"Lives are being saved on an unprecedented scale," said Michel Kazatchkine, executive director of the Global Fund to Fight AIDS, Tuberculosis and Malaria, at closing ceremonies to the six-day parlay.
But, he warned, "We cannot leave Mexico with any sense of complacency."
Kazatchkine named three priorities: defeating the discrimination in which the AIDS virus flourished; focussing research on smarter, coordinated paths rather than a scattergun approach; and beefing up health systems in poor countries.
He named his fourth priority as ensuring that the surge in funding for fighting AIDS in poor countries, which began in mid-decade and in 2007 reached 8.1 billion dollars, was sustained.
So far, less than a third of the 9.7 million poor, badly infected people have been able to grasp the antiretroviral drug lifeline, leaving precious little time to reach the goal of universal access of 2010 enshrined by the UN General Assembly and Group of Eight (G8) countries.
"We... should be deeply concerned that with less than two years to go before our deadline for universal access, the G8 has committed little more than a third of the resources that it has promised to deliver by 2010," Kazatchkine said.
He also called on countries to pitch in more to tackle their own HIV problems.
The conference staged seminars, skills-building workshops, round tables and presentations of scientific research dwelling on almost every aspect of the fight against AIDS.
On the medical front, the search for a preventative vaccine and virus-thwarting vaginal gel is mired in problems, the conference heard.
Optimistic news, though, surfaced about male circumcision.
Surgical removal of the foreskin decreased 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.
But transforming this research breakthrough into an on-the-ground campaign to encourage circumcision among men in sub-Saharan Africa, where two-thirds of the people with HIV live, will take time.
It will need funding and long preparations to ensure that operations are performed in hygienic conditions and with full consent. Any mistakes could cause the strategy to fail disastrously, experts aid.
As in past AIDS conferences, other key themes in Mexico City included vital, but often unacknowledged, grassroots work to encourage condom use, prevent violence against women and roll back the stigma that lets HIV flourish in sidelined groups such as gays, intravenous drug users and sex workers.
"Ignoring the needs of children and adolescents and women affected by HIV and continuing to marginalise groups at greatest risks for infection will only lead to more infections and fewer people on treatment," said Luis Soto Ramirez, a Mexican virologist who co-chaired the conference.
"We will pay for such foolishness in the future."
The Mexico City conference is the 17th to be held since acquired immune deficiency syndrome (AIDS) emerged in 1981.
Two years later, French and US researchers identified the pathogen as a virus that subverts and then destroys key immune cells, leaving the body exposed to common infections.
More than 25 million people have been killed by AIDS and 33 million people today are infected with HIV. Treating those in need is likely to cost tens of billions of dollar by 2015, as the regimen of drugs is daily and for life.
The conference, the first to be staged in Latin America, gathered 20,716 scientists, policymakers and fieldworkers from around the world, according to figures issued by the International AIDS Society (IAS) on Friday. It had previously put the tally at around 22,000.
The next meeting takes place in Vienna in 2010.