FDA walks back lettuce test but keeps outbreak focus on Taylor Farms

A key lettuce test in the federal cyclosporiasis probe was wrong, the Food and Drug Administration said, but the agency is not backing away from its central finding: shredded iceberg lettuce from Taylor Farms locations in central Mexico remains the focus.

The FDA said Sunday that a sample of iceberg lettuce supplied by Taylor Farms de Mexico had produced a false positive for the cyclospora parasite. On Monday, the agency clarified that the result applied to one shipment and did not alter its conclusion about the broader outbreak, which has sickened more than 1,600 people across 34 states, according to CNBC.

The FDA said its traceback work and outbreak data still point to shredded iceberg lettuce from Taylor Farms sites in central Mexico. Some of that lettuce was served at Taco Bell restaurants, the agency has said.

“FDA’s traceback investigation and outbreak data continue to converge on shredded iceberg lettuce from Taylor Farms locations in central Mexico,” the agency said in a statement. The FDA said it will keep working with federal and state partners and make sure implicated products are off the market.

The agency is still telling Americans not to eat recalled iceberg lettuce.

What the false positive changes

Former FDA Commissioner Dr. Scott Gottlieb told CNBC the faulty test does not remove Taylor Farms from the investigation. He said the recalled product announced Friday had been imported weeks earlier and was separate from the lettuce tied to the positive FDA test.

Gottlieb also said cyclospora’s incubation period, which can run as long as two weeks, complicates testing because lettuce does not last long on shelves. That makes it necessary to examine multiple shipments, even from the same farm, he told CNBC.

Cyclospora can cause symptoms that resemble a severe stomach illness and may last for days or weeks, according to the report.

Dr. Norman Beatty, an associate professor of medicine at the University of Florida College of Medicine, told CNBC that investigators may still find smaller related outbreaks because the parasite has been detected in more than 30 states.

Companies pull products as consumers hesitate

Taylor Farms said Monday it would continue its voluntary recall of implicated iceberg lettuce from central Mexico. Taco Bell said it had begun removing the suspected lettuce from restaurants in affected states.

Walmart also moved products off shelves. The retailer said Monday it proactively removed four Marketside bagged salad kits supplied by Taylor Farms from stores in 27 states, while saying there was no indication the products were part of the outbreak.

“There have been no confirmed illnesses associated with these products at this time,” Walmart said in a statement, adding that it was working with its supplier.

Michigan health officials, in a state where cases have grown quickly, said they continue to recommend that shoppers buy whole heads of lettuce rather than pre-washed, bagged or mixed salad kits. The state agency said interviews with more than 2,000 infected patients showed many did not report eating lettuce at a restaurant, though they often said they had eaten lettuce somewhere.

Taco Bell told CNBC it removed suspected lettuce from its locations within 72 hours of starting the process and adjusted its supply chain. The chain said it is confident customers can eat safely at its restaurants.

Foot traffic at Taco Bell fell about 19% on Friday compared with the average for that day of the week this year, according to Placer.ai data cited by CNBC. Chopt, Panera Bread and Chipotle also saw declines, the data showed.

Restaurant analysts told CNBC they do not expect a lasting financial blow to companies tied to the outbreak, though sales could take a short-term hit. Shares of Taco Bell parent Yum Brands were down nearly 9% over five days, according to CNBC.

This story draws on original reporting from CNBC.