Multistate Outbreak of Cyclosporiasis

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 Given the historical nature of this content, the methods that are referenced on this site may be outdated practices in some settings.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

Students with limited knowledge of basic epidemiologic concepts who are interested in learning more about the practice of epidemiology

Learning Objectives

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

  • Use the modes of transmission and incubation period for a disease to focus the search for the source of an outbreak.
  • Describe the two most common types of epidemiologic studies routinely used to investigate outbreaks.
  • Interpret the results of an epidemiologic study.
  • Consider potential sources of error in designing or carrying out an epidemiologic study.
  • Apply the criteria for causation to the results of an outbreak investigation.
  • List considerations in implementing control measures before confirmation of the source of an outbreak.
  • Describe the occurrence, signs and symptoms, and control of cyclosporiasis.


Successful completion of basic training in infectious disease epidemiology, descriptive epidemiology, study design, measures of association, 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 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
  • Epidemiology Program Office, Office of Scientific and Health Communications
  • Public Health Practice Program Office, Division of Professional Development and Evaluation

Development of the case study was funded by the John S. and James L. Knight Foundation and the CDC.

Original Investigation Team

The following individuals investigated the original multistate outbreak of cyclosporiasis: Barbara L. Herwaldt, Marta-Louise Ackers, Michael J. Beach, and the Cyclospora Working Group.