But the 17th International AIDS Conference that ended here Friday has highlighted the dilemma of this success: the more lives you save, the more the bill goes up.
With no cure or vaccine in sight, and with the lifeline comprising a regimen of powerful drugs that must be taken daily, the money crunch is doomed to return -- and with a vengeance.
"It is extremely improbable that we will have the structure and financial ability to take on all the people who require ART [antiretroviral therapy] and then treat them for life," Anthony Fauci, director of the US National Institute of Allergy and Infectious Diseases (NIAID), warned on Wednesday.
In 2007, 8.1 billion dollars were mustered to fight HIV/AIDS in the developing world, home to 90 percent of the 33 million people with the human immunodeficiency virus (HIV), according to the UN agency UNAIDS.
That effort is already a Herculean advance compared with the start of the decade, yet even so, less than a third of the 9.7 million poor people whose immune systems are so impaired by HIV that they urgently need the drugs have access to them.
At the current pace of scaleup, 22 billion dollars will be needed in 2015 just to get antiretrovirals to eight million infected people.
And that's just the minimum.
If the world is serious about achieving universal AIDS drug and care access by 2010, a goal enshrined by the UN General Assembly in 2006 and endorsed by the Group of Eight (G8), the bill rises almost exponentially.
The cost of universal access would be 42.2 billion dollars in 2010, five times 2007's expenditure -- and in 2015 it would be a whopping 54 billion dollars, to keep 21.9 million infected people alive.
"If you add the current 35 billion that is being spent in the developed world, you're talking at that time [about annually needing] almost 90 billion dollars, in a continuous fashion," Seth Berkley, head of the New York-based International AIDS Vaccine Initiative (IAVI), told AFP.
"And that doesn't even take into account complications with secondary resistance to drugs and other issues."
With no cure in sight, the pendulum of debate is swinging from treatment to prevention to stop the tally of infections from rising further.
One of the big focuses of the conference was on how to reinvigorate grassroots work.
This often-overlooked business involves promoting safe sex among young people, ending coercive sex for women and easing stigma against gays, intravenous drug users, sex workers and other groups where the virus finds fertile ground for leaping into the wider population.
By far the brightest news from the conference was about male circumcision.
Surgical removal of the foreskin decreases the risk of contracting HIV by 65 percent, according to the latest data from a US-led study in Kenya.
Those findings, three and a half years after the project began, compared favorably with 60 percent protection measured at the two-year mark.
This extraordinary evidence will put pressure to launch a broad campaign of circumcision among men in sub-Saharan Africa, where two-thirds of the world's HIV population resides.
Experts warn, though, that such a campaign has to be thoroughly prepared and financed, as botched operations and cultural or religious resistance could cause the whole strategy to backfire disastrously.
Veteran AIDS campaigners, questioned at the conference by AFP, agreed that there seemed to be a lull in a war that has claimed more than 25 million lives since the disease emerged in 1981.
Stephen Lewis, former UN special envoy for AIDS in Africa, attacked what he called "a kind of curious passivity among the international AIDS establishment" after the achievements in money-raising and drug access over the past two or three years.
He believed that "generational change" would come, as younger people would take the baton handed on by the men and women in their fifties and sixties who had been fighting AIDS for two decades or more -- a sign indeed that the world is in for the long haul in combating this peril.