Geographical information systems and tropical diseases.

The geographical information system (GIS) revolution started in the mid 1980s and has since snread to all countries of the world. A GIS is a comput&software package that is concerned with the capture, storage, manipulation, query, display and analysis of any and all types of geographical information, (BLJRROUGH, 1986; CHORLEY, 1987; LAURINI & THOMPSON, 1992; ESRI, 1993). There are now many different GIS packages available throughout the world. The unique attraction of GIS is that it adds a geographical dimension to information held in computer systems that previously lacked it or was stored using database software which was inadequate to handle and manipulate the geography associated with the data. Traditional geographical information consists of virtually everything shown on maps of any kind; for example, atlas maps, large scale topographical maps, maps of underground pipes and wires, town plans, and thematic maps such as those showing land-use, geology, soils, climatic variation, and disease. It had been known since the 1970s how to store these cartographic map objects in a digital form; essentially as very large numbers of twodimensional map co-ordinates (longitude and latitude) that represent the elemental points, lines, and polygons that maps are built from and can be decomposed into. The GIS revolution occurred when suddenly, over a short period of time, software availability and dramatic price and performance improvements in computer hardware made it feasible and economic to start converting all these traditional geographical information sources stored in analogue form on paper maps into a digital format suitable for computer processing. In many countries the first task was to regenerate the existing national paper map resources in a digital form so that the cartography could be done automatically. So, at its simplest, a GIS is little more than a spatial database and mapping system that runs on a work station of some kind and which greatly eases the task of drawing maps. This was undoubtedly convenient, it greatly speeded the mapping process and made computer storage and retrieval of paper map records far more efficient. However, there is much more to GIS than its origins in the automation of cartography and in land and facilities management might indicate. Subsequent developments permit geographical references to be added to many other databases, where previously they were present only in an implicit and indirect form; for example, as a postal address. Furthermore, the availability of digital map data in a common format greatly facilitates the task of data integration, cross referencing and, perhaps more relevant in the present context, modelling and analysis of the spatial patterns and processes locked up in the data. Today, geographical information extends far beyond the traditional map-based sources but includes all types and forms of information that can be related to a map. These extend from databases about people to remote sensing systems based on space platforms, and include real-time tracking and other automatic data capture devices in which spatial location is an important feature. Properly developed and applied by competent and modern organizations, GIS provides an integrating computer database technology that allows all types of geographical information to be integrated, interrelated, and handled in a unified way. The task now is to start to exploit the tremendous explosion in the availability of spatial information that has occurred during the last 5 years as a result of GIS and also, more generally, because of the increased use of information technology in all areas of life and in all parts of the world. There has never been so much information available about the world in which we live. The challenge is to convert the dreams of the GIS missionaries and ‘fhe sometimes exaggerated sales talk of the GIS vendors into useful, valuable, and life-critical systems and applications relevant to tropical disease management, prevention, and research. There are many areas of medical interest that could well benefit from the availability of GIS and the increasingly spatial data-rich world in which we live. Some of the current principal impediments are discussed below. (i) Organizational problems, when the impact of GIS is greatly diminished and sometimes totally negated, at least in the short term, due to a failure to realize or accept the corporate nature of both the technology and the associated databases with the consequential need for management restructuring. (ii) Problems of access to the necessary information, either because of the cost of acquiring copyright information or because for various reasons the critical information sources are either not yet available or are not in a suitable form for analysis. (iii) Lack of attention by the GIS vendors to the development of applicable spatial analysis and modelling technologies, as the principal markets have so far been mainly in areas related to the capture, management, and mapping of geographical information and not its analysis. (iv) Absence of a strong analytical tradition in areas where previously analysis was either impossible or impracticable, which continues to hinder future potential applications that are largely analysis-based. (v) Negative or unnecessarily defensive attitudes that allow largely unwarranted fears of a breach of data confidentiality or theoretical concerns about the misuse of personal information to prevent any analysis being performed regardless of the public good-an argument that should ideally override such concerns, particularly in a medical context. (vi) Lack of demonstrated benefit, which makes the first application so difficult to establish and often engenders a high level of exaggeration and unrealistic expectations as innovators struggle to develop applications against well entrenched opposition, ignorance and lack of resources.