FDA says false positive doesn't change focus on Taylor Farms lettuce in US cyclospora outbreak

US health officials revealed on Monday (local time) that they continue to focus on lettuce supplied by Taylor Farms as the primary source of the cyclospora parasite that causes diarrhea in many countries, despite inconclusive laboratory test results released by the US government over the weekend.

Food and Drug Administration (FDA) officials revealed Monday that a positive result for cyclospora in a sample of Taylor Farms lettuce was misidentified. The FDA published the findings on its website on Saturday, but revealed on Sunday that the result was a false positive, the Associated Press reported.

Both federal and state authorities have been investigating an increase in cases of cyclosporiasis linked to the parasite and initially linked the outbreak in five states to the delivery of lettuce to Taco Bell locations.

Read also | Taco Bell lettuce supplier linked to US cyclosporiasis outbreak: Report

Taylor Farms announced Saturday that it is recalling 25 of its shredded lettuces as well as salad mixes, which it sells under eight different brand codes. These products have been used by a number of US grocery chains and suppliers.

“The FDA’s traceback investigation and outbreak data continue to converge on chopped iceberg lettuce from Taylor Farms locations in central Mexico,” Donald Prater, the FDA’s acting food chief, told reporters Monday, according to the AP.

In addition to monitoring the country’s lettuce supply chain, the FDA has also begun testing lettuce samples that come into the U.S. across the border.

On Monday, FDA officials said the false positive result came from a rapid test used to screen for traces of cyclospora. Although the sample initially tested positive for the parasite, it turned out not to be part of the lettuce the company recalled.

Subsequent quality control revealed that the positive result was a mistake, which FDA officials then disclosed to Taylor Farms.

The company offered updated test results on social media and claimed that “the FDA has apologized to us.” Agency officials told The Associated Press that there has been no official apology.

Read also | Cyclosporiasis: Taco Bell is removing some ingredients as a precaution

1,645 individuals fell ill in the outbreak

Cyclospora is a microscopic parasite that infects food that has come into contact with human feces, which most often occurs when produce is washed with contaminated water. When ingested, these parasites caused an intestinal illness characterized by “frequent and sometimes explosive bowel movements,” according to the CDC.

In the 2026 cyclospora outbreak, approximately 1,645 people in the U.S. became ill, while 141 were hospitalized, the FDA and CDC said. Agencies are investigating five separate clusters of illnesses, including the one traced to Taylor Farms.

Kyle Diamantas, the FDA’s acting commissioner, said health officials continue to see new cases linked to the outbreak.

“Which means it is necessary for us to take measures to ensure that the contaminated product does not reach the market,” Diamantas explained, according to the AP.

Down to Taco Bell, other chains

Amid concerns about the disease, foot traffic at a number of food chains across the United States fell compared to the weekday average between Jan. 1 and July 6, according to Placer.ai, the AP reported.

Taco Bell suffered the biggest drop, about 18.9%, after the chain was named by federal officials in an investigation into the cyclosporiasis outbreak. Foot traffic also dropped at Chopt, Chipotle and Parenra Bread.