Taylor Farms lettuce remains the focus of cyclosporiasis investigation, despite false positive test

Investigators from health agencies looking into a significant cyclospora-related diarrhea outbreak have found “very strong” indications that shredded iceberg lettuce from Taylor Farms is the suspected cause, even though a test over the weekend returned a false positive for the parasite.

The US Food and Drug Administration (FDA) stated in a press release on Monday that “the traceback investigation and outbreak information are continuing to point towards shredded iceberg lettuce from Taylor Farms locations in Central Mexico.”

“Our top priority is protecting the American public. We advise consumers to refrain from consuming all products included in Taylor Farms’ voluntary recall,” the FDA added.

On Sunday, Taylor Farms issued a recall for iceberg lettuce distributed across 27 states.

As a significant supplier of produce in the US, Taylor Farms provides lettuce and bagged salad kits under various private labels. Nevertheless, the company did not specify any particular retailers, restaurants, or product names in their recall announcement.

Taco Bell has also taken steps to remove the implicated shredded iceberg lettuce supplied by Taylor Farms from its restaurants in five states due to the outbreak.

The FDA announced on Saturday that a lettuce sample from Taylor Farms had tested positive for cyclospora; however, a subsequent statement from the agency on Sunday indicated that this result “should be considered a false positive.”

On Monday, Taylor Farms reported that the “FDA apologized to us” regarding the false positive result.

“To clarify, at this time, the FDA has not identified a single positive product test result for Cyclospora,” the company’s statement noted.

The FDA provided its own clarification on Monday.

“To clarify, this false-positive lab sample does NOT alter the basis for the FDA’s ongoing outbreak investigation or the substantial epidemiological data that backs the current voluntary recall by Taylor Farms,” it stated.

Officials from health agencies stated that they did not extend an official apology to Taylor Farms.

Frank Yiannas, who previously served as the deputy commissioner for food policy and response at the FDA, referred to the false positive result as “unfortunate – and consequential.”

He noted that it’s understandable why consumers might think that since the lab result was deemed a false positive, the recall itself was unwarranted.

“However, that is not what this indicates,” Yiannas clarified in a statement.

Given the difficulty in detecting cyclospora on produce, he explained, “epidemiological evidence alone can, in some cases, justify taking public health actions.”

“The FDA should be recognized for its transparency in quickly disclosing the laboratory error,” Yiannas continued. “Nonetheless, transparency is not sufficient by itself. It is equally vital for the agency to identify the underlying cause of the laboratory or quality control failure, take suitable corrective measures, and relay the lessons learned to both the public and the regulated industry.”

During a media briefing on Monday, FDA officials acknowledged that tracking cyclospora in fresh produce has always been a complex task. Since symptoms can take over a week to manifest, the produce item responsible for illness may no longer be available for testing.

“Given the elapsed time as well as the necessity for epidemiological investigation, all potentially contaminated products may have already been discarded or consumed,” stated an FDA official.

“Thus, it becomes somewhat of a pursuit when it comes to testing. However, the epidemiological data and traceback information are, in our view, very solid.”

The recall was prompted by evidence gathered from interviews with individuals who tested positive for cyclospora and who were confirmed to be part of the same illness cluster.

As of Monday, there have been over 8,000 reported cases of cyclosporiasis linked to the outbreak affecting Michigan, Ohio, Indiana, Kentucky, and West Virginia. If all cases are confirmed to be connected, it would mark the largest foodborne illness outbreak recorded in the US.

Michigan is particularly affected, with more than 6,100 cases reported as of Monday.

“Based on interviews with 2,025 individuals affected by cyclosporiasis in Michigan, many did not report consuming lettuce at restaurants or other food venues. Nevertheless, lettuce was frequently mentioned in food questionnaires, including those without any restaurant or fast-food involvement,” stated Laina Stebbins, spokesperson for the Michigan Department of Health and Human Services.

Stebbins noted that Michigan health authorities have not altered their recommendations following the false positive test result.

“MDHHS continues to advise residents of Michigan to opt for whole heads of lettuce instead of pre-washed, bagged varieties or pre-mixed salad kits and to adhere to safety guidelines issued by the department,” she concluded.

Not every case of cyclosporiasis nationwide is associated with the outbreak occurring in the Midwest. The FDA indicates that it has looked into five separate subclusters of cyclospora since the onset of the season in May.

According to FDA Acting Commissioner Kyle Diamantas, three of these investigations are now deemed complete.

The US Centers for Disease Control and Prevention reports that symptoms of cyclosporiasis can manifest anywhere from two days to two weeks after ingesting contaminated food or water.

Symptoms may include: