Salmonella Enteritidis infections centered in Texas and Oklahoma, but also spread over 8 other states, sickened 68 people who ate at a Mexican-style fast food restaurant chain in October and November, the Centers for Disease Control and Prevention reported Thursday.

The CDC did not identify the restaurant chain, nor did it explain why it was reporting this outbreak for the first time now, nearly two months after it occurred. The investigation report was labeled “final update,” although it was also the first announcement of the multistate outbreak.

No specific food or ingredient was determined to be responsible for the illnesses. The CDC said investigators concluded that whatever the food source was, it likely was contaminated before it reached the fast-food restaurant outlets.

Unidentified Restaurants

This isn’t the first time a CDC investigation report did not reveal the name of a restaurant chain associated with customer illnesses. In August, 2010, the federal public-health agency reported 155 people sick in two multistate outbreaks of Salmonella Hartford and Salmonella Baildon infections.

The Mexican-style fast food restaurant chain implicated then was initially referred to only as Restaurant Chain A.  Days later, CDC confirmed that Taco Bell was the chain responsible.

Once again, CDC refers to the company involved in the latest outbreak as Restaurant Chain A.

“I am bewildered why the government keeps this type of information from the public,” said food safety attorney Bill Marler, publisher of Food Safety News. “Secrecy in public health serves no useful purpose – especially in foodborne outbreak investigations.”

“Can anyone at CDC spell ‘transparency?,’ ” asked microbiologist Phyllis Entis, author of the eFoodAlert website.

Entis said not naming the implicated Mexican-style fast food restaurant chain “does a disservice to all of the ‘Mexican-style fast food” chains that were not involved in the outbreak.” She also observed that the CDC commented favorably on this anonymous chain’s handling and cooking of ground beef:

“I would think that Chain A would want to be named, so that its customers could have the comfort of knowing that its procedures for handling and cooking meat were appropriate and safe.”

Outbreak Profile

The CDC said Texas reported 43 people infected with the outbreak strain of Salmonella Enteritidis, Oklahoma reported 16 cases, Kansas 2 and Iowa, Michigan, Missouri, Nebraska, New Mexico, Ohio and Tennessee each reported 1.

Nearly one-third of those sickened were hospitalized.

Victims ranged in age from under one year to 79 years old, with a median age of 25.

The outbreak began about Oct. 13, 2011 and “appears to be over,” according to the investigation report.

Food histories were obtained for 52 of the ill people, and 60 percent of them reported eating at 18 different locations of Restaurant Chain A in the week before they were sick.

The epidemiologic control study, which compared 48 of the Salmonella-infected people and 103 well people, found that significantly more of the sick people had eaten at Chain A (62 percent compared with 17 percent).

No Known Source

But the investigators were unable to pinpoint the source of these people’s infections.

Ninety percent reported eating lettuce, 94 percent reported eating ground beef, 77 percent reported eating cheese and 35 percent reported eating tomatoes, according to the report. Investigators ruled out the ground beef, saying it was “an unlikely source” because of Chain A’s procedures for handling and cooking meat.

U.S. Food and Drug Administration investigators, the report says, tried to figure out which food was the culprit by tracking supply truck delivery routes and schedules. But that line of inquiry hit a dead end when “FDA found locations where more than one ill person reported eating in the week before becoming ill were on two separate trucking routes. Comparison of records from suspected foods received by these locations revealed no commonalities across a variety of suppliers.”

The unnamed fast-food restaurant chain, the unnamed food suppliers and the unnamed distributers were all “very cooperative” with the investigation, the report noted.

“At this time, there is no specific advice to consumers,” the CDC said in concluding the report. “Consumers are not warned to avoid specific foods or restaurants.”

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