Disease diffusion mapping

rdf:langString Disease diffusion mapping

rdf:langString Disease diffusion occurs when a disease is transmitted to a new location. It implies that a disease spreads, or pours out, from a central source. The idea of showing the spread of disease using a diffusion pattern is relatively modern, compared to earlier methods of mapping disease, which are still used today. According to Rytokonen, the goals of disease mapping are: 1) to describe the spatial variation in disease incidence to formulate an etiological hypothesis; 2) to identify areas of high risk in order to increase prevention; and 3) to provide a map of disease risk for a region for better risk preparedness. Torsten Hägerstrand’s early work on “waves of innovation” is the basis that many medical cartographers and geographers use for mapping spatial diffusion (1968). The diffusion of disease can be described in four patterns: expansion diffusion, contagious diffusion, hierarchal diffusion and relocation diffusion. Cromley and McLafferty also mention network diffusion and mixed diffusion. The diffusion of infectious disease tends to occur in a ‘wave’ fashion, spreading from a central source. Pyle mentions barriers that pose a resistance towards a wave of diffusion, which include but are not limited to: physiographic features (i.e. mountains, water bodies), political boundaries, , and with diseases, a barrier could be differing control programs. The diffusion of disease can be identified as a normal distribution over time and translated into an S-shaped curve to show the phases of disease diffusion. The phases are: Infusion (25th percentile), Inflection (50th percentile), Saturation (75th percentile), and Waning to the upper limits.