The U.S. Food and Drug Administration said Friday its traceback investigation found the stomach flu-like illness clusters at four restaurants were traced to a common supplier, Taylor Farms de Mexico, S. de R.L. de C.V.
The investigation has not implicated consumer packages sold in grocery stores, FDA officials said.
Taylor Farms de Mexico was cooperating with all FDA requests during the investigation and both the FDA and the company will be conducting an environmental assessment of the company's processing facility in Mexico to try to learn the probable cause of the outbreak and identify preventive controls to put in place to prevent a recurrence.
The most recent inspection, in 2011, of the processing facility of Taylor Farms de Mexico, S. de R.L. de C.V. conducted by the FDA found no notable issues. Additionally, as a result of the current investigation FDA is increasing its surveillance efforts on green leafy products exported to the United States from Mexico, officials said.
The Iowa Department of Inspections and Appeals and the Nebraska Department of Health and Human Services said the contaminated salad was most likely no longer in the food supply in these states. The last date someone reportedly became ill with cyclosporiasis in Iowa was July 1 and in Nebraska July 2, and the typical shelf life for a salad mix is up to 14 days, the FDA said.
It is not yet clear if the 173 cases reported from the other 15 states infected with cyclospora were part of the same outbreak, officials said.
As of Thursday, the Centers for Disease Control and Prevention said there were 400 cases nationally of cyclosporiasis -- 146 in Iowa and 81 in Nebraska.