A world AIDS assembly opens in Amsterdam on Monday hoping to harness the star power of activists Elton John and Prince Harry to bolster the battle against an epidemic experts warn may yet spiral out of control.
Thousands of delegates -- researchers, campaigners, activists and people living with the killer virus -- have arrived for the 22nd International AIDS Conference amid warnings that "dangerous complacency" may cause an unstoppable resurgence.
In recent days, experts have alerted that new HIV infections, while down overall, have surged in some parts of the world as global attention has waned and funding leveled off.
And they lamented that too sharp a focus on virus-suppressing treatment may have diverted attention from basic prevention programs such as condom distribution, with the result that the AIDS-causing virus is still spreading easily among vulnerable groups.
"The encouraging reductions in new HIV infections that occurred for about a decade has emboldened some to declare that we are within reach of ending AIDS," Peter Piot, virus researcher and founder of the UNAIDS agency, said last week.
However, "there is absolutely no evidence to support this conclusion," he insisted, and warned: "The language on ending AIDS has bred a dangerous complacency."
A UNAIDS report has warned of a long and difficult road ahead even as it reported an overall drop in new infections and AIDS deaths, and a record number of people on life-saving antiretroviral therapy (ART).
These hard-fought gains could be reversed, experts said ahead of Monday evening's opening of the five-day conference attended by some 15,000 delegates -- also including celebrities Charlize Theron and Conchita.
An alarming rate of new infections coupled with an exploding young population in hard-hit countries could spell "a crisis of epic proportions," Mark Dybul, a veteran American AIDS researcher and diplomat told a preparatory conference Sunday.
"Bad things will happen if we don't have more money," he said, and warned the world was "probably at the highest risk ever of losing control of this epidemic."
Dybul and colleagues said donor and domestic funding has dropped significantly and would likely continue to decline, from about 20.6 billion euros ($24.1 billion) last year -- most of it financed from the domestic budgets of nations with the heaviest AIDS burden.
According to UNAIDS, the funding gap is almost $7 billion per year.
Under Donald Trump, the U.S. administration has proposed massive spending cuts, though these have so far failed to pass through Congress.
The United States is by far the biggest funder of the global AIDS response.
The immune system-attacking HIV virus has infected nearly 80 million people since the early 1980s. More than 35 million have died.
Today, data show the infection rate is rising in about 50 countries and has more than doubled in eastern Europe and central Asia.
A major cause is the criminalization of injecting drugs in many countries, which compels users onto the fringes of society and puts them at risk of infection through needle-sharing.
"Close to half -- more than 45 -- percent of all new HIV infections in the world are in... the most affected and hard to reach groups, and that of course includes people who use drugs," Chris Beyrer, director of the Center for Public Health and Human Rights at John Hopkins University, said Monday.
"Progressive drug policy can really be a critical part of controlling the HIV epidemic," the former International AIDS Society president said.
NGOs at the conference are pushing a liberalization campaign titled: "Just say no to the war on drugs," a direct challenge to the 1980s Reagan administration's "Just say no" message at the height of the "war on drugs."