Multistate Outbreak of E. coli O157:H7 Infection

These Epidemiologic Case Studies are based on historical events and include epidemiologic methods that were practiced at the time. Given the historical nature of this content, the methods that are referenced on this site may be outdated practices in some settings. As some of the practices are still used, they continue to offer educational value.

Target Audience

Public health practitioners with knowledge of basic epidemiologic concepts and experience in data collection and analysis.

Learning Objectives

After completing this case study, the student should be able to:

  • Describe the unique role the laboratory can play in the detection and investigation of a foodborne disease outbreak.
  • Perform in-depth interviews of selected case-patients to generate hypotheses about the source of an outbreak and mode of transmission.
  • Determine the most efficient epidemiologic study design to test a hypothesis (including the case definition and appropriate comparison group).
  • List three ways to select a comparison group for a case-control study and the advantages and disadvantages of each method.
  • List detailed product information that will facilitate a traceback procedure.
  • Discuss the relative merits of an intervention based on changes in product processing (or design) versus changes in consumer or producer behaviors.


Successful completion of training in descriptive epidemiology, epidemic curves, measures of association, stratified analysis, study design, and outbreak investigation.






3 to 4 hours

Continuing Education

Continuing education credits are not available for completing this case study.

Developed By

Jeanette K. Stehr-Green, MD, developed this case study in close collaboration with individuals from the Centers for Disease Control and Prevention (CDC):

  • National Center for Infectious Diseases, Division of Bacterial and Mycotic Diseases, Foodborne and Diarrheal Diseases Branch, Food Safety Office, Division of Parasitic Diseases
  • Epidemiology Program Office, Division of International Health
  • Public Health Practice Program Office, Division of Professional Development and Evaluation

Original Investigation Team

The following individuals investigated the original outbreak of E. coli O157:H7 infection in Michigan and Virginia: Thomas Breuer, Denise H. Benkel, Roger L. Shapiro, William N. Hall, Mary M. Winnett, Mary Jean Linn, Jakob Neimann, Timothy Barrett, Stephen Dietrich, Francis P. Downes, Denise M. Toney, James L. Pearson, Henry Rolka, Laurence Slutsker, and Patricia M. Griffin.