[0:02]Um, thanks so much everyone for coming and thanks to Columbia Engineering also for inviting me here. Um,
[0:13]so I'm going to be talking about uh, this region of the world, the East and Southern rim of the African continent, which is, um,
[0:25]home to less than 5% of the world's population, but roughly half of all new HIV cases occur here each year.
[0:35]Situation there is very, very severe as I'm sure you all know, but after 30 years HIV rates are finally, uh, beginning to fall in many African countries. But why has progress
[0:46]been so low, so slow? One possibility is that without really understanding why the epidemic is so severe, it's been very hard to figure out what to do about it.
[0:56]And so I'm going to talk a bit about, uh, some ideas as to why HIV, um, infection rates might be so high in this region. One of the earliest hypotheses, in fact the first assumption
[1:08]was that HIV rates were high in this region because of, um, high rates of, um, prostitution, particularly exacerbated by the migrant
[1:18]labor system, uh, especially around South Africa, uh, where there are large numbers of gold mines and many migrant laborers throughout the continent and a kind of
[1:28]lively sex trade around those mines. But when researchers in the 1990s began to, um, uh, investigate the situation down
[1:38]there, they asked men who lived around these mines or who were migrant miners from far away, um, whether they actually had visited a
[1:48]prostitute in the past year. And they also interviewed men in places that sent miners to these mines like, uh, Maseru, which is the capital
[1:59]of Lesotho, a little kingdom which is within South Africa. And what they found was, um, relatively few men actually
[2:08]said that they visited prostitutes. Um, fewer than 5% even of the, um, migrant mine workers said that they had visited a prostitute in the past year,
[2:20]according to this survey. And there have been many, many surveys like this, and um, that that come up with similar results. So, it's not that these guys aren't
[2:32]having sex, but it may be that prostitutes are not their first choice. But they don't seem to be having many partners, either. Many surveys suggest that numbers of
[2:42]sexual partners are not especially high in highly affected African countries. Uh, for example, here's some data from parallel studies that were conducted in
[2:52]very similar ways in Uganda and the United States in 1994. And at that time, the HIV infection rate in Uganda was 20 times higher or more
[3:02]than it was in the United States at that time. But when men and women were asked, um, "Have you had more than 10 sexual partners in your life?" the fraction who
[3:14]said yes was higher in the United States among both men and women than it was in Uganda. And, um, you know, people don't always tell the truth on these surveys, but when you've seen enough of
[3:26]them and you've spoken to enough people over a long period of time, um, as I have, I spent a long time in this region, you begin to believe them.
[3:37]And, uh, so these, uh, results are probably pretty close to the truth. So, what's going on? Well, one hypothesis that seems to be
[3:48]gaining a certain amount of traction, um, is that it's not the numbers of part sexual partners that people have, but the tend but there's a greater tendency
[3:58]of people, both men and women in this part of the world to report more than one long-term partnership at a time. So, a man may have a wife and a girlfriend or two wives, and one of
[4:10]those women may have another partner. Um and uh um, that partner may have another partner or more than one.
[4:21]And uh some evidence for that comes from these early World Health Organization studies that were conducted in the late 1980s, where men and women from
[4:32]different world regions were asked about their sexual behavior. And on these surveys, Africans did not stand out on any measure. Numbers of sexual
[4:42]partners were similar, uh were not especially high in Africa. And age of sexual debut is about the same wherever you go in the world. Uh
[4:52]it's about between 16 and 18 years. But the fraction of people who um answer in the affirmative to the question, do you have more than one
[5:02]spouse or regular partner, does uh seem to stand out, uh as shown here. These um sites here are
[5:12]all in Africa. And as you can see, men, who are the blue bars, and women, who are the purple bars, are much more likely to report uh having more than one uh long-term
[5:23]ongoing relationship. Interestingly, men in Thailand are much more likely to say that they've had more than 10 partners in their life, but
[5:34]fraction who have more than one long-term partner is very small. And we know that this um um is a tradition in this part of of
[5:45]world. These are there's of uh group of um young Masai warriors. This is a tribe that's been very studied in great depth by anthropologists.
[5:55]And these are young men and as they grow older, they will and accumulate more wealth, which is in the form of cattle in this group. Um they will
[6:07]marry successively younger wives and accumulate two, three, or four perhaps over their lifetimes. Some of those younger women
[6:16]may also have other boyfriends at the same time. And that's these they aren't spoken of. But everyone knows this is this is a sort of um
[6:27]um part of their culture. And even in more modern African settings, uh polygamous marriages and multiple long-term relationships are certainly
[6:38]not unknown. This is President Jacob Zuma of South Africa with two of his wives and his fiance. Um this is not at all a uniquely African
[6:49]pattern of behavior, of course. It's also common in the Middle East and other places. And historical and anthropolo- anthropological studies suggest that informal polygamy and other types of
[7:00]concurrency were probably quite common in the West until a few hundred years ago. The nuclear family with its aspirational norm of monogamy is probably a relatively recent innovation
[7:11]that emerged with a growing cultural emphasis on private property, inheritance, and Judeo-Christian beliefs. Monogamy certainly has its drawbacks. As
[7:21]we all know, high divorce rates and the often frustrating search for that one perfect mate who may not exist. But when it comes to avoiding HIV, even serial monogamy has some advantages and
[7:33]here's why. This is a kind of cartoon uh explanation of why concurrent ongoing uh uh relationships can be
[7:44]quite dangerous. Um if we have a hypothetical network of concurrent sexual partnerships uh with men as squares and women as circles,
[7:56]all these people are linked up to each other. Uh they're having ongoing sexual relationships with each other. They know and trust each other. Um and no one is having very many partners.
[8:07]And uh people are not necessarily switching partners. But look what happens if one person becomes HIV positive. The virus can
[8:18]spread very, very rapidly. Um however, in the
[8:29]case of serial monogamy, where people um pledge uh undying affection to each other for some period of time, whether
[8:39]it's weeks, months, or years, and then break up and move on to someone else, um this is uh HIV can't really get a
[8:49]foothold in that kind of situation. So, even though people are switching partners far more often in this scenario, HIV can't spread until people break up
[9:00]and move on to new partners, and that really slows the virus down. So, anyway, this is a very oversimplified uh view of what's going on. Um but there's
[9:11]for anyone who's interested, there's some review articles that summarize computer modeling and real-world evidence that um concurrency is a factor in driving the
[9:22]epidemic in Africa. And those uh papers are available free online, or I can send them to you if you get in touch with me. Um
[9:32]so, let's assume that uh concurrent sexual partnerships are a factor in helping to drive the epidemic in East and Southern Africa. What do we do about it?
[9:42]Well, um, for a long time people working on HIV prevention emphasized the use of condoms and ads like this, billboards and so on,
[9:53]to promote condom use appeared all over, uh, across the continent and in many towns and cities. And they tended to be sort of sexy and have slogans like these, even the best
[10:05]ballers take a safe dunk with it. And as you can, um, imagine, these sorts of, um,
[10:15]campaigns really addressed casual sexual behavior, multiple partners, people who went with, uh, prostitutes, not the kind of long-term,
[10:25]uh, ongoing partnerships that, um, are seen to be underlying the epidemic in Africa, where people often have a sense of intimacy and trust, even if
[10:37]there are other partners involved, and where people often also want to conceive children. And that may be why, uh, despite the fact that condom, this is, uh, that poster was from Botswana,
[10:49]and here's what happened as in Botswana during the 1990s, the HIV rate in urban and in rural areas soared, so that by
[10:58]the end of the decade, 45% of pregnant women, uh, in the major towns were HIV positive. A very tragic situation. It's only now starting to fall, by the way.
[11:09]Um, but, um, condom sales were also increasing at the same time, but they didn't seem to have much, uh, influence on the epidemic at that
[11:19]time, and this may be why. So, uh, in response to problems with the condom campaigns, the US government under the Bush administration changed
[11:31]tactics and began to promote uh programs that um urged people to abstain from sexual relationships until they got married and
[11:42]remained monogamous thereafter. And these campaigns began in about 2004 or so and involved posters like these. She's keeping herself for marriage, what
[11:53]about you? And unfortunately, they haven't been very successful either. Uh perhaps because they were unrealistic and at odds with the culture.
[12:03]Scientists don't tend to like to look at history, but sometimes they should. And in fact, uh this little nation in
[12:12]the middle of Africa, Uganda, had some very valuable lessons for fighting HIV. During the late 1980s, the HIV rate
[12:23]soared in this country to about um 20% of adults. And then it very abruptly fell by about 2/3 during the early 1990s. And here's
[12:35]some data uh showing the HIV prevalence rate among teenage pregnant women, about 70% of teenage girls have had a child or
[12:46]are pregnant uh or were pregnant in this in this population at this time. The teenage pregnancy rate has since fallen, but as of about 1995, it was very still very very high.
[12:58]And yet the HIV rate in this group was falling very fast. Now, it can't be because of um because the girls were abstaining unless
[13:07]um I mean, these were not virgin births. And it can't be that they were using condoms either because um they were obviously becoming pregnant, so they weren't using them very
[13:18]effectively if they were using them. It must have been that they or their partners were having fewer other partners. And that is uh just so happens that that was what the government of Uganda at
[13:28]that time was urging people to do. The government itself created this very brilliant campaign which essentially recognized that
[13:38]multiple long-term relationships were a norm in the society. But it warned people to love carefully or zero graze was the other famous
[13:48]slogan at the time. In other words, avoid outside relationships. Keep if you have one partner stick to one, if you have two stick to two and so on. That's what the campaign really meant. And you
[13:59]saw murals like this all over the country and and so on. And you also saw posters like this. Young girls were urged to stay away from sugar daddies who might
[14:10]try to seduce them with money and gifts and so on. And indeed partner reduction occurred in this country very dramatically. Many studies
[14:20]have shown this during the time that HIV rates were falling most rapidly. The fraction of men and women reporting multiple partners in the past year fell
[14:30]by about 60%. Partner reduction in response to the threat of AIDS, pragmatic changes in behavior
[14:41]have also occurred in many other countries in the American and European gay communities, in Zimbabwe, in India, Thailand, Kenya, Ethiopia and many other
[14:52]countries. Innumerable lives have been spared as a result. There are other ways to reduce HIV infection rates and they're also very important. I just like
[15:04]to mention them briefly. Male circumcision reduces a man's risk of contracting HIV by 60 to 70% and programs are now underway to offer voluntary circumcision to men in many
[15:16]African countries. This will almost certainly slow the epidemic, but it's unlikely to eliminate it, so behavior change remains important.
[15:26]In addition, uh mass treatment of all HIV-positive people, including those who aren't yet showing symptoms of AIDS with antiretroviral drugs is the latest fashion in HIV prevention. It does work
[15:38]in some circumstances. Hillary Clinton has just announced US support for such uh programs. However, I'd urge her to consider also
[15:50]that um these programs have a very large cost potentially, and at the moment I don't know how many of you are aware about the Global Fund for AIDS, Tuberculosis, and Malaria that purchases
[16:01]a lot of the drugs and services for people with HIV um won't be issuing new rounds of funding until 2014. And currently, we can't afford to treat the people who are sick and need
[16:12]treatment right now. In addition, the drugs have side effects, which means some people who feel otherwise healthy may stop taking them. And this risks accelerating drug
[16:22]resistance, which could increase the costs of treatment even further. Um So, in addition to these programs, which are of course important, concurrency
[16:34]education is also cheap and very safe, especially if it's done in schools where AIDS education is going on anyway. Um but it's not being done, or at least not
[16:45]being done sufficiently um at the moment. And a sufficiently wide scale. And part of the reason is that there's a widespread assumption among amongst uh
[16:56]global health opinion leaders that behavior change doesn't work. We need a technological solution to the epidemic. Um but the evidence shows that this is actually not true. When people get the
[17:08]right message and speak openly and compassionately about AIDS, behavior change has saved lives. We don't know exactly how to make it work in every setting, but we can start by giving people clear messages about where their
[17:19]risks are really coming from. And to that end, um just look to leave you with the words of a woman who attended um an AIDS play
[17:29]about concurrency uh in a village in Lesotho not long ago. And here was her reaction. The The play, by the way, was called "It's Just You
[17:38]and Me and My Wife and Your Boyfriend." "I was really struck by the concurrency network because it's something we just had as gossips going around the village, but noticing that one person would be
[17:49]thinking, 'I'm the only one and you're the only one.' Unless that chain is cut or is taken care of somehow, then that's the only way we can curb the spread of the virus. But it's If it's still going
[17:59]to be like that, it's a hopeless case." Thank you very much for listening.