Discover Dialogue: Virologist David Baltimore

The danger of getting sick from this disease in the United States is trivial

By Kathy A. Svitil|Friday, August 01, 2003
RELATED TAGS: INFECTIOUS DISEASES



Photograph courtesy of California Institute of Technology.

The first known victim of severe acute respiratory syndrome was Johnny Chen, a Chinese American businessman living in Hong Kong. He apparently picked up SARS at a hotel in the southern Chinese province of Guangdong. Then he traveled from Hong Kong to Hanoi, where he was admitted to a hospital on February 26. In less than a month, hundreds of people were sick on three continents.Virologist David Baltimore, president of the California Institute of Technology, says SARS is not the first disease to spread rapidly via air travel—AIDS was. Baltimore shared a Nobel Prize in 1975 for his discovery of reverse transcriptase, the enzyme that viruses like HIV use to insert their genetic material into a host's cell. Molecular biologists now use it to engineer new genes and novel organisms. Several months ago, Baltimore criticized the media for overreacting to SARS. He says the disease was never a threat in the United States.

Why did SARS cause a panic?
B: It was new to our experience, although presumably it has been out there in the world for many years. It's frightening to people because they don't know its full capabilities; they don't know how to respond to it. The virus clearly had spread fairly widely before we were aware of it, and that made it more scary. You didn't know where it was and where it wasn't.

Do you think that the World Health Organization and the Centers for Disease Control handled the outbreak correctly?
B: I think they handled it wonderfully. The CDC mobilized itself very rapidly. The United States ended up basically free of the disease—a few patients, no deaths. And the WHO offered its assistance widely and helped the Vietnamese very early, so that they got rid of their problem. If WHO had gotten into China as early as last fall, they might have been able to prevent the whole thing.

Why were you so critical of the media?
B: I think the problem we have in such a fearful moment is that the media doesn't put enough effort into putting things in perspective, into saying what people can quite safely do. Nothing is absolutely safe, and nothing is absolutely certain. But the media needs to convey that there are hierarchies to dangers. Things like smoking, driving, and climbing ladders are high on the hierarchy. In that context, the danger of SARS is negligible to a citizen of the United States. There's no reason for people here to be staying away from Chinese restaurants, or for people to say, as they did in a survey, that they think there's a 25 percent chance that their family will have a SARS case before the end of the year. The chance of any family in the United States having a SARS case is probably one in a million.

The fear of Chinese restaurants really touched a nerve with you.
B: Well, I happen to be married to a Chinese woman, and I love Chinese restaurants.

Do you think that people in the media believe the public wants to be afraid?
B: I actually think the public does like to be afraid, and the media plays to that fear. In this case I'm not saying they create it, but they do play to it. I think a lot of the SARS coverage was because the newspapers know that people get excited by somebody else's misfortune.

Some people argue that the media response, even if it was overkill, helped prevent a more severe outbreak. Do you agree?
B: I think that's true. That's the other side of the story. It's necessary that the media cover these things, and in fact, in a public-health emergency, openness is an absolute necessity. So on the one hand, the media has the responsibility to help people respond to a problem like this. But on the other hand, I think the media has a responsibility to make sure the reaction is not excessive and that a lot of innocent people don't suffer.

What was your reaction to the University of California at Berkeley's decision to bar foreign students who came from SARS-affected areas?
B: I thought that was quite unfortunate. I know that they're taking some risk in getting students from those areas, but I really think that they should have found a way to honor their commitment to those students. You can do that with careful surveillance. They overreacted.

Did it surprise you that the SARS coronavirus was isolated so quickly?
B: I'm not sure it surprised me, because I know the power of modern biology. Luckily, the SARS virus was something you could find. Coronavirus is obvious under a microscope. HIV was much more difficult to find. It is harder to see, and we had less experience with that class of virus.

Dozens of new diseases, transmitted from animals to humans, have emerged since the 1970s. Is the pace picking up?
B: I don't think so. It has always been going on. We can go back over the last couple of decades, and once a year something happens—West Nile, hantavirus, Ebola. It's been pretty consistent, and it may have been going on for eons. We don't have very good records, because we didn't know one agent from another. We didn't know one disease from another. It could be that this SARS virus is slightly mutated and is more easily spread than the natural SARS virus. Or it could be that it just adventitiously got spread widely because travelers ended up in this hotel and took it with them.

Did it surprise you that something like coronavirus, which has never really been that problematic in humans, turned deadly?
B: No. We know that a given virus can be deadly in one species and benign in another. I would think that any virus, any virus class, has the potential to become deadly to humans. It happened with retroviruses, in the case of HIV.

Should we worry that other benign viruses will mutate into something dangerous?
B: Yes, I think more nasty things will show up, although it's not necessarily that they mutate. We don't really know what goes on. It may be that the virus is exactly the same as it would be in an animal, except that in humans it causes a severe disease. HIV, for example, seems to be relatively benign in chimpanzees. So the jump to a new species often leads to a great increase in pathologic capabilities. We don't know how much is a mutational change in the virus and how much a matter of the virus simply finding itself in a new host where it hasn't evolved a modus vivendi as it has in its natural host.

So as the viruses evolve they will cause fewer and fewer problems?
B: You have to see it from the virus's point of view: A virus doesn't want to be lethal. What it wants to do is spread itself from one person to another, and ideally without any symptoms, so people don't know to protect themselves. Successful viruses in humans get spread before the individual is so sick that he ends up in bed and there's nobody left to spread it to except close contacts.

Is that why Ebola never became the epidemic people feared it would?
B: Ebola is too pathogenic for its own good. It apparently doesn't spread well in a non-symptomatic phase, so it only spreads to very close contacts and medical personnel, which limits its scope. The same seems to be true with SARS. It is most infectious when you are already symptomatic.

The death rate from SARS is much lower in children than in adults. Is that unusual?
B: No. It's very common. Viruses like measles and mumps are benign in children, but we vaccinate because if you get the disease as an adult, the effect is much more severe. The same is true with polio. Polio was hardly a serious problem in the days when it spread among young children. But then as sanitation improved, it spread less well among young children, and more adolescents got it. They're the ones who were paralyzed.

How can you tell at the beginning of an outbreak if it will turn disastrous or if it will peak early and then taper off?
B: As they say, the future is the hardest thing to predict. It's very hard to tell which way it will go. We encountered this with swine flu, which appeared in the spring of 1976 in some military personnel who had gotten it from a farm. The CDC became very concerned and encouraged the federal government to start a vaccination program, which it did. By the fall we had a vaccine and gave it to tens of millions of people. The virus never reappeared. So we made entirely the wrong guess. If we'd been wrong in the opposite direction we would have felt even more stupid.

Do you just vaccinate against everything? Wouldn't you hit vaccination overload?
B: Well, you worry about that. You have to be very hard-nosed about the decision to vaccinate large numbers of people. It's a concern with smallpox today. We know the smallpox vaccine causes problems in a small fraction of people, but that number is large enough that if we vaccinated everybody in the country we'd have hundreds of deaths and thousands of people who were debilitated. You don't want to do that lightly. You have to consider what the probability is that we'll have an epidemic of smallpox. It's a hard question to answer.

If it were your choice, what would you do about combating smallpox?
B: I wouldn't go any farther than vaccinating a small number of medical personnel so that they can safely treat patients if there's a necessity.

Compared with a lot of people in similar positions, you're very outspoken about science and public-policy issues. What motivates you to get involved in these issues?
B: I think I understand how much of an interrelationship there is between science and the rest of the world, and it gives me a sense of responsibility to try to help people understand what science is about, when it's doing well, and when it isn't doing well.


David Baltimore has more to say about genetic engineering, cancer and stem cell research. Click here for a Discover.com Web exclusive extension to this Dialogue.


For the latest news on SARS, see the World Health Organization's site (www.who.int/csr/sars/en) or visit the Centers for Disease Control's information page (www.cdc.gov/ncidod/sars).

For biographical information on David Baltimore, visit www.caltech.edu/president/index.html.


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