Residential segregation and the epidemiology of infectious diseases.

Several empirical studies have documented the effects of residential segregation on health inequalities between the US African-American and white populations. However, the majority of such studies have not explained the pathways that link residential segregation and specific health outcomes. This paper presents a conceptual framework of the role that residential segregation may play in the epidemiology of tuberculosis (TB) and other infectious diseases. This is an important issue given the concentration of TB cases among US racial/ethnic minorities and the increasing gap in the incidence of infectious diseases between minorities and the white majority. Segregation may have an indirect effect on the transmission of TB because of its negative impact on the quality of neighborhood environment in segregated communities. Segregation concentrates poverty, overcrowded and dilapidated housing and social disintegration in minority areas, and results in limited access to health care. Furthermore, two dimensions of residential segregation (isolation and concentration) may have direct effects on TB transmission. The isolation of minorities confines TB to segregated areas and prevents transmission to the rest of the population. High-density levels in minority areas increase the probability of transmission within the segregated group. In order to operationalize the above pathways, health researchers may rely on the segregation literature, which has conceptualized various dimensions of residential segregation and proposed ways to measure them. The indirect pathways that link segregation and TB can be captured through exposure indices, which quantify the concentration of risk factors for TB for various racial and ethnic groups. The direct pathways can be captured through the isolation index (which is a proxy for the degree of interaction between the segregated group and the rest of the population) and two proposed measures of density (which are proxies for the likelihood of transmission within the segregated group and from the segregated group to the rest of the population).