The Mexican-style fast food chain referred to only as “Restaurant Chain A” in a report on a 10-state outbreak of Salmonella Enteritidis by the Centers for Disease Control and Prevention (CDC) is Taco Bell, Food Safety News has learned.

While Taco Bell was suspected ever since the CDC’s outbreak report was issued on January 19, confirmation that the chain was central to the investigation comes in a document from the Oklahoma State Department of Health’s Acute Disease Service titled, “Summary of Supplemental Questionnaire Responses Specific to Taco Bell Exposure of Oklahoma Outbreak associated cases Multistate Salmonella Enterititis Outbreak Investigation.”

Oklahoma, with 16 confirmed cases, was second only to Texas in the number of illnesses connected to the outbreak. Ill Oklahomans reported onset dates from Oct. 21 to Nov. 18, 2011.

Half of Oklahoma’s 16 victims specifically reported consuming food at a Taco Bell outlet. Four others either refused to complete the supplemental case-control questionnaire or were not available for follow-up.

CDC initially declined to name Taco Bell, saying there was no public health reason to do so. At the time of its report, CDC said a total of 68 individuals infected with the outbreak strain of Salmonella Enteritidis had been reported from 10 states. The number of ill persons identified in each state with the outbreak strain was as follows: Texas (43), Oklahoma (16), Kansas (2), Iowa (1), Michigan (1), Missouri (1), Nebraska (1), New Mexico (1), Ohio (1), and Tennessee (1).

Food Safety News has contacted Taco Bell repeatedly over the past week but has yet to receive a comment from the company.

Taco Bell has 5,600 fast food Mexican-style outlets in the United States with 36.8 million weekly customers. It is a unit of Yum! Brands Inc. (NYSE: YUM).