AIDS in Africa

[Fenris]

[Edited just a little, for bolding]

Emily Oster, an economist, has an intriguing article on AIDS, its contagion throughout Africa, and how it should be dealt with:


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 wanted 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 entire groups of people think and act—account for broader 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. Below are three things the world needs to know about AIDS in Africa.

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 rates?

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 transmitted 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.

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 almost 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 income 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, researchers, 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 childbearing 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.


So the good news is there; but it's temporary. It at least leaves us with hope.

Thoughts?

õ
Always hopeful!

[Iangould]

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.

Overall this seems to be really well-done work - and a great example of how economics as its actually practiced is quite different to what most people think.

But the bit I quoted worries me somewhat for a couple of reasons:

1. Other surveys (e.g. of army recruits) tend to produce figures more in line with maternity clinic figures than with Oster's.

2. The idea may be simple but implementing it certainly isn't - see the argument over post-war Iraqi mortality where professional statisticians are deriving estimates for pre-war mortality that differ by a factor of two.

How do we know that AIDS is the only major cause of fatalities excluded from Oster's business-as-usual model? There could be some other epidemic out there. (Of course this specific example of a potential problem would mean Oster was overestimating not underestimating AIDS deaths.)

Similarly, what is Oster's estimate for life expectancy amongst HIV-Positive Africans? Has he adequately accounted for the increased availability of HIV drugs in recent years?

We're used to endless bad news from Africa so we tend to overlook the fact that several of major civil wars in Africa have ended and that African economies have been growing at a record pace for the past several years. Given that and the poor quality of African statistics I think his "business as usual" case may be over-estimating baseline mortality.

These comments are off the top of my head, if I were still working as an economist I'd obviously take a long look at his work and consult epidemiologists and the like before drawing any conclusions.

[Fenris]

Overall this seems to be really well-done work - and a great example of how economics as its actually practiced is quite different to what most people think.

But the bit I quoted worries me somewhat for a couple of reasons:

1. Other surveys (e.g. of army recruits) tend to produce figures more in line with maternity clinic figures than with Oster's.

2. The idea may be simple but implementing it certainly isn't - see the argument over post-war Iraqi mortality where professional statisticians are deriving estimates for pre-war mortality that differ by a factor of two.

Particularly considering that we're dealing with an entire continent- and not a fairly unified one, like North America or Australia, but one with a multitude of different countries and ethnic groups. Thus there may be different measurement issues, different contributing circumstances, and so on from one region to another. All of which just adds to the general complexity and uncertainty.

I agree that the low AIDS rate seemed like the weakest point of the article.

How do we know that AIDS is the only major cause of fatalities excluded from Oster's business-as-usual model? There could be some other epidemic out there. (Of course this specific example of a potential problem would mean Oster was overestimating not underestimating AIDS deaths.)

But if there's one example, there could be others; at any rate, it may be better to just say, "We can't get reliable information on African AIDS rates." Which is frustrating, but at least it's undeniably true.

Similarly, what is Oster's estimate for life expectancy amongst HIV-Positive Africans? Has he adequately accounted for the increased availability of HIV drugs in recent years?

Petty nitpick: I think Oster's female.

We're used to endless bad news from Africa so we tend to overlook the fact that several of major civil wars in Africa have ended and that African economies have been growing at a record pace for the past several years. Given that and the poor quality of African statistics I think his "business as usual" case may be over-estimating baseline mortality.

So... by being unduly pessimistic about Africa's general death rate, she's being unduly optimistic about Africa's AIDS death rate.

*Head spins*

But yes, I see what you mean. I think.

These comments are off the top of my head, if I were still working as an economist I'd obviously take a long look at his work and consult epidemiologists and the like before drawing any conclusions.

Now that it's published, that will presumably happen. It'll be interesting to see what her peers make of it.

õ
I'm up too late for statistics!

[Iangould]

Petty nitpick: I think Oster's female.

Ouch and here I was trying to look all enlightened.

So... by being unduly pessimistic about Africa's general death rate, she's being unduly optimistic about Africa's AIDS death rate.

*Head spins*

But yes, I see what you mean. I think.

Basically, Death rate total = Death rate (non HIV) + Death rate (HIV)

[JeffreyWKramer]

Given the poor quality of reporting and record-keeping of all sorts throughout Africa, I'd not particularly trust Oster's conclusions re: prevalence of HIV infection. I don't think we know the actual number with much certainty at all, but I'd be inclined to trust the numbers from observers on the ground more than I would those someone at a distance that is working with data twice-removed.

Other than that, it's a pretty sound article, and the number issue doesn't really change the picture or the conclusions.

[Stellar]

In other words: stop handing out condoms in Africa instead of improving medical resources.

The fable that there are a large number of HIV infected in Africa because everybody there fucks around has been bannished for quite some time. Sexual activity in America is actually higher, but it's also easier to get treated for minor infections.

[JeffreyWKramer]

In other words: stop handing out condoms in Africa instead of improving medical resources.

Well, it's not really an either/or. But yes, the bigger answer is better health care. And really, the bigger answer yet is economic improvement. Much of Africa's health crisis - including the higher susceptibility to STDs and all sorts of other infections - is related to chronic malnutrition and lack of clean water and basic hygiene.

[Stellar]

Discovery Channel had a report on this once. Numerous American institutions visited African High School's promoting abstinance, but experts cleary said it's health care that needs to be approached. Although that's easier said than done.

[JeffreyWKramer]

Discovery Channel had a report on this once. Numerous American institutions visited African High School's promoting abstinance, but experts cleary said it's health care that needs to be approached. Although that's easier said than done.

Yeah, that's the truth. It's easier - and a lot cheaper - to go in and do some moralistic preaching and/or hand out some condoms than it is to actually address the core problems. Addressing core problems costs money, takes time and long-term commitment and forces one to deal with the corruption that is endemic to most African governments, at every level.

As an example of people trying to do the job right, look up the efforts to fight HIV and malaria in Africa that are funded by the Bill and Melinda Gates Foundation. The Gates projects provide a better, more qualtified bang-for-the-buck than any other effort out there.

[Stellar]

Yeah, that's the truth. It's easier - and a lot cheaper - to go in and do some moralistic preaching and/or hand out some condoms than it is to actually address the core problems. Addressing core problems costs money, takes time and long-term commitment and forces one to deal with the corruption that is endemic to most African governments, at every level.

As an example of people trying to do the job right, look up the efforts to fight HIV and malaria in Africa that are funded by the Bill and Melinda Gates Foundation. The Gates projects provide a better, more qualtified bang-for-the-buck than any other effort out there.

Well they have the 'buck' to back it. I've had a lot of discussions with friends about this sort of problem. Some find first world countries should do more to aid third world countries, while others feel they shouldn't because why should thrid world countries be the responsibility of first world countries. Around this time, the debate always gets heated because one guy in particular says if the first world countries hadn't plundered poorer countries centuries ago, they'd be a lot more developed by now.

Touchy subject.

[Rampaging Rabbit]

Around this time, the debate always gets heated because one guy in particular says if the first world countries hadn't plundered poorer countries centuries ago, they'd be a lot more developed by now.

Touchy subject.

He's right, except they havent stopped plundering it, Africa is still being raped by the corporations and organised religions as much as their indigenous kleptocrats.

[cactusmaac]

From a comment at Greg Mankiw's blog:

http://www.blogger.com/comment.g?blo...94899381636585

The Esquire article by Emily Oster is quite interesting for a variety of reasons. Some of these reasons may not be entirely intentional. It turns out that the Esquire article, doesn't match the original paper in the Quarterly Journal of Economics, nor the summary over at University of Chicago GSB. Links to all three versions of her work can be found at the bottom. Perhaps the most important point is how few of her statements in Esquire are supported by the original paper. By contrast, the U of C GSB summary is quite close to the paper.

The Esquire article contains statements along the lines of "We assume everyone is fundamentally alike; we believe circumstances, not culture, drive people's decisions, including decisions about sex and disease" and "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". These may be her actual views on the subject. However, her paper has very different data. Table III shows that only 7.2% of single women in Niger have casual partners versus 29.9% in Zambia (other countries are higher). As one might expect, differences in sexual behavior have large impacts on HIV infection rates (1.2% for Niger, 16.5% for Zambia) according to the CIA World Factbook).

As mentioned before, Niger has a low HIV infection rate in spite of being very poor (the disease arrived later in Niger as well). Conversely Botswana and South Africa are not poor (both are middle income) and have very high infection rates. By contrast, Cuba has quite limited resources and very little HIV (0.1% infection rate). Clearly poverty does not determine the spread of HIV/AIDS. Indeed, the only obvious linkage is that richer countries should be able to afford STD treatment that should in turn minimize the spread of HIV. However, Cuba and other countries show that poverty need not result in high levels of HIV infection.

The original paper appear to be a substantive well substantiated piece of work (at least to me). I don't regard it as a economics paper. However, that doesn't diminish its value. By contrast, the Esquire article is neither well supported by the paper or other information presented to the reader.

So yeah, sexual behaviour would seem to matter more and poverty less than is implied in the Oster piece.

[Stellar]

I agree with everything in that article except that they compare Cuba to Nigeria.

[Solaris]

I like the connections she draws on two points in particular:

1. Relation of other STDs to catching the disease: Now this is a very common-sense observation, and ought to have been looked at before. Open sores and/or an immune system already under siege to another disease *is* going to increase the chances that, having had sexual contact with someone who has AIDS,you too will contract it. In fact, that probably holds true for anyone with *any* kind of disease that is already taxing their immune system, and/or creates open sores in the skin/contact areas.

2. Life quality expectancy: I think it's equally true that if someone sees little in their future, they're going to take more risks.

For these two points alone, the analysis is worth it, and ought to be looked at.

[Iangould]

In other words: stop handing out condoms in Africa instead of improving medical resources.

The fable that there are a large number of HIV infected in Africa because everybody there fucks around has been bannished for quite some time. Sexual activity in America is actually higher, but it's also easier to get treated for minor infections.

Another reason for the high transmission rate in Africs is the high level of female genital circumcision and of teenage sex (often coerced).

Women who've been mutilated and girls in their early teesn who're froced to have sex are far more liekly to suffer abrasions and vaginal tearing which make them far more likely to be infected and to go on to transmit the disease to others.

I wouldn't say "stop distributing condoms" I'd say "stop acting like condoms and antiviral drugs are the only solutions."