Lettuce Sold By CA Grower Provided 'False Positive' For Parasite, FDA Says

Federal officials are still searching for the source of a multistate diarrhea parasite outbreak after a lettuce sample provided a "false positive," the FDA said Sunday.

Taylor Fresh Foods voluntarily recalled some of its products last week after federal officials said a lettuce sample from Taylor Farms de Mexico came back positive for Cyclospora, a bacteria linked to an illness that can cause relentless watery diarrhea.

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But the FDA on Sunday said it made a mistake during testing.

"Due to the complexity in detection of Cyclospora, FDA laboratory experts re-reviewed the sample results and have concluded that the finding does not represent true amplification and should be considered a false positive," officials said in a statement.

The statement continued: As of Sunday "there are no confirmed positive sample results for product testing for Cyclospora."

Despite the false positive, Salinas-based Taylor Farms is still voluntarily recalling its iceberg lettuce that was sourced from central Mexico.

Officials said Taylor Farms, which produces lettuce for Taco Bell and multiple grocery retailers, is "working with the firm to ensure product implicated in this outbreak has been removed from the market."

"All other Taylor Farms products, including all Taylor Farms brand products available for purchase, are not involved in the recall," the company said in a statement.

The recall came after the FDA focused on lettuce served at multiple Taco Bell locations across five states. FDA investigators tied 1,644 cyclosporiasis cases in Michigan, Indiana, Kentucky, Ohio and West Virginia to food from Taco Bell from May 13 to July 13.

Taco Bell quickly announced it would stop serving the lettuce.

"Ingredient-level analyses on meals eaten by these cases indicate that 90 percent of those interviewed reported eating iceberg lettuce," FDA officials said.

Health officials also believe lettuce and other salad mixes are tied to the outbreak, but they have not yet identified an exact source.

As of Monday, there have been no statewide recalls connected to the outbreak.

The parasitic gastrointestinal illness has infected 309 people — with 24 hospitalizations — in Illinois in addition to thousands of others nationally, the Illinois Department of Public Health reported Friday.

Michigan is reporting the highest number of outbreaks — 5,002 people and 102 hospitalizations — in the country, leading health officials to believe the state's case numbers alone likely make it the largest cyclosporiasis outbreak in U.S. history.

In California, 41 provisional cases of cyclosporiasis have been reported to the California Department of Public Health as of Thursday. Officials say they are not believed to linked to the current nationwide outbreak.

Taylor Farms, the Salinas-based manufacturer that supplied the lettuce, describes itself as one of the leading global products of salads and healthy fresh foods, according to its website.

The company has production facilities across the U.S., Canada, Mexico and Western Europe.

In 2024, Taylor Farms made headlines as a potential source of an E. coli outbreak found in slivered onions sold at McDonald's restaurants across the country.