The epidemiological legacy of war: The Philippine-American War and the diffusion of cholera in Batangas and La Laguna, South-West Luzon, 1902-1904

This paper presents a geographical examination of the impact of war and its aftermath upon the spread of an infectious disease in a civilian settlement system. The choice of area (the neighbouring provinces of Batangas and La Laguna, Philippine Islands), the time (a two year period in the closing stages and immediate aftermath of the war against US annexation, March 1902 - February 1904) and the epidemic (cholera) are conditioned by the detailed reports prepared by the chief quarantine officer for the Philippine Islands and published weekly in the contemporary US Public Health Reports. The reports include textual accounts of the progress of the epidemic in Batangas and La Laguna, and numerical evidence regarding the weekly incidence of cholera in the settlements of the two provinces. Based on this information, a variety of geographical techniques (lag times, centroids, trend surfaces and autocorrelation on graphs) are introduced to reconstruct the spread of cholera, and to examine the diffusion processes that underpinned the spread patterns. It is demonstrated that the mass population movements associated with war had the effect of speeding up the geographical propagation of cholera as compared with peace, but did not destroy the basic channels of disease spread.