Federal health officials say a laboratory result that initially suggested the presence of Cyclospora in a Taylor Farms lettuce sample has been determined to be a false positive, but the finding has not changed the course of the ongoing foodborne illness investigation.
The U.S. Food and Drug Administration (FDA) announced Sunday that no product samples have been confirmed positive for Cyclospora through laboratory testing. The following day, the agency clarified that investigators continue to focus on shredded iceberg lettuce produced by Taylor Farms in central Mexico based on extensive epidemiological evidence gathered during the outbreak investigation.
The FDA emphasized that the false-positive test result does not affect its assessment of the outbreak or the agency’s recommendation regarding the voluntary recall.
Taylor Farms announced Friday that it is voluntarily removing iceberg lettuce sourced from central Mexico from distribution while the investigation continues. Company officials said the action was taken out of an abundance of caution after the FDA’s traceback investigation identified an independent farm in the region as the likely source of contamination.
According to Taylor Farms, the farm identified by investigators accounts for less than one percent of the iceberg lettuce supplied to the U.S. market. Even so, the company has suspended sourcing all iceberg lettuce from the region indefinitely.
Cyclospora is a microscopic parasite that can contaminate fresh produce and cause cyclosporiasis, an intestinal illness that often results in prolonged diarrhea, stomach cramps, nausea, fatigue and loss of appetite. Symptoms may appear several days after consuming contaminated food and can last for weeks if left untreated.
Food safety experts say confirming the presence of Cyclospora is more difficult than testing for common foodborne bacteria such as E. coli or Salmonella. Jennifer McEntire, founder of Food Safety Strategy, said the parasite’s complex testing process can make investigations more challenging.
The FDA’s investigation remains ongoing as officials continue working to identify the precise source of the outbreak and reduce the risk of additional illnesses.