Epidemiological spaces: the use of multidimensional scaling to identify cholera diffusion processes in wake of the Philippines insurrection, 1899–1902

Between 1902 and 1904 an epidemic of cholera, fuelled initially by the operations of the Philippine-American War (1899–1902), swept through the Philippine Islands in two waves. In earlier papers, the authors showed that spatially contagious spread dominated the waves at the geographical levels of province, island and nation (Smallman-Raynor and Cliff 1998a, b). To explore the visualization and analysis of epidemic transmission in an alternative metric, the present paper uses multidimensional scaling (MDS) to translate the spread corridors followed by the waves from conventional geographical space into non-Euclidean cholera spaces. The re-mapping confirms the importance of contagious diffusion in the spread of the epidemic, but also picks out the moments in time in which spread driven through the population hierarchy switched in. In addition, the analysis illustrates the utility of constructing non-Euclidean spaces to identify disease diffusion processes.