One in four people infected with the Aids virus in Southern Africa are hyper-infectious super-carriers, scientists at Harvard University have discovered. By targeting these individuals for treatment, the scientists hope it may be possible to counter the rising number of new HIV infections in the worst-affected parts of the world in what could be a major breakthrough in the fight against the spread of Aids.
A bold and radical plan to open a new front in the battle against Aids will begin in Southern Africa next year with a clinical trial to "test and treat" hundreds of HIV-positive people believed to be at the highest risk of transmitting the virus.
Each year, some 2.7 million people around the world become infected with HIV. An overwhelming proportion of them live in the worst-affected countries of Southern Africa despite intensive efforts to prevent new infections with education and condoms.
The researchers believe that one of the reasons Southern Africa is so badly hit by Aids is because the prevalent strain of HIV in the region, called HIV-1C, causes a significant proportion of infected people to go through a prolonged period when they are super-infectious. Scientists have called this large minority "hypertransmitters".
The aim of the project in Botswana is to identify these hypertransmitters as soon as they become infected so that they can be treated with a powerful cocktail of antiretroviral drugs which should limit their ability to transmit HIV to their sexual partners.
If the plan works, it may be possible to extend the initiative across Southern Africa where HIV-1C is rampant and rates of infection are the highest in the world, said Max Essex, a professor of health sciences at Harvard University in Cambridge, Massachusetts.
Professor Essex said: "This is different from all the other approaches based on prevention, such as vaccines or condom use, because they are based on somehow lowering your own chances of getting infected by someone who is already infected.
"Whereas this approach is designed to target that subset of individuals who are most likely to infect you or others in general by treating them in the same way we treated breast-feeding mothers so that they didn't infect their infants."
Anti-retroviral drugs are usually only given to infected people who fulfil certain criteria, such as a low concentration of white blood cells. In the trial next year in the village of Mochudi, 20 miles from Gaborone, the capital of Botswana, Professor Essex plans to add another category – healthy people in the "acute" phase of infection who have been identified with high viral loads. "If we could target these putative hypertransmitters who are going through this extended acute phase, and selectively give them antiretroviral drugs to prevent their infection to others, that might be a cost-effective way to reduce new infections in specific regions," Professor Essex said.
"What we're proposing is not to treat everyone, but to selectively treat a quarter or so of the newly infected people who are, we believe, much more likely to infect others than the rest. You test everybody to see if they have a [high] viral load, and if they do you put them on drugs independent of any Aids-defining illness criteria. If they don't have a high viral load, you don't put them on drugs.
"Within a few years you would decrease incidence significantly because the number of people who can infect others is going down."
One of the reasons why the village of Mochudi was chosen is because it has a high prevalence of HIV. About a quarter of the adult population of 23,000 people are estimated to be infected with the HIV-1C strain of the virus.
An added advantage of working with a largely self-contained village such as Mochudi is that scientists believe it may be possible to study how the virus mutates as it travels from one person to another through the community.
The science behind the trial
People newly infected with HIV go through a feverish period of "viraemia" when levels of virus circulating in their bloodstream rise rapidly. These high "viral loads" make the person more infectious and the phase usually lasts for about two months before the immune system brings the virus levels back down to a lower "set point".
However, with the Southern African strain of the Aids virus, HIV-1C, this period of viraemia can last for a year or more in a high proportion of newly infected people, making them "hypertransmitters" for longer than is usual in other parts of the world, said Professor Max Essex of Harvard University.
"What we've shown in Southern Africa is that something like 20 or 30 per cent of people do not drop down to that lower 'set point' after their initial peak of infection with high viral load. They maintain a high viral load for at least a year or two," Professor Essex said.
By studying the genetics of the virus in the village of Mochudi in Botswana, the scientists hope to find the reasons why this particular strain has such a long acute phase when viral loads are high.
"Essentially the entire epidemic in Southern Africa is HIV-1C. There may be a sub-subset of viruses that leads to this high extended acute stage of viraemia hypertransmission and we're testing to see if we can map that genotype," Professor Essex said.
Elton's Heroes: #1 Gary Hume
Gary Hume's paintings are joyful and uplifting. They distil pure moments of joy – a bit like some of Elton John's best songs. Like his work, Gary himself seems deceptively straightforward – but when you analyse what he says, there's nothing superfluous. He puts in a lot of thinking. I asked him, does it require discipline to stick to a regular routine?
"Painting is what I like doing more than anything, so it's hardly a chore," he says. "The discipline isn't needed to work, but to leave my studio and go out. This is where I am happiest... some days you don't care enough to be able to do it, other days you care too much and you just get stuck, pacing about, cursing."
Years ago, Elton commissioned a piece of work for his shower room, at a time when Gary didn't really make sculptures. He couldn't get started, and in the end Elton said: "Do whatever you like, just write Elton is a cunt, I don't care." In the end he made a beautiful marble piece and their relationship took off. According to Gary, "that kind of patronage, where you want to produce your very best, enabled me to go on and make other pieces for Elton".
Gary made a sculpture of a snowman – two giant spheres, one balanced on top of the other ("because a snowman is just so romantic, they're not around very long"). Elton installed it in his garden in Nice. As you drive up the steep slope to the house, through mature trees and lush green lawns bordered with white flowers, The Snowman sits in a commanding position, Lord of all he surveys. You can't help but smile.
Then Gary made four sculptures for the formal garden, which is lined with box hedges. Inspired by American cheerleaders, they're called The Parade. Elton gave him no brief at all, letting Gary get on with it. For an artist this is liberating, and all too rare: "Too often people come to the studio and say, will you make me a piece in a different size or colour, and I tell them you might as well make it yourself!"
Gary's paintings make you look at the everyday with fresh eyes. Their beauty is timeless, classic. I wondered how he lets them go.
"I kiss them goodbye. I sell everything I do, but when I sometimes borrow them back for a museum show, it's lovely to meet them again."
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