FDA Keeps Focus on Taylor Farms Lettuce in Cyclospora Outbreak Despite Retracted Test

Agency says shredded iceberg lettuce from Mexico remains the likely source even after a positive sample was walked back

The Food and Drug Administration said Monday it remains focused on Taylor Farms as the likely source of a multistate cyclospora outbreak, even after a positive test on a lettuce sample announced Sunday was retracted as a false positive.

The agency said its investigation and data "continue to converge on shredded iceberg lettuce from Taylor Farms locations in central Mexico," according to CBS News. NPR reported that lettuce distributed by Taylor Fresh Foods and Taylor Farms de Mexico is still linked to the outbreak, though officials acknowledged the source may be difficult to definitively trace.

Epidemiologist Ben Miller told CBS News' "The Daily Report" that laboratory testing for cyclospora, a microscopic parasite, is prone to false positives and negatives, which can complicate efforts to pinpoint contamination even when investigators have strong circumstantial evidence pointing to a particular product.

Cyclosporiasis causes prolonged diarrhea and other gastrointestinal symptoms and has sickened people across multiple states this summer. Health officials continued to advise consumers to follow updated guidance on the outbreak as the investigation proceeds.

— Compiled from reporting by CBS News and NPR.