The CDC has declared the multistate Cyclospora outbreak linked to iceberg lettuce over, closing the largest cyclosporiasis outbreak ever recorded in the United States at 12,883 illnesses across 21 states.
The agency's final update on the iceberg lettuce outbreak added Virginia as a 21st state and confirmed at least 570 hospitalizations and two deaths, both in Michigan, in people state officials said had significant underlying health conditions. Illness onsets ran from June 14 through Aug. 17. The CDC said there is no longer any risk of getting sick with cyclosporiasis from this source.
For shoppers, the closure removes a summer-long uncertainty about bagged and shredded lettuce. It does not remove the reason Cyclospora became a household word this year. The FDA's investigation into how the contamination happened remains open, and thousands of this year's cyclosporiasis cases were never linked to the lettuce at all.
Closing Numbers from a Record Summer
Epidemiologic and traceback work pointed to processed iceberg lettuce from Taylor Farms de Mexico, a Taylor Farms processor based in central Mexico. On July 17, the company recalled all iceberg lettuce sourced from that region. The recalled product reached both retail and food service, including restaurants; many of the people who got sick had eaten at Taco Bell.
Most illnesses began before that recall, which is the ordinary shape of a Cyclospora outbreak. Symptoms typically appear about a week after exposure, ranging from two days to two weeks or more, so cases kept surfacing well after contaminated product left shelves.
The count also grew in uneven jumps rather than a smooth curve. It can take up to six weeks after symptoms start for a case to be reported, so state and local health officials kept adding confirmed cases long after people fell ill. The CDC also cautioned that the true number of illnesses was almost certainly higher than the confirmed count, because many people recover without care and are never tested, and that the state totals include people who traveled to one of the 21 states but live elsewhere.
Michigan carried the heaviest burden of any state. According to CNN, about one in every 1,000 Michigan residents had cyclosporiasis. Best-by dates on all recalled products have long passed.
Thousands of Cases Still Have No Named Source
This is the part that matters for the months ahead. The FDA's post-outbreak response page for the Cyclospora investigations reports that the CDC logged 19,595 laboratory-confirmed cyclosporiasis cases nationally as of Sept. 8, of which more than 12,000 belong to the lettuce outbreak.
That leaves roughly 6,700 confirmed infections this year that are not part of the closed outbreak. The FDA says it is still investigating smaller Cyclospora clusters from this summer alongside the Taylor Farms investigation. Those clusters have no publicly identified food vehicle.
The word "over" therefore applies narrowly. It means the lettuce-linked chain has ended, not that the parasite has stopped circulating in the U.S. food supply.
In its own update, the FDA said it remains confident that "all recalled iceberg lettuce related to this specific Cyclospora outbreak is off the market." The agency added that its investigation continues and that it will keep working with federal, state and international partners.
Regulators have also moved toward prevention. The FDA announced on Aug. 20 that it had begun onsite inspections and sample collection at lettuce growers in Mexico. During the week of Sept. 8, senior FDA officials met with Mexican public health and agricultural counterparts to encourage a prevention-focused framework for produce grown in Mexico, and the agency has issued a letter to industry calling for supply-chain collaboration on Cyclospora contamination.
Lingering Symptoms and the Test a Doctor Has to Order
Cyclospora is not a 24-hour stomach bug. Untreated, cyclosporiasis can produce weeks of watery diarrhea, cramping, bloating, nausea, appetite loss, and fatigue, sometimes with symptoms that improve and then return.
That matters now because a person who got sick in July or August may still be unwell and may have been told it was something else. Testing for Cyclospora is not routinely performed in most U.S. laboratories, even when stool is tested for parasites, so a clinician has to request it specifically. The infection is treated with a particular antibiotic regimen rather than ordinary supportive care.
Anyone with prolonged or relapsing diarrhea dating to this summer should contact a clinician and ask directly about Cyclospora testing. People with weakened immune systems tend to have more severe and longer illness. Severe dehydration, high fever or bloody stool warrants prompt medical evaluation. This is general information and not a diagnosis.
Cyclospora spreads through food or water contaminated with human waste, not from person to person and not from animal sources. Food safety specialists say there is no evidence that washing produce removes the parasite, and chlorine and other sanitizers do not kill it, which is part of why pre-cut product can spread contamination from one head across many packages. Thorough cooking does kill it, which is impractical for salad.
The unresolved clusters remain the open question heading into next year, when U.S. Cyclospora cases typically begin rising again in late spring. The CDC's investigation update notes that infections acquired during this outbreak will still be reported as they are identified, even though the page will not be updated again.
Key Questions Answered
What did the CDC announce? On Sept. 11, the agency declared the iceberg lettuce Cyclospora outbreak over, with final totals of 12,883 illnesses, at least 570 hospitalizations, and two deaths across 21 states.
Is the investigation finished? No. The CDC closed its outbreak page, but the FDA's investigation into the contamination continues, as do investigations into separate Cyclospora clusters from this summer.
Is lettuce safe to buy now? The recalled product's best-by dates have passed, and the FDA says it is off the market. The CDC says there is no remaining risk from this source.
Why are national case numbers so much higher? The CDC counted 19,595 laboratory-confirmed cyclosporiasis cases nationally through Sept. 8. More than 12,000 belong to this outbreak, leaving thousands with no identified source.
What symptoms should people watch for? Watery diarrhea that persists or returns, cramping, bloating, nausea, appetite loss, and fatigue, typically starting about a week after exposure.
What should someone still sick do? Contact a clinician and ask specifically about Cyclospora testing, since most laboratories do not check for it routinely and treatment requires a specific antibiotic.
Can Cyclospora spread between people? No. It spreads only through food or water contaminated with human waste.
