Update: multistate outbreak of Escherichia coli O157:H7 infections from hamburgers--western United States, 1992-1993.

From November 15, 1992, through February 28, 1993, more than 500 laboratory-confirmed infections with E. coli O157:H7 and four associated deaths occurred in four states--Washington, Idaho, California, and Nevada. This report summarizes the findings from an ongoing investigation that identified a multistate outbreak resulting from consumption of hamburgers from one restaurant chain.