False‑positive Cyclospora test adds uncertainty to U.S. lettuce outbreak

The U.S. National Notifiable Disease Surveillance System has been tracking a sudden spike in a parasitic disease known as cyclospora, linked to iceberg lettuce supplied by Taylor Farms and sold in Taco Bell restaurants across several states. Almost a hundred people have been hospitalized, but no deaths have been reported.

On Saturday, the Food and Drug Administration (FDA) announced that a sample collected from Taylor Farms had tested positive for cyclospora. However, the laboratory re‑examined the sample on Sunday and concluded that the result was a false‑positive, adding a new layer of uncertainty to the outbreak’s investigation.

“Because of the complexity involved in detecting Cyclospora, the FDA’s laboratory experts re‑reviewed the sample and have determined that the finding does not represent true amplification and should be considered a false positive,” the agency said in a statement. The sample came from an import that the FDA was monitoring as part of its broader surveillance effort.

Taylor Farms had already voluntarily removed all iceberg lettuce produced in central Mexico from the U.S. market, and the company indicated it would continue working with the FDA, CDC, and state health authorities to identify the pathogen’s source. The company also announced that it had stopped receiving product from the implicated lot and had notified its customers.

The Centers for Disease Control and Prevention (CDC) has advised residents in Indiana, Kentucky, Michigan, Ohio and West Virginia to avoid eating shredded iceberg lettuce served at Taco Bell locations. The fast‑food chain confirmed that it has removed the affected lettuce from its restaurants.

Until the true source of cyclospora can be identified, authorities remain on high alert, tightening surveillance and urging the public to remain cautious, especially consumers who frequently eat fresh leafy greens.