Taco Bell said in a statement on Wednesday that investigators found that some of the people who became ill ate at Taco Bell, while others did not.

"They believe that the problem likely occurred at the supplier level before it was delivered to any restaurant or food outlet. We take food quality and safety very seriously," Taco Bell said, echoing information from the Centers for Disease Control and Prevention's January 19 final report on the outbreak.

The cluster of illness from salmonella enteritidis infections is believed to have begun in mid-October and ended by the time CDC issued its final report. Illnesses were reported in Texas, Oklahoma, Kansas, Iowa, Michigan, Missouri, Nebraska, New Mexico, Ohio and Tennessee.

CDC said 31 percent of patients were hospitalized. No deaths were reported.

The outbreak had an air of mystery about it because CDC's final report said it was linked to a Mexican-style fast-food chain identified only as "Restaurant A."

Food Safety News was the first to identify Taco Bell as Restaurant A, citing a document from the Oklahoma State Department of Health's Acute Disease Service.

Taco Bell has been tied to two other outbreaks in the last six years.

In 2006, CDC identified contaminated lettuce served by Taco Bell restaurants in the northeastern United States as the source of an outbreak of a virulent strain of E. coli O157 that sickened 71 people.

Four years later, CDC confirmed that Taco Bell was linked to two outbreaks of rare strains of salmonella that made at least 155 people sick in 21 states. CDC originally linked that outbreak to an unnamed Mexican-style fast-food restaurant chain.

News of the 2011 outbreak comes as Taco Bell works to fully recover from a bogus, but ultimately sales-denting lawsuit over the contents of its seasoned ground beef.

Salmonella infections often cause diarrhea, fever and abdominal cramps. The illness usually last four to seven days and most people recover without treatment.

CDC estimates that one in six people in the United States gets sick from eating contaminated food each year. Food-borne illnesses are blamed for about 3,000 deaths annually.

(Reporting By Lisa Baertlein in Los Angeles' Editing by Andre Grenon)

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