Three Things You Don't Know About Aids In Africa
By Emily Oster
At just twenty-six, economist Emily Oster may have the highest
controversies-generated-to-years-in-academia ratio of anyone in her field.
That's because, as a Ph.D. student at Harvard, she chose to hop the fence and
explore a topic already claimed by doctors, social scientists, and policy
wonks: the AIDS epidemic in Africa. Her studies suggest some uncomfortable
possibilities-not least that the so-called experts have gotten their approach
to the crisis dead wrong.
Now a Becker Fellow at the University of Chicago, Oster continues to blur
academic boundaries with further work on AIDS and a volatile new interest: the
reported wave of female infanticide in Asia.
When I began studying the HIV epidemic in Africa a few years ago, there were
few other economists working on the topic and almost none on the specific
issues that interested me. It's not that the questions I want¬ed to answer
weren't being asked. They were. But they were being asked by anthropologists,
sociologists, and public-health officials.
That's an important distinction. These disciplines believe that cultural
differences-differences in how en¬tire groups of people think and act-account
for broad¬er social and regional trends. AIDS became a disaster in Africa, the
thinking goes, because Africans didn't know how to deal with it.
Economists like me don't trust that argument. We assume everyone is
fundamentally alike; we believe circumstances, not culture, drive people's
decisions, including decisions about sex and disease.
I've studied the epidemic from that perspective. I'm one of the few people
who have done so. And I've learned that a lot of what we've been told about it
is wrong. Be¬low are three things the world needs to know about AIDS in
1. It's the wrong disease to attack. Approximately 6 percent of adults in
sub-Saharan Africa are infected with HIV; in the United States, the number is
around 0.8 percent. Very often, this disparity is attributed to differences in
sexual behavior-in the number of sexual partners, the types of sexual
activities, and so on. But these differences cannot, in fact, be seen in the
data on sexual behavior. So what actually accounts for the gulf in infection
According to my research, the major difference lies in transmission rates of
the virus. For a given unprotected sexual relationship with an HIV-infected
person, Africans are between four and five times more likely than Americans to
become infected with HIV themselves. This stark fact accounts for virtually all
of the difference in population-wide HIV rates in the two regions.
There is more than one reason why HIV spreads more easily in Africa than
America, but the most important one seems to be related to the prevalence of
other sexually transmitted infections. Estimates suggest that around 11 percent
of individuals in Africa have untreated bacterial sexually transmit¬ted
infections at any given time and close to half have the herpes virus. Because
many of these infections cause open sores on the genitals, transmission of the
HIV virus is much more efficient.