Test that found source of US explosive diarrhoea outbreak was false positive, health officials say

Federal health officials have identified shredded iceberg lettuce served at Taco Bell restaurants in five states as the source of a widespread outbreak of Cyclospora, a parasite causing diarrheal illness. The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) linked over 1,600 confirmed cases to the contaminated lettuce across Indiana, Kentucky, Michigan, Ohio, and West Virginia, with Michigan being the most affected state. This parasitic infection, Cyclospora cayetanensis, can lead to severe gastrointestinal symptoms, including prolonged watery diarrhea, and has resulted in 94 hospitalizations in the affected states, though no deaths have been reported.

The FDA's investigation traced the contaminated iceberg lettuce to a single supplier from Mexico, which news reports and federal officials have identified as Taylor Farms. Following these findings, Taylor Farms announced it was voluntarily removing all iceberg lettuce sourced from central Mexico from the U.S. market. Taco Bell proactively responded by voluntarily removing the potentially affected lettuce from its supply chain in the implicated states and committed to using a different supplier.

While over 1,600 cases have been specifically tied to Taco Bell lettuce, federal health officials are also investigating other outbreaks and illnesses of cyclosporiasis nationally, with a record number of cases reported across more than 30 states, totaling nearly 7,000 confirmed or suspected cases. Not all these cases are necessarily linked to this specific Taco Bell outbreak. Symptoms of Cyclospora infection typically appear between two and fourteen days after exposure.