Pining for a Common Source, a Foodborne Illness Outbreak Investigation: Case Study 

The Pining for a Common Source case study is based on a real investigation conducted by the New York State Department of Health in 2011. It emphasizes the importance of early identification of patient exposures to determine a common source of illness and the implementation of effective control efforts. The case study will exercise outbreak investigation techniques such as obtaining shopper card information, engaging industry, and initiating steps leading to a product recall.  

This activity is tailored for state and local public health agency staff involved in foodborne outbreak investigations. It reinforces fundamental epidemiology, environmental health, and laboratory skills necessary for responding effectively to such incidents. 

After completing this case study, you will be able to: 

  • Explain what constitutes a foodborne illness cluster/outbreak. 
  • Describe the steps in a foodborne illness outbreak investigation. 
  • Identify the roles and responsibilities of the outbreak investigation team. 
  • Understand the importance of information sharing during an outbreak investigation. 
  • Draw and interpret an epidemic curve. 
  • Establish and refine an outbreak case definition. 
  • Describe the types of epidemiologic tools used during an outbreak investigation, including novel techniques. 
  • Describe the purpose of conducting an environmental assessment and traceback investigations. 
  • Describe the types of laboratory techniques used during an outbreak investigation. 
  • Explain how to summarize and communicate outbreak investigation findings. 

The case study is available in two different formats to meet your training needs.  


Online and Self-Paced  

Complete the case study at your own pace via the online, interactive format. The exercise takes approximately 2 – 2.5 hours to complete.  

Access Online Training


In-person Team Activity 

Complete the case study in-person with your team using a downloadable set of materials, including an instructor manual, student manual, and evaluation form. The exercise takes approximately 3 hours to complete.  

View Student Manual PDF

View Instructor Manual PDF

View Evaluation Form PDF

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