FDA admits false‑positive Cyclospora test on Taylor Farms lettuce

On Saturday, the Food and Drug Administration announced that a lettuce sample from Taylor Farms de Mexico had tested positive for the parasite Cyclospora – a finding that set off alarm bells across the country. A day later, the same agency back‑tracked, saying the result was a false positive caused by a lab glitch.

According to the FDA’s own statement, the erroneous result was uncovered when the agency re‑examined the sample on Sunday. "As of July 19, 2026, there are no confirmed positive sample results for Cyclospora," the agency wrote, effectively wiping the earlier claim off the record.

The mix‑up didn’t alter the recall that Taylor Farms had already initiated. Earlier in the week, the company voluntarily pulled iceberg lettuce grown in central Mexico from grocery shelves in 27 states, citing a potential Cyclospora contamination that had been linked to a multistate outbreak.

In a brief response, Taylor Farms echoed the FDA’s correction and apologized for the mistake. "The FDA has not identified a single positive product test result for Cyclospora," the company said, assuring consumers that its recall remains in force and that it continues to cooperate with public‑health investigators.

The backdrop to all this is a fairly large outbreak: the Centers for Disease Control and Prevention has logged nearly 7,000 probable or confirmed cases of cyclosporiasis since May 1. The illness typically brings nasty watery diarrhea, fatigue and loss of appetite, symptoms that can linger for weeks.

So what went wrong in the lab? The FDA explained that the test used an amplification technique – essentially a way to copy tiny amounts of DNA so that a pathogen can be spotted more easily. In this instance, the amplification step produced a false signal, a “false positive,” rather than detecting genuine Cyclospora DNA.

Experts aren’t surprised. "Testing for this organism is notoriously tricky," said Thomas Gremillion of the Consumer Federation of America. Donald W. Schaffner, a food‑science professor at Rutgers, called the recall “the right thing to do” and praised the FDA for owning up to the error, even if it may sow some confusion among shoppers. He added that agencies should be more transparent about false‑positive rates when they issue such alerts.

For now, consumers are advised to stay clear of the recalled lettuce and to keep an eye on any future FDA updates. The episode underscores how complex food‑safety science can be, and why both companies and regulators need to tread carefully when communicating risks.