Submitted to: Clinical Infectious Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/22/2003
Publication Date: 6/11/2004
Citation: Jay, M., Garrett, V., Mohle-Boetani, J., Barros, M., Farrar, J.A., Abbott, S., Rios, R., Sowadsky, R., Komatsu, K., Mandrell, R.E. 2004. A multi-state outbreak of escherichia coli o157:h7 linked to consumption of beef tacos at a fast-food restaurant chain. Clinical Infectious Diseases. 39(1):1-7.
Interpretive Summary: An outbreak of E. coli O157:H7 occurred multiple western states in 1999. Traceback investigations determined that the most likely cause of this outbreak was due to a meat product used to prepare tacos at restaurants of a national taco food chain. Limited studies of the fitness of the outbreak strains resulted in the conclusion that these strains were not more resistant to heat or acid than other pathogenic E. coli strains and some generic E. coli strains. The processed taco meat was supplied by a single supplier to the restaurant chain. However, no reason for the failure of the normally well-controlled heating process could be identified.
Technical Abstract: We investigated a multi-state outbreak of Escherichia coli O157:H7. Thirteen case-patients from California, Nevada, and Arizona had onsets in November 1999. Five (38%) were hospitalized and 3 (23%) developed hemolytic uremic syndrome; there were no deaths. The median age was 12 years (range 2-75) and 10 (77%) were female. Case-control studies found an association between illness and eating beef tacos at a national fast-food restaurant chain (88% of case-patients versus 38% of controls; MOR = undefined, 95% C.I. = 1.49-infinity, p value = 0.009). A traceback investigation implicated an upstream supplier of beef, but a farm investigation was not possible because of inadequate record keeping by the slaughterhouse. This outbreak illustrates the value of hospital surveillance combined with molecular surveillance to identify clusters and link related cases that are geographically widespread. The outbreak further demonstrates the need for a more efficient tracking system for beef products.