Why is southern Africa's HIV rate so high?

One continent stands out as bearing the brunt of HIV disease, and that’s Africa. It accounts for two thirds of the world’s AIDS burden, with 27 million people living with the virus. Most of them live in the south, with disease prevalence being particularly high in Lesotho, Botswana, Zimbabwe, Eswatini and South Africa. In the latter case, in some locales, as many as one in every two young black women attending antenatal clinics are testing positive. So why is this so high, and what measures can be brought to bear to stop the spread. Salim Abdool Karim is a world-leading epidemiologist and virologist at the University of Kwa-Zulu Natal in South Africa; he also chairs the UNAIDS Scientific Expert Panel…

Salim - Globally, we are seeing a steady trend in HIV, of declining incidence rates and prevalence. That's true as much in Africa as it is in most other parts of the world. However, at a global level, there are three groups where incidents has been somewhat more recalcitrant. One of those is in Southern Africa. Now, Southern Africa comprises about half of the global epidemic. And within southern Africa, South Africa accounts for about one fifth of the global burden of HIV. And within South Africa, the group that's at the highest risk of HIV are young women.

Chris - Is the reason that South Africa has such high prevalence, because it's also slightly unusual amongst African nations in being quite moneyed and therefore one of the few countries that could afford quite aggressive treatment for HIV earlier on in the pandemic? So you've kept people alive and well who otherwise might not have been in a less well developed setting.

Salim - In most of Southern Africa, the higher rates of HIV in young women are being driven by what is referred to as age disparate sex. Put another way, this is about teenage girls who are having sex with men who are about 10 years or so older than they are. But another way, we have what you call the cycle of HIV transmission. Men in their late twenties, early thirties are having sex with these teenage girls. So these young girls below the age of 25, these young girls then grow up and when they reach their late twenties and thirties, they have a very high prevalence of HIV. In some communities in Kwa-Zulu Natal, over half of the women in their thirties have HIV. These women are now having sex with men that they are going to marry as their husbands or their long-term partners. And so these women then infect men in their thirties.

Salim - These men in their thirties have sex with teenage girls. They infect the teenage girls. Those girls grow up when they reach 30, they infect the next group of 30-year-old men who infect the next. So this cycle continues. The problem you have is that when you look at the technologies to prevent HIV, what you used to euphemistically call the ABCs, Abstinence, Be faithful, Condoms and circumcised, those technologies essentially are under the control of men. So we didn't really have technologies that women could use to control their risk until a long comes PrEP. Pre-exposure prophylaxis is used in over a hundred countries throughout the world and it now gives women the power and the ability to control their risk of HIV. A challenge though is that it's very hard for somebody, especially a young teenage girl, to contemplate that she's going to get HIV and so she better go and take the time to stand in the queue. You know, take the bus, go to the clinic, get the tablets that she's got to take every day. Now that could possibly change, because we have newer technologies, in particular an injection that you can take once every six months. This particular injection, if taken once every six months, was shown to be a hundred percent effective in young women. That's a very powerful tool.

Chris - Is there a risk though, that if people use things like these pre-exposure prophylaxis approaches, that they are then less careful and you prevent one disease and HIV is very important, yes. But are people then placing themselves at risk of others because they're not using condoms or other barrier methods for example?

Salim - In most of the places where we do reproductive health promotion, it does not lead to, you know, everybody just having sex. But what does happen is that when these educated individuals do have sex, they understand the importance of protection. Now we have seen with pre-exposure prophylaxis that there are in certain instances, a situation where we see an increase in the prevalence of gonorrhoea. In other words, we are seeing sexual activity and we are seeing a risk of other sexually transmitted infections. Overall, the key goal, which is to reduce the prevalence of HIV, which is the disease that can't be cured, the focus is on trying to bring down the number of new infections with HIV.

Chris - You mentioned earlier the role that circumcision can play. It's going to be quiet on that front because a lot was said about that, about 10-15 years ago when these various manoeuvres were put in place to try to do this. How's that working out, has that made a difference?

Salim - So three clinical trials undertaken in the early two thousands all showed quite consistently that circumcision is effective in preventing HIV in men, protection is around 60% or so. So on that basis, huge programs were put in place to roll out circumcision. And when we rolled out circumcision, we rolled it out to those men we thought were at highest risk. The uptake is a challenge, and what we found was the ability to roll it out at scale was a challenge, you know, as to start doing hundreds of thousands of circumcision, not easy to do. So circumcision has had a role to play in particular communities where a circumcision can make a difference. As an overall population strategy, it has not been as effective as we would like it to be. So that's why newer technologies like pre-exposure prophylaxis become more important when we are now aiming towards the 2030 goal of ending AIDS as a public health threat.