U.S. officials declare an end to record-setting cyclospora outbreak, but its origin is still unknown

U.S. health officials said Friday that the largest cyclospora food poisoning outbreak in U.S. history is over. FDA officials said they are confident all recalled iceberg lettuce tied to this specific outbreak is off the market. Nearly 13,000 reported cyclospora cases were linked to the multistate outbreak, representing the bulk of an unprecedented surge in the parasitic diarrheal illness this year. Even with the outbreak declared over, several questions remain, including its origin: the parasite spreads through human feces, and it still isn’t clear how sewage could have contaminated enough food to sicken so many people. Ellen Shumaker, director of outreach for North Carolina State University’s Safe Plates food safety program, said contamination can happen if produce is grown in soil or comes into contact with contaminated water.

Since May 1, the government received reports of nearly 20,000 lab-confirmed cyclospora cases—more than 16 times the number reported during the same period last year—plus more than 6,100 suspected cases. The worst previous U.S. year was 2019, when about 4,700 illnesses were reported nationally. This year’s surge was dominated by an outbreak in 21 states linked to iceberg lettuce, but thousands of other cases were not linked to that outbreak. Michigan was the hardest-hit state, with the most reported cases and the two U.S. deaths tied to the outbreak.

Cyclospora is a microscopic, spherical parasite that commonly causes watery diarrhea "with frequent and sometimes explosive bowel movements," according to the CDC. Outbreaks tend to occur most often in late spring and summer. The illness, cyclosporiasis, is less common than foodborne illnesses caused by salmonella and E. coli, and many cases are never linked to a specific food or other source.

In this outbreak, investigators initially focused on lettuce served at Taco Bell. Federal officials subsequently focused on Taylor Farms as the source of the lettuce, and the company recalled iceberg lettuce grown in central Mexico. The recall involved thousands of packaged salad products combining iceberg lettuce with other vegetables, shipped to major U.S. restaurant chains including Yum Brands, which owns Taco Bell, Pizza Hut and KFC. The FDA said Friday it has ended on-site inspections and sample collection at iceberg lettuce growers and the processing facility in Mexico, with samples from the inspections pending analysis. The outbreak also cast a spotlight on a worsening problem: U.S. regulators are conducting fewer international inspections to catch contaminated produce before it lands on American plates.