WASHINGTON — The U.S. Food and Drug Administration is continuing to investigate a multistate outbreak of Cyclospora infections linked to iceberg lettuce supplied by Taylor Farms de Mexico, even after determining that an earlier laboratory result indicating contamination in a lettuce sample was a false positive.
The FDA said its investigation remains focused on shredded iceberg lettuce supplied by Taylor Farms de Mexico after epidemiological and traceback evidence identified the company as the common supplier for lettuce served at Taco Bell restaurants where many infected people reported eating before becoming ill. Federal officials said the investigation is continuing with the Centers for Disease Control and Prevention and state health agencies.
According to the FDA, Taylor Farms de Mexico voluntarily removed all iceberg lettuce sourced from central Mexico from the U.S. market on July 17 and initiated a recall covering certain retail and food-service products. The recall includes selected Marketside-branded iceberg salad and shredded lettuce products sold through Walmart as well as products distributed to restaurants and other food-service customers.
The agency updated its investigation on July 19 after laboratory experts re-examined a lettuce sample that had initially been reported as testing positive for Cyclospora cayetanensis, the parasite that causes cyclosporiasis. FDA officials said the finding did not represent true amplification and should be considered a false positive. As of the latest update, the agency said it had no confirmed positive product test results for Cyclospora but continued collecting and analyzing food samples.
Health authorities said the absence of a confirmed positive product sample does not alter the epidemiological evidence supporting the investigation. Former FDA Commissioner Scott Gottlieb and agency officials have noted that Cyclospora is difficult to detect in fresh produce and that outbreak investigations often rely heavily on traceback and illness data rather than laboratory confirmation alone.
The FDA and CDC said illnesses linked to the five-state outbreak represent a subset of Cyclospora infections reported nationwide. Federal investigators previously reported 1,644 outbreak-associated illnesses, including 94 hospitalizations and no deaths, with most interviewed patients reporting consumption of iceberg lettuce at Taco Bell locations in Indiana, Kentucky, Michigan, Ohio and West Virginia.
Taylor Farms said it is cooperating with federal and state authorities and voluntarily recalled the products out of caution. The company has suspended distribution of the implicated iceberg lettuce from central Mexico while the investigation continues.
The FDA continues to advise consumers, retailers and restaurants not to consume or serve recalled iceberg lettuce and to discard affected products while investigators work to determine the source of the contamination.
