FDA identifies false-positive result, clarifies source of Cyclospora outbreak

WASHINGTON —

The Food and Drug Administration (FDA) is walking back its initial “positive” test of Cyclospora, tracing its origin to Taylor Farms’ iceberg lettuce imported from Mexico. On Monday, agency officials clarified that a quality check determined the test was a “false positive,” warranting the correction.

Still, the FDA says other epidemiological data and interviews conducted around the outbreak support a nationwide voluntary recall of the lettuce.

“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,” a social media post from the agency read in part. “FDA’s traceback investigation and outbreak data continue to converge on shredded iceberg lettuce from Taylor Farms locations in central Mexico. FDA will continue to work with federal and state partners to investigate this multistate outbreak and ensure products implicated in this outbreak have been removed from the market.”

Health experts say Cyclospora is difficult to detect and cannot be recreated in a lab. Investigators must then rely on testing tiny traces of the parasite, which requires human interpretation and could leave the potential for error, like the recent false-positive result.

Still, at least one health expert says the federal outbreak response is functioning as intended, as coordination and investigations rely on state and local health department responses.

“When there are increased cases in multiple states, that information is being reported to CDC. Then, we see a sort of a multi-state investigation start to occur coordinated by CDC. That is sort of the basic way our public health system works,” University of Minnesota School of Public Health professor Craig Hedberg said.

The FDA says protecting the American public remains its top priority as it continues to investigate two of five identified sub-clusters linked to Cyclospora.

Officials on Monday also said nationwide recalls for lettuce were ongoing, and screenings, including other potentially contaminated products, have increased at the southern border.

When asked why the FDA shared the test result before confirming its accuracy, officials said it was important to publicize the positive test result since the affected sample was not part of the initial recall.

Still, the agency stressed the false-positive did not alter the data or their suspicion of the contamination source from Mexico.

The FDA said it shared the corrected information with Taylor Farms but did not issue an apology.

The FDA advises consumers to check the recall list and discard any items that may be listed.

When possible, remove the outer layers of fruits and vegetables, wash all produce thoroughly with clean water, and avoid using soap or bleach.

Since Cyclospora is resistant to routine chemical disinfection and washing alone may not be sufficient, cooking produce is the safest option.

Washing hands before and after handling food is also recommended.

Watch more on the nationwide Cyclospora outbreak: