Line Lists


Definition: A line list is a table that summarizes information about persons who may be associated with an outbreak. Each row represents a single individual, and each column represents a specific characteristic about that person. Column information includes identifying, demographic, clinical, and other epidemiologic information, including risk factors possibly related to the illness.

A line list helps organize preliminary information gathered during the early part of an outbreak investigation. As the investigation progresses, the line list can be updated. Line listings can be created by hand (paper copy) or on a computer. One advantage of creating an electronic line list is that frequency distributions and epidemic curves can be generated rapidly.

The information that goes into a line list is generally collected on a questionnaire. The important elements from the questionnaire are then used to create a line list.

The data obtained during a case finding can provide clues about the outbreak and potential risk factors associated with illness. The Enteric Disease Supplemental Questionnaire includes information from the ill persons, including identifying information, demographic information, clinical information, and risk factor information. The CDC epidemiologist uses this information to create both the case definition and the line list.

Kansas Foodborne Illness Form

Criteria: To set up a line list, the epidemiologist creates a table in which each row represents a case and each column represents a characteristic of the outbreak.

Line List Example

ID Name Age Sex Ill OnsetD OnsetT D N V C Game
1 M.M. 11 F Y 1-Aug 1:00a Y Y Y N Y
2 C.H. 12 F Y 1-Aug 2:20a Y Y N Y Y
3 D.L. 15 M Y 1-Aug 2:00a Y N N Y Y
4 K.W. 17 M N N N N Y Y
5 S.T. 11 F N N N N Y Y
6 Q.Z. 10 M Y 1-Aug 1:30a N Y N Y Y



The line list shows that several ill individuals experienced similar symptoms around the same time after midnight on August 1st. Based on this limited information, it is highly possible that these indivduals became ill after eating something served to the teams after the game.

Example adapted from the Foodborne Illness and Outbreak Investigation Manual (March 2008)