Epidemiological summaries

An epidemiological summary (“epi summary”) is a useful tool to share information about an outbreak investigation, and to ensure that all individuals involved are using the same information to guide response activities such as public communications or food recalls. Outbreak investigations may evolve quickly and involve large volumes of information. Communication is very important during an outbreak, not only among the investigation team, but also with other internal and external partners and/or stakeholders (which may include the media and the general public). The epi summary contains contextual information for the outbreak and describes the steps taken and findings to date. It is usually updated throughout the course of the outbreak, as new information becomes available.

Determining the audience

The outbreak investigative team should determine who the epi summary will be shared with. This may be situation-dependent and vary with the specific circumstances of the outbreak. The epi summary may have many audiences, such as external partners, senior management, or the general public. The complexity and tone of the summary should be reflective of the intended audience. There may be different versions of the same epi summary designed for different audiences.

Sections of an epi summary

The objectives, structure, content, frequency, and distribution of the epi summary will vary from outbreak to outbreak, as dictated by the purpose and audience of the document. Although the format can vary, epi summaries should convey the progress of the investigation and case information. The information presented should be as simple and succinct as possible, using tables and figures where appropriate.

Epi summaries created during an investigation are often more simple and concise than the epi summaries produced at the conclusion of an investigation (often called the “final epi summary” or “outbreak investigation report”). The final epi summary will have similar content and layout to the epi summaries that are provided to investigative partners throughout the investigation; it often serves as the official record of the outbreak investigation and is usually distributed more widely. Therefore, the final epi summary tends to be longer, with more background and context than typical epi summaries, and should include overall investigative conclusions and recommendations for future outbreaks. Additional information on final epi summaries and other outbreak wrap-up activities can be found on the “Post-outbreak” page.

The following elements may be included in an epi summary:

Formatting:

• Title (including the etiologic agent)
• Date/time of update/release
• Page numbers
• Confidentiality disclaimer or watermark

Summary/ New Issues:

• Number of cases, hospitalizations, deaths
• What is known about the source
• Key laboratory information
• New issues should clearly state the information that is new in the investigation from the last time the epi summary was distributed. This could be included as a separate section or combined with the summary section.

Outbreak Identification:

• How and when the outbreak was first reported/detected
• Steps taken to confirm the existence of an outbreak

Actions Taken/Chronology:

• Actions taken by the outbreak team and important dates over the course of the investigation, such as the date a hypothesis-generating questionnaire was introduced or the dates of product recalls
• This may be included as an appendix

Descriptive Epidemiology:

• Case definitions (clearly highlight any changes made to the case definition as the investigation progresses)
• Information on person, place and time as available and as relevant to the investigation, for example:
  • Case counts
  • Demographic information
  • Case status (e.g., hospitalizations, deaths)
  • Timing and distribution of cases (e.g., epidemic curves, maps)
  • Risk factor and exposure information

  Analytical Epidemiology:

  • Methods and results (e.g., comparisons of cases and controls, or those exposed and not exposed)

  Laboratory:

  • Key laboratory findings for cases, as well as any food and environmental samples

  Environmental/Food Safety Investigation:

  • Key elements of the environmental and food safety investigations (e.g., results of food handler/staff investigation, risk assessment analysis, traceback investigations)

  Discussion/ Conclusions:

  • Highlight significant findings, interpret the results, critically examine the methods and state lessons learned
  • Consider integrating results with what is known about the subject and suggesting areas for additional work or research

  Recommendations:

  • Explain what actions and policy changes may help prevent similar outbreaks in the future (e.g., food-handling procedures or training)

  References:

  • Include as required

  Examples

  • Case Study, Module 1 – Epi summaries
  • Case Study, Module 1 – Epi summary example
  • Case Study, Module 2 – Exercise 3: Creating an epi summary
  • Case Study, Module 4 – Final epi summary
  • Example: 2008 Listeriosis Outbreak in Ontario Epidemiological Summary

  Tools

  • This document provides a suggested template for the content and layout of an epidemiological summary.
  • This Microsoft Word document provides a suggested template for the content and layout of an outbreak investigation report or final epidemiological summary.
  • This Microsoft Excel-based tool is designed to be used as a template for foodborne outbreak investigation line lists. Once data has been entered, common descriptive statistics are automatically calculated. A data dictionary describing each data field in the line list is available in the final tab.