Spatial Structures and Scientific Paradoxes in the Aids Pandemic

A geographical analysis of the AIDS epidemic in the United States requires a reification of the individual by adopting a 'social physics' perspective. Carefully employed, spatial aggregation of individual cases circumvents the problem of patient confidentiality, and produces spatial series containing valuable scientific information generally ignored by traditional epidemiologists. The diffusion of AIDS from 1982 to 1990 at the national level provides the setting for a detailed analysis of a major epicenter, the New York Metropolitan Region. Here the space is strongly structured by daily commuter flows, which both focus the epidemic on Manhattan, and provide the detailed mechanisms for the spatially contagious diffusion generalized at the national scale. AIDS rates are highly predictable over time and space from measures of commuting intensity derived from a Markov analysis. This leads to a consideration of a canonical form related to classical diffusion theory, except that spatial homogeneity is now replaced by the complex structures of commuting in the region. Three phases in the epidemic, homosexual, drug injection, and heterosexual are all associated with social and spatial marginalization reflected in the movement of HIV acting as a tracer for social pathologies. Controlling the HIV requires the serious address of such pathologies.