The outbreak of cyclospora infections has sickened more than 400 people in 16 states. The agency says it is working to determine whether the salad mix is the source of illnesses in the other 14 states.
"It is not yet clear whether the cases reported from other states are all part of the same outbreak," the agency said in a statement. "The investigation of increased cases of cyclosporiasis in other states continues."
Both Olive Garden and Red Lobster are owned by Orlando-based Darden Restaurants. In a statement, the company questioned the FDA findings, saying it has "no reason to believe that anyone was exposed to cyclospora in any of our restaurants."
"We have done extensive trace-backs on all our produce, including looking at analyses of the irrigation water used in our suppliers' growing fields, and there are no issues or concerns with any of the products we use," said Darden spokesman Mike Bernstein.
The FDA said it traced illnesses from the restaurants in Nebraska and Iowa to Taylor Farms de Mexico, a processor of food service salads based in Salinas, Calif. The company, which has a branch about 180 miles north of Mexico City in San Miguel de Allende, did not immediately return calls.
The agency said its investigation has not implicated packaged salad sold in grocery stores.
The salad mix may be out of the commercial food chain as the most recent known illness in those two states was in Nebraska a month ago. The typical shelf life for a salad mix is up to 14 days.
There have been more recent illnesses in other states. According to the Centers for Disease Control and Prevention, the most recent illness was July 23.
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