The Food and Drug Administration walked back an earlier statement that a sample of lettuce from Taylor Farms tested positive for cyclospora, but noted that tests are continuing on products pulled from the market.
The finding complicates the messaging from health authorities tracking the sources behind major outbreaks of foodborne illnesses and efforts to address concerns from the public about which foods are safe to eat.
The FDA said its investigation is ongoing. It is still advising consumers not to eat recalled iceberg lettuce from Taylor Farms. "To clarify, this false-positive lab sample DOES NOT change the basis for FDA's ongoing outbreak investigation or the overwhelming epidemiological data supporting the current voluntary recall by Taylor Farms," the FDA said in a Monday post on X.
Taylor Farms, a major supplier of lettuce and produce to restaurant chains and grocers, is navigating the fallout from the outbreaks while many of its other products remain on store shelves.
Government agencies last week identified shredded iceberg lettuce, including products served at locations of the restaurant chain Taco Bell, to thousands of reports of foodborne illness in five states.
After interviewing people sickened by the parasite, health authorities linked the illnesses to lettuce supplied by Taylor Farms. The company said it voluntarily recalled the shredded iceberg lettuce grown and processed in central Mexico "in an abundance of caution." The recalled lettuce was distributed from June 29 to July 16 across 27 states.
"Our thoughts remain with everyone who has fallen ill in this outbreak," Taylor Farms said in a statement. "We are committed to working with public health authorities as the ongoing outbreak investigation continues."
State and federal health authorities are still collecting and analyzing lettuce samples from the company. Future lab tests could identify the parasite's presence on other products.
Authorities use lab tests to confirm their findings linking an outbreak to a particular farm. Yet it is hard for testing to definitively make the connection. The source of the contamination might not remain, and it is challenging for scientists to culture enough for study in a lab.
As cyclospora-related illnesses have been on the rise, the FDA increased its screening of lettuce entering the U.S. from the southern border.
The FDA on Saturday said that a sample of shredded iceberg lettuce supplied by Taylor Farms de Mexico had tested positive for cyclospora. The lettuce sample wasn't covered by Taylor Farms' existing recall, prompting the FDA to make its finding public, an agency official said Monday.
However, lab personnel determined during a quality check that the result was a false positive, leading the agency to update its findings.
Taylor Farms said the FDA has apologized. An FDA official said Monday that the agency hadn't issued a formal apology but explained the circumstances around the test result. The official said that positive product samples can be difficult to come by in outbreak investigations, especially cyclospora, and that other evidence linking Taylor Farms' lettuce to illnesses is strong.
The outbreak has cast a pall over purchases of leafy greens at stores and restaurants with menu items using lettuce. Placer.ai, which analyzes foot traffic at businesses, estimated Monday that visits to U.S. Taco Bell locations Wednesday through Friday last week were down between 16.9% and 18.9%, compared with the day-of-week average between Jan. 1 and July 6. Other chains that typically use fresh produce also saw slower traffic.
Most people infected with cyclospora develop diarrhea with frequent bowel movements, health authorities have said. Symptoms also include loss of appetite, weight loss and stomach pain. The illness can last a few days, or even weeks.
Testing for cyclospora is very challenging, said Jennifer McEntire, a food-safety professional who consults for companies including Taylor.
In part, that is because it is impossible to grow in a lab. Unlike bacteria such as E. coli and salmonella, cyclospora can't be cultured to produce a larger amount of genetic material for study, McEntire said. That limits scientists' ability to link individual cases to a common source.
"You're looking for a needle in a haystack," she said. "With E. coli and salmonella if you find it you can make the needle bigger. That doesn't happen for cyclospora."
Write to Bowdeya Tweh at bowdeya.tweh@wsj.com, Jesse Newman at jesse.newman@wsj.com, and Heather Haddon
(END) Dow Jones Newswires
July 20, 2026 15:17 ET (19:17 GMT)
Copyright (c) 2026 Dow Jones & Company, Inc.
Comments