[Social networks, risk dyads, and their role in the epidemiology and prevention of drug related infectious diseases].

In the case of risk behaviors where infection transmission occurs through social relationships (e.g. via sharing drugs and injecting equipment, or through sexual relations), prevention should follow (among others) the path of the social network. Previous studies have shown that sharing of injecting equipment is more likely to occur in larger and denser networks and that more popular individuals are more likely to engage in risk behaviors, become infected or transmit infection. Primary targets of social network interventions are central individuals, and information diffuses from them to the more peripheral members of the network. The most effective preventions are those where social network interventions targeting high-risk, central individuals are complemented by concurrent individual counseling and/or dyad interventions. Injecting drug users in Hungary would also benefit from such a multifaceted prevention approach aiming to reduce risky injecting behavior. This population needs prevention, in whatever form available, to prevent the deterioration of the current HCV and HIV epidemiological situation in Hungary and the development of an HIV epidemic that will eventually spread over to the general population.