FDA says Taylor Farms’ lettuce samples tested for Cyclospora produced false positives for the parasite

Lettuce samples from a supplier whose products were recalled after outbreaks of Cyclospora in multiple states gave false positive results for the parasite, federal officials announced Sunday.

The false positive was discovered Saturday when the U.S. Food and Drug Administration reviewed results from a sample from Mexico’s Taylor Farms, which had a positive report.

“As of July 19, 2026, there have been no confirmed positive product test results for Cyclospora,” the FDA said in a statement.

This false positive does not change the company’s previous voluntary recall of iceberg lettuce sourced from central Mexico.

Taylor Farms, which produces lettuce for Taco Bell and several grocery retailers, “continues to work with the company to ensure that products associated with this outbreak are removed from the market,” the FDA said in a statement Sunday night.

Taylor Farms said in a statement Sunday night that the FDA made a mistake and apologized. It reiterated the FDA’s statement, saying the agency had not identified “a single positive product test result for Cyclospora.”

The company said it will continue to work with public health authorities to investigate the source of the infection.

The FDA issued a notice about the positive test on Saturday, but later removed it from its update on the outbreak, in which the agency said the product was not part of an existing Taylor Farms recall and that the company was “working to determine whether some of this involved lot is available in commercial or consumer homes.”

The company announced Friday that Taylor Farms de Mexico is voluntarily recalling iceberg lettuce from central Mexico from the U.S. market “due to possible contamination with Cyclospora bacteria.” According to the FDA, the recalled products were distributed in stores in 27 states.

The recall comes after the FDA focused on the product, which was served at Taco Bell stores in five states and where people were eating it before they became sick.

On the same day, Taco Bell announced it would no longer use this producer for its lettuce.

The FDA issued a warning to consumers Friday saying, “Do not eat shredded Mexican iceberg lettuce served at Taco Bell stores in Indiana, Kentucky, Michigan, Ohio, and West Virginia.”

Since May 1, nearly 7,000 cases of cyclosporiasis have been confirmed or are under investigation in the United States, according to the Centers for Disease Control and Prevention. Experts say food poisoning can cause severe watery diarrhea, fatigue and loss of appetite.

The FDA said Saturday’s positive test result was an erroneous result based on erroneous amplification. “This finding does not represent true amplification and should be considered a false positive,” the researchers said.

Amplification creates copies of the sample that are used to investigate pathogens, and amplification makes identification easier. According to a study in the Annals of Clinical & Laboratory Science, “Amplification-based techniques are now routinely used in clinical laboratories to detect microorganisms that do not grow in conventional media.”

“It’s very difficult to grow Cyclospora in the lab,” Thomas Gremillion, food policy director for the Consumer Federation of America, said last week.

Donald W. Schaffner, dean of Rutgers University’s School of Food Science, said Sunday that the Taylor Farms recall “was the right thing to do” regardless of the status of the laboratory test, and that the FDA showed courage in admitting it was wrong about the positive test.

“Unfortunately, testing for this organism is difficult,” he said in an email. “False positives are always a possibility, and I think this can create further confusion and uncertainty in the minds of consumers.”

He said regulators need to provide more data when announcing positive results, including false-positive rates.

Regarding false positives, he said, “I hope consumers don’t ignore them, but I want them to understand that the science is complex.”