The US Food and Drug Administration (FDA) on Monday issued a fresh update on its investigation into a multistate Cyclospora outbreak linked to shredded iceberg lettuce served at Taco Bell restaurants. The agency said a lettuce sample that initially tested positive for the parasite should now be treated as a false positive after experts reviewed the laboratory results.
In an update released on July 19, the FDA said laboratory specialists carried out another review because Cyclospora testing is highly complex. After completing that review, officials concluded that the earlier result did not represent a true detection of the parasite.
“As of July 19, 2026, there are no confirmed positive sample results for product testing for Cyclospora,” the FDA said. The agency removed information about the earlier positive sample from its July 18 advisory. It also said it had informed Taylor Farms de Mexico about the revised findings.
Even though the sample proved to be a false positive, the FDA said the investigation remains active. Officials continue to work with Taylor Farms de Mexico to ensure products linked to the outbreak have been removed from the market. State and federal investigators also continue collecting and testing lettuce samples.
Cyclospora outbreak investigation
The investigation began after the FDA and the US Centers for Disease Control and Prevention (CDC), along with state health departments, linked hundreds of illnesses to shredded iceberg lettuce served at Taco Bell restaurants.
According to the FDA, investigators traced the suspected source to Taylor Farms de Mexico, a supplier based in Guanajuato, Mexico. The company supplied shredded iceberg lettuce to Taco Bell restaurants where many affected customers reported eating before falling ill.
On July 17, Taylor Farms de Mexico voluntarily removed all iceberg lettuce sourced from central Mexico from the US market. The company also launched a recall covering products supplied to restaurants and retailers.
The recall includes Marketside-brand iceberg lettuce products sold at Walmart stores. The affected products include 12-ounce and 24-ounce Iceberg Salad packs and 8-ounce and 16-ounce Shredded Lettuce packs with “Best if Used By” dates between July 18 and August 3, 2026.
The FDA said Taco Bell has also stopped using lettuce supplied by Taylor Farms de Mexico. The agency added that its traceback investigation continues because epidemiological evidence strongly links the supplier to illnesses reported in several states, even though laboratory testing has not yet confirmed Cyclospora in lettuce samples.
The FDA said it has increased border screening of products connected to the investigation and continues working with state partners to identify the exact source of contamination.
What consumers should know about recall and illness
Health officials have confirmed 1,644 Cyclospora infections linked to Taco Bell exposure across Indiana, Kentucky, Michigan, Ohio and West Virginia. Patients became ill between May 13 and July 13, 2026.
The outbreak has led to 94 hospitalisations. No deaths have been reported yet.
Investigators studied meals eaten by 190 affected people in Michigan. About 90% said they had consumed iceberg lettuce before becoming sick. Those findings helped investigators narrow their search to shredded iceberg lettuce.
Cyclospora is a microscopic parasite that causes an intestinal illness known as cyclosporiasis. Most infected people develop diarrhoea, frequent bowel movements, stomach cramps, nausea, bloating, loss of appetite, weight loss and fatigue. Some patients also develop fever, headaches, vomiting and body aches.
Without treatment, symptoms can last for weeks or even longer. Some patients recover before symptoms return again. People with weakened immune systems can develop more severe illnesses.
The FDA urged consumers, restaurants and retailers to throw away recalled iceberg lettuce immediately and avoid eating recalled lettuce served at Taco Bell or any other restaurant. Consumers who purchased recalled Marketside products from Walmart can return them for a full refund.
The agency also advised consumers to clean and sanitise any containers or surfaces that came into contact with recalled lettuce.