WASHINGTON - The ongoing 19th International AIDS Conference is an occasion for both optimism and caution as to whether humans could get rid of the AIDS epidemic with existing tools and continued development of vaccines.

It's possible to end the AIDS pandemic via proven methods of prevention, treatment interventions and continued development of vaccines, said Anthony Fauci, director of US National Institute of Allergy and Infectious Disease.

"Decades of basic and clinical research has led to the development of interventions in the forms of treatment and prevention," said Fauci. "We now have a robust armamentarium of approximately 30 antiretroviral drugs that are life-saving when given in combination, allowing people with access to these medications to live healthy and productive lives."

Antiretroviral therapy can also dramatically reduce HIV-infected people's chances of transmitting the virus to their sexual partners, or, in the case of pregnant women, to their infants, he said.

In addition, there have been dramatic results with biologically based prevention modalities.

Fauci took voluntary medical male circumcision (VMMC) as an example, saying the simple surgical procedure "is highly effective and durable" in protecting heterosexual men from acquiring HIV infection.

Used along with condoms and other prevention tools, it's generally accepted that VMMC holds great promise in reducing new HIV infections, especially in parts of Africa with high rates of HIV and low rates of male circumcision.

"Taken together, these new developments provide a robust toolkit of prevention and treatment interventions," Fauci said. "It is not only conceivable but it is almost certain that you will see a diminution of the trajectory of the AIDS pandemic to the point where it starts to go towards essentially disappearing."

However, Fauci said, this will require increased financial resources, innovation, political will, an overall strengthening of health systems and greater efforts by all countries to tackle HIV/AIDS within their borders.

"We have the scientific means, we have the interventions. We just need to do it," Fauci said. "I think that over a period of time whether it takes 15, 20 or 30 years, it depends on how much resources and how much implementation."

However, Francoise Barre-Sinoussi, co-discoverer of the HIV virus and president-elect of the International AIDS Society, is cautious about ending the epidemic.

"Of course, if we can implement the tools and treat all the patients that can be treated in the world, then we can be optimistic. But the reality is not that," Sinoussi told Xinhua.

"It's kind of controversy between the optimistic view -- we have the tools -- it should end the epidemic. But the reality is that the tools are not implemented and it will be very difficult to be implemented to everywhere in the world."

Bill Gates, co-founder of the Bill & Melinda Gates Foundation, a major funder of AIDS research, is more skeptical.

"No one should think that we have got the tools (to end AIDS epidemic) yet. We will get the tools but only if we stay the course in terms of the scientific investments," Gates told the Conference on Monday.

The International AIDS Conference, inaugurated in 1985 in Atlanta, the United States, is the largest gathering of professionals working in the field of HIV, including people with HIV.

It was held annually before 1994, when the gathering became a biennial event.

Over 20,000 delegates from all over the world attended this year's conference. Activities on the agenda include a series of meetings and discussions focusing on mobilizing governments and communities to achieve the vision of zero new HIV infections, zero discrimination and zero AIDS-related deaths.

There are as many as 34.2 million people worldwide infected with HIV/AIDS, according to the UNAIDS. In 2011 alone, 2.5 million new cases were diagnosed.