Michigan health officials link iceberg lettuce and Taco Bell to large cyclosporiasis outbreak
An interim report finds that consumption of iceberg lettuce, particularly at Taco Bell, was associated with Michigan's biggest cyclosporiasis outbreak, which has caused over 14,000 cases.
Michigan health officials have released interim findings that connect iceberg lettuce and meals purchased at Taco Bell with the state's largest cyclosporiasis outbreak, which has recorded 14,510 cases as of Aug. 27. The investigation, detailed in a Sept. 2 article in NEJM Evidence, involved interviews with 3,114 patients who fell ill through late July. Of those, nearly 70% reported eating at a single restaurant chain, later identified by the department as Taco Bell.
Among an early group of 190 Taco Bell diners, 89.5% said they ate menu items containing iceberg lettuce. The department also examined 946 patients who did not recall eating at Taco Bell; 729 of them provided information on lettuce exposure, indicating that iceberg lettuce was a common factor regardless of the restaurant.
"It's really important as part of any outbreak investigation to make sure that we are writing up the scientific aspects of that outbreak investigation and sharing with the rest of the scientific community," said Dr. Natasha Bagdasarian, Michigan's chief medical executive and co-author of the report.
The Centers for Disease Control and Prevention reported that shredded iceberg lettuce served at some Taco Bell locations was contaminated with Cyclospora. The lettuce supplier, Taylor Fresh Foods, voluntarily recalled all iceberg lettuce grown in central Mexico on July 17.
Dr. Bagdasarian emphasized that while the data show a correlation between iceberg lettuce, Taco Bell and the illness, it does not prove causation. She noted that the outbreak displayed two peaks, in late June and early July, suggesting two contaminated batches of produce or staggered distribution of a single lot.
"We did this very early public health intervention in warning the public because we felt it was in the public's best interest," she added.
The department continues to monitor the situation, with more recent data on its website indicating an even higher second peak of cases.