Taco Bell E coli outbreak grows; source still unclear

Lisa Schnirring

Dec 8, 2006 (CIDRAP News) The number of people affected by an Escherichia coli O157:H7 outbreak linked to Taco Bell restaurants has climbed to 62 in 6 states, and it's too early to blame the outbreak on green onions, federal officials said today.

Christopher Braden, MD, a medical epidemiologist with the US Centers for Disease Control and Prevention (CDC), said at a press conference that the case count is expected to grow over the next several days because there are several more suspected cases in more states.

Taco Bell stopped serving green onions at all of its US restaurants this week, after preliminary tests showed a few samples were positive for E coli O157. But confirmatory test results have not yet been announced.

"No specific food has been implicated yet," the CDC said in a news release today. Because the source has not been pinpointed, the risk of further cases still exists, officials said at the news conference.

"The risk to the public is considered ongoing, and we expect additional cases to be identified in the coming days," the CDC statement said.

David Acheson, MD, chief medical officer for the FDA's Center for Food Safety and Applied Nutrition, said at the press conference that all of the tests implicating green onions have been preliminary, and the FDA can't rule out other products as sources of exposure.

"You can't be sure until you've grown the bacteria out of the culturethat takes about 24 hours. Then you need to do genetic fingerprinting, and that takes a couple days," Acheson said. "We're working around the clock to get a handle on this."

Of the confirmed cases, 49 (78%) patients were hospitalized, and 7 (11%) developed hemolytic uremic syndrome, a type of kidney failure that can be fatal, the CDC said. No deaths have been linked to the outbreak. The age range of the patients was not available.

Most of the cases have been in the Northeast, with 28 in New Jersey, 21 in New York, 9 in Pennsylvania, and 2 in Delaware. However, South Carolina and Utah have each reported 1 case.

Illness onset dates ranged from Nov 20 to Dec 2, the CDC reported. Federal officials said at the press conference that it can take up to a week for a person to become ill after eating food tainted with E coli O157:H7.

Acheson said the FDA is testing several types of produce from the Taco Bell chain, as well as cheese. Some of the tested items are from samples that producers voluntarily hold at the factory in case investigators need to do traceback investigations of tainted foods, he said.

Media reports said state and local investigators have linked two distributors, a food processor, and a California farm to green onions that tested positive for E coli in preliminary tests. But Acheson said the FDA is focusing on collecting extensive traceback information from Taco Bell and its affiliates not only for green onions, but also other produce and cheese.

E coli O157:H7, which often causes bloody diarrhea but no fever, was also blamed for an outbreak earlier this fall that was traced to fresh spinach. That outbreak sickened 200 people and resulted in 3 deaths.