Host: Mignon Fogarty & Adam Lowe
Transcript: This episode originally aired April 7, 2006
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INTRODUCTION
Adam: Hi Mignon,
I'm hear again with Dr. Mitch Katz, director of the San Francisco department of public health that does disease control for San Francisco county. Dr. Katz is also a professor of medicine at the University of California, San Francisco.
Interesting to hear a little bit about local preparations about the avian flu. And you have some interesting opinions about what sort of risk the avian flu poses.
WHAT IS THE RISK TO HUMANS?
Katz: Well, I think that the avian flu is a major risk, especially if you are a bird. For the humans among us, I think the risk is much lower, after all this is a virus that has been around for quite a number of years in Asia, where chickens and other birds live very close to humans, and to date it has not yet jumped from species of birds to human species. That is a large jump going from bird to humans, because of course humans are mammals, and in general those organisms that infect birds do not infect humans. Also a lot of the concern about avian flu has been how quickly and significantly it has spread among birds. So again, I would turn to the idea that it is a major risk for birds, but that to date it has not been shown to be a major risk to humans.
There are human cases, and when this virus affects humans it has an affinity for the lung tissue. The virus adheres to the lung tissue and causes bleeding directly into the lungs. And I think part of what feeds concern about this virus, in particular, is how severe it is when a human does become infected.
Nonetheless, even though I don't believe that avian flu poses a major risk for humans, as a country health director we have to go about planning for the possibility of avian flu, or some other organism that is novel affecting the health of people in the county.
LOCAL PREPARATIONS
One of the things we try to do to make sure that our efforts are useful, is that rather than focus on any one organism that may or may not be the organism that poses a problem for San Francisco, we try to focus on what are our systems for dealing with any organism of an infectious nature. So that way if it turns out that avian flu never jumps from birds to humans but some other flu does. For example, we could have a significant outbreak of influenza A of which bird flu is one type, that does effect humans, and certainly we saw that early in the 20th century. So what does a health department do?
Well, we make sure that we have detailed plans for or isolation of people, as well as quarantine. The difference between isolation and quarantine...isolation is what you do for people who are already sick. So the person who has active tuberculosis is isolated, and part of our plans is knowing every hospital room in the city that has the appropriate negative pressure ventilation to be used for isolating somebody with a respiratory illness.
Quarantine is what you do for healthy people who have been exposed. So in that case, what you want is to make sure that they are not exposing other people. We have detailed plans in the case of avian flu or other infectious agent, how we would quarantine people, and the answer would probably be mostly at home. When you do quarantine what you are trying to do is eliminate opportunities for the virus to spread.
QUARANTINE & ISOLATION
Adam: How would you enforce a quarantine at home?
Katz: Well, both isolation and quarantine are backed in the U.S. by the police powers of health officers. So as the health officer of San Francisco, I actually have quite broad powers to isolate and quarantine, including the ability to arrest people who are not complying with the isolation or quarantine order. Now you are absolutely right to point out that in practice, that if you are having to quarantine literally thousands and thousands of people, you would have to be appealing to people's sense of protection to the community. I think if you are in that sort of scenario, where you are having to quarantine so many people that you can't keep track of them, I don't think people are going to be concerned about keeping their business appointments.
Adam:Have you ever in your years as health director had cause or reason to quarantine anyone?
Katz: We most commonly isolate people. The most common use of health officer powers are on people who have tuberculosis and don't want to take their medications. And we will do an incarceration order, and I have done that multiple times during the time I have been health officer.
IS HUMAN-TO-HUMAN TRANSMISSION LIKELY?
Adam: Going back to the avian flu question...Do you think it is significant or not significant that there have been a number of bird-to-human cases of transmission? Does that cause any concern or indicate that there is a greater likelihood of human-to-human transmission?
Katz: Those cases are certainly of great significance to people who had them, and to family members who lost those individuals. From a population point of view, when people are talking about endemics or epidemics, they're talking about the fear not that in parts of Asia, a few people have died of avian flu. I think it is actually between 100 and 200 people. Because in those places, diseases like malaria and measles and tuberculosis that we have pretty much eliminated her here in the united states kill millions of individuals. The concern about the possibility of an epidemic of avian flu is that this virus develops the ability to easily go from birds to humans. And in the last 10 years that this virus has been tracked it has not done that in an environment where birds and humans live much more closely together than they do in most areas of the united States. So the opportunity has certainly been there. It's also true that when it comes to viruses they can mutate in any direction. So could the avian flu, could it mutate to become easily infectious to humans? Absolutely, but it could easily mutate to become less infectious.
Isn't the likelihood that all of those possible mutations are going to happen within a short period of time?
Katz: Well those mutations likely already exist, and yet we haven't seen it.
Adam: Do you think that there is some kind of mutational control in that a virus that would be more easily transmitted from human to human might be less fit in some other way?
Katz: Generally when you mutate to gain something, you lose something, and the thing you usually lose is reproductive capabilities. So for example, most viruses exist to reproduce themselves. So if a virus creates multiple mutations, chances are the predominant mutation will be whichever one replicates the most rapidly. That's what the wild type is, always the one that replicates most rapidly. In general, if a virus gains some other characteristic, like drug resistance, that mutation isn't going to reproduce as rapidly, because if so that mutation would have been the wild type. So somewhat by definition...On the other hand, there are some interesting twists in the entire field of viral and bacterial mutations that is fascinating. For example, other scientists and epidemiologists have pointed out that if avian flu were to become more infectious to humans, it could potentially be worse, if in becoming more infectious to humans it became less severe. Well that seems counterintuitive, because viruses that are lethal killers tend not to be spread very well. The virus joins the host, it kills the host rapidly, the host doesn't take airplane from Hong Kong to mid-town Manhattan. So some of the most dangerous viruses – and this was certainly true of the influenza epidemic that was spread throughout Europe at the beginning of the 20th century -- most of the people who got it survived. And while that seems like a good thing, a virus that kills everyone and doesn't move is going to in the end kill fewer people than a virus that kills say 5% of effected people but is spread all over the world.
IN-HOME PREPARATIONS?
Adam: Are there preparations that you would advise people to do on their own, in their homes, to be prepared for any kind of epidemic or outbreak?
Katz: There are not. There are people who are keeping stockpiles of Tamiflu, a drug which may or may not be effective against avian flu. And their concern as well if there were an outbreak, how would I know that I would be able to get it rapidly for myself and for my family. In general, we believe first that people having in their homes medications they do not need pose more risks, just a child ingesting a medication that is unneeded. A few deaths or poisonings from that given that there are currently no risks at all from avian flu would result in a worse scenario. Second, Tamiflu and other drugs that are used to fight influenza, do have important clinical uses, and to the extent that people stockpile medications, those medications will not be available for people who actually use it.
And then they simply may not work.
Adam: Are there also risks that inappropriate uses of those antiviral drugs might promote mutations that would result in a more resistant strain?
Katz: Potentially, but remember, that in order to develop resistance, you have to actually have the organism. So, even if multiple people, millions of people took Tamiflu, if avian flu isn't in their system, avian flu itself cannot become resistant to the Tamiflu.
BIRD FLU FUNDING
Adam: Have there been changes in funding for epidemic preparedness because of avian flu? Is there any good that is coming out of this?
Katz: Well those in some ways are different questions. Has funding increased for preparation around avian flu? Absolutely. And the CDC is actively working on developing vaccines, which would certainly be the most effective way to block an epidemic, assuming that such a vaccine could be developed. Is that a good side? It would be a good side if the money weren't coming from other health issues, but in general the money is coming from fighting other diseases like tuberculosis that millions of people still die of, and that we could absolutely save lives. So in the end, whether or not spending money on a disease that we may never see as opposed to spending money on diseases that are currently killing people, I'm not sure that is such a great bargain.
Adam: So your kind of saying in the larger scheme of things, while preparedness for an epidemic is a public health activity, we may not be looking at the larger health picture in how we spend our health care dollars?
Katz: Right, so the relevant question would be what is the most cost-effective way to bring about health status improvement in my community, and it would be hard to choose as it's model, developing a preventive strategy against avian flu as that. Right? Probably addressing some of the socio-economic determinants of poor health in areas of San Francisco like the Bay View would probably be the number one way that you could improve health cost-effectively.
Adam: Do you think a lot of that is due to media coverage, and politics and hype?
Katz: Oh, absolutely. Doctors have a lot of cache, everyone is afraid of epidemics, you hear epidemics, you turn and look, we think of science fiction, it is something that provokes people. There's also on the positive side, there is a tremendous amount that can be learned every time you encounter a new organism, whether that is Ebola or avian flu or west nile, so that even if those organisms themselves either don't pose true dangers or you don't solve those dangers, to the extent that you learn something useful for science. It's also why we try to emphasize here that our efforts on preparedness should be preparedness for anything. So when we put together our list of how we are going to move doctors and nurses who work for San Francisco department of public health efficiently from the east Bay if the bridge collapses or can't be traveled. That's a model that might be helpful for a pandemic, or for an earthquake. And earthquake is certainly a more likely catastrophic event in San Francisco than avian flu.
CLOSING
Adam: And on that happy note, I'd like to thank you for talking with us.
Katz: Thank you, it was my pleasure.
Adam: Good luck with all of your health preparedness efforts.
Katz: Thank you.
