The Food and Drug Administration (FDA) said Sunday that a sample of Taylor Farms iceberg lettuce that was reported to have been found to have Cyclospora on Saturday was a false positive, leaving investigators with no confirmed positive test result for the product as the outbreak continues in several states.
After reanalyzing the sample results, FDA laboratory experts concluded that the positive result was false, stating that the detected substance "does not reflect a true potentiation and should be considered a false positive." The agency removed information about the sample from its Saturday update and notified Taylor Farms of its conclusion.
Taylor Fresh Foods announced on Sunday that the FDA had apologized. "To be clear, the FDA has not identified any positive test results for cyclosporiasis at this time," the company said in a statement.
Taylor Farms' voluntary recall of iceberg lettuce grown and processed in central Mexico, initiated last week, remains in effect despite a false-positive test result. The FDA stated that it continues to work with Taylor Farms to ensure the recalled products are removed from the market, and that state-level partners are continuing to collect and analyze product samples.
Donald W. Schaffner, chair of the Department of Food Science at Rutgers University, told NBC News that the recall was justified regardless of the laboratory test results and praised the FDA for its courage in admitting its error. "Unfortunately, testing for this microorganism is difficult," he said. "False positives are always possible.".
An FDA investigation identified Taylor Farms de Mexico as the supplier of shredded iceberg lettuce served at Taco Bell restaurants in Indiana, Kentucky, Michigan, Ohio, and West Virginia where sick customers ate. Of those who reported visiting Taco Bell restaurants, 1,644 cases have been confirmed in five states, with 94 hospitalizations and no deaths. Taco Bell stated that it stopped using Taylor Farms de Mexico lettuce as of July 17.
The Taco Bell outbreak is part of a broader nationwide surge in cyclosporiasis cases. According to NBC News, since May 1, the Centers for Disease Control and Prevention (CDC) has recorded nearly 7,000 cases of cyclosporiasis nationwide, either confirmed or still under investigation. The FDA and state agencies stated that they are continuing to collect samples and investigate the source of the contamination.
The Food and Drug Administration (FDA) advises consumers who purchased recalled Taylor Farms iceberg lettuce to discard it and not eat it. Anyone experiencing symptoms of cyclosporiasis should consult a doctor.