The FDA Still Doesn't Know Who Caused the Diarrhea Parasite Outbreak

Dmitri Bolt | July 20, 2026 4:30 PM

The U.S. Food and Drug Administration (FDA) has walked back its earlier claim that a cyclospora outbreak originated from contaminated iceberg lettuce supplied by Taylor Farms de Mexico.

The parasite, which causes diarrhea and frequent bowel movements, affected multiple states across the country, and the FDA traced the outbreak to shredded lettuce distributed to Taco Bell locations.

The FDA has walked back an earlier detection of the cyclospora parasite on lettuce from Taylor Farms, adding that the result was a false positive https://t.co/7kxA7xLsA2
— The Wall Street Journal (@WSJ) July 20, 2026

"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," the FDA wrote in a statement. "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."

Taylor Farms, which is likely to face business fallout from the false identification, issued its own statement.

Yesterday, FDA informed Taylor Fresh Foods that one of its iceberg lettuce products from central Mexico had a “confirmed positive” test 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. Acting on initial information provided by health officials, in an abundance of caution, we completed a voluntary recall of iceberg lettuce from central Mexico. Recalled product was limited to iceberg lettuce grown and processed in central Mexico. All other Taylor Farms products, including all Taylor Farms brand products, are not involved in the recall.
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.