Geographic Information Systems (GIS)

Geographic Information Systems (GIS) is a powerful tool for planning and assessment of health interventions and is more and more recognized to be an essential tool in disease control. As new perspectives and ways of addressing disease control are needed, GIS can be usefully applied to improve disease control.

A Geographic Information system (GIS) is an organized collection of computer hardware, software, geographical data, and personnel. It is designed to effectively capture (input), store and update (data management), manipulate and analyze (transform), and display all forms of geographically reference data (output).

In the field of public health/epidemiology there are several usages of GIS:

1. The most basic usage of GIS is mapping of diseases and thus visualizing the data. This will give an impression of the spread of the disease and indicate areas with high or low prevalence. It is usually a starting point from where hypothesis are generated. Furthermore, maps are an attractive tool for advocacy.
2. Another usage of GIS is the performance of spatial statistical analyses to identify environmental factors that affect disease risk, to uncover mechanisms of disease transmission and to identify high risk groups or locations of high prevalence (clusters).
3. GIS can also be used for modeling disease spread. Prediction models enable users to identify ecological and environmental factors that represent a threat to public health, furthermore it can produce an algorithm to predict outbreaks.
4. Monitoring health interventions and plan and assess control activities is another usage of GIS. GIS is used, for example, to map the spatial distribution of patients, monitor and evaluate program and surveillance activities and to determine accessibility to health care.

Different data sources are used in preparing a GIS. Global Positioning System (GPS) is used to collect latitude and longitude of features such as houses, health centres and hospitals. Environmental data come from remote sensing and satellite images.