Legionnaires' disease outbreak investigation toolbox

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2.4 Meteorological Data

Meteorological data can help to provide additional insight into the dynamics of a Legionnaires' disease outbreak but is not essential to the use of GIS for outbreak analysis. Climatic data can be important in understanding the dispersal of aerosols, contaminated with Legionella bacteria, from potential outbreak source locations such cooling towers. Meteorological values such as temperature, humidity, atmospheric stability, wind speed and wind direction can all be incorporated into analyses looking to model the 'plume(s)' of a potential source. If the wind conditions are fairly stable over the course of an outbreak, plume modelling can indicate the likely downwind dispersal area of the Legionella bacteria. Conversely if wind conditions are variable over the course of an outbreak the area in which people would be likely to be infected can move over time. Given that releases of bacteria potentially occur over a number of weeks the 'contaminated' zone may be large and knowledge of infectious dose is uncertain so bounding the plume is challenging.

Considerations for cross-border outbreak: The sharing of meteorological data across borders should be possible, however it is not realistic in a European context to assume that those responding to a Legionnaires' disease outbreak would always have access to sufficient meteorological data or perhaps the software/expertise to incorporate plume modelling into a GIS based analysis (see section 1.5).