According to Nbdpn. org (2010), Geographic Information Systems (GIS) may be defined as the powerful tools which combine data, geography and computer mapping. There are various software packages that integrate several GIS functions such as MapInfo and ArcMap. GIS applications rely on either the raster or vector map format or in other cases a combination of these two. When using vector maps the geographic features will be represented in terms of points like location of infants who have birth defects, or in terms of polygons and lines. Vector maps are the commonly applied in public health.
GIS technology for example has been used as an excellent tool with inherent potential for health management and research in Africa (Tanser and Sueur, 2002). Spatial modeling capacity provided by GIS is applicable in understanding spatial variation of a disease and the relationship it has with the health care system and the environmental factors. Public health practitioners require timely information on a given disease course and other health events in implementing the right actions and GIS is a vital technology in generation of such kind of information.
GIS is a tool that has evolved from a map making tradition. However, detailed history is not clearly understood since GIS technology developed via multiple parallel and separate applications in different disciplines. Early packages of GIS were produced only for specific applications. They also needed mainframe computing systems that are mainly found in university and government settings. Off-the-self packages were offered by private vendors as early as 1970s. Different application, management and analysis methods used in a GIS have lengthy theoretical foundations in various fields.
Such fields include mathematics, political science, biology, systems theory and landscape architecture. These fields provide conceptual models for GIS potential in about five areas, significance/meaning, synthesis/integration, analysis/operation and features. The GIS theoretical foundations is thus shown in five general areas which include; models for description of relationships and features, models for tasks and functions, models for description of space, models for creating meaningful results and models for integration and whole systems (Convis, 1996).
The late 80s and early 90s saw strategies of GIS implementation focus more on acquisition of software and hardware, aspects of system management, data collection and organization staffing. Even if the considerations of implementation strategies are still important today, technology has evolved such that GIS software companies offer a product range that accommodates various organizational models and approaches. As a single person in an organization uses GIS (small-scale GIS) at one side of the continuum, on the extreme the whole organization still utilizes it.
Some organizations use three-tier client server architecture in provision of services and other geographic information to their clients. In this case, Tier 1 is for data server/warehouse, Tier 2 is the application server accessing data from Tier 1. Tier 2 uses this data in application like Internet map server in providing information to the client. We can cite an example of application from GIS program of Research Triangle Institute. This organization uses this application in provision of project management support in epidemiological projects.