During February-March, 1999, an outbreak of E. coli O157:H7 infections involving guests and employees at the Sunday River Ski resort, in Maine, was investigated. The outbreak was associated with consumption of ground beef patties produced by a company based in Rochester, Minnesota. Isolates of E. coli O157:H7 from case-patients and from intact packages of ground beef patties were a genetic match to one another. Ground beef products produced by the company on December 1, 1998, were subsequently recalled. The outbreak pattern was posted on PulseNet.

The Minnesota Department of Health (MDH) Public Health Laboratory identified three matching isolates of E. coli O157:H7 obtained from Minnesota residents during January 1999. These cases reportedly had consumed hamburger produced by the same company.