By Meredith Wadman of Nature magazine

Thirty years after AIDS was first recognized as a human scourge, major recent gains in treatment and prevention risk being derailed by the global financial crisis.

On 23 November, the Global Fund to Fight AIDS, Tuberculosis and Malaria announced that it will not fund new grants for prevention and treatment until 2014, owing to "substantial budget challenges in some donor countries". The fund's HIV activities run the gamut from counseling and testing pregnant women in India to providing medications to infected children in Kenya.

And on 7 December, a report from Policy Cures in Sydney, Australia, a group that monitors global research and development for neglected diseases, showed that public and private funders last year cut their commitments to HIV/AIDS research targeted at the developing world by US$67.5 million, or 5.9%. The decline was due entirely to cutbacks by wealthy nations, which slashed spending by $72.6 million; poorer countries actually increased funding by $5.1 million. Where research is concerned, "AIDS had a bigger drop in dollar terms than any other disease", says Mary Moran, the executive director of Policy Cures and the lead author on the report.

The threat comes even as US President Barack Obama last week promised that the United States will step up its worldwide attack on AIDS. Breaking the White House's past reticence on the issue, he urged nations to honor their unmet pledges to the Global Fund.

"Countries that have committed to the Global Fund need to give the money that they promised," he said on 1 December, World AIDS Day. "Countries that haven't made a pledge, they need to do so," he added, singling out emerging nations such as China that are recipients of funds "but now are in a position to step up as major donors".

The United States has given $6.1 billion to the Global Fund since 2004, and last year pledged to contribute $4 billion between 2011 and 2013. Congress approved $1.05 billion in 2011, meaning that allotments must increase substantially in 2012 and 2013 to honor the pledge. Obama has asked Congress to provide $1.3 billion in 2012, but Senate lawmakers have so far resisted the increase.

Obama pledged to increase by 50% -- to 6 million -- the number of people receiving antiretroviral therapy (ART) worldwide by 2013 through the President's Emergency Plan for AIDS Relief (PEPFAR), the nation's major global treatment and prevention program. He also said PEPFAR would aim to provide ART to an additional 1.5 million pregnant women with HIV in the next two years. The international promises came with no new money immediately attached. But Obama has asked Congress to provide nearly $7.2 billion -- a 6% increase -- for PEPFAR in 2012, part of the unfinished budget bills still being debated.

Advocates said that his speech marked a significant turning point. "This is the first time he's signaled that he's going to champion global HIV in this way," says Jennifer Cohn, an assistant professor of infectious diseases at the University of Pennsylvania in Philadelphia, and a policy adviser in Nairobi for Médecins Sans Frontières (MSF; also known as Doctors Without Borders). "Whether or not this gets translated into the president's 2013 budget request, or what Congress chooses to protect during the 2012 budget negotiations -- that's what I'm waiting to hear."

Even if the United States manages to expand treatment for HIV/AIDS, research and development aimed at poor countries is suffering. Moran points out that of the $67.5 million cut from HIV/AIDS research spending in 2010, $32 million was due to cuts by the US National Institutes of Health, and a further $17 million was cut by the UK Department for International Development (see 'Fighting a killer'). Other neglected diseases are seeing similar reductions in research funding (see go.nature.com/sgv7oj).

"A lot of this reflects the financial crisis, that's undoubted," Moran adds. "But with HIV, some of it also reflects a shift from the more costly late-stage vaccine and microbicide trials that haven't worked. We are moving back to basic research, which is cheaper."

The cutbacks coincide with encouraging results on HIV/AIDS treatment. One study published in August found that early treatment of those infected greatly decreases sexual transmission to their uninfected partners, (M. S. Cohen et al. N. Engl. J. Med. 365, 493-505; 2011). Other recent work suggests that ART, although costly, will pay for itself and more by increasing labor productivity, reducing the need for orphan care and deferring medical treatment costs (S. Resch et al. PLoS ONE 6, e25310; 2011). "Not only is [treatment] the right thing to do, it's also the smart thing to do," says Sharonann Lynch, an HIV policy adviser with MSF in New York.

But the 'treatment equals prevention' equation invoked by Obama is not selling in all quarters. Roger Bate, a health economist and HIV expert at the American Enterprise Institute, a think tank in Washington DC, says that he is not yet persuaded by the studies suggesting that treatment prevents transmission. "There is a lot of effort out there to ignore noise in those studies," he says.

He adds that, even if treatment does prevent transmission, the commitment to treat infected people for their lifetimes quickly becomes an enormous financial outlay in future years. "Is it sustainable to treat even more people under current budgets?" he asks. "I don't think it is."

This article is reproduced with permission from the magazine Nature. The article was first published on December 7, 2011.