Lesson 7: Etiologic Studies (2) Outbreak Investigation; Advanced Case-Control Design

Overview Section

In this course, we have often assumed that investigators have knowledge of a potentially harmful exposure coincidentally with or prior to observing the disease or illness. In other situations, the first indication of a harmful exposure is a report of a potential outbreak of disease or illness. Increased numbers of cases of disease or illness may necessitate an outbreak investigation. Questions to be answered in an outbreak investigation include the following:

  1. Are there an unusual number of adverse health outcomes in this community?
  2. If so, how many? Is the number increasing, decreasing or stable?
  3. What type of exposure may have caused the increase?
  4. What is the anticipated future course and spread of this outbreak?

Basic case-control studies are very useful when investigating an outbreak of disease. Last week we studied the basic case-control study. This week we will see some more advanced case-control designs, but these are rarely used in outbreak investigations because they take longer to implement and are more complex.

Note! The material for outbreak investigation has been adapted from CDC source materials

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Upon completion of this lesson, you should be able to:

  • Use common terms in outbreak investigation appropriately
  • Develop an outbreak investigation plan
  • Describe a potential outbreak with regard to person, place and time.
  • Construct and interpret an epi-curve to describe the course of an outbreak
  • Differentiate between a nested case-control study, a case-cohort design and a case-crossover design