Sevgi O. Aral, PhD, Division of STD Prevention, Centers for Disease Control and Prevention, 1600 Clifton Road, Mailstop E02, Atlanta, GA 30333, (404) 639-8259, soa1@cdc.gov

During the past ten to fifteen years we have witnessed remarkable advances in a number of scientific domains each of which has important implications for our understanding of the epidemiology and prevention of STIs. These include: the role of the temporal dimension in STI epidemiology; the advances in the “science-of-networks”; the convergence between the population transmission dynamics framework and the network framework whose main focus is population structure. Ongoing empirical work in STI/HIV epidemiology and prevention has also led to new appreciation of the importance of the ubiquity of heterogeneity in populations. It is now clear that populations are composed of many, diverse subpopulations and each population-level epidemic trajectory consists of many distinct subpopulation epidemic trajectories. The epidemic trajectory of an STI tends to differ depending on when and where the infection was introduced; the natural history and transmissibility of the infection; the structure of sexual networks; the demographic, economic, social and epidemiologic context; and the state of the health system. The trajectory by which an STI epidemic evolves through epidemic phases differs for different types of population—pathogen interactions. Comparisons of STI morbidity across populations and evaluation of similar preventive interventions in different settings have highlighted the importance of contextual factors in STI epidemiology and prevention. Factors that shape the spread of STI in populations exist at several levels, ranging from the micro to the macro levels. Just as individuals are embedded in sex partnerships, partnerships are embedded in sexual networks.

Learning Objectives: