E. coli O157:H7 was first recognized as a pathogen in 1982 during an investigation into an outbreak of hemorrhagic colitis associated with consumption of hamburgers from a fast food chain restaurant. [9] Retrospective examination of more than three thousand E. coli cultures obtained between 1973 and 1982 found only one isolate with serotype O157:H7, and that was a case in 1975.[4, 9] In the ten years that followed, there were approximately thirty outbreaks recorded in the United States. [10] This number is likely misleading, however, because E. coli O157:H7 infections did not become a reportable disease in any state until 1987, when Washington became the first state to mandate its reporting to public health authorities. [11, 12] Consequently, an outbreak would not be detected if it was not large enough to prompt investigation.