Emily Oster tackles this question:
I generate new data on HIV incidence and prevalence in Africa based on inference from mortality rates. I use these data to relate economic activity (specifically, exports) to new HIV infections in Africa and argue there is a significant and large positive relationship between the two: a doubling of exports leads to as much as a quadrupling in new HIV infections. This relationship is consistent with a model of the epidemic in which truckers and other migrants have higher rates of risky behavior, and their numbers increase in periods with greater exports. I present evidence suggesting that the relationship between exports and HIV is causal and works, at least in part, through increased transit. The result has important policy implications, suggesting (for example) that there is significant value in prevention focused on these transit-oriented groups. I apply this result to study the case of Uganda, and argue that a decline in exports in the early 1990s in that country appears to explain between 30% and 60% of the decline in HIV infections. This suggests that the success of the Ugandan education campaign against HIV…has been overstated.
Since I used to believe Samuel Brittan when he argued that trade spreads sex, this result accords with my intuitions.
I thank Scott for the pointer. There should be an algorithm informing me every time there is a new Emily Oster paper. If Scott is indeed such an algorithm, I am pleased. And of course I am that algorithm for you.