Steps in an outbreak investigation

In the investigation of an outbreak, correctly solving the puzzle as quickly as possible is essential.

A systematic approach is helpful in such situations; the list below outlines a thirteen-step approach to the investigation of an outbreak. It must be recognized that many of the steps might be undertaken simultaneously or in a different order depending on the circumstances of the particular outbreak. Steps may also be repeated after new information is discovered. Control and prevention measures should be applied as soon in the investigation as reasoned action will allow.

Steps in an outbreak investigation

  1. Prepare for field work

  2. Establish the existence of an outbreak 

  3. Verify the diagnosis 

  4. Construct a working case definition 

  5. Find cases systematically and record information

  6. Perform descriptive epidemiology

  7. Develop hypotheses

  8. Evaluate hypotheses epidemiologically

  9. As necessary, reconsider, refine, and re-evaluate hypotheses 

  10. Compare and reconcile with laboratory and/or environmental studies 

  11. Implement control and prevention measures

  12. Initiate or maintain surveillance

  13. Communicate findings

Note - you will find each step described in detail in the next set of Topics in this course. You can also click on the hyperlinks above to take you straight to each of these steps.

(CDC, 2012, p.419)

U.S. Department of Health and Human Services, Centers for Disease Control and Prevention (CDC), Office of Workforce and Career Development. (2012). Principles of epidemiology in public health practice: an introduction to applied epidemiology and biostatistics.  Retrieved from: