At the open-air Panorama bar on a hill outside Blantyre, Malawi, a local band pumps out heavy rock into the warm African night. Girls with spray-on trousers and plunging necklines eye the men, approaching strangers as if they were old friends.
Young urban Malawians are no different from young people everywhere. They like to go out, to drink and dance and flirt. But one in four of those shaking their booty on the dance floor will be infected with HIV - and an untold number will pass the virus on through unprotected sex.
Out of the desire that drives men and women together has come a disease which is destroying Africa - and has spread around the world. Twenty-five years after an outbreak of the illness that would become known as Aids was first reported, more than 40 million people are living with HIV infection and 25 million have died.
One of the tragedies of the Aids story is that while vast sums of money have been poured into research aimed at finding a cure for the disease, far less effort has been expended on understanding the social and cultural forces that have fanned the flames of the pandemic.
World leaders attending a UN summit in June described it as an "unprecedented human catastrophe" and set a new "funding need" of between $20bn and $23bn a year - more than double the sum set by the last UN summit on the disease five years ago.
But to the anger of Aids activists, they refused to commit to hard targets in funding, treatment and prevention and failed to identify the groups at highest risk - gay men, injecting drug users, sex workers - or the strategies required to tackle the disease among them for fear of upsetting where nations which do not acknowledge that they have a drug problem or gay citizens.
Today the biggest ever conference on Aids opens in Toronto, Canada, attended by 20,000 researchers, campaigners, lobbyists and patients from around the globe and featuring headline speeches by Bill Clinton and Bill Gates. Its theme, "Time to Deliver", illustrates the frustration many feel with the slowness of the international response, and the failure of scientists, policy makers and national leaders to mount an effective response against the virus.
There are some grounds for optimism. For the first time in its history, the Aids pandemic appears to be slowing and, in some countries, even receding. Adult HIV infection rates have declined in Kenya, Zimbabwe, urban parts of Haiti and Burkina Faso, according to Purnima Mane, policy director of UNAids.
Worldwide, HIV incidence rates are believed to have peaked in the late 1990s and to have stabilised since, UNAids reported. But in many parts of the globe - India, China, Russia - the epidemic is still in its early stages, growing fast and nowhere close to its peak.
At the same time, the roll-out of cheaper, life-saving antiretroviral drugs is pushing ahead. At least 1.3 million people in poorer countries were receiving the drugs by the end of last year, a threefold increase since December 2003, and there has been a further surge in the numbers since. This is vastly in excess of what was thought possible a few years ago but still far short of the World Health Organization's old "three by five" target - three million patients on drugs by the end of 2005.
Vast new resources have been pumped into the fight against the disease over the past five years, current global funding topping $8bn. Political leaders, with some notable exceptions, have woken up to the threat and to the need to mobilise their populations. But in some of the worst-hit countries there is still denial of the challenge faced, marginalisation of the highest risk groups and lack of investment.
Richard Feachem, executive director of the Geneva-based Global Fund to Fight Aids, Tuberculosis and Malaria, which has pledged over $10bn in support to 132 countries, said: "Our optimism is mixed with impatience, anger and the need to re-energise ourselves for the massive scale up that is needed over the next five years. We are spending $8bn a year, which is a huge improvement on where we were but we need to be spending $20bn a year."
The world is better prepared to deal with the pandemic than ever before, according to UNAids. Clear strategies to halt the spread of the virus have been worked out, there is more funding, and drug treatment that can keep people alive - although not cure them - is slowly reaching people in the poorest countries. But huge political, social, financial and technical problems remain.
The Toronto conference marks a second key milestone in the epidemic. It is exactly 10 years since the stunning breakthroughs in clinical research that led to highly active antiretroviral therapy (Haart) - the three-drug cocktail which is now the mainstay of Aids treatment - announced at the last international Aids conference held in Canada, in 1996.
Haart revolutionised HIV treatment, and for a few heady days at that conference in Vancouver fostered a mood of unbridled optimism. Aids had been transformed from a killer disease from which people died rapidly to a chronic disease, like diabetes, with which people might live out a near-normal lifespan. And it held out the tantalising promise of a cure.
That has not happened. There have been advances - new, better drugs, simpler combinations that are easier to take and the first one-pill-a-day, a combination of three drugs called Atripla, was approved by the US Food and Drug Administration last month.
These advances, combined with better, quicker, simpler diagnostic tests will bring treatment to more people and improve compliance which is crucial to preventing the development of drug resistance.
But the Holy Grail of Aids research - a vaccine to prevent the disease - continues to elude scientists. The most promising candidate, Vaxgen, flopped disastrously after trials in Thailand in 2004, despite promising results in the lab. Hope now rests on a Phase 3 trial involving 16,000 volunteers in Thailand using two proteins from the HIV virus to trigger an immune response. Results are expected in 2007 or 2008.
No one is holding their breath. So far $3.4bn has been invested by the US National Institutes of Health and $528m by the Gates Foundation to develop a vaccine, and some scientists are questioning whether the money could be better spent.
Sheena McCormack, a scientist specialising in HIV prevention at the Medical Research Council clinical trials unit in London says: "The Vaxgen failure was a definite setback. There is a feeling that we have to go back to the drawing board. What makes it so difficult is that the virus keeps changing to evade the immune response.
"Maybe we can never protect against HIV and the most we can do is modulate the infection, reduce the viral load, reduce infectivity and delay the time to treatment. That would be a gain."
A trial of such a vaccine, made by the US company Merck using an adenovirus vector (a virus used like a Trojan horse), is being planned. But it will be years, if not decades, before a usable vaccine reaches the market.
One man who is defying the doom-mongers who say the project is impossible is the computer magnate Bill Gates. Last month, his foundation gave $287m to the search for a vaccine, the largest grant it has awarded to HIV research. "We're not going to give up working on an Aids vaccine. Not in my lifetime," the Microsoft billionaire said.
One of the most promising areas of scientific advance is in the development of microbicides - gels or creams which women can insert into the vagina before sex to protect themselves from HIV infection.
Details of the latest research, to be presented at the Toronto conference will focus on five products being trialed in Africa, India and the US.
One, called PRO-2000 being tested by the Medical Research Council, is halfway through recruiting almost 10,000 women in Africa. A second, called Carraguard, is undergoing trials which are expected to report in 2007.
"If they are shown to be effective at a high enough level to get a licence they could be on the market by 2008," said Dr McCormack. "That would be very fast but there would be a huge will to do so and enormous public pressure."
An effective product could transform the outlook for women. For most of its 25-year history, Aids affected more men than women. It was first recognised among the white, middle-class gay patrons of the bath-houses of San Francisco. Even a decade ago, in sub-Saharan Africa, the disease was most prevalent among men who had left their homes and families in rural areas for jobs in the towns where they sought consolation with female sex workers.
But in recent years the virus has taken hold among women because of their greater biological and social vulnerability. During sexual intercourse the virus transmits more readily from men to women, and the lower social ranking of women combined with their lack of power means they cannot negotiate to avoid sex or to protect themselves with condoms.
However, experts warn that even an effective product may fail if women are not prepared to use it. Deborah Jack, chief executive of the National Aids Trust, said: "The science is moving forward and that is great. But what we need to ensure is that communities accept it. Would a woman need to tell her partner? Would he be able to detect it? If it were promoted as a vaginal hygiene product people might be more likely to use it."
Microbicides are among key developments in prevention that will be debated in Toronto - along with a parallel discovery in men. Research published last year showed circumcision reduced the risk of HIV infection in men by 60 per cent. The removal of the foreskin - rich in receptors and blood vessels and thought to be the main point of entry for the virus - could save three million lives over 20 years if all men in sub-Saharan Africa were circumcised, scientists have calculated.
The discovery has already led to a surge in young adult men seeking circumcision in South Africa, and some experts believe it heralds a global change in attitudes to the operation, which has fallen out of favour in the west over the last 50 years.
Yet despite all the advances in science, medicine and prevention the epidemic continues to outpace efforts to prevent it.
India has overtaken South Africa as the country with the most people living with HIV. The biennial UNAids report issued in May on the progress of the epidemic estimated that 5.7 million Indians were infected by the end of 2005 compared with 5.5 million people in South Africa.
As a proportion of the population, however, Africa remains the continent hardest hit by Aids - fewer than 1 per cent of Indians are infected compared with 18.8 per cent of South Africans.
The remorseless advance of the virus continues to infect a further nine people every minute, devastating families, communities and economies. It will claim almost four million lives this year, more than 500,000 of them children.
The steepest increase in HIV infections last year, however, was in Eastern Europe and Central Asia, where they rose 25 per cent to 1.6 million. In this region and in Latin America, drug users who inject and sex workers are the chief drivers of the epidemic.
In Russia, where an estimated 1 per cent of the population is infected, experts fear the country is on the cusp of a catastrophe. In 2001, 95 per cent of new HIV infections in Russia were transmitted by injecting drug users who shared needles, mainly men.
By 2005, almost half of new cases - 43 per cent - were contracted through heterosexual sex - and the victims were mostly young women aged 20 to 29. Experts say Russia is where South Africa was in 1991, and the virus is poised to rampage through the heterosexual population and into western Europe.
But sub-Saharan Africa remains the worst-hit region, with three million new infections, almost two thirds of the global total of 4.9 million. Even in those areas where infections rates have fallen, such as Rakai in southern Uganda, researchers found most of the gain came for higher death rates. HIV had spread so far within the community that victims were dying faster than new ones could become infected.
The fall in rates also led to complacency in the local population and signs of a "possible resurgence" in HIV infection in men and women aged 15 to 24.
Peter Piot, executive director of UNAids, says: "The reality is the Aids epidemic continues to outstrip global and national efforts to contain it. I think we will see a further globalisation of the epidemic spreading to every single corner of the planet. It won't go away one fine day, and then we wake up and say, 'Oh, Aids is gone.'
"A rapid increase in the scale and scope of HIV prevention programmes is urgently needed"
The US President's Emergency Plan for Aids Relief, while unlocking funds and boosting treatment worth $15bn, has had a disastrous impact on prevention because of its emphasis on abstinence and its resistance to condoms. The American veto on sex outside marriage has led to family planning organisations across Africa losing funding.
Hopes were raised earlier this year that Pope Benedict XVI was poised to relax the Roman Catholic church's opposition to condom use for married couples where one partner was HIV-infected. Cardinal Javier Lozano Barragan, head of health policy at the Vatican, disclosed that his office was a preparing a report on the issue but there was no indication of when or whether the Pontiff would pronounce on the matter.
The failure to distribute treatment to more than a fraction of those who desperately need it continues to anger Aids activists. Problems of access are certain to dominate the Toronto conference. Yet 10 years ago, when Haart was first announced, no one could imagine that such costly and technologically-advanced medicines would ever be made available in poor countries.
Since then HIV/Aids research and activism have revolutionised the notion of public health and shown it can be done, according to Helene Gayle, president of the International Aids Society.
"The World Health Organization's 'three by five' initiative fundamentally altered our thinking about what we can accomplish in the developing world. It shattered for ever the tacit acceptance in industrialised regions that millions in developing nations would die simply because they were poor," she wrote in The Lancet.
Increasing access to treatment is the key to successful prevention. Once drugs are available, people have a reason to go and get tested and once they know their HIV status they can be counselled to avoid further spread.
As treatment is rolled out, however, it will bring new challenges. Drug resistance is already a reality and will grow as the numbers on drugs expand - creating a constant pressure for new and better drugs. At the same time, as more people are living longer with HIV/Aids, thanks to treatment, there is an increased risk that the virus will be passed on.
"We have an effective therapy and we have an absolute duty to deliver it to those who need it," Richard Feachem of the Global Fund said. "We have to put as many people on therapy as we can and by so doing extend their lives by many decades and avoid creating more orphans. But these are challenges we will face. We need more monitoring in the field to track resistance and stay ahead of the curve. Science has to keep one step ahead."
The Specialist: Your chance to help HIV sufferers
Dr Macky Natha, a specialist in HIV medicine in the UK, is taking a year out to work in a Zambian Health Service clinic. He is heading for an area where 20 per cent of the population is HIV positive, and will join a dedicated team treating 30,000 people (a figure equivalent to half the total HIV positive population in the UK), helping to educate people and treat and contain the virus.
Although antiretro-viral drugs are now free, the hospital has no trained HIV/Aids clinician. Dr Natha will be heading this initiative but needs to raise money for the clinic to cover the costs of the project and fund a documentary.
If you would like more information or to make a donation, contact Dr Natha by email on macky_natha@ yahoo.co.uk
Born HIV positive: 'It's never stopped me from doing anything'
Tanya Fletcher, 20, lives in London. She is looking for work as a secretary.
"When I was told that I had HIV I felt numb and then became suicidal. I was 13 and it's likely that I was born with HIV. My parents and I don't speak any more so I don't know all the details. My mother lives in South Africa, and my father lives here. I was put into care because I didn't want to be at home any more. It's not the end of the world having HIV. It's never stopped me from doing anything. I only really think about it when I go to the hospital for a check-up every six months.
"My virus has been undetectable for the past five years. I've been taking medication since I was 13. I've never had a bad reaction from anyone I've told. I've only had one sexual partner and he was one of the first people I told when I first knew. I'd like a boyfriend now. I would tell him, of course. If he couldn't handle it, I wouldn't think all men were like that. I don't want to have children. I know there's a chance that the child would have HIV and I don't think I could cope with that. I might change my mind. If I continue to take my medication and keep healthy, my HIV status is likely to take a very long time to develop into Aids. I don't worry about it. I'm happy with who I am, what I have.
"People's lack of knowledge about HIV really annoys me, as well as the stigma. Another problem is that people think that HIV is treatable and assume they can sleep with as many people they like. "
Interview by Julia Stuart. Tanya Fletcher is a pseudonym. Children with Aids Charity: 020-7247 9115; www.cwac.org
Long-term survivor: 'You don't treat disease. You treat people...'
Dr Rupert Whitaker, 43, is a consultant in behavioural medicine. He lives in London.
"I have lived with HIV for about 25 years - there are very few of us left. Statistically, I should be dead. I was diagnosed in 1983, the year after my partner, Terry Higgins, died. I was told not to expect to live more than a year, but I did. I can't imagine who I would be if I didn't have HIV; it has defined my life from such an early age.
"After co-founding the Terrence Higgins Trust, I went to America and got a double doctorate in psychiatry and immunology, specialising in HIV. At the age of 30, I had a stroke and spent two years learning how to control my body again. I've been on combination therapy for 10 years but came off it about six weeks ago. Over the past two years I've had a really awful illness. I suffered from psychosis and lost control of my muscles again and the ability to walk. It was caused by an HIV medication. Since I came off those medications, I'm back to feeling well, but my viral load has shot through the roof and my T cells are starting to tumble.I'll have to go on other medications. Hopefully, they will help me to make my life worth living; I didn't survive this long to live that sort of a life.
"I've been working on the design of clinical services for chronic illness, quality of care and patient safety. The problem people with HIV are facing in is NHS indifference and lack of co-operation. Generally, I'm a happy person, however there is a deep vein of anger over box-ticking in the NHS. You don't treat disease, you treat people. After 25 years, NHS physicians still don't want to learn this."
Interview by Julia Stuart. Terrence Higgins Trust: 020 7812 1600; www.tht.org.uk
Recently Diagnosed: 'You get a sense of your own mortality'
Clayton Brown, 38, lives in London and is a freelance writer for Positive Nation.
"I'd undergone regular testing for years and had always been very careful, apart from the odd slip - and it was by the odd slip that I contracted it. I traced it back to the person who infected me, and he didn't want to know - he wouldn't even look at me. I was mortified, but above all I felt that my dignity had been stripped away by one individual. Sexual diseases make people uncomfortable. Are they going to think that I have been promiscuous? It's hypocritical because there isn't a man or woman on this planet that hasn't ever had unsafe sex.
"I started attending a support group that offered counselling and discussions for newly diagnosed people, but it didn't work for me. These groups can't help the feeling of isolation that comes with HIV; what you need is the support of your family and friends. Unfortunately, my family hasn't spoken to me since, but it is still early days and I am lucky to have friends I can talk to.
"Being diagnosed has propelled me into action, because you really get a sense of your mortality. I have finally started doing all the things I wanted to do but have been putting off. I decided to start writing about my experiences for Positive Nation. I started to get fair-weather friends out of my life, to sell my flat and go travelling in the Caribbean for the next six months.
"My intention is to continue living well, to go out of this world doing what I have always wanted to do. HIV is not a death sentence. If you don't look at the positives your life will be even shorter."
Positive Nation: www.positivenation.co.uk
The infected wife: 'He had unprotected sex before we were married'
Aanannandi Yuvaraj, 41, is a programme officer for the International HIV/AIDS Alliance in Delhi.
"Most Indian women contract HIV from their spouses. Society thinks that marriage protects women, but it doesn't. I contracted the virus from my husband: I was married in 1995 and I was diagnosed in 1997. He told me that he had unprotected sex before the marriage, but we didn't fully realise the risks - I didn't relate unprotected sex to HIV.
"Eighty to 85 per cent of HIV women in India have monogamous relationships but get HIV from their husbands. In Indian society it is acceptable for men to be promiscuous, but not for women. If the men are being unfaithful to their wives they don't want to buy condoms because they think it creates suspicion, and in a marital relationship you cannot use condoms.
"When I found out that I was HIV positive my husband was so guilty that I actually ended up having to comfort him. He refused to talk about it; he tore up the test results and said, 'No one should see that.' Eventually we had to separate legally. My mum couldn't quite understand the concept of me being ill because I seem healthy and active.
"My husband died six years ago, but I have been well for many years now by eating right and looking after my body. I've postponed treatment for many years but when I visited my doctor recently he told me I should start the drugs in October. In this country we didn't have access to these kinds of drugs before, so I am very lucky to have them available to me on the public health system. I had a deep-seated fear of a life-long dependency on drugs, but I do not have much choice at this stage."
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