A leading American AIDS researcher says the world already has the tools it needs to stop the spread of HIV, the virus that causes AIDS. His comments come on the 25th anniversary of the first documented cases of human immunodeficiency virus.

When the first cases of HIV were diagnosed 25 years ago, researchers thought it was just a matter of time before they found a cure or developed a vaccine. But the quest has eluded them with tragic results. Since 1981, the disease has claimed more 25 million lives globally.

A report issued by the United Nations on the eve of a conference on AIDS this week in New York estimates that there were four million new infections last year. But that's better than the last decade, when the report says the number of new cases of HIV peaked.

Dr. Anthony Fauci (file photo)

Anthony Fauci, head of the Institute of Allergy and Infectious Diseases at the U.S. National Institutes of Health, says unlike other viral illnesses, such as small pox, measles and polio, the human immune system seems unable to overpower HIV.

"When we figure that out, that's the last of the real major scientific obstacles, then we will be much further towards developing a vaccine. It's that lack of understanding, and it's a very difficult problem, that has really been a major stumbling blocks on the road to a vaccine," he said.

In comments to journalists, Fauci said the world already has the tools it needs to stop the spread of HIV.

"We have good drugs. We know how to prevent this infection. We don't have a vaccine for sure. But you can prevent HIV by getting a good preventive measure [program], education and behavioral modification, distribution of condoms, safe sex, enlightening people, getting people to be monogamous, getting people to be abstinent where appropriate, and where it's feasible and, where it's not, to practice safe sex," he said.

Fauci called the world a "global society," and said richer nations have a responsibility to help disadvantaged countries fight AIDS with the latest know-how.

"The resource rich nations must work with the resource poor nations to make sure that not only prevention methods and methodologies get to the developing nations, but that we get them the resources to get them the drugs to treat those people that need it," he said.

At the same time, Fauci scolded less developed countries that would impede progress toward elimination of HIV.

"The leaders of developing nations must not stand in the way of the progress in HIV by being closed-minded, or not removing the stigma, or not appreciating the seriousness of the problem, or not even investing important resources in helping their countrymen," he said.

Fauci called AIDS one of the top diseases of all time, alongside pandemic flu and bubonic plague.

Fauci said the Bush administration's $15 billion emergency plan for global AIDS relief is on target for full funding by 2008, and he criticized other nations for falling short of their commitments for matching funds.

Fauci also said the Bush administration supports the development of generic anti-viral drugs by hard hit countries to reduce the cost of fighting the deadly virus.