Project Summary/Abstract Release from prison is a time of serious dislocation and significant challenges to the well being of the HIV-infected former inmate as well as to their social networks and the communities to which they return. Not only must the pressing exigent questions of food, clothing and shelter be addressed, s/he must also re- integrate into family and social networks. These challenges are particularly acute for the HIV-infected former inmate who, in addition to meeting the needs described above, must also establish a relationship with a regular source of medical care and find a way to pay for expensive medications. Despite the public health implications of the drug and sexual risk taking of these individuals, there have been few comprehensive assessments of the risk behaviors of HIV-infected releasees. Our preliminary data indicate that HIV-infected former inmates frequently have multiple sexual partners and low rates of condom usage. A large number of studies have established a central role for social networks in defining HIV risk behaviors. Social network-based studies of HIV-infected individuals have relied largely on respondent- driven sampling/recruiting (RDS). RDS strategies have been helpful in mapping connections; however, strategies that rely on self-report to characterize behavior that is stigmatized and illegal face significant limitations. These approaches are particularly problematic in characterizing networks in which partnerships may be anonymous. Given the critical role that interactions between network members play in influencing the spread of the HIV epidemic and the concerns regarding the validity of self-reported behavior, novel and robust approaches are required to provide a more complete understanding of these social structures. In this R21 application, we propose to conduct a preliminary assessment of the utility of a biomarker for social network involvement by HIV-infected former inmates; specifically, we will characterize the molecular epidemiology of nasal colonization with Staphylococcus aureus (SA). Our goal is to determine whether nasal carriage with SA can be used both to verify an epidemiologic connection as well as to identify connections among people that were previously unknown. In this series of pilot studies, we will: 1) Characterize SA nasal colonization among 250 HIV-infected inmates incarcerated in the North Carolina Department of Corrections (NCDOC). 2) Characterize the relationship between SA genotypes and social network characteristics among HIV- infected former inmates who are colonized with SA. Project Narrative Despite the public health implications of the drug and sexual risk taking of prison releasees, there have been few comprehensive assessments of the risk behaviors of HIV-infected releasees. Strategies that rely on self-report to characterize behavior that is stigmatized and illegal face significant limitations; therefore, we propose to conduct a preliminary assessment of the utility of a biomarker for social network involvement by HIV-infected former inmates. [unreadable] [unreadable] [unreadable]