for policies that would increase the distance between production fields and CAFOs during meetings between food safety advocates, the FDA and the US Department of Agriculture .
“It’s a challenge because the people who run CAFOs want to keep running, and the people who grow lettuce want to keep growing lettuce,” he said. “The (question) is, how did you get both?”
E. coli bacteria live in the intestines of humans and animals. Only certain strains, such as shigatoxin-producing E. coli, are harmful. STEC can cause severe diarrhea, stomach cramps and vomiting. In the most severe cases, those infected develop a life-threatening hemolytic-uremic syndrome.
In the two years since the announcement of the FDA’s Leafy Greens STEC action plan, the number of recorded outbreaks has roughly equaled the number of confirmed outbreaks linked to leafy greens during the decade preceding the FDA plan.
Leafy greens were confirmed as the source of 18 STEC outbreaks between 2009 and 2018, and were the suspected source of 22 additional outbreaks during that time, according to a study by the FDA and the Centers for Disease Control and Prevention.
An FDA spokesperson told Investigate Midwest that the FDA is “laser focused” on reducing the risk of E. coli in leafy greens.
“Our ability to detect foodborne illness is better than ever. And that’s a good thing,” the spokesperson said. “We now have the ability to take microbial fingerprints of harmful bacteria found in patients and link food-related illnesses that in years past would have gone unnoticed.”
Preventing outbreaks is difficult because bacteria can be picked up and transferred to fields from a wide range of sources: rainwater runoff, bird droppings, nearby livestock, field workers, and water. irrigation.
No one wants their farm to be linked to an outbreak. No one wants their neighbor’s farm to be linked to an outbreak. So there are a lot of very strong incentives for companies to want to fix the problem.
– Sarah Sorscher, Deputy Director of Regulatory Affairs at the Center for Science in the Public Interest
Some food safety advocates like Hanson want government agencies to enforce greater distance between livestock operations and crop fields, given that livestock manure has been linked to two outbreaks of E. coli in recent years.
But industry groups — such as the California Leafy Greens Marketing Agreement, which covers 90% of leafy greens grown in the United States — already require a 1-mile “buffer zone” between fields and concentrated animal feed operations. (It’s 30 feet for small trusses.)
“There’s still a lot of work going on trying to understand how (outbreaks) happen,” LGMA spokeswoman Marilyn Freeman said. “If we knew how to stop it, I can guarantee you we would, but there’s a lot going on – there’s still a lot of research going on.”
Because the FDA is better than ever at detecting disease, it’s possible the agency will find and publish outbreaks of E. coli at a higher rate than other types of foodborne illness, said Sarah Sorscher, deputy director of regulatory affairs at the Center. for science in the public interest.
All that attention could make leafy greens look more suspect than other produce, she said.
But certain characteristics of leafy greens make crops more susceptible to contamination.
“Fresh leafy greens are typically grown outdoors, close to the ground and subject to contamination from air, soil, water, animals and workers,” the spokesperson said. FDA. “Unlike beef, for fresh leafy greens there is usually no killing step as they are usually eaten raw.”
The STEC action plan, last updated in April 2021, said the agency would work with government agencies and industry stakeholders to minimize “the risks presented by the presence of livestock on land. Adjacent and Nearby” in addition to educating federal and state inspectors on the risks posed by land uses adjacent to crop fields.
Hanson said the FDA has been slow to address the role of livestock operations in outbreaks of E. coli, but the agency is starting to change its language and its approach to the issue.
For example, the FDA said stakeholders know the importance of the agency labeling a certain strain of E. coli – O157:H7 – as a “reasonably foreseeable hazard” for the first time in a fall 2020 outbreak report. The report also identified livestock as a “recurring safety issue”.
In many ways, the leafy greens industry is ahead of the FDA when it comes to food safety practices, Sorscher said, and farmers often take steps beyond what’s required by the federal government to reduce the risk of foodborne illness.
For example, after an outbreak of E. coli caused by spinach grown in California, farmers created the LGMA under the supervision of the state Department of Food and Agriculture to voluntarily raise the bar for food safety practices.
“There’s an industry-wide interest in getting it right,” Sorscher said. “Nobody wants their farm to be linked to an outbreak. No one wants their neighbor’s farm to be linked to an outbreak. So there are a lot of very strong incentives for companies to want to fix the problem.
Gaps in food safety science, technology
The exact source of E. coli contamination is often difficult to determine.
As of January 2021, the FDA has been unable to determine which food products have caused three different outbreaks of E. coli disease. For example, investigators may encounter traceability issues if a person with a foodborne illness does not remember all the food items they have eaten in previous days, or if they have discarded food labels. products at home.
Even when the product is identified, investigators cannot always tell how the product was contaminated in the first place. In the three outbreaks of E. coli caused by leafy greens as of November 2021, FDA officials have not determined where the bacteria came from and how it got into the produce.
In one case, the FDA collected samples of STEC from farms in Yuma, Arizona, and Salinas, California, but the strains were different from the strain the FDA was investigating, according to a January outbreak report. caused by packaged salads.
During outbreaks of E. coli from 2019 romaine and leafy greens In 2020, FDA officials found matching bacterial strains in cow manure near fields linked to outbreaks. But investigators couldn’t figure out exactly how the bacteria reached the fields.
Animals, vehicles, runoff, rivers and wind could all have transferred E. coli with lettuce.
If a farmer doesn’t know how his field became contaminated in the first place, he may not know the best way to prevent the bacteria from entering in the future, Sorscher said.
Testing and treating water used to irrigate crops, especially in the weeks before harvest, is one way to mitigate the risk of contamination. But most commercially available E. coli tests only detect generic E. coli. Although these tests can alert farmers to the presence of feces in the water, they do not signal the presence of E. Pathogen coli, Sorscher said.
California’s LGMA currently requires farmers who do not use municipal water sources to regularly test for E. generic coli. A new rule proposed by the FDA would require farmers to perform annual water assessments to identify potential sources of contamination, including nearby livestock operations.
As for water treatment, many common federally approved water treatments have been developed for use in municipal water sources, which do not contain sediment, Sorscher said, and if farmers use muddy water in their fields, treatments may not be as effective.
The FDA action plan also included measures to improve outbreak response. The agency has proposed a rule requiring additional records to be kept throughout the supply chain for foods on the agency’s food traceability list, which includes leafy greens. If passed, the rule will streamline investigators’ ability to trace foodborne illnesses to their source.
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