The statistical information which we have about the prevalence and spread of AIDS in Africa is fairly rudimentary. As a result many of the commonly held beliefs about AIDS in Africa and the economic and cultural circumstances in which it spreads may be incorrect, according to University of Chicago economist Emily Oster, speaking at the TED conference in March 2007.
The available figures seem to show that the AIDS epidemic has had very little effect on the incidence of extra-marital sex in Africa, whereas it had a significant effect on the incidence of unprotected gay sex in the west. This appears puzzling, in view of the high risk of contracting AIDS. However, Ms Oster suggests that in areas where there is already a reduced life expectancy because of malaria, there is no great incentive for people to avoid AIDS, whereas in areas which have a reasonable life expectancy, there is a substantial reduction in unprotected extra-marital sex.
Current statistics on AIDS prevalence depend on unreliable estimates. If mortality data – which is available – is used, the implied HIV infection rates are significantly lower than currently accepted rates. There seems to be a correlation between export activity and infection rates, with people such as truck drivers and migrants more likely to be infected, and the successful anti-AIDS program in Uganda occurred at the same time as a significant decline in export activity.