Problem: A Multistate Outbreak of E. coli O157:H7 Infection Original investigators: Thomas Breuer,1 Denise H. Benkel,1,2 Roger L. Shapiro,1 William N. Hall,3 Mary M. Winnett,4 Mary Jean Linn,2 Jakob Neimann,1 Timothy Barrett,1 Stephen Dietrich,3 Francis P. Downes,3 Denise M. Toney,5 James L. Pearson,5 Henry Rolka,1 Laurence Slutsker,1 and Patricia M. Griffin1 1Centers for Disease Control and Prevention, 2Virginia Department of Health, 3Michigan Department of Community Health, 4Medical College of Virginia, 5Virginia Division of Consolidated Laboratory Services Case study and instructor's guide created by: Jeanette K. Stehr-Green, MD Describe three epidemiological principles, concepts, or practices that were presented in the case study exercise and discuss the role and importance of each in a foodborne illness outbreak investigation. Do not include lab testing in the answer