How to fight AIDS in Africa

A new paper, "Sexually Transmitted Infections, Sexual Behavior and the HIV/AIDS Epidemic" by Harvard economics graduate student Emily Oster, asks why prevalence rates for HIV/AIDS are ten to fifteen times higher in Africa than in the United States. Using a simple model that decomposes infection levels into differences in sexual behavior and differences in transmission rates, she attributes the entire difference in HIV prevalence between the United States and Sub-Saharan Africa to differences in transmission rates. The intuition, as she writes, is that "Higher transmission rates produce more infections this period, and each new infected person can infect people next period, so the result of a higher transmission rate is multiplied many times over."

One of the implications of her findings is that lowering transmission rates by targeting STDs is more cost effective than trying to reduce HIV prevalence using expensive antiretrovirals or education programs aimed at changing behavior.

Read more here.