After researching HIV for over a decade, I know that we now have the information, the tools and the money required to eradicate Aids in most of the world. But we’re not doing it – and that makes me very angry.

To be fair, Britain has been a world leader in sensible HIV prevention. Under Margaret Thatcher, we were the first country to fund clean needles for drug injectors at a national level, and to make methadone widely available so that heroin addicts could stop injecting. The result: fewer than one in 75 drug injectors in Britain is infected with HIV, compared with one in two in Indonesia, for example.

For all its sensible policies, though, Britain won’t give out needles in prison. Yet two-thirds of all injectors in Britain have been to prison at some point; and nearly a quarter of all male injectors in prison say they’ve shot up while inside. Meanwhile, taxpayers fund needle-exchange programmes in prisons in other countries through the Department for International Development. But in Britain, the Home Office dictates what happens in prison, and denial rules.

I call it the Three Monkeys approach to HIV: we close our eyes to people injecting drugs, to people buying and selling sex, to people getting plastered and getting laid. We close our eyes, in short, to all the things that do the most to spread HIV.

Yet we can’t close our eyes to the fact that nearly 60m people have been infected with a preventable, fatal disease. About 25m of those are already in their graves. It’s also hard to ignore the fact that two-thirds of people with HIV in the world are Africans. Yet few people ask why.

HIV is largely a sexually transmitted infection, so there must be something different about sex in Africa. Yet you can’t say that without appearing to be racist. So campaigners have come up with other reasons that HIV is worse in Africa: poverty, ignorance, men having more power than women. All politically correct, but not epidemiologically correct.

The truth is that a society in which many people have two or three partners on the go at any one time will produce a bigger epidemic than a society where people may have 10 partners in five years, but only one at a time. And it’s a fact that in parts of Africa, it’s more common for both men and women to have two or three simultaneous relationships than to have serial partners. Do people behave in this way because they are poor and ignorant? Not in Bangladesh, or Bolivia, or dozens of other countries where incomes and literacy are low. Indeed, in Africa, the incidence of HIV infection is highest in the richest households and the richest countries.

In east Africa, HIV spread first among people who had lots of partners – in other words, men and women who traded sex for money or favours. Had condom use in commercial sex been pushed to very high levels at the time – as happened in Thailand – the epidemic would have been contained.

But most African leaders played Three Monkeys. So a miner infected a prostitute, who infected another client, who went home and infected his wife, who infected her regular boyfriend. Suddenly, HIV was everyone’s problem.

In Africa. Outside the continent, most people infected with HIV are men who have anal sex with other men, people who inject drugs and people who buy and sell sex, as well as their lovers. Indeed, it was these groups that first surfed into public consciousness. Early in the epidemic, the virus was treated as a sign of wickedness, a black mark for bad behaviour. But voters don’t care for the wicked; ergo, politicians don’t care for the wicked. Ergo, no money for HIV.

God knows, we needed it. When I started out in this business in the mid1990s, the world was spending just $250m a year on HIV in poor countries. Later, as African infection rates soared, HIV was repositioned as an affliction of the innocent. The cash started to roll in and, last year, the world spent $10 billion on HIV in poor countries.

When the funding pie was small, HIV prevention meant doing helpful things for sex workers, gay men and drug injectors. Now that the pie has grown to 40 times its original size, and HIV has been painted as almost exclusively a matter of poverty, youth and “innocent victims”, everyone wants a bite.

The UN agencies were the first to jump on to the growing pile of funding, each finding a way to link the blood-borne virus to its own mandate. Other agencies dealing with children, development, economics, labour and agriculture all suddenly found that HIV was fundamental to their work. But the trail of funding hasn’t always taken them in the right direction.

It’s true, of course, that HIV has become a generalised problem in east and southern Africa, where, frankly, it is hard to know what to do about it except pray for better leaders. But what is true of those areas is simply not true for the rest of the world – where the “Aids is everyone’s problem” approach can do a lot of damage. A couple of years ago, I received an e-mail from Save the Children UK, asking for a reference for someone who had applied to be their HIV adviser in Indonesia. I asked why they needed an HIV adviser when only one in 22,000 of that nation’s children suffer from HIV – and most infections are in adult men. The charity would have been better off working on routine health services, education, even sanitation, I suggested. But no, Save the Children would do HIV in Indonesia, come hell or high water, because it was a corporate priority.

I felt like sending them to see Lenny Sugiharto. Lenny had come to the HIV prevention group I worked with, looking for funding for an “information, education and communication” programme for transgender sex workers (waria) in Jakarta.

Our information on HIV among waria was sorely out of date. So we did a study; and a week later, I went to the lab to pick up the colour-coded HIV test results – red for positive, blue for negative. The list was a quarter red.

To the embarrassment of the lab staff, I wept. And when I told Lenny the results, she went as grey as her Muslim headscarf. Then she drew up a new proposal for prevention and care. If only the policy-makers of the world were more like this transgender sex worker. If only governments, UN agencies, even big nongovernmental organisations could relate the science to the reality and do the things that make the most difference. Sadly, it doesn’t work like that.

Organisations raise money through appeals; and photos of orphans with big eyes set the registers ringing. Have you ever seen a flyer with a prostitute on it? Or a picture of a young guy about to inject himself?

Even Irish pop star Bono, so gifted at whipping up moral outrage, can recognise a losing battle when he sees one. Bono’s Product (Red) campaign, which allows people to feel good about buying gadgets because a fraction of the profit goes to “fighting Aids”, is very careful about what it funds. So careful that it actually breaks the rules of the Global Fund on Aids, TB and malaria, to which it gives the “red pound”.

The fund was supposed to make it easier to pay for the difficult stuff – such as needle exchanges, or clinics for sex workers. In theory, all the money goes into a single pot. Poor countries put forward proposals, a panel of experts vets each request, then millions are dished out to the most deserving.

Donors are not supposed to cherry-pick (“I’ll have the orphans, please; thanks, but no junkies”). Yet (Red) has ploughed more than $100m into the Global Fund – and every penny is earmarked for drugs to prevent pregnant women from passing HIV on to their babies, for treatment of the sick and for support for orphans.

In other words, (Red) has chosen the projects that consumers of iPods and Gap T-shirts can feel good about. Because nearly everyone feels good about treating sick people – but preventing them getting sick in the first place: well, that’s a lot more controversial.

In east and southern Africa, two decades of denial and mismanagement have allowed the HIV virus to hollow out whole countries. In the rest of the world, HIV continues to threaten men and women who inject drugs, buy sex or sell it, as well as men who have sex with one another. The lovers of those people are at risk, too.

Together, they add up to tens of millions of souls – so we don’t want funding for HIV to evaporate. We just want to be able to use more of the money doing sensible things to prevent new infections.

Elizabeth Pisani’s new book, The Wisdom of Whores, is published by Granta on Tuesday, priced £17.99. She blogs on sex and science at www.wisdomofwhores.com

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