FDA ends cyclospora probe, finds parasite in Mexico but no source

The U.S. Food and Drug Administration closed its investigation Friday into the largest known cyclosporiasis outbreak in U.S. history, which sickened 12,883 people across 21 states and was linked to shredded iceberg lettuce from Taylor Farms de Mexico. The outbreak hospitalized at least 570 people and was associated with two deaths in Michigan.

FDA investigators found the parasite in two environmental samples in Mexico: one from a wastewater tank at the Taylor Farms de Mexico processing facility and another from a drainage ditch at an iceberg lettuce grower identified through traceback. However, the agency stated there was not enough evidence to conclusively determine how the contamination occurred.

“While there is currently not enough evidence to conclusively determine how contamination occurred in this outbreak, the positive samples show that Cyclospora was present in the environment where lettuce was grown and processed.”

A separate Salmonella Javiana investigation was also closed after all environmental samples tested negative, with the FDA unable to determine a contamination source or vehicle.

Mexico's Federal Commission for Protection against Sanitary Risks (Cofepris) and the Ministry of Health said the findings do not establish that Mexican products were the source of the infections. Cofepris emphasized that detecting the parasite in environmental samples alone does not prove agricultural products were responsible.

The Taylor Farms de Mexico facility remains closed while the company works to implement enhanced safety protocols. Scientists are continuing to compare genetic analysis from the positive samples with clinical data from those who fell ill.