Federal health regulators announced Friday that inspectors discovered the cyclospora parasite at a Taylor Farms facility in Guanajuato, Mexico, the site linked to the largest cyclospora foodborne illness outbreak ever recorded in the United States.
The outbreak sickened nearly 13,000 people across the country with symptoms including watery diarrhea and severe gastrointestinal distress. The FDA has officially closed its investigation into the outbreak, which U.S. health officials declared over last month.
Inspectors found the microscopic parasite in two specific locations at the farm: a wastewater holding tank and a drainage ditch associated with lettuce cultivation. Despite these findings, the FDA acknowledged it remains unclear exactly how the contamination made its way into the lettuce supply.
The agency described the samples as providing strong epidemiological evidence connecting the outbreak to the Taylor Farms operation. The inspection was the FDA’s first visit to the facility in over seven years, a gap attributed largely to a significant decline in international food safety inspections following the COVID-19 pandemic.
Taylor Farms responded Friday by pointing to an independent grower it said is no longer part of its supplier network as the source of the contamination cited by the FDA. The company added that its central Mexico facility remains closed as it works to strengthen safety protocols throughout its supply chain.
The investigation has not been without complications. Mexican food safety authorities concluded in August that their own separate probe found no cyclospora in lettuce or water samples taken from the facility. That announcement followed an embarrassing setback for the FDA when the agency was forced to retract an earlier test result that had incorrectly identified the parasite in a border sample of Taylor Farms lettuce.
Cyclospora is a microscopic parasite transmitted through contaminated food or water that has come into contact with human feces. According to the Centers for Disease Control and Prevention the illness it causes known as cyclosporiasis typically produces frequent and sometimes explosive bouts of diarrhea. It is considered less common than foodborne illnesses caused by pathogens such as salmonella or E. coli.
Investigators have not yet determined how sewage-related contamination could have occurred on a scale large enough to trigger thousands of illnesses nationwide. The FDA’s closure of the investigation leaves that central question unanswered even as the agency cites the physical evidence found at the farm as a key link to the outbreak.