AIDS Conference Ends on Note of Confidence : Health: But participants are reminded that the worldwide epidemic remains out of control.

After five hectic days of activism and science, the Sixth International Conference on AIDS concluded Sunday with optimism over the prospects for better treatments and a vaccine but sobering reminders that the worldwide AIDS epidemic remains out of control.

While promising, preliminary studies of new antiviral drugs and prototype vaccines grabbed the headlines, many researchers stressed that educating people to avoid infection with the human immunodeficiency virus still remains the only way to significantly affect the course of the disease both in the United States and abroad.

“The epidemics in Africa, Latin America, the Caribbean and Southeast Asia are not coming under control--they are expanding,” said Dr. Jonathan Mann, the American physician who many view as the conscience of the global AIDS battle. “The hard-learned lessons from San Francisco, Amsterdam, Sydney and Nairobi (where AIDS prevention efforts have been most intensive) are not being systematically applied.”

Dr. James W. Curran of the U.S. Centers for Disease Control said the estimated 40,000 to 80,000 new infections a year in the United States indicate that the epidemic is still growing. “We are nowhere near level yet.”

Frustration over the U.S. government’s response to the epidemic erupted at the conference’s closing ceremonies. Several hundred AIDS activists drowned out remarks by Dr. Louis Sullivan, the U.S. secretary of Health and Human Services. Sullivan emphasized the need for tolerance and unity in the fight against AIDS.

But despite the grim global statistics--an estimated 6 to 8 million people worldwide already infected with HIV and a cumulative total of 15 to 20 million infections predicted by the end of the decade--this was the first international AIDS conference where the promise of eventual success loomed large, if only the political, economic and social will can be found to implement the key research advances.

“The goal for the 1990s should be a lofty one, namely the ability to completely and indefinitely suppress HIV in infected individuals,” said Dr. Anthony S. Fauci, the director of the National Institute of Allergy and Infectious Diseases. Fauci spoke at Sunday’s closing session, during which activists heckled Sullivan.

“The pandemic’s short history also means that the potential to influence its future course remains high,” said Mann, the former director of the World Health Organization’s AIDS program. “There is no country and no population in which AIDS is a ‘lost cause’--unless it is abandoned.”

This new optimism is based not on dramatic breakthroughs--of which there were none reported this week--but on the cumulative effect of reports of promising experimental drugs and successful AIDS vaccine tests in animals.

Many leading vaccine researchers predicted that large-scale tests of experimental AIDS vaccines could begin in humans within two to four years and that tests to determine if vaccines can protect the fetuses of infected pregnant women could begin next year.

Researchers at UC Davis reported preliminary success in protecting cats against an immunodeficiency virus similar to HIV. Scientists at the Medical Biology Institute in La Jolla also described advances in a mouse model for HIV infection that may prove useful in testing prototype vaccines.

There was general agreement that combinations of anti-HIV drugs now under development will yield superior results to single drugs. Scientists here also concurred that, as Dr. Margaret Fischl of the University of Miami said, “Intervention should occur as early as possible. . . . This will be associated with the best benefit and delay in progression to AIDS.”

HIV gradually destroys the body’s immune system, leaving infected individuals vulnerable to many life-threatening infections and tumors. AIDS, however, can sometimes be postponed with the antiviral drug AZT or antibiotics to prevent AIDS-related Pneumocystis carinii pneumonia.

Yet years of profound suppression of the immune system seem to take an inevitable toll. Dr. Robert Yarchoan, a senior investigator at the U.S. National Cancer Institute, reported that a group of severely immuno-suppressed AIDS patients on long-term AZT therapy had a 46% risk after three years of developing “high-grade” non-Hodgkins lymphoma.

This cancer of the lymph node is notoriously difficult to treat in HIV-infected individuals. Although many AIDS-related pneumonias are being prevented, cases of non-Hodgkins lymphomas are rapidly increasing across the country.

According to updated results from the San Francisco Department of Public Health, about half of HIV-infected individuals develop AIDS within 10 years of becoming infected. About 15%, however, not only have not developed AIDS but continue to have normal or near-normal immune systems. It is unclear whether these individuals will eventually develop AIDS.

These findings offer hope that all infected individuals can someday be maintained with functioning immune systems.

“I don’t think anyone is talking about a cure in the sense of getting rid of every last piece of virus,” Yarchoan said. “But there are many viruses that we have in our body and that we live with and they really don’t bother us.”

Yarchoan added: “Most adults in this country are infected with Epstein-Barr virus (which causes mononucleosis) and yet it doesn’t do them any harm. The goal is to convert HIV into a virus like that.”

Dozens of new AIDS drugs are in various stages of development, ranging from compounds similar to AZT, such as DDI, DDC, AzDU and d4T, to various therapies to boost the immune system, such as Dr. Jonas Salk’s HIV-immunogen, to novel substances that may block the growth of the virus, such as protease inhibitors and so-called “TIBO derivatives.”

If a sufficient number of these drugs maintain their early promise, AIDS researchers and government officials may need to reset priorities for large clinical trials so that the combinations of agents most likely to be safe and effective are tested first. As a result, many highly touted drugs are likely to fall by the wayside as the more active and less toxic agents are identified.

Fauci cautioned, however, that researchers were “far from reaching our goal regarding therapy.” Drugs such as AZT, DDI and DDC “have considerable toxicity and are generally only temporarily effective,” he said.

But while “early intervention” against AIDS emerged as a new buzz phrase among American researchers and their Western European counterparts, the high cost of such therapy illustrated the increasing gap between rich and poor--both within nations and between nations--when it comes to AIDS treatments.

“Early intervention is still a meaningless concept in developing countries; AZT remains too expensive for most of the people who need it,” Mann said. (The wholesale price for the 500 mg daily dosage regimen recommended for adults with asymptomatic HIV infections is about $2,200 a year.)

As examples, Mann pointed out that the total budget of the average national AIDS program in the developing world “is less than the cost of caring for only 15 people with AIDS in the United States.” And the industrialized world’s total contribution to AIDS in the developing world is about $200 million a year, or one-fifth the total annual expenditure on AIDS prevention and care in New York state alone.

Through intravenous drug use and prostitution, the number of HIV-infected individuals in Thailand has increased from less than 1,000 in late 1987 to more than 100,000. In India, heterosexual transmission in cities such as Bombay has spawned a rapidly growing HIV epidemic that is already larger than the Thai epidemic.

The profound effect of inadequate resources to fight AIDS is most evident in sub-Saharan Africa. Between 1987 and 1989, the number of infected individuals increased from 2.5 million to more than 4 million as the virus spread from cities to rural areas, according to Dr. James Chin of the World Health Organization’s AIDS program. Hundreds of thousands of children are either infected or orphaned.

The number of HIV infections in these areas represents at least half of the global total. In Uganda alone--a nation of 16.8 million--an estimated 1 million people are infected, which is about the same number of HIV infections as in the entire United States .

At the same time, the HIV epidemic in sub-Saharan Africa has sparked an equally alarming epidemic of tuberculosis. One and a half million people there are estimated to be dually infected with HIV and tuberculosis.

Unlike AIDS, tuberculosis is relatively easy to treat and prevent. HIV infection is “the most potent activator of dormant tuberculosis ever detected,” according to Dr. Peter Eriki of the WHO.

“They were unable to contain a relatively small tuberculosis problem before the arrival of HIV and they are singularly ill prepared for coping with a very large problem ahead,” Eriki said.

It is for such reasons that Mann and current WHO officials urged a global vision to confront a global problem.

“AIDS has become the crucible in which the future of health is being forged,” Mann said. “Either we build upon and strengthen and expand what has already been accomplished, or in the years to come we will fall further and further behind the pace of the worldwide epidemic.”