The U.S. Food and Drug Administration announced Sunday that a test indicating Cyclospora in Taylor Farms shredded iceberg lettuce was a false positive [1].
This correction is critical for food safety monitoring and the reputation of the lettuce producer, as it clarifies whether a specific product line is actively contributing to a parasite outbreak.
The FDA issued the initial announcement on July 19, 2026 [1], followed by a subsequent statement on Monday, July 20. An FDA spokesperson said that as of July 19, 2026, there are zero confirmed positive sample results for product testing for Cyclospora [2].
The shredded iceberg lettuce in question was grown at Taylor Farms facilities in central Mexico [3]. Laboratory experts rechecked the results and determined the original finding was a false positive [4].
Epidemiologist Ben Miller explained the technical failure during an appearance on CBS News – The Daily Report. Miller said the assay used can cross-react with other organisms, which can generate a false-positive result for Cyclospora [5]. This cross-reactivity or other procedural issues likely prompted the original erroneous result, leading to the re-examination of the sample [6].
Despite the corrected laboratory result, reports regarding the broader outbreak remain inconsistent. Some reports indicate that Taylor Farms remains tied to the Cyclospora outbreak regardless of the false-positive test [7], while others suggest no confirmed cases are linked to the product [4].
“The assay we used can cross‑react with other organisms, which can generate a false‑positive result for Cyclospora.”
The incident highlights the limitations of rapid diagnostic assays in food safety, where cross-reactivity can lead to temporary but costly false alarms. While the FDA has cleared this specific sample, the ongoing contradiction regarding Taylor Farms' link to the wider outbreak suggests that epidemiological data—based on patient interviews—may still point to the producer even when laboratory samples are negative.
