Canada's unique geography and population distribution has prompted innovation in such areas as natural resource management and regional planning. One such innovation was the Geographic Information System (GIS), a concept that originated in Canada three decades ago. This concept is now being applied by the health sector as the demand increases for information and analysis on the relationship between people, their environment, and their health. GIS can provide health researchers, planners, program managers, and policymakers with novel information about the distribution and interaction of disease risk factors, patterns of morbidity and mortality, and the allocation of health resources. Now that many commercially available GIS software packages are becoming increasingly user friendly, and can be run on PC computers, this important tool is being actively explored for use in health improvements in developing countries.
So what is a GIS? Essentially, it is a computer-assisted information management system of geographically referenced data. It contains two closely integrated databases: one spatial (locational) and the other attribute (statistical). The spatial database contains information in the form of digital coordinates, usually from maps or from remote sensing. These can be points (for example, health clinics or houses), lines (rivers and roads), or polygons (district health units). The attribute database contains information about the characteristics or qualities of the spatial features, for example, demographic information, immunization rates, number of health personnel at a clinic, or the type of road access.
A GIS differs from conventional computer-assisted mapping and statistical analysis systems. Although computer-assisted cartographic systems emphasize map production and presentation of spatial data, they cannot analyze spatially-defined statistical data. Statistical analysis systems, on the other hand, analyze aspatial data. A GIS blends these into a more powerful analytical tool. The system can be applied to a variety of problems. For example, a GIS can be used to investigate questions about location (what are the attributes at a specific place?), condition (where are the sites that possess certain attributes?), trends (how do attributes change spatially over time?), routing (what is the shortest/least expensive/most cost-effective path between places?), and patterns (what is the distribution of attributes and the process/reason accounting for their distribution?). A GIS can also be used to simulate "what if" scenarios (modelling).
For example, let's say someone wanted to identify districts that have a health centre and where the immunization coverage rate for the third dose of DPT (diphtheria, pertussis and tetanus) vaccine for children 0-1 years of age is less than 50%. We also want to compare this information to data about family size, the availability of health personnel, traditional water supply sources (lakes, rivers, ponds), and improved water supply facilities.
A GIS is required because the health service facility, immunization, demographic, health personnel, hydrological system, and improved water supply facility databases have different geographically defined information. The GIS can also define very specific correlations. For example, by combining areas where the immunization coverage rate is low, the number of young children per family is high and the access to improved water supply sources is difficult, the analyst or researcher can define areas and populations at greater or lesser risk.
Traditional database analysis systems are only adequate for analysis of attributes belonging to the same entities. But the analytical tools available within a GIS make it possible to "overlay" the databases for different entities. This is similar to overlaying transparent maps for each database on top of each other. The maps produced by the GIS show the correlation among the different databases. An additional comparative advantage of a GIS is its ability to use data from, and interface with, other sophisticated statistical databases.
GIS is a fairly new analytical and planning tool for both the North and the South. Its proponents highlight its capacity to produce a comprehensive and timely analysis of complex databases and its potential to improve data collection, analysis and presentation processes. The visual impact of GIS-produced maps on decision-making and management is a tangible benefit that is often underestimated.
Although the sectors concerned with agriculture, natural resources, urban and regional planning, and tourism in developing countries have been using GIS for many years, the health sector has only recently begun to work with this tool. The papers collected in these proceedings represent examples of some of the first attempts to identify and explore opportunities to apply GIS for health in developing countries.
Don de Savigny is with the Health Sciences Division, IDRC, Ottawa, Canada; Luc Loslier is with the Department of Geography, Université du Québec à Montréal, Canada; and Jim Chauvin is with the International Health Program, Canadian Public Health Association, Ottawa, Canada.
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This file was created 23 February 1996