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Three Things You Don't Know About Aids In Africa


So what do we learn from this? First, the fact that Africa is so heavily affected by HIV has very little to do with differences in sexual behavior and very much to do with differences in circumstances. Second, and perhaps more important, there is potential for significant reductions in HIV transmission in Africa through the treatment of other sexually transmitted diseases.

Such an approach would cost around $3.50 per year per life saved. Treating AIDS itself costs around $300 per year. There are reasons to provide AIDS treatment in Africa, but cost-effectiveness is not one of them.

It won't disappear until poverty does.

In the United States, the discovery of the HIV epidemic led to dramatic changes in sexual behavior. In Africa, it didn't. Yet in both places, encouraging safe sexual behavior has long been standard practice. Why haven't the lessons caught on in Africa?

The key is to think about why we expect people to change their behavior in response to HIV-namely because, in a world with HIV, sex carries a larger risk of death than it does in a world without HIV. But how much people care about dying from AIDS ten years from now depends on how many years they expect to live today and how enjoyable they expect those future years to be.

My studies show that while there have been very limited changes in sexual behavior in Africa on average, Africans who are richer or who live in areas with higher life expectancies have changed their behavior more. And men in Africa have responded in al¬most exactly the same way to their relative "life forecasts" as gay men in the United States did in the 1980s. To put it bluntly, if in¬come and life expectancy in Africa were the same as they are in the United States, we would see the same change in sexual behavior-and the AIDS epidemic would begin to slow.

There is less of it than we thought, but it's spreading as fast as ever.

According to the UN, the HIV rates in Botswana and Zimbabwe are around 30 percent, and it's more than 10 percent in many other countries. These estimates are relied on by policymakers, re¬searchers, and the popular press. Yet many people who study the AIDS epidemic believe that the numbers are inflated.

The reason is quite simple: bias in who is tested. The UN's estimates are not based on diagnoses of whole populations or even a random sample. They are based on tests of pregnant women at prenatal clinics. And in Africa, sexually active women of child¬bearing age have the highest rates of HIV infection.

To eliminate the bias, I took a new approach to estimating the HIV infection rate: I inferred it from mortality data. The idea is simple: In a world without HIV, we have some expectation of what the death rate will be. In a world with HIV, we observe the actual death rate to be higher. The difference between the two gives an estimate of the number of people who have died from AIDS, and we can use that figure to estimate the prevalence of HIV in the population.

My work suggests that the HIV rates reported by the UN are about three times too high. Which sounds like good news-but isn't. The overall number of HIV-positive people may be lower than we thought, but my study, which estimated changes in the infection rate over time, also drew a second, chilling conclusion: In Africa, HIV is spreading as quickly as ever.


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