Personal risk taking and the spread of disease: beyond core groups.

Disease control efforts directed at human immunodeficiency virus are predicated on the need to reduce personal risk behaviors; that approach may not adequately reflect the complicated interplay between personal behaviors and the social setting in which they occur. Efforts to date, including the application of population ecology, the development of the core group hypothesis, and the use of compartment models to describe disease transmission, have aided in understanding the dynamics of transmission and have highlighted the relationship between personal risk taking and population risk. An area for further development is the application of the techniques of social network analysis to infectious disease spread. Initial work suggests that social structure may act as a barrier (or facilitator) in disease transmission and that the epidemiologic impact of a risky act varies with the social setting. The local context for risk behaviors has important implications for the dynamics of transmission.