Recalls

FDA retracts positive lettuce test, but Cyclospora outbreak investigation continues

The FDA now says a laboratory test that appeared to detect Cyclospora in Taylor Farms iceberg lettuce was a false positive, but the outbreak investigation is continuing and the recall remains in effect.

Image: MidJourney

The Food and Drug Administration has walked back one of the most dramatic developments in the ongoing Cyclospora outbreak, saying that what initially appeared to be a positive laboratory test for the parasite in Taylor Farms iceberg lettuce was, after further review, a false positive.

The agency said laboratory experts re-examined the test because Cyclospora detection is technically challenging and concluded that the result "does not represent true amplification." As a result, FDA has removed the positive-test reference from its public outbreak investigation.

But regulators stress that the outbreak itself remains very real.

FDA says it continues working with state investigators and Taylor Farms while collecting and analyzing additional product samples. As of the latest update, no food sample has been confirmed positive for Cyclospora, even though epidemiological evidence continues to point investigators toward shredded iceberg lettuce supplied by Taylor Farms de Mexico.

Recall remains in effect

Despite the testing error, Taylor Farms' voluntary recall remains in place.

The company withdrew shredded iceberg lettuce sourced from central Mexico that was distributed to retailers and food-service customers in 27 states between late June and mid-July.

FDA continues to advise consumers to:

Check whether recalled lettuce is in their refrigerator.
Throw away recalled products.
Wash and sanitize containers, cutting boards and refrigerator shelves that may have come into contact with the lettuce.
Contact a healthcare provider if symptoms develop after eating recalled products.

Taylor Farms said FDA apologized for the erroneous laboratory finding but emphasized that it voluntarily initiated the recall out of caution while the investigation continues.

Why outbreaks are so difficult to solve

Unlike bacterial contamination, Cyclospora is notoriously difficult to detect in food samples.

The parasite often contaminates produce in very low numbers, laboratory testing is technically demanding, and contaminated food may already be consumed before investigators identify a common source.

That means epidemiological evidence—identifying what sick people ate—often carries more weight than laboratory confirmation.

What consumers should do

Until the investigation is completed, food safety experts recommend:

Discard recalled shredded iceberg lettuce.
Choose whole heads of lettuce instead of pre-shredded products if possible.
Wash hands, utensils and food-preparation surfaces thoroughly.
Seek medical care if severe diarrhea develops within about two weeks after eating leafy greens.

Cyclospora infection commonly causes: