FDA Admits Major Error In Cyclospora Outbreak Investigation… But It May Still Be Right

on Jul 20, 2026 • Updated Jul 20, 2026

Days after announcing it had identified a source responsible for the growing cases of "explosive diarrhea" from cyclospora, the FDA has backtracked its report, citing a "false positive."

Days after announcing it had identified a source responsible for the growing cases of "explosive diarrhea" from cyclospora, the FDA backtracked its report, citing a "false positive." However, it's not that simple... (Photo credit: Theo Braddock / Unsplash)

On July 16, the U.S. Food & Drug Administration (FDA) announced that it had identified a source in the growing cyclospora-related infections causing “explosive diarrhea” in over 30 states.

Iceberg lettuce distributed to Taco Bell and Walmart by Taylor Farms — which has a Mexico-based farm that was isolated by the FDA’s investigation — was reportedly determined to be the culprit for cases of cyclosporiasis in at least five states.

Taylor Farms went on to recall its iceberg products in 28 states.

However, just a matter of days later, the FDA has announced that its testing of Taylor Farms’ lettuce resulted in a “false positive.”

The FDA added, “As of July 19, 2026, there are no confirmed positive sample results for product testing for Cyclospora.”

This comes as cases in the United States continue to rise, with Michigan alone reporting at least 6,100 cases as of Monday, July 20.

The FDA And Taylor Farms Respond To The “False Positive”

The FDA reported on July 17, just one day after honing in on the popular fast food restaurant chain Taco Bell, that its “traceback investigation identified convergence on a single supplier, Taylor Farms de Mexico, that provided shredded iceberg lettuce used by Taco Bell locations where sick people ate before becoming ill.”

Taylor Farms cooperated with this report, saying on July 17 that it was “voluntarily removing all iceberg lettuce sourced from central Mexico from the U.S. market, because it has the potential to be contaminated with Cyclospora.”

Doing as it said it would, Taylor Farms recalled its iceberg products from Taco Bell and the Marketside-brand at Walmart locations, including iceberg salads and iceberg lettuce with Best If Used By dates ranging from July 18 to Aug. 3.

However, on July 19, the FDA released an important update to this story.

“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,” the FDA said in its statement, noting that it has notified Taylor Farms and “continues working with the firm to ensure product implicated in this outbreak has been removed from the market.”

Further, the FDA said it is working with state partners to “continue to collect and analyze product samples.”

In light of the false positive, the FDA was back to the drawing board, writing, “There are no confirmed positive sample results for product testing for Cyclospora.”

Responding to the news of the “false positive” from the FDA, Taylor Farms wrote on its website, “Today, FDA apologized to us.”

Further, it said:

“Yesterday, FDA informed Taylor Fresh Foods that one of its iceberg lettuce products from central Mexico tested positive for cyclospora. Today, we were informed that FDA made a mistake, and this was a false positive. To be clear, at this moment, FDA has not identified a single positive product test result for Cyclospora.”

Taylor Farms went on to note that it has followed through with the recall out of “an abundance of caution,” adding, “We completed a voluntary recall of iceberg lettuce from central Mexico. Recalled product was limited to iceberg lettuce grown and processed in central Mexico.”

Continuing, Taylor Farms wrote, “All other Taylor Farms products, including all Taylor Farms brand products available for purchase, are not involved in the recall.”

Concluding its statement, Taylor Farms wrote:

“Our thoughts remain with everyone who has fallen ill in this outbreak. We are committed to working with public health authorities as the ongoing outbreak investigation continues.”

On Monday, July 20, the FDA clarified that it is still pursuing Taylor Farms as the source of the five-state outbreak of cyclosporiasis.

Posting on X, formerly Twitter, the FDA wrote, “To clarify, this false-positive lab sample DOES NOT change the basis for FDA’s ongoing outbreak investigation or the overwhelming epidemiological data supporting the current voluntary recall by Taylor Farms.”

Expounding upon this, the FDA wrote:

“Over the weekend, FDA alerted Taylor Farms that a new sample of shredded lettuce from Taylor Farms de Mexico tested positive for Cyclospora during import examination at the Southern Border. This ended up being a false positive, and Taylor Farms was alerted to the corrective test result Sunday. FDA’s traceback investigation and outbreak data continue to converge on shredded iceberg lettuce from Taylor Farms locations in central Mexico.”

See the full post, here:

To clarify, this false-positive lab sample DOES NOT change the basis for FDA’s ongoing outbreak investigation or the overwhelming epidemiological data supporting the current voluntary recall by Taylor Farms.

Over the weekend, FDA alerted Taylor Farms that a new sample of… https://t.co/hedRwhPLd8
— U.S. FDA (@US_FDA) July 20, 2026

The Latest Reported Cases

While the U.S. Centers for Disease Control (CDC) has been slow to update its figures pertaining to confirmed cases of cyclosporiasis, which comes from a parasitic cyclospora infection, it reports as of July 14 that there are “1,645 confirmed domestic cases of cyclosporiasis and is aware of more than 5,100 cases that require further analysis.”

The state of Michigan, as of July 20, has seen over 6,100 reported cases of this infection.

Here is the map from the CDC, as of July 14, showing confirmed cases of Cyclosporiasis:

In this July 13 map from the CDC, states in light blue have reported 1 to 10 cases of cyclosporiasis, the slightly darker blue reflects 11 to 30 cases, progressively darker denotes 31 to 80 cases, darker yet again indicates 81 to 160, the next shade is for 161-300, and the deepest blue indicates 501 to 900 cases. (Image: CDC)

As of July 10, NBC News reports there were 30 states reporting cases of cyclosporiasis, with four of those having suspected cases that were under investigation. This map differs from the CDC’s map, in many cases by hundreds.

Figures have been updated in some cases from the NBC News map to reflect July 20 data, courtesy of Fox 2 Now and Click On Detroit, with the following states reporting cases of cyclosporiasis: