Photo: SANDY HUFFAKER / AFP / Getty Images
Federal health officials have been investigating five separate clusters of cyclosporiasis cases since the start of the parasite season in May, with the largest group of illnesses linked to shredded iceberg lettuce served at Taco Bell restaurants in Indiana, Kentucky, Michigan, Ohio, and West Virginia. The Food and Drug Administration (FDA) stated during a press conference on Monday that three of these clusters are now considered over, but the largest outbreak continues, with new cases reported as recently as last week.
The majority of cases have occurred in Michigan, where the Michigan Department of Health and Human Services (MDHHS) has reported over 6,100 cases as of Monday (July 20) morning—an increase of more than 1,000 in just a few days. Nationally, the Centers for Disease Control and Prevention (CDC) has confirmed 1,644 infections linked to this outbreak and has advised the public not to eat shredded iceberg lettuce from Taco Bell in the five affected states.
The contaminated lettuce was traced back to Taylor Farms de Mexico, which issued a voluntary recall of all iceberg lettuce from central Mexico on July 17. The recall covers products distributed from June 29 through July 16 with best-by dates up to August 3, affecting 27 states and products sold at Walmart in 15 states. Taco Bell has since stopped using lettuce from Taylor Farms de Mexico at all its restaurants.
The FDA initially announced that a sample of shredded iceberg lettuce from Taylor Farms had tested positive for the Cyclospora parasite. However, the agency later clarified the lab result was a false positive after further review. "To be clear, at this moment, FDA has not identified a single positive product test result for Cyclospora," Taylor Farms wrote in a statement posted Sunday. Even with the retraction, acting FDA Commissioner Kyle Diamantas said the agency's investigation and the recall remain in place due to strong epidemiological data.
Interviews by Michigan health officials with more than 2,000 patients found that many did not eat at Taco Bell or any restaurant, but lettuce was often mentioned, pointing to possible contamination earlier in the supply chain and distribution to grocery stores.
Cyclosporiasis is a foodborne illness caused by the Cyclospora parasite, leading to diarrhea, fatigue, and nausea. Ninety-four people have been hospitalized, but no deaths have been reported. The CDC reports that the true number of cases is likely higher, as many people recover without seeking medical care or being tested.
The FDA continues to test produce samples—including at the southern border—and to work with state health agencies to remove contaminated products from the market. The agency has encouraged consumers to avoid recalled iceberg lettuce and to cook produce to 158 F to reduce the risk of infection.
While health officials investigate additional clusters and unrelated cases in other states, the source of all cyclosporiasis cases is not fully known. Experts remind the public that outbreaks of this size are rare, but cyclosporiasis cases do occur every summer. The investigation into this outbreak and related clusters remains ongoing.