E. coli O157:H7 was identified for the first time at the CDC in 1975, but it was not until seven years later, in 1982, that E. coli O157:H7 was conclusively determined to be a cause of enteric disease. Following outbreaks of foodborne illness that involved several cases of bloody diarrhea, E. coli O157:H7 was firmly associated with hemorrhagic colitis.
The Centers for Disease Control and Prevention (CDC) estimated in 1999 that 73,000 cases of E. coli O157:H7 occur each year in the United States. Approximately 2,000 people are hospitalized, and 60 people die as a direct result of E. coli O157:H7 infections and complications. The majority of infections are thought to be foodborne-related, although E. coli O157:H7 accounts for less than 1% of all foodborne illness.