An Outbreak of Legionnaires' Disease
Subject areas: Biology, mathematics, statistics, environmental health
Grade level: 11th or 12th
Level of difficulty: High
Prerequisite: Familiarity with the basic steps of epidemic investigation (such as that gained from the modules on outbreak investigation in a community hospital or disease outbreak investigation—food-borne illness) and understanding of the case–control method (such as that gained from the module on case–control studies). Familiarity with spreadsheet programs would be useful.
Summary: Students analyze data from an actual outbreak of Legionnaires' disease in order to identify the source.
Students are first provided with background information about Legionnaires' disease, a form of pneumonia caused by bacteria that live in warm water, and then told about the initial recognition of a 1996 outbreak of 34 cases in Michigan. They are asked to suggest additional studies that might help identify the source and then are provided data from the studies that were actually done by the original investigators. Students are asked to analyze those data, including information about recent activity by those who were ill and a comparison group of people who remained well. Students will likely vary in the amount of information that they extract from the data; most should be able to reproduce the central conclusion of the original investigators, but some may discover evidence that suggests a deeper layer of understanding about the cause.
Download An Outbreak of Legionnaires' Disease Case Control file (.xls/329k)
Requires Microsoft Excel (latest version recommended).