Taylor Farms Lettuce Sample Provided 'False Positive' For Cyclospora, FDA Says

The FDA said it made a mistake during testing, wrongly tying a Cyclospora outbreak to lettuce sold in Maryland and other states.

By Gaby Arancibia, Patch Staff

Jul 20, 2026 12:06 pm EDT

This undated photo taken through a microscope provided by the CDC shows Cyclospora cayetanensis oocysts found in a fresh stool sample which had been prepared with a formalin solution and stained with safranin. (CDC via AP)

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 tested positive for Cyclospora, a bacteria linked to a parasitic illness that officials say causes explosive, watery diarrhea.

The FDA 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.

Despite the false positive, Taylor Farms (whose parent company is Taylor Fresh Foods in California) is still 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."

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.

In Maryland, health officials have confirmed 69 cases of the parasitic gastrointestinal illness. The Maryland Department of Health said 65 of the cases were documented between May 1 and July 14.

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.