• Some highlights from this interview
• The Haiti-Congo connection
• The reaction in Washington to his 1983 findings
• How did HIV jump from primates to humans?
• His research on AIDS in Muslim countries

• Related feature
• More on the origins of HIV

[Why did you first go to the Congo?]

I went to the Congo in 1965 as a schoolteacher. I had graduated from undergraduate school in '64 ... and majored in science and math. I decided I wanted to go someplace in the world where I could teach science and math in a different language.

Namely French. When you were there, you encountered Haitians. Tell me how they came to be there.

In the second year that I was teaching school in the Congo, two Haitians came to our school under contract from the Congolese government to teach. It turns out they were part of a large population, relatively large. No one knows exactly how many, but somewhere between probably 5,000 and 10,000 Haitians came over to the Congo to help fill needs that were brought on by independence, when most of the Belgians left. There were ... very few Congolese schoolteachers, lawyers, doctors, other professionals who normally would have helped to run the country, so they had this contract with the Haitian government to send people over to help fill these gaps. Two of those teachers came to teach in our primary school. ...

To the Haitians' point of view it made sense, because they were in a rather difficult political situation at that time. This was during the time of Papa Doc Duvalier, so the political conditions in Haiti were very difficult, so many Haitians were happy to get a nice contract to go to a country where they could speak their language and work effectively.

Now, there's a theory that some of those Haitians contracted HIV/AIDS and went home, and that's what brought it into the Western Hemisphere. ...

Well, I think it's more than a theory. I don't think there's any doubt that Haitians got HIV/AIDS while they were there, some of them. And they probably went more than one place. We know that there was a fair migration of Haitians from the Congo into Europe and to Canada. Of course there are also Haitians who went back to Haiti.

We asked a lot of questions during our investigation, which we did in 1983, about this issue, and we found that quite a number of Haitians we could actually document got this disease and went back to Haiti, to their families, particularly when they were very ill.

When you say quite a number, [how many]?

A handful that we were able to document, but this was 1983, many years after the initial entry of the Haitians. Many of them had gone to a lot of different places, and there were very few Haitians left in the Congo at that time. It was difficult to find Haitians who were still in the Congo who had knowledge of people who were Haitians who had contracted the disease, but we did find them.

You said some Haitians went from the Congo to Belgium; some went to actually Montreal; some went back to Haiti. Why [did] AIDS not pop up in Belgium, Montreal? ...

Well, it may have. In fact, remember that there may well have been some earlier cases in some of these countries that were never detected and that died from tuberculosis or some other infection, and they were never perceived to have AIDS. I think the answer to that is [there] may well have been people who were infected who went to these other areas, but we didn't have any surveillance in the 1970s for this. There was no one looking for something like that, and it's highly unlikely that we would have detected someone at that time.

When did you yourself first encounter AIDS in Africa?

I was at a meeting on hemorrhagic fevers actually, which was my main area of work, in ... May, late May of 1983. I met a colleague, Jan Desmyter, from Antwerp. Jan began telling me about these few Congolese who had come to Belgium with a disease that looked to him like the acquired immune deficiency or the lymphadenopathy syndrome, as it was also called in those days. He was just wondering about what this meant.

Having already worked in the Congo [for] a number of areas, not just as a teacher but having gone back to work on monkeypox, I realized that there was a lot more going on, because first of all, less than one-tenth of 1 percent of Congolese could have ever have afforded to get on an airplane or a boat or any other kind of conveyance and gone to Belgium for the treatment of any infections, of any disease at all. I realized that if they'd already seen a dozen or 15 that that must mean there were more back in the Congo.

Many more.

Many more. So I organized a group to go to the Congo to look into this. ... We went there in September of 1983 to begin our investigation, and those were the first cases. We started looking for patients with typical symptoms of AIDS, and we found them on the wards of the Mama Yemo Hospital and also at the University Hospital in Kinshasa. ...

How many did you find?

My recollection was we found 38 patients that we later confirmed. In 1983, [when] we went to do the investigation, there was no antibody test. We were using the old method of CD4-CD8 ratios. We would look at patients clinically and see if they had symptoms that were reasonably compatible. We would take a blood specimen in the afternoon and evening, working with our technician. My technician at that time was Sheila Mitchell. We actually did the CD4-CD8 ratios to help us confirm at last with that test that they were likely AIDS patients. That's how we diagnosed the first, and we saw 38 of these patients.

How sick were they?

Some of them were very, very ill. In fact, I saw seven patients during that period -- and it was a period of about five weeks or so -- I saw seven patients with a condition caused by a fungal meningitis that most physicians wouldn't see even more than one or two in their entire lifetime. I saw seven of these patients in that period of time. That tells you that there were already people [in whom] the epidemic was already well advanced, because we were seeing people at this stage of their disease dying actually in front of us, with these kinds of opportunistic infections.

Just spell that out. Why did that tell you it was quite advanced?

The reason that this told us that the disease was advanced is because you have to have the HIV virus infection for a fair amount of time to kill off a number of your CD4 cells to make you susceptible to these opportunistic infections. In this case it was a fungus infection of the central nervous system that a number of these patients came in with. ...

Why was it important to go to Africa at this point?

The major reason for going to Africa for this particular issue was that the appearance of cases in Europe made it fairly obvious, to me at least, that there must be a much bigger epidemic going on in Africa, and we needed to get to the bottom of this. We needed to understand what was the potential of this, because we were already beginning to realize that this disease had real potential outside of Africa.

Secondly, none of us had any understanding of how it might be transmitted. Going to Africa was going to, one, help us to understand the problem there better, but perhaps more importantly, to understand the disease itself better, because here was a completely different social, cultural setting in which we were going to be able to look at this and try to better understand the biology of this disease. We didn't know it was a virus then, although we suspected it was a virus.

And what insights did the African trip give you?

The major insight was -- and this was the substance of a substantial discussion when I got back -- the major insight was that there was an equal ratio of male to female cases. It was very clear from this that we were looking at heterosexual transmission, not the homosexual transmission that had been touted at the major mode of transmission in the United States and in Europe. This was a real revelation.

Why was that so significant?

This changed the landscape of AIDS forever, because this showed us that everybody ... was susceptible to AIDS. This was not something special to people who practiced a gay lifestyle. This was something that could affect anyone. ...

When you returned to the States, how did Jim Curran [of the Centers for Disease Control and Prevention (CDC)] react to your findings?

Well, of course Jim had been a supporter of going out there. He had clearly grasped the significance of this and had helped to and given support to go out to do the study.

Jim was very enthusiastic about the results of this, and in fact, I came back and said to Jim and to Bill Foege, who was the head of CDC at that time, I said: "We need to establish a long-term study of this disease here in Kinshasa now. It's absolutely essential that we have a base here and that we start to study this disease." They were 100 percent supportive of this. We started immediately in November of 1983, just after I got back, to recruit somebody and to get the nuts and bolts in place, the organizational nuts and bolts, to try to make this happen as soon as possible. ...

Why was it so important to set up a long-term study? Hadn't you found out enough [when] you found it was heterosexually transmitted? What else was there to know?

Well, there was a lot. The importance of this long-term study was to understand much more about what were the risk factors besides just heterosexual transmission that might be associated. We were particularly concerned about women transmitting the disease to their children, because we'd already realized that could happen, so we needed to understand much more about it. Plus, we needed to understand a lot culturally about this issue in order to develop the tools that would be necessary for prevention programs, particularly for educational programs. ...

We needed to understand more about the dynamics of the virus itself in this population: What was it doing? How long did people incubate this virus before they actually became ill? Was it different from what we were seeing elsewhere?

We needed to understand what diseases were causing the opportunistic infections. Were they different from those in United States, and does that require then a different approach to being able to address a person with HIV in terms of prevention of opportunistic infections and other issues that clearly were important for the management of AIDS cases in Africa?

When you reported your findings to [Reagan's Assistant Secretary for Health] Ed Brandt and people in Washington, what was the reaction there?

One of the interesting things that happened was that Bill Foege ... said: "We're going to call the assistant secretary for health and give him this information. He needs to know this, because this is [a] very important finding." As you know, the government at that time, the U.S. government, they had considered this a gay disease, so they were not really necessarily going to be inclined to look favorably at new data.

Anyway, we went to Bill's office, and he made this phone call. ... They got Dr. Brandt on the phone, and I gave him the data and information and told him that our conclusion was that this was already probably at epidemic proportions and that it was primarily heterosexually transmitted. His response was: "There must be another explanation. This can't be right."

A total denial?

It was a total denial, in my opinion. He broached the old thing about there are a lot of mosquitoes in Africa. And we said, well, yes, there are a lot of mosquitoes in Africa, but guess who gets bit the most by these mosquitoes, is children. If this were the culprit, then we'd be seeing more disease in children, and we're not. We saw some, but we didn't see very much. I would say it was pretty total denial.

What consequence flowed from that? Was that a setback for the fight against AIDS? ...

I believe that it was a setback for the work on AIDS and for the prevention of AIDS. ... I believe that an earlier and more visionary understanding of this by the people at that level in the government could have made a huge difference in our approach, in how we determined that we were going to learn about this disease and, probably more importantly, how we were going to support the effort to prevent the disease. ...

[Tell me more about what your study suggested about the Haiti connection.]

We went to look at the situation in Kinshasa in 1983 with fairly open minds about what we were doing to find in the way of AIDS. We knew that there were these cases in Belgium. We knew that. That implied that ... the disease might be important in the Congo, so we started by looking in Kinshasa because ... it was the biggest city, and it was obviously a place where we could start.

We didn't have a bias in what we thought we might find in the way of transmission, in the way of risk factors of who was most at risk or what practices put them at most risk. We went out, first of all, to look for patients in the hospitals, in the two hospitals there, and then we did questionnaires of the patients that had symptoms that seemed to be associated with AIDS, and then other people.

What we learned from this was that the frequency of sexual contact and the number of sexual contacts, just as it had been in the United States, was important, but that these sexual contacts were heterosexual, not homosexual. We looked for evidence of homosexual transmission and could find almost no evidence of homosexual practices that were at least anywhere near out in the open in Kinshasa. Plus, we found an equal number of males and females, so we felt that implied that this was a heterosexually transmitted disease.

Now then, the question was, OK, we've got this disease here; we now know, based on the advanced symptoms that we saw, many patients already [are ailing] with opportunistic infections. This told us the disease had been circulating for quite a while. It wasn't just like two years like we knew about in the U.S. and in Europe. We understood that this had been around for a while there, and therefore we had to understand better where it might have come from, and in particular where did it go. We were clearly cognizant of the fact that somehow the disease had gotten into the U.S. and Europe.

Our assumption, and I think the history has borne this out, was it must have come from Africa. The question is, how did it come from Africa? It was clear to us that heterosexual transmission was important, so the question is, well, who would have been at risk and could have taken the disease out of the Congo?

Well, there were a few choices: Europeans living there, which there were -- some Belgians primarily, but French and others; and Congolese who were leaving the country to go abroad; and Haitians who I had already experienced contact with back when I was a schoolteacher in the 1960s. We knew that these were all possibilities. ...

We were particularly keenly interested in knowing what had been the experience of the Haitians. We found very few of the Haitian community still there. It appeared to us that most of the Haitian community had probably ... migrated elsewhere, because times had become difficult in the Congo economically, politically, and there would have been little reason for them to stick around, so most of them had gone. ...

But remember, this is a disease with a long incubation period, so some of these [people], yes, had become ill and gone back to Haiti when they were ill. But knowing that this was a long-incubation disease, it's quite feasible, therefore, that a number of these people emigrated not knowing that they had HIV, but only developed it later in the areas that they emigrated to.

I believe that this is a credible and likely source, but I want to emphasize it's not the only source. I've already alluded to others. We know that there were some missionaries and other Europeans who clearly got AIDS in the Congo and went back to Belgium with AIDS. So it wasn't just the Haitian population, but particularly for North America, they may have played a role that was important.

One of the clues to this is that we know that it's the clade B virus that first appeared in Haiti, and it's also the virus that is the major virus in North America. We know that this virus also circulated in Central Africa. That's just a clue; it's not proof of anything. But these are all the populations that may well have played a role. I'm not trying to implicate any one particular group, but history says the Haitians were there. We have evidence that some of them, at least, got this disease, and we know that some of them went to Europe, to North America and back to Haiti.

You encountered the disease in '83, and all the evidence was that it had been around for a while. How far back do you think or do we now know that the disease goes? What spread it from the small jungle, rural communities to cities, continents?

I got very interested in this issue obviously once we had done our initial studies. In late 1985 and early 1986, when I realized that we still had all of our serum that we had gathered in 1976 in a remote village up in the northern part of the Congo still in my freezer at CDC, I stepped back and said, "What can we learn about what HIV has been doing before it got to the point of causing epidemics?" That was really the major question of that study. ...

My hypothesis was that HIV does not spread that easily. It's not influenza; it's not measles. Even the evidence in the 1980s was that you had to have frequent sexual contact in order to make this happen. So the question was, if we go back to a small village where the sexual practices are radically different from what we see in the big cities, my hypothesis was we would find some infection, but it would be very low and that it wouldn't be epidemic, and that it wouldn't become epidemic.

We had the ideal situation to be able to look at this, and we pulled out all of the serum of 600 [people] that we had from our village in northern Congo. We tested them and found that five of those 600 were positive for HIV. By this time, we had a test we could do for antibodies.

We also, I might add, isolated what today is still the oldest HIV virus from one of those sera.

When was that?

This was someone that we saw in 1976, bled them and brought it back to our laboratory, and the virus was still there. Kevin de Kock, who was working with me at that time as an [Epidemic] Intelligence Service [EIS] officer -- I assigned Kevin the job of ... going back to the Congo to go back to these villages, look for HIV or evidence of AIDS, and to re-bleed the population. This was 10 years later. ...

Kevin went back and did a random survey of all of the villages in that same area and brought the sera back. He also found [two] of the people that we had originally bled who were HIV positive. ... Three had died; two were still alive, of which one had a still-normal CD4 count and the other had a very abnormal CD4 count. We found the prevalence of HIV antibody in that first 1976 sample was 0.8 percent, so less than 1 percent. Kevin brought back about 340 samples from the second bleed. Ten years later, we did those antibody tests -- 0.8 percent. Over a 10-year period, there was not one single change in the prevalence of HIV in those group of villages. They are very remote villages up in the northern part [of the country].

At the same time, in the city of Lisala, which was about 100 kilometers away from that cluster of villages, on the river, the prevalence of HIV antibody in the prostitute population, or what was identified as that, was almost 11 percent. The prevalence of HIV antibody among pregnant women in prenatal clinics in Kinshasa was about 2.5 percent. You can see that we had plenty of evidence that HIV was marching on in the right setting. ...

The question is, how did it get to these villages? Where did it come from? ... People there hunted primates, nonhuman primates as well as other animals, for food. I believe that in the process of hunting, the hunters encountered primates, particularly chimpanzees and perhaps others, because we know there are other monkeys that carry the simian viruses -- they encountered these viruses particularly when they were preparing the meat in the food, either for taking to the market, but most of the time for their village and that they periodically would become infected. This is how it got to the villages.

It didn't become epidemic in this setting because people, the rurals and the [villagers], were very different from what happened when we went to the cities, just like the rurals in rural England or rural United States are very different from what happens when you go to Los Angeles or London. This is still true in Africa. When I was teaching school, I lived in a small village; I understood what the dynamics were. This is why I believed that it was not a setting where you would see epidemic disease.

I believe what happened was that these hunters would get infected periodically, and this was probably happening in various places in Central Africa. It wasn't high frequency but periodically, and often it would probably die out, and the hunter might die; he might transmit it to one or two people. But there were a few places where it would still continue at this low level that we found in the villages.

To me, this is also what accounts for all of the diversity of viruses that we see in Central Africa. No one's been able to explain any other way to me why we have such a diversity of viruses that we don't see anywhere else, and why all the viruses we see elsewhere are found in Central Africa. I believe it's because these infections cropped up kind of helter-skelter, periodically, often died out. But those that continued then created little foci of infection in these, and ... then when people started going from these villages to the cities is when we saw the changes. When we saw the change in behavior, this is what created the epidemic. ...

Just spell it out then. When you say the behavior changed, what exactly do you mean?

I believe that when people live in small villages, they couldn't have highly frequent, promiscuous sex. For one thing, young girls were married at a quite young age, at the beginning of puberty. This was a practice of most tribes, certainly in Central Africa, for a very long time. And even though there was polygamy, this was a well-practiced, well-organized polygamy. Sure, a man might have three or four wives, but he was pretty faithful to those wives. I'm not saying there was no promiscuity in villages. What I am saying is that they were highly organized, and it was no more acceptable to have promiscuous sex in the villages than it would be in a small town anywhere else back in the '40s and '50s and '30s.

But when people go to the big cities and they come in contact with many more people, no one is standing over their shoulder. We don't have the kind of social structure that we have in a small village; they start having more sexual contact. This is what's happened in every city that I know about, and I believe this is without any doubt what happened. ...

I think that one of our big failures early on was to have the understanding of how serious this problem was, and secondly, what it was going to take to really mount a major prevention program. This disease requires a substantial change in people's behavior. In a setting like Africa, where the cultural understanding and the cultural attitude towards sex is very different from ours, trying to understand what that was and how to use it best for mounting effective prevention programs certainly should have been our number one priority. I don't believe any of us did that very well or effectively.

I also don't think that we were able to convince governments, such as the governments in India and elsewhere, who later experienced this disease of the likelihood of it coming to them and the potential for the public health and dare I say economic impact that it was going to have.

[Were you at the 1987 amfAR (American Foundation for AIDS Research) dinner where Reagan spoke about AIDS?]

I was invited, and I'm trying to remember how I got an invitation, because I was not any particular muckety-muck in the government. I was just a guy at CDC working on AIDS. But I had a couple of friends who invited me to come up, and I thought this was an occasion I should go to, so I did. ...

Knowing what I did, ... I was struck still by the lack of understanding of the gravity of this problem and the inability to talk about this problem other than to say it was a gay person's disease. That was really still the emphasis at that time. There was no mention of the problem in Africa or elsewhere. It was, in my opinion, surely one of the low marks of our government during that period. ...

You've written, "In the world of viruses, we are the invaders." What do you mean?

I once said, when I wrote my book a number of years ago about my adventures [Virus Hunters of the CDC], that "In the world of viruses [that] we are the invaders." What I meant by that is often our practices, our behaviors get into the niches where viruses live and cause them to then infect us because of our practices. HIV is a wonderful example of this, because these viruses clearly had a good symbiosis with, or at least a reasonable one with, nonhuman primates. But human practice, [the] one that killed the primates and ate them, probably is the very likely the source of the virus in humans. Then when humans changed their behavior to create the conditions for the virus to expand its space, then that allowed the epidemic to occur.

But we see this with others. We see this with the hemorrhagic fever viruses, for example, where people going into areas that they haven't gone into before, encountering either wildlife or mosquitoes or other things that are carrying new or different viruses, provides the opportunities for these viruses to infect them. ...

In January 1984, you called [former head of the World Health Organization's Global Program on AIDS] Jonathan Mann. Why did you call, and what happened?

After our investigation in 1983 in Kinshasa and my recommendation in my report to Bill Foege and to Jim Curran that we start a long-term study, the question was then OK, so who's going to go do this? I was the head of the Viral Hemorrhagic Fever[s] laboratory, the level 4 laboratory at CDC. I had just become the head of the laboratory and had already a big field program in another part of Africa, and I was not anxious to leave that and go myself to Kinshasa to set this project up, so we had to look around for somebody to go get this project going.

Jonathan Mann was a former [Epidemic] Intelligence Service officer in New Mexico who I knew from before, who was looking around for a new challenge. ... One of his great assets was not only was he smart, but he spoke French. His wife was French, and Jonathan was a very fluent French speaker.

I told him about what we'd found and that we wanted to set up a long-term study and that I thought that he would be a terrific person to think about doing this, even if he had never been to Africa. ... He decided that this was a real challenge and it was something he wanted to do, so he persuaded his family to do this. ...

Mann went on to make an enormous impact on the world of AIDS. How do you sum up his achievements and what he came to represent?

Jonathan Mann was a tremendous scientist. He was a good epidemiologist. But he was much more than that in terms of his dimension. He was a very astute politician, and he was a great humanitarian. He understood very much about the human condition.

Jonathan was exceedingly well read and very literate, and I think all of this really made him a leader in the fight against AIDS. He was one of the exceptional leaders because of all this, because his ability to understand the science, to translate that science to ordinary people, and to translate it to politicians and to get them to see what they needed to do was exceptional.

He was able to do this in so many different countries. Setting up the Global Program on AIDS was a tremendous undertaking, and I can't think of anyone who could have done it better than Jonathan because of his ability to understand the science and translate it to those who really needed to make the policies to make things happen. ...

Why did his career at the WHO come to a very abrupt end? Was that a failure in his own character, personality?

The fact that Jonathan left WHO when he did has always to me been one of the great tragedies. Perhaps we all make mistakes. I know that. I know what Jonathan thought at that time. He decided that he could no longer effectively work with people from WHO because he was being impeded by the new director of WHO [Hiroshi Nakajima]. It was pretty clear to all of us that the new director of WHO felt, coming from the culture and where he did, felt that he was being totally overshadowed by this media superstar. ... He actually limited Jonathan's travel. There were instances when he wouldn't let him go to a meeting. He wouldn't sign off on travel to a meeting. Whether Jonathan should have stayed and weathered the storm or whether he made the right move to leave, I think that's an arguable point. The fact is he made that decision to leave and to resign. ...

What finally happened to Mann?

Dr. Mann went to Harvard, became a professor at Harvard, and created the Institute for Health and Human Rights. He had received about a $20 million endowment from a foundation in Switzerland to establish this new institute, and his passion there was to continue the fight against AIDS but to try to do it through persuasion of people to change the laws and improve the laws that provided more civil rights and more human rights to people. ...

He then was asked to be the head of a new school of public health, the dean of a new school of public health in Philadelphia [the Health Sciences' School of Public Health at Allegheny University]. He went there to create this new school of public health. His wife, Mary Lou Clements, was an active AIDS researcher at Johns Hopkins, and Mary Lou was invited to a WHO meeting to talk about AIDS vaccine, and Jonathan decided to go with her, because at that time I was working in France at the Institute Pasteur, and he decided to come with her. Then we were going to meet that weekend to plan a meeting with the Institute Mérieux [foundation specializing in vaccine research and emerging diseases in Lyon, France], an AIDS meeting.

We were going to pick Jonathan and Mary Lou up on Friday night from Geneva and then spend the weekend hiking in [and] around Geneva and planning this meeting. As we all know, tragically they were on the Swissair flight that took off from New York for Geneva, that then crashed near St. [Margarets Bay] off of Nova Scotia, and we lost two tremendous leaders in the world of AIDS.

Some people said that his death kind of made people realize what had been lost and how much momentum and idealism had gone.

... To me one of the great losses of Jonathan, before his death, was when he left WHO, because [the] WHO program, the WHO AIDS program has never, in my opinion, been the same since. It lost a tremendous amount of momentum. It became a bureaucracy rather than a place of passion and action.

Jonathan was a field guy who believed that he had to get out there with the troops as much as possible as well as lead the troops, and we lost all of that. I'm afraid it was filled with relatively inarticulate bureaucrats who have, in my opinion, not been able to continue the same kind of programs and the same level of leadership that Jonathan was able to do. ...

[Talk about AIDS in Muslim countries where you've worked.]

AIDS in Muslim countries is a fascinating subject, because the facts are that the rate of HIV in Muslim countries thus far, for the most part, is relatively low - in fact, sometimes very low. We experienced this when I worked in Pakistan for a number of years, and we found that the prevalence of HIV there was below one-tenth of 1 percent. We had difficulty finding AIDS cases. There were very few around.

We actually did a study of IV drug abusers in Karachi -- and there's a lot of drug abuse in Pakistan, because the drug ... route comes down from Afghanistan down into northern Pakistan, down into southern Pakistan -- and of course Karachi being the big city, we saw a lot of IV drug abusers.

We studied over 200 IV drug abusers, and we had no infections at that time in 1995 and 1996. However, I'm understanding that today the virus has now gotten into the population of IV drug abusers in Karachi, and it's going to be interesting to see whether that is going to be the source for transmission out into other parts of the population. That has been the case for countries like Thailand and some of the other countries that are less Muslim.

But the cultural practices of keeping women indoors, which is true even in the big cities, such as Karachi, and literally almost imprisoning women, certainly may reduce to some degree the rate of spread, if not the spread of HIV in the population. I would say that in Muslim countries where they have been very strict in this practice, this has been the case.

If you contrast Pakistan with India next door, which has a large Muslim population but it is diluted by many other ethnic groups that have different practices, you see that India is experiencing a major epidemic of HIV, yet Pakistan is not. One can only conclude that it is one of these things that you can't prove, but one has to conclude that somehow it is the cultural practices -- and there are many different cultural practices that may contribute to this lack of HIV, which is very good in a population like Pakistan, and probably other populations like Iran and Iraq and other areas where we've seen very little HIV.