The U.S. Food and Drug Administration continues to identify Taylor Farms' shredded iceberg lettuce, sourced from central Mexico, as the culprit behind a large cyclospora outbreak. Then things got messy.
The agency had tested a sample of that lettuce and gotten a positive signal for the parasite. But follow-up tests could not reproduce that result. That is a classic false positive.
Still, the FDA says the broader investigation never changed direction. In a statement, the agency said its "traceback investigation and outbreak data continue to converge" on that same lettuce.
Cyclospora is a tricky parasite. It is hard to grow in a lab, which means false positives happen. Former FDA commissioner Dr. Scott Gottlieb said the false positive does not clear Taylor Farms. And former deputy commissioner Frank Yiannas warned that this reversal "may add further confusion to what has already been a complex situation for consumers."
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The parasite's incubation period of one to two weeks complicates efforts to identify the source quickly. Health departments have relied on extensive patient interviews and genomic sequencing to trace the outbreak, with Michigan alone interviewing more than 2,000 infected patients. Dr. Norman Beatty, a professor at the University of Florida's medical school, suspects the outbreak may have generated additional secondary outbreaks due to the parasite's transmission dynamics.
The outbreak spans 30 states.
Taco Bell was a major restaurant chain that served the suspected lettuce. The company said it removed all of it from its stores within 72 hours of learning about the contamination. It also stated that this is "a nationwide industry-wide issue, not a Taco Bell-specific issue."
But the numbers show customers are staying away. Data from research firm Placer.ai reveals that Taco Bell's visitor count fell by approximately 19% on that Friday when measured against its typical daily traffic for that day of the week so far this year.
Other chains felt the ripple too. Chopt, Panera Bread, and Chipotle all saw traffic declines. Walmart took the precautionary step of pulling four bagged salad kit products under its Marketside brand from stores in 27 states. The retailer said there have been no confirmed illnesses linked to those products, but it took the step anyway "working closely with our supplier."
The National Restaurant Association said the industry takes food safety seriously, noting that "The Food Code requires that every restaurant must have a manager that is food safety certified on every shift."
According to industry analysts, Taco Bell and the other implicated companies are unlikely to suffer a lasting financial blow. The outbreak will probably weigh on sales for one to two quarters at most.
The bigger question may be about the supply chain itself. The FDA is still investigating whether other ingredients or suppliers played a role. For now, the agency recommends watching where your lettuce comes from. The Michigan Department of Health and Human Services suggests buying whole heads of lettuce instead of pre-washed, bagged or pre-mixed salad kits.
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