Abhatoo - Centre Nationale de Documentation

We develop a theory of how community-level ethnic heterogeneity determines the formation of sexual networks, and how this in turn affects the diffusion of HIV/AIDS. Specifically, the model assumes that agents derive utility from sexual relationships, but sexual infidelity is socially prohibited and penalized if detected. It implies a mechanism wherein ethnic heterogeneity provides incentives for optimizing agents to multiply sexual partners across ethnic groups while lowering the probability of infidelity detection, and thus positively affects the spread of HIV/AIDS. We use individual level data from six representative countries of sub-Saharan Africa to test the model. In doing so, we find a direct effect of ethnic heterogeneity on both the number of sexual partners and HIV infection. Robustness checks show that this effect is not driven by a lack of public goods in ethnically diverse communities. Interestingly, ethnic heterogeneity is shown to have no effect on anemia which is largely untreated like HIV/AIDS, but which unlike HIV/AIDS, does not involve socially prohibited human interactions. This finding supports our theory that diseases which involve socially prohibited human interactions spread through hidden and anonymous networks. Our study offers a new and fresh explanation for the high concentration of the AIDS epidemic in sub-Saharan Africa.