Taylor Farms lettuce still the center of cyclosporiasis investigation, despite false positive test

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Testing that showed iceberg lettuce from Taylor Fresh Foods was tainted with cyclospora was a false positive, federal officials say. But that lettuce is still at the center of the investigation.

Officials with the U.S. Food and Drug Administration said Sunday that a lettuce sample from the supplier was re-reviewed, finding the test “does not represent true amplification and should be considered a false positive.”

However, the FDA clarified Monday that the its “traceback investigation and outbreak data continue to converge on shredded iceberg lettuce from Taylor Farms locations in central Mexico.”

NBC reported that the sample did not come from lettuce already linked to the outbreak and recall, but rather from a new, separate shipment collected by the agency during routine import inspections.

Above video | Dr. Steven Goldberg talks about the parasite behind explosive diarrhea

Frank Yiannas, former deputy commissioner of food policy and reponse at the FDA, called the false positive result “unfortunate – and consequential.”

He said he could see why the average consumer might assume that because the laboratory result was determined to be a false positive, the recall itself was unnecessary.

“That not what this means,” Yiannas said in a statement, CNN reported.

The false positive does not change the company’s earlier voluntary recall.

On Friday, Taylor Farms — which produces lettuce for Taco Bell and multiple grocery chains — said it was removing all of its iceberg lettuce produced in central Mexico from the U.S. market as cases of cyclosporiasis have surged across the nation.

That recall still stands, Taylor Farms said in a statement Sunday. “Recalled product was limited to iceberg lettuce grown and processed in central Mexico. All other Taylor Farms products, including all Taylor Farms brand products available for purchase, are not involved in the recall.”

Click here to see a full list of recalled products.

The evidence that led to the recall comes from interviews with people who tested positive for cyclospora and were confirmed to be part of the same cluster of illnesses.

In its now-removed Saturday update, the FDA said the positive test came from a lettuce sample that was not part of the existing Taylor Farms recall. At the time, the agency said the company was working to determine whether any of the implicated lot remained on the market or in consumers’ homes.

Cases of the intestinal illness caused by a microscopic parasite are surging across the U.S., with nearly 7,000 cases confirmed or under investigation since May 1, according to data published Tuesday by the CDC. States have reported at least 180 hospitalizations.

The outbreak linked to the lettuce, however, is considered to be a regional one, centered in the Midwest. The CDC has identified at least 1,644 cases associated with the outbreak across the five affected states. The FDA says additional states may be added as the investigation continues.

Cyclosporiasis is not usually spread directly from person to person. Instead, people can become infected by consuming contaminated food or water. Previous outbreaks have been linked to fresh produce, the CDC says.

People with cyclosporiasis may have symptoms that include watery diarrhea, cramping and bloating for weeks.

CNN contributed to this report.