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Foodborne and Diarrheal Diseases Branch

Multistate Outbreak of E. coli O157 Infections,
November-December 2006

Updated December 12, 2006


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NOTE: This document is provided for historical purposes. The content of this document has not been revised since its original release and therefore may no longer be up to date.

This outbreak was clearly linked to Taco Bell restaurants in the northeastern United States. As of 12 PM (ET) December 12, 2006, Tuesday, 67 persons with illness associated with the Taco Bell restaurant outbreak have been reported to CDC from 5 states: New Jersey (30), New York (22), Pennsylvania (12), Delaware (2), and South Carolina (1). States with Taco Bell restaurants where persons confirmed to have the outbreak strain have eaten are New Jersey, New York, Pennsylvania, and Delaware. (The patient from South Carolina ate at a Taco Bell restaurant in Pennsylvania.) Other cases of illness are under investigation by state public health officials.

Among these 67 ill persons, 51 (76%) were hospitalized and 8 (12%) developed a type of kidney failure called hemolytic-uremic syndrome (HUS). Illness onset dates have ranged from November 20 to December 5. The peak of the outbreak was in the last week of November; the number of new cases being identified has declined substantially.

Cases in 47 of the 67 patients are confirmed, meaning that the patients’ E. coli O157 strains have the outbreak “DNA fingerprint.” E. coli O157 strains are routinely “DNA fingerprinted” at public health laboratories in all states as part of PulseNet (the network of public health laboratories that sub-type bacteria). E. coli O157 strains from other cases are being tested by PulseNet. As a result of testing by PulseNet, cases with the outbreak strain “fingerprint” pattern are being re-classified as confirmed cases, and cases with an unrelated “fingerprint” pattern are being dropped from the outbreak case count.

Map of states where persons with illness live
Map of states where persons
with illness live

The source of the outbreak has not been determined though it is presumed to be a contaminated food or foods. CDC is working with state and local health officials, the Food and Drug Administration (FDA), the Department of Agriculture (USDA), and the restaurant chain to determine what food caused the outbreak. These investigations include an ongoing study that involves interviews of ill and well Taco Bell restaurant patrons about what food items they consumed. By comparing foods consumed by ill and well persons, investigators can show statistical links to particular food ingredients. Public health officials are focusing on ingredients that were consumed by many ill persons and fewer well persons. Of these ingredients, those consumed raw are of particular interest. This analysis is also demonstrating that onions of any type are probably not linked to this outbreak. Health officials and the restaurant chain are working collaboratively to learn more about the ingredients of particular interest to help pinpoint the food that caused the outbreak and to determine how it became contaminated.

Map of states with Taco Bells where persons with confirmed cases have eaten
Map of states with Taco Bells where persons with confirmed cases have eaten

Public health laboratories are testing food samples from Taco Bell restaurants. A sample of chopped yellow onions collected on December 4 from an open bin in a Taco Bell restaurant in Nassau County, New York tested positive for E. coli O157:H7. This strain has a “DNA fingerprint” pattern that is different from that of the outbreak strain; the pattern of the chopped onion strain has not been seen before in ill persons in this country. Samples of green onions obtained by the restaurant chain tested negative for E. coli O157; the initial report of a preliminary positive on these samples by a laboratory hired by the restaurant chain was not confirmed. At this time, no other food item has a definite or preliminary test indicating the presence of E. coli O157.

E. coli O157 causes diarrhea that is often bloody and accompanied by severe abdominal cramps, but fever is typically absent or mild. Persons who have developed such symptoms after eating at a Taco Bell restaurant in an affected state are advised to consult a physician and to inform their local health department.

For more information on E. coli infection, please refer to the following website:

Page last modified December 12, 2006
Content source: National Center for Infectious Diseases

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