A general model of late-stage epidemic risk.

<p>The strongest population-level associations between HIV and social environment, in our studies and other studies, can be reduced to three distinct but interrelated social determinants: social inequality, income income inequality and poverty. These generate a loss of social cohesion as sexual relationships destabilize due to rising material expectations, an inability to meet material needs, gender imbalances and increased expectations for long-term commitment. All of these increase the frequency of concurrent partners. Social inequality restricts sexual networks, increasing the effect of HIV-positive individuals in those networks. Both poverty and inequality decrease access to health care, compromising prevention. Diminished expectations for the future, a common effect of poverty, makes individuals more resistant to the message of behavior change. Finally, the route of transmission matters, with shared needles, anal sex and receptive partners carrying more physiological risk. Differences in genetic susceptibility, little studied, also likely contribute to risk. Individuals experience more risk as the number of biological and sociological determinants they experience increases. Arrows here may be more interconnected than this diagram assumes; however it provides a testable model.