Earlier this week, the FDA told Taylor Farms that a cyclospora test on its iceberg lettuce, which originated in central Mexico, was positive. That sent the supplier into recall mode, and restaurants like Taco Bell and stores like Walmart started pulling products off shelves.
Then the FDA changed its story. In a statement, the agency said its lab experts re-reviewed the sample and decided the result did not hold up. "Due to the complexity in detection of cyclospora, FDA laboratory experts re-reviewed the sample results and have concluded that the finding does not represent true amplification and should be considered a false positive," the agency said.
Taylor Farms did not hold back. In its own statement, the company said the FDA apologized and admitted the mistake. The supplier had already voluntarily recalled product.
The false positive complicated an already complex investigation. The CDC and FDA are working to trace the true source of the outbreak, which is believed to be linked to a common supplier of shredded lettuce used by Taco Bell. Historical data shows cyclospora outbreaks often originate from imported produce.
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Even without that false positive, the real outbreak is serious. Nationwide, there have been 1,645 total infections across 34 states as of July 13.
Michigan stands out. Michigan health authorities have reported more than 5,000 cyclospora cases as of July 16. That is a huge number for a single state, and it points to a widespread contamination source.
No one has died from this outbreak.
Cyclospora causes intestinal illness with symptoms like watery diarrhea, cramping, and nausea that can linger for weeks if untreated. The parasite has an incubation period of about one week.
Walmart removed four Marketside-brand bagged iceberg salad products from nearly 30 states as a precaution, even though the retailer said there is no indication its products are affected.
Cyclospora is not like typical foodborne bugs. It does not spread from person to person. Instead, it comes from contaminated water used during farming or washing produce. Professor Amira Roess, a former CDC disease detective now at George Mason University, said it plainly: "Typically, it's the contaminated water that is leading to the contaminated produce."
Detecting the parasite is hard. The agency itself acknowledged the complexity. And because cyclospora thrives in untreated environmental water, the contamination likely happened somewhere in the supply chain before the lettuce reached stores.
One important note for home cooks: cyclospora dies at 158 degrees Fahrenheit. So if you are cooking your veggies, you are fine. But most people eat lettuce raw. That is why recalls matter.
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