Seminar explores scientific battle against infectious diseases


Infectious diseases, once considered a hazard of the past, have re-emerged as a surprisingly complex and intractable problem, said scientists at a joint Whitehead Institute/Massachusetts General Hospital press seminar, "Modern Plagues," held on May 29-30.

More than 60 reporters from major media, including NBC, CBS, ABC, The New York Times, The Boston Globe, The Dallas Morning News and The Los Angeles Times, attended the seminar, where they heard lectures from many of the nation's top infectious disease researchers.

"People were saying 10 or 15 years ago that we had conquered infectious disease," said Dr. Samuel Thier, chairman and CEO of Partners Healthcare System, who spoke at Friday's all-day session at Whitehead. "We were almost there. But now our major problems again are infectious diseases."

"It's an arms race, there's no question about that" added Dr. Gerald Fink, director of the Whitehead Institute. "Unless we continue to develop new weapons to fight disease, microbes will evolve ways to defend themselves against the ones we have."

The 25 speakers described a host of current and emerging threats, from AIDS to drug-resistant tuberculosis and pathogenic E. coli, and explained how the habits of modern civilization have created or exacerbated most of them. But they also offered hope in the form of scientific breakthroughs that promise new weapons and a better understanding of the advancing plagues.

Dr. Mary Wilson, chief of infectious diseases at Mt. Auburn Hospital, and Dr. Arnold Weinberg, MIT medical director, provided an overview of the challenges that modern medicine faces. Sweeping ecological changes worldwide, coupled with the increasing speed of international travel and the emergence of antibiotic resistance, are opening the door for an onslaught of new epidemics, Dr. Wilson said. Dr. Weinberg agreed, saying that while the developing world may bear the brunt of emerging disease, the developed world is by no means safe.

Pointing to such recent scares as the deadly hanta virus outbreak in New Mexico and the Cryptosporidium-tainted water in Milwaukee that gave 300,000 people diarrhea, he said, "There are a lot of ways in which we are very fragile."

AIDS FIGHT DISCUSSED

Many of the speakers focused on AIDS, today's most high-profile disease. MIT Professor of Biology Peter Kim, a member of the Whitehead Institute, described a recent discovery by his lab--solving the three-dimensional structure of a key part of one of the proteins that HIV uses to dock onto human cells--might lead to powerful new treatments for the disease.

Dr. Martin Hirsch of MGH discussed the new triple-drug cocktails that are raising hopes of eliminating HIV from patients' systems. He said that while the approach looks promising, it is still far from perfect. HIV adapts quickly to any one of the drugs in the treatment, so if patients fail to keep up their complicated medication regimens, their virus may soon become resistant to therapy.

Institute Professor David Baltimore, Ivan R. Cottrell Professor of Molecular Biology and Immunology, discussed new efforts toward the development of an AIDS vaccine at a luncheon session. Dr. Baltimore, the chairman of the National Institutes of Health advisory committee on AIDS vaccines, said that, in the long run, the best chance of controlling the disease would be the creation of an effective vaccine.

Unfortunately, that effort has proved to be far more difficult than previous vaccine development. In most diseases, the immune system does a good job of killing off invading microbes; only when the body's response is a little too slow does an actual disease develop. In these cases, a vaccine helps by priming the body's defenses, giving it a head start against the germ in question. But when HIV attacks, Professor Baltimore said, the immune system almost never prevails. Its response is too slow and too weak.

But there is still hope, he added. The immune system does have some effect on the virus, keeping it under control for years before finally succumbing. Perhaps with some help, he suggested, it could eventually destroy the virus altogether.

Furthermore, a vaccine need not be 100 percent effective. Even one that weakened the virus to the point that it couldn't infect an HIV-positive person's partner would significantly slow the epidemic. Unfortunately, Professor Baltimore said, technical problems have slowed the development of even a partial vaccine, and it may be at least 10 years before one appears. "To tell you the truth, we have only just begun the search for a vaccine," he said.

On Friday, at sessions held at MGH, speakers focused on the growing problem of antibiotic resistance. Dr. Stuart Levy, director of the Center for Adaptation Genetics and Drug Resistance at Tufts University School of Medicine, cautioned that unless people reduce their use of antibiotics, some of the world's most powerful drugs may soon be useless.

He explained that as bacteria encounter antibiotics, they gradually adapt. Although the drugs kill most of their target microbes, a few slightly resistant bugs survive long enough to pass on their resistant genes. Eventually, one that is utterly unaffected by the drug appears and begins to spread. Worse, that bacterium sometimes can transfer its newfound resistance to other species, leading to many resistant species.

By using antibiotics the way we do today, we are accelerating that process, Dr. Levy said. Important antibiotics are sprayed on plants and included in animal feed, greatly increasing the chance that dangerous germs will be pushed toward resistance. Indeed, even soaps and toys now contain antibacterial substances, which increase the problem of drug resistance.

Other speakers charted ways of avoiding the problem of resistance altogether by stimulating the body's immune system rather than attacking microbes directly. Professor Richard Young, a Whitehead member, described a method of using genetic techniques to find proteins that improve the immune responses. Meanwhile, Claire Broome, deputy director of the Centers for Disease Control, and Dennis Kasper, executive vice chairman of the Department of Medicine at Brigham and Women's Hospital, described new techniques for creating vaccines from small pieces of microbes' cells.

Other speakers focused on individual microbial threats rising around the world: hanta virus, E. coli 0157, group B Streptococcus and cholera. The seminar concluded with Dr. Matthew Meselson, who discussed the possibility of biological warfare and how society could act to reduce this threat.

A version of this article appeared in MIT Tech Talk on June 4, 1997.


Topics: Health sciences and technology, Special events and guest speakers

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