Twenty-five years ago, U.S. public health officials reported the first known cases of a disease that would come to be called AIDS.  Since then, AIDS has grown into a global pandemic that governments and donor agencies are spending billions of dollars to try to control. Medical science has delivered the tools to tame the virus, but its biological nature causes experts to fear it will not soon be eliminated.

It was 1981 and American doctors were mystified by what they saw.  Young, previously healthy homosexual men were suffering from a rare and often deadly form of pneumonia.  When the U.S. government's disease tracking agency, the Centers for Disease Control, first reported the mysterious cluster of cases on June 5, 1981, two of the young men had died.

These were the first reported fatalities of an illness initially considered by many to be one of only gay men and people who injected illegal drugs.  But the chief of U.S. government AIDS research, Dr. Anthony Fauci, notes that they were only the vanguard of a pandemic that would sweep across continents.

AIDS Pandemic

A model of the H.I.V. virus

"So now we fast forward 25 years and we see that what people were somewhat skeptical about, whether this was going to be anything but an epidemiologically restricted disease, has exploded into one of the most devastating pandemics in the history of civilization," says Dr. Fauci.

Since 1981, AIDS has infiltrated all segments of society and claimed the lives of 25 million men, women, and children.  The United Nations AIDS Program says 40 million are living with it and eight-thousand are dying daily, mostly in developing countries,"... which means that H.I.V.-AIDS has now transcended malaria and tuberculosis as the leading cause of microbial death in the world," says Dr. Fauci. "Remember, malaria and T.B. were the two big killers before then, and just a couple of years ago, H.I.V.-AIDS superseded them."

Because the first AIDS patients were people with unorthodox lifestyles, politicians ignored the disease, but Fauci and other researchers strove to understand it.  Within a few years, scientists identified the H.I.V. virus that causes AIDS and developed a rapid blood test to detect it.  They also began revealing its molecular structure, a necessary step in designing drugs to block it.

As a result of that work, current medicines can subdue H.I.V. to undetectable levels in the blood, extending patients' lives indefinitely from an initial life expectancy of two or three years.

Dr. Paul Stoffels of Tibotec Pharmaceuticals Limited says that is the good news. "Today, H.I.V. patients theoretically should not die anymore from the disease if therapy is correctly administered and there is good infrastructure to do the follow up of the patient.  So there was a massive evolution by making new drugs available from a deadly disease to a chronic infection," Dr. Stoffels.

Little Hope for a Cure

An H.I.V. infected family in Tanzania

But the bad news is that drugs cannot yet cure H.I.V.  Stoffels says patients will probably have to take them for decades to stay alive, an enormous challenge even in the most highly developed societies.

This is because when H.I.V. enters a person's cells, it is tenacious, despite the onslaught of medicines.  Anthony Fauci's studies have showed that it can hide for years at undetectable levels, but is never gone and is ready to multiply at high levels again if drugs are stopped.  He holds little hope that drugs will ever cure AIDS.

"I'd have to say that you never say never in biology, but if in fact we do it, it's going to be very, very tough to do.  So I am not totally optimistic that we are going to be able to truly eradicate virus from huge numbers of infected people.  We may do it rarely in an individual at first, but I don't see this happening as a routine phenomenon," says Fauci.

The Quest for a Vaccine

As a result, the search for an H.I.V. vaccine assumes tremendous importance.  Many experimental vaccines are in development, with some being tested in Africa and Asia.

But vaccine research is another big challenge, according to Mitchell Warren.  He is the Executive Director of the AIDS Vaccine and Advocacy Coalition, a private group promoting vaccine research.

"Every time we think we've learned one more piece of the puzzle around this virus, and we have unlocked and uncovered many of those puzzle pieces over 25 years, every time we do that, we continually are defied in turning that information into a vaccine," says Warren.

But Warren says vaccine research is coming to an important juncture.  He believes that within three to five years, scientists will have discovered which vaccine concept works best and will focus on that.  But don't hope for a vaccine for at least another decade.

Expensive medications prolong life, but a vaccine may be at least a decade away

"I can tell you we won't have the ultimate vaccine, the one that we really long for -- a safe and efficacious vaccine delivered once, ideally without a needle, delivered cheaply with 100 percent prevention.  That won't happen within the next decade.  We might be further along the way.  That may sound rather cynical, but what I want to make very clear is I think we are at a really critical turning point in the search for an AIDS vaccine," says Warren.

But even if a vaccine becomes available, Warren says it will not be a panacea because the H.I.V. pandemic will not be stopped by one technology or any other single approach, be it therapeutic or behavioral.

The chief of the World Health Organization's H.I.V. Department, Dr. Kevin De Cock, foresees a world still fighting AIDS 25 years from now. "I don't think we will have this problem solved.  This is a problem that is going to take generations to address.  All of us talking about it now, like you and I, will be gone before the story is finished."

This story was first broadcast on the English news program,VOA News Now. For other Focus reports click here.