• Michelle A Tsang, John A Schneider, Vana Sypsa, Phil Schumm, Georgios K Nikolopoulos, Dimitrios Paraskevis, Samuel R Friedman, Meni Malliori, and Angelos Hatzakis.
• *Departments of Medicine, and †Health Studies, University of Chicago, Chicago, Illinois, USA; ‡Department of Hygiene, Epidemiology and Medical Statistics, Athens University Medical School, Athens, Greece; §Hellenic Center for Disease Control and Prevention, Athens, Greece; ‖National Development and Research Institutes (NDRI), New York, New York, USA; and ¶Organization Against Drugs, Athens, Greece.
• J. Acquir. Immune Defic. Syndr. 2015 Aug 1; 69 (4): 499-508.

BackgroundGreece experienced an unprecedented increase in HIV cases among drug injectors in 2011 after economic crisis. Network-level factors are increasingly understood to drive HIV transmission in emerging epidemics.MethodsWe examined the relationship between networks, risk behaviors, and HIV serostatus among 1404 people who inject drugs in Athens, Greece. We generated networks using the chain-referral structure within a large HIV screening program. Network proportions, the proportion of a respondent's network with a given characteristic, were calculated. Multiple logistic regression models were used to assess the relationship between network proportions and individual HIV seroprevalence, injection frequency and unprotected sex.ResultsOf note, 1030 networks were generated. Respondent HIV seroprevalence was associated with greater proportions of network members who were HIV infected (ie, those with ≥ 50% of network members HIV positive vs. those with no network members HIV positive) (AOR: 3.11; 95% CI: 2.10 to 4.62), divided drugs (AOR: 1.60; 95% CI: 1.10 to 2.35), or injected frequently (AOR: 1.50; 95% CI: 1.02 to 2.21). Homelessness was the only sociodemographic characteristic associated with a risk outcome measure--high-frequency injecting (AOR: 1.41; 95% CI: 1.03 to 1.93). These associations were weaker for more distal second- and third-degree networks and not present when examined within random networks.ConclusionsNetworks are an independently important contributor to the HIV outbreak in Athens, Greece. Network associations were strongest for the immediate network, with residual associations for distal networks. Homelessness was associated with high-frequency injecting. Prevention programs should consider including network-level interventions to prevent future emerging epidemics.

14 keywords...

hide…