Background and objectives: The concept of a core group of individuals who change sexual partners frequently has played an important role in the study of the epidemiology of sexually transmitted diseases (STDs). It is widely believed that the core group is important in the persistence of infection and that it provides a sensible target for control interventions. GOAL OF THIS STUDY AND STUDY DESIGN: Simple mathematical models are used to assess the significance of sexual mixing between core and noncore groups. Published data from contact tracing studies, which base the definition of the core group on gonorrhea incidence by area of residence, are used to derive estimates of the degree of mixing within and between groups.
Results: Analyses reveal patterns of high mixing within core groups in the urban study sites, which suggests that within-group transmission ensures the persistence of gonococcal infection in the community as a whole.
Conclusions: An extension of the analysis of contact tracing data to facilitate the development of mathematical models of STD transmission is detailed.