Legionnaires' disease outbreak investigation toolbox

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1.1 Data Visualisation

Data requirements: Case data, Potential outbreak source locations

Description: The most basic use of a Geographic Information System (GIS) is to visualise data spatially. Having collated as comprehensive a record as possible of the locations cases have visited, the routes they have travelled and the dates they have occupied those spaces, it is possible to visualise the data in a number of ways. A GIS enables us to visualise such a dataset at either the individual case level or as a composite of all patients (or perhaps a subset). Attribution attached to the 'point' and 'line' geometries, such as a date, also enables us to view the data in time-series, perhaps visualising daily movements of cases to identify common spaces they have either visited or moved through. Essentially by collecting data of this nature, which can be easily entered into a GIS, those investigating an outbreak are presented with a very simple, very flexible and potentially very informative spatial picture of how all cases have interacted with their environment.

GIS tools required: All GIS systems will be capable of displaying spatial data. The ability to present data in a time-series animation may also be useful.

Considerations for a cross-border outbreak: In a cross border outbreak it is unlikely that individual-based case data will be shared between nations. As such it would not be possible to present a complete picture of the locations visited and routes taken by each case as described above. Individual-based case data would be replaced by data aggregated to small-area geographic units as described in section 2.1 Case data, making thematic mapping possible for information such as: the number of home locations per area; the number of locations visited in the area; the number of travel routes that have passed through the area; and the number of unique cases that have been through an area.