DESCRIPTION (provided by applicant): The long-term objective of this research is to use dynamic network-based mathematical models of human migration and HIV transmission dynamics for designing and evaluating HIV prevention interventions, such as the message of concurrency. There are three specific aims of this research project. The first aim is to review existing data on migration and HIV in Ghana. This literature review and empirical research will 1) highlight migration patterns and HIV disparities in Ghana 2) emphasize gaps in our knowledge of the complex association between migration and HIV transmission, and 3) reveal the limitations of standard cross- sectional data collection. Thus the second aim of this research is to design and implement a small-scale pilot survey of sexual networks, migration history, and HIV sexual risk behaviors. The PI will also determine the feasibility of collecting HIV biomarkers for HIV for future cross-discipline work. The third aim is to develop a mathematical model based on the network sample in order to quantify the impact of migration on the spread of HIV. This pilot modeling work will be the basis of an R01 application toward the end of the K99/R00 grant cycle. The support of a K99/R00 will enable the PI to engage in substantial public health training (MPH in epidemiology) as well as formal training in infectious disease modeling and social network theory and analysis. The PI has plans for an academic career in global health; therefore, this additional training and experience conducting research in an international setting will help ensure success in this endeavor. Past work has suggested that migrants exhibit riskier sexual behavior than non-migrants and have a higher risk of acquiring HIV; nonetheless, the mechanism in which migration may enhance HIV spread is unclear. This work hypothesizes that migration may significantly enhance HIV transmission because 1) migration changes the timing and sequence of partnership formation and duration which promotes concurrency, and 2) concurrency links individuals together to create large connected "components" in a network that allow a pathogen to travel rapidly and efficiently. Restricting people from moving is not a viable HIV prevention intervention, but messages of behavioral change (i.e. one partner at a time) and earlier antiretroviral therapy (ART) to reduce infectiousness for migrants are practical policies to prevent additional HIV infections.