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How to Investigate Unexplained Respiratory Disease Outbreaks (URDO)

Epidemiological Curve

Generate an EpiCurve Learn more about Adobe Acrobat Reader (32K, 2 pages)
Persons with disabilities having problems accessing the above file may call 1-800-CDC-INFO (1-800-232-4636) for assistance.

This tool is designed to be used as a template to generate an epidemiologic curve or “epi curve." This sheds light on whether the outbreak is most likely due to a point source or person-to-person transmission, whether an outbreak is increasing or waning, and whether the pathogen has a long or short incubation period.  The resulting histogram will illustrate the number of cases of respiratory disease over time.

See Interpreting an Epidemic Curve and for more information on how to interpret an epi curve.

The tool consists of an Excel file with two worksheets. Entering information into the first worksheet (Case Data) will automatically construct an epi curve in the second worksheet (Epi Curve).

Step 1: Click on the Case Data tab at the bottom of the workbook.  Replace the generic dates ("Date 1", etc) with the range of illness onset dates for the cases. In Columns C-E, enter the number of cases in the row and column that corresponds with the appropriate illness consecutive onset date and case classification category [confirmed (Column C), probable (Column D), and suspect cases (Column E)].

Step 2: Click on the Epi Curve tab at the bottom of the workbook to see the graph automatically populated.  Changes can be made to the graph by right clicking on the graph and selecting the appropriate option or by changing the data entered into the first excel worksheet (Case Data).


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