WASHINGTON (AP) — An outbreak of more than 600 severe stomach illnesses around the country remains a mystery as the FDA says it found no food safety violations at a Mexican farm linked to some of the illnesses.
The FDA said Tuesday that Taylor Farms de Mexico could resume operations after investigators found conditions there "in accordance with known food safety protocols." The firm shut down voluntarily earlier this month after its salad mix served at Olive Garden and Red Lobster restaurants was linked to 242 cyclospora infections in Nebraska and Iowa.
Similar illnesses in 20 other states were never definitively linked to the farm, and officials say they do not know why the number of illnesses is still growing in some other states, including Texas, which has seen more than 280 sickened. The CDC says it has found evidence that many of those sickened in Texas ate at the same restaurant, but that it does not "show a connection" to salad mix produced at Taylor Farms. The CDC would not identify the restaurant, and officials say it is possible that there are multiple outbreaks.
Cyclospora is usually found outside the United States and is caused by parasites that are spread when people ingest food or water contaminated with feces. People who are exposed usually become sick after about a week and have diarrhea and other flu-like symptoms that can last from a few days to several months if not treated with antibiotics.
The outbreak investigation is unusual in that federal and state officials have not been able to trace all of the illnesses back to one item and that the farm did not show any evidence of contamination. In large outbreaks, officials trace the illnesses through interviews and laboratory tests and then, ideally, later find contamination at a farm, processing plant or other location where the food has been produced or held. Recent large outbreaks of illness in cantaloupe, peanuts, and eggs have followed this pattern.
One factor making the investigation more difficult is that cyclospora is not common in the United States, and there may be many illnesses that have not been identified. Doctors have to test specifically for cyclospora and many don't because it is rare. The CDC said it doesn't have the tools to distinguish one strain of the infection from another, making it harder to determine if there are multiple outbreaks.
It can also be difficult to pinpoint the exact source of contamination. While some investigations find unclean conditions, other outbreaks can remain a mystery forever. Food can be tainted by the smallest of transgressions, including an animal that broke through a fence and defecated on a patch of lettuce or a worker who doesn't wash his or her hands after going to the bathroom.
The FDA said it worked with Taylor Farms and the Mexican government to do a thorough inspection of the farm. In a statement Tuesday, California-based Taylor Farms said it also did its own investigation of its Mexican branch and took over 1,000 samples from water, soil, greens and other areas of the farms. All of them were negative for cyclospora, the company said.
"Taylor Farms has reviewed thousands of other data points for the production dates in question and have found no irregularities that would indicate a potential for contamination," the company said in a statement.
The FDA said Taylor Farms has committed to a "comprehensive cyclospora sampling program" including sampling of water and monitoring the cleanliness of its facilities.
Associated Press writer Christopher Sherman contributed to this report from McAllen, Texas.