FDA Finds False Positive in Lettuce Test as Cyclosporiasis Outbreak Grows

The U.S. Food and Drug Administration determined on July 19 that a sample of shredded iceberg lettuce supplied by Taylor Farms was a false positive for cyclospora. Laboratory experts re-reviewed the results from the prior day and concluded the finding did not represent true amplification.

As of July 19 the agency reported no confirmed positive sample results for cyclospora in product testing. Taylor Farms voluntarily recalled all shredded lettuce products grown and processed in central Mexico on July 17. The company expanded the recall the same day to include four Marketside-brand items sold at Walmart.

Walmart removed four bagged iceberg lettuce salad products from select locations in nearly 30 states as a precaution. An FDA traceback investigation identified Taylor Farms de Mexico as the single supplier of iceberg lettuce used by Taco Bell locations in Indiana, Kentucky, Michigan, Ohio, and West Virginia.

The agency linked that lettuce to 1,644 confirmed cyclosporiasis cases at those restaurants. Taco Bell removed possibly impacted lettuce from its supply chain nationwide on July 16.

The Centers for Disease Control and Prevention reported 1,645 confirmed cyclosporiasis cases and 141 hospitalizations across 34 states since May 1, with no confirmed deaths, as of July 13. Michigan health authorities reported more than 5,000 cases as of July 16.

The outbreak has caused nearly 7,000 infections across 34 states. Taylor Farms stated that the FDA apologized for the error. The tested sample originated from the Taylor Farms de Mexico facility in Guanajuato and was packed in five-pound bags; it was not part of the current recall.