Cyclospora outbreak: FDA declares Taylor Farms lettuce test false positive, but data still supports recall

BRANDON, Fla. - Federal health officials declared that a recent Cyclospora-positive test result from Taylor Farms iceberg lettuce samples was a false positive.

The U.S. Food and Drug Administration says its investigation into the nationwide parasitic outbreak is ongoing.

FDA Cyclospora Test Update

What we know:

The FDA announced the update on Sunday, after initially saying a sample from Taylor Farms de Mexico tested positive on Saturday.

Lab experts reexamined the results on Sunday and determined the finding was a false positive, according to the FDA.

"Due to the complexity in detection of Cyclospora, FDA laboratory experts re-reviewed the sample results and have concluded that the finding does not represent true amplification and should be considered a false positive," the FDA said on its website on Sunday.

As of Sunday, the FDA said there are no confirmed positive sample results for Cyclospora in any food products.

In a post on X on Monday, the agency said the false result does not change the basis of its investigation or the data supporting the voluntary recall by Taylor Farms of iceberg lettuce sourced from central Mexico.

"To clarify, this false-positive lab sample DOES NOT change the basis for FDA’s ongoing outbreak investigation or the overwhelming epidemiological data supporting the current voluntary recall by Taylor Farms," the FDA said. "Over the weekend, FDA alerted Taylor Farms that a new sample of shredded lettuce from Taylor Farms de Mexico tested positive for Cyclospora during import examination at the Southern Border. This ended up being a false positive, and Taylor Farms was alerted to the corrective test result Sunday. FDA’s traceback investigation and outbreak data continue to converge on shredded iceberg lettuce from Taylor Farms locations in central Mexico. FDA will continue to work with federal and state partners to investigate this multistate outbreak and ensure products implicated in this outbreak have been removed from the market.

Nationwide Parasitic Illness Rise

By the numbers:

The Centers for Disease Control and Prevention reports more than 1,600 confirmed cases of cyclosporiasis across the country.

Health authorities note the parasite causes gastrointestinal illness, specifically prolonged diarrhea, in addition to vomiting and abdominal pains.

Difficulties Tracking Produce Parasites

What they're saying:

Medical experts explain that cyclospora cannot be grown in a laboratory like bacteria, making origin tracing extremely difficult.

"It's really very difficult to trace on which is the source because it's a parasite," Dr. Adelor Zamora, an Infectious Disease Specialist with HCA Florida Brandon Hospital said.

Doctors say the parasite is also difficult to test for, because it's microscopic.

"It's hard to test it on a lettuce or other type of produce because you might be testing a small batch of that lettuce, but the oocysts, which are the infectious version of the Cyclospora, could be on another part of the lettuce that you do not test," Isis Lamphier, the Director of Infection Prevention at HCA Florida Brandon Hospital said.

Delayed Symptoms Obscure Origin

The backstory:

The incubation period for cyclosporiasis ranges from three to seven days.

"So, it's really a long time," Zamora said. "By that time, nobody knows exactly what they have eaten, so you cannot really pinpoint if the source is from a salad or from a fruit."

Diagnosing patient samples also requires multiple rounds of stool testing due to the nature of the infection.

"It's recommended to test the patient three times, 24 hours between each of the tests if the first one is not positive, because in that initial test that you might have had, it might not have had the parasite in that stool sample," Lamphier said.

If you are having symptoms, doctors recommend you go to a nearby emergency department because they have the specific testing necessary.

Recalled Central Mexico Lettuce

The other side:

Taylor Farms released a statement addressing the updated test findings from the FDA.

"To be clear, at this moment, FDA has not identified a single positive product test result for Cyclospora," the company said in part of a post on social media. "Acting on initial information provided by health officials, in an abundance of caution, we completed a voluntary recall of iceberg lettuce from central Mexico."

Company officials confirmed that all other Taylor Farms products remain unaffected and available to consumers.

Consumer Grocery Identification Tips

What you can do:

Shoppers can verify where produce was grown by reading shelf tags, packaging, or country-of-origin markings on individual items. Consumers can also inspect price look-up stickers or check for "Manufactured for" and "Distributed by" labels on product packages.

Doctors advise people to continue being diligent about washing all fresh produce. They also recommend peeling fruit skins and discarding the outer leaves of a head of lettuce before consuming.

Mystery Outbreak Source Unclear

What we don't know:

Investigators have not identified the specific source of the Cyclospora parasite. Officials also have not confirmed whether additional produce items or distribution chains are potentially involved in the outbreak.

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