Introduction: Spatial Analysis and Health

Medical Geography or Spatial Epidemiology is concerned with two fundamental questions: (1) where and when do diseases tend to occur? and (2) why do such patterns exist? The field has experienced substantial growth over the last decade with the widespread recognition that the concept of “place” plays a significant role in our understanding of individual health (Kwan 2012) while advances in geographical modeling techniques have made it easier to conduct spatial analysis at different granularities, both spatially and temporally (Cromley and McLafferty 2011). Several journals (for example Health and Place, Spatial and Spatio-Temporal Epidemiology, International Journal of Health Geographics, Geospatial Health and Environmental Health) have a long tradition to publishing research on topics in Spatial Epidemiology. This introductory chapter reviews some contemporary themes and techniques in medical geography. Specifically, we discuss the nature of epidemiological data and review the best approaches to geocode and map information while maintaining a certain level of privacy. Analytical and visualization methods can inform public health decision makers of the reoccurrence of a disease at a certain place and time. Clustering techniques, for instance, can inform on whether diseases tend to concentrate around specific locations. We examine the role of the environment in explaining spatial variations of disease rates. Next, we address the importance of accessibility models, travel estimation and the optimal location of health centers to reduce spatial inequalities when accessing health services. We also review the increasing contributions of volunteered geographic information and social networks, helping to raise public awareness of the risk posed by certain diseases, especially vector-borne diseases following a disaster. The concepts of scale and uncertainty are discussed throughout as they are known to affect the suitability of certain methods and consequently impact the stability of the results. Some of the concepts set forth are illustrated with a data set of a 2010 dengue fever outbreak in Cali, Columbia. We conclude this chapter by discussing the layout and contributions of this volume to Spatial Epidemiology.