But there are still major challenges ahead, according to Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases and one of the pioneers in the fight to stop the AIDS epidemic.

“The more people you get on therapy, the earlier you diagnose it, the less deaths you will see, that’s good news. The sobering news is we still have a long way to go. We still don’t have the epidemic under control,” Fauci said.

The U.N. data show that in sub-Saharan Africa, for example, more than a million people are still dying of the disease every year.

In these HIV hot zones, experts agree that early intervention with antiretroviral drugs can save lives and slow transmission rates. But Dr. Fauci says pairing this treatment with proven prevention strategies is key to getting the epidemic under control.

"The fact that you put people on treatment, get their viral load to a level that’s low enough, then it is extremely unlikely that those people will transmit the infection to their uninfected sexual partner. So, if you combine all of the prevention modalities and superimpose upon that treatment of more and more people, then you could start to see some significant downturn in the pandemic,” Fauci said.

Funding is also essential to continued research on an HIV vaccine and other prevention and treatment efforts. But humanitarian organizations report that donor support has dropped for the first time, from 7.6 billion dollars in 2009 to 6.9 billion dollars in 2010. Sidibe says U.N. member countries have promised to fill the gap, and he's hopeful they will: