In Our Time - Man and Disease

Episode Date: December 12, 2002

Melvyn Bragg and guests discuss man and disease. The Book of Exodus makes clear that when God wants to strike humankind, he does so with plague and disease. For millennia epidemics were understood exactly that way - as acts of divine retribution, a force of nature that could devastate empires and annihilate great swathes of population at a stroke. From the bubonic plague to measles, from cholera to smallpox, epidemics have constantly reshaped our world, leaving destruction and huge social upheaval in their wake. Before advanced science, what defences did humankind have? How much did the ancient Greeks understand of the root causes of disease - or did they simply explain it as an imbalance of the four humours that governed the body? What were the social and political consequences of The Black Death of 14th century Europe which wiped out a third of the population? How did the scientific breakthroughs of the 19th century - and the discovery of germ theory - alter people's perception of disease? And is it possible to live in a disease free society? How have we understood these afflictions, how have we fought against them and is it a war we can ever win?With Dr Anne Hardy, Reader in the History of Medicine at the Wellcome Trust Centre at University College London; David Bradley, Professor of Tropical Hygiene at the London School of Hygiene and Tropical Medicine; Dr Chris Dye, epidemiologist with the World Health Organisation.

This BBC podcast is supported by ads outside the UK. Thanks for downloading the In Our Time podcast. For more details about In Our Time and for our terms of use, please go to BBC.co.com.uk forward slash radio 4. I hope you enjoy the programme. Hello, the Book of Exodus makes clear that when God wants to strike man, he does so with plague and disease. For millennia, epidemics were understood exactly that way

as acts of divine retribution, a force of nature that could devastate empires and annihilated great swel. ways of population at a stroke. From the bubonic plague to measles, from cholera to smallpox, epidemics have constantly reshaped our world, leaving destruction and often huge social upheaval in their wake. Before advanced science, what defences did humankind have? How much did the ancient Greeks understand of the root causes of disease?

What were the social and political consequences of the black death of 14th century of Europe, which wiped out its said, a third of the population? How did the scientific breakthroughs of the 19th century and the discovery of germ theory alter people's perceptions of disease and is it possible to arrive at a disease-free society? With me to discuss this, Dr. Anne Hardy, reader in the history of medicine

at the Welcome Trust Centre at University College London, David Bradley, Professor of Tropical Hygiene at the London School of Hygiene and Tropical Medicine, and Dr. Chris Dye, Infectious Diseases Specialist with the World Health Organisation. Anne Hardy, can we talk about the origins of disease itself? When did human kind begin to suffer from disease? Human kind begins to suffer from disease.

Well, almost from the beginning, I think it's fair to say, in that in hunter-gatherer societies, people bear a load of parasites which can result in disease over a long period of time. But disease, as we understand it, probably only came into being once societies settled down, once they became agricultural, once they established towns and villages, and particularly once human beings started organising themselves into cities,

and cities ruled by governments and settling down into states. So it's a long process before diseases, as we know them, emerged and began to affect human societies. When you say as we know them, we mean that we can pass on to each other in close communities because hunter scavengers would have diseases, but the groups so small and they were moving so nomadically that these diseases would not spread in the way that the fear now isn't the fact, though, is the spread of disease?

That's exactly right. You need a mass of population before diseases can begin to operate and communicate from person to person. Diseases, as we know them, probably originated in animal communities because, as you know, cattle and horses are herd creatures and in the distant past, we think that disease originates, among those populations. And once humans settle down and start domesticating animals,

they then come into contact with the animal infections. And several diseases that we still have today, measles, for example, are thought to have close relations in the animal world and to have transmitted to have passed between species at some point in the distant past. So we're talking around about 10,000 years ago when the crossover into agricultural communities began.

I've got the date of 3,000 BC, in my head, but I think that that's to do with critical population mass in humans. That's when I think it's a Sumerian society first reaches that critical density in which... What is a critical density? I mean, what's the size of a critical density? You need half a million population, I think I'm right, in saying, before you can infectious diseases can establish themselves on a basis where they're constantly circulating in human society. So a disease like measles might have appeared in small population groups and then disappeared, before that. But once you have a critical mass of half a million people, they can keep circulating.

So you have the domestication of animals and you have the density. What about the environment? Does that play a factor from early on as well? Environment does play a factor from early on. That's part of the emergence of infectious disease when human society is settled down, is the increasing density of parasite load in settled populations, where you have to work out to of disposing of your feces, disposing of your garbage, that kind of thing. And if those systems aren't properly, well, I say properly, that's a bit of an anachronism to put it that way. But in societies where those sort of disposal mechanisms are fairly primitive, you get the build-up of infection on site. Right, thank you. David Bradley, to what extent did the Greeks and Romans, We've had to just mention the environment.

What extent did they link diseases with the environment? Well, the Greeks, going right back to Hippocrates, about 400 BC, had a fairly clear idea of the environment, one of the hypocritic writings, airs, waters and places, sets out in quite considerable detail how the doctor has to go and think about the seasons of the year and which side of the town and whether the inhabitants drink soft water or hard water.

So they had a very clear idea. I think there were sort of two sets of ideas going on at the same time, in fact. You had the sort of Greek one, which was a rather rational mechanical, what is this disease and how has it come about mechanically. And then the much more widespread ideas in other groups where they were more asking the question, Why have we got this disease, less worrying about which disease, but why is it that we've got it and you haven't?

Other groups inside Greek society, you mean? No, I was thinking beyond Greek society. But about the same time? Yes, and I think those two strains have really run in parallel ever since, in fact. The other thing people did was to build quite complicated systems of how they thought about disease. I mean, the sort of things that Galen in the West and Chinese medicine and so on had systems. We'd like to know about that.

with great complexity. Can you give us some idea of Galen's system and the Chinese system you're talking about? A lot of them seem to have had fours, earth, air, fire and water, and then reflection of that in the human organism in terms of, I think, what was called, yellow bile, black bile, blood and...

Flam. Flam. And flam, yes. Flem on my right. Precisely. Leaving that one for Creas. Those four. And then quite complex. systems were built up around that.

And quite a lot of those systems were about an equilibrium state which got disturbed by an excess or a scarcity of one of those. What about the Chinese system? You mentioned Chinese. They again had very complex systems related to that, not quite the same and much more elaborate in some respects. But they had features in common. System building seems to have been a feature of physicians

rather than the surgeons who were much more empirics and were concerned with dealing with a practical thing that was in front of them and without a philosophical system for dealing with their diseases. When the great monotheisms came in, of course, people saw disease as an act of divine retribution, isn't there? And that rather dealt with the other question of why me? Why have I got whatever the disease is rather than somebody else? Well, you must have been wicked.

I think one of the interesting things is the way that later on in the 19th century you've got to swing away from the why me to the question of what disease. And everyone lost interest in the why me question. And now with genetics, we're beginning to come back to the why me and be able to say, well, actually, you've got this particular enzyme and so you'll get malaria worse than somebody else or whatever the... Fascinating.

Chris died, the black death, for instance, in the 14th century Europe, there's not a person who doesn't know about the black death, and maybe the fear of rats come from that and so on. It's supposed to have killed about a third of the population in Europe. as I said in the opening bit. Can you just tell us how it came and what it was, where it came from? The Black Death is plague in the strict sense, as distinct from the biblical plagues of locusts or what have you.

And it's caused by a bacterium called Yusinia, which usually lives in rats and is transmitted between rats by fleas. People get it when they intervene in that. transmission cycle. What does that mean? And that's what happened when black death spread across Europe. People were taking rats and fleas with them as baggage, for example, on the trading caravans from China through the Black Sea ports and into Europe. They were living in close association with a natural transmission cycle between the fleas and the rats. It was inevitable that fleas would from time to time bite people instead of rats. And that's why people contracted the

infection which normally lives in rats. But the rats came out of the east, the opening up of the trade routes of the Mongol Empire, and that sort of thing. What's going on in the east that makes the rats have that in the first place? The transmission cycle of plague bacillus in rats has evolved over a very long period of time. The precise origin of the bacterium that causes plague is obscure. What's become much more clear is what happened, when rats flees and humans came into contact. Through documents of historians,

the effect of one third of people approximately being killed in Europe between the years of 1347 and about 1350. Because of a series of events, including the movement of caravans, including wars in Eastern Europe, and including Europe deep in economic recession in the early 14th century. You actually said that the black death did kill, was supposed to kill about a third of the people in Europe, and as it were, reduced its strength for several hundred years to come.

Could you develop that a little? Certainly the population size was reduced, but there were probably both positive and negative benefits of that reduction. In one popular theory, the black death played a contributing factor in the peasant's revolt, which came around by 1381. The black death sowed the seeds of social discontent in the relationship between landlords and peasants working on the land, which eventually was manifest in the Peasant's Revolt in 1380.

And in another popular theory led on to the much larger effects of the later Renaissance. One effect that the black death had was to reduce belief, and faith in the Christian church. The Christian church was on its back foot after the Black Death. And in the views of some historians, that encouraged the rise of the secular city state, the rise of individualism, and that rise in individualism led to the flowering that we saw as the Renaissance.

That's a very grand theory, and some historians subscribe to that. others are more reluctant and they're happy to say that the back death was a contributing factor but probably not the principal catalyzing event. I'd like to talk about bringing in cholera in the 19th century, but I don't think we've got time for that. But one more thing that was brought, if the three of you can join in here, the epidemic of Spanish influenza in 1918, which is we're always told wiped out more people than were lost in the First World War.

And yet, and it's a devastating statistic. But why is it called Spanish and why did it come from and why did it wipe up so many people? Would you like to start? I'll start at the end. Leave the first question to the others. Why did it wipe out so many people? Well, the 1918 pandemic of influenza

was evidently a new strain of influenza. New strains of influenza come from southern China, broadly. They come from the mixing of influenza virus. in pig and duck populations where there's a great deal of opportunity for genetic exchange among the viruses, which throws up new types. When those new types emerge,

they sweep westwards across Asia and into Europe and then on to the Americas. And if they're completely new types of influenza to which the human population hasn't previously exposed, then people are very susceptible to developing disease. So that was one factor. The other factor was, of course, that the world had just emerged from the First World War,

which had its own devastating consequences on health. And the world was in economic recession. It was in a depressed state. There were probably a lot of particularly susceptible people around at that time, which contributed to this very large death toll, supposedly 30 million people. And why was it called Spanish, then? There's always a tendency to cast blame on other people

when a new disease arrives. Why is it called Chinese? Well, I'm not quite sure that we know the real details, but it broke out simultaneously in three different parts of the world in the United States and in Africa and in, I think it was a French port of breast. And I suppose that it's partly because it's a disease which initially appears to have travelled through trade routes, as Chris was saying earlier, about the plague.

But I think Spain also was not involved in the First World War to a large extent. And there is a sense in which you're casting blame on Spain for having been an anthropo where people travelling to other countries would go via Spain in order to have a safe passage. And therefore it became a sort of great mixing area, presumably, in all sorts of senses. And so there's a tendency to blame it on Spain. Right. Let's talk about the 19th century when the breakthroughs. began where it seems quite a number of people, but we can name a few key scientists who began

to get to grips through this and enable you to have your jobs as modern infectious diseases. Get on, get to grip. David Bradley, who she was started with, Kosh or Pasteur? Can we start with one of those and tell us what they do? Either of them or, you might get one's Ross, but. We've come to Ross, I wouldn't mind keeping Ross for a little bit lighter. I suppose Pasteur comes first. So there's a movement there to get to grips with this.

Now, it's partly technological. They've got the stuff, they've got microscopes, and they've got stethoscopes, and so it's partly technologically assisted, if not lead. Partly that, partly experimental methods, and partly the need to get the idea that organisms are not spontaneously generated. And so Pasteur was originally, before he got so heavily into disease, was looking at putrefaction, and showed that actually things don't putrefify,

if you sterilize them, and even if you're in combination with the air, if you put a little cotton wool in the end of your flask, so that particular matter can't get in from the air, things remain undecayed, and you actually need bacteria to get in, and then they multiply rapidly. And so the issue of microbes was the thing that Pasteur

made an enormous contribution to establishing the idea, that microbes are not spontaneously generated. They're not a product of disease, they might be the cause of disease. And then following through from that, looking at diseases, paparine in the silkworms. Yes. Yes, silkworms.

And then getting into trying to prevent human disease. He was essentially responding to particular things. But I suppose at that point, then the science moves to Koch, who was able to produce a solid medium, Instead of having to grow bacteria in soup where you can't really sort out all the millions from each other, he got gelatin on a plate, and by taking a tiny drop of the soup and spreading it out,

you can separate out of these tiny microscopic bacteria, and each one will grow, and he found that they make particular shapes of colony, which become visible to the naked eye after a time, and so you had a way of getting at specific microbes and showing that specific ones are linked to specific diseases. And he did that with tuberculosis and then later with cholera. And these were the sort of two dramatic things which put bacteriology on the map.

To an outsider like myself looking at this, one of the things you notice is the remarkable rapidity with which these discoveries arrived once they'd gone on the track, really. And then we have, and it's happening all over the place. There's a sort of charm about it as well, isn't it, English country doctor, Jenner, Edward Jenner, pioneered vaccination into smallpox.

Which proceeded. It came from his observation of milkmates. It's got a little fairy story element, hasn't it? But perhaps one of the factors that encouraged the productivity of Pasteur and Koch was the rivalry between them. They were quite hostile to each other, each trying to outdo the other.

and that sense of competition probably increased their workload and productivity. But Jenna came before both of them with his remarkable findings, single-handedly, apparently, that you could vaccinate to prevent viral diseases. He didn't know there were viral diseases at the time, but you could vaccinate to prevent common diseases like cowpox and smallpox. But that was an observation. I mean, I wasn't being physicians. I'm reading this thing that he observed that milkmen,

in this country practice did not get smallpox and he concluded that was because they got cowpox and he took cowpox and used that as a vaccine to prevent smallpox. Is that right? That's right. And he was kind of lucky that they were related cowpox and smallpox. Yes, there was an element

of luck as there are in many discoveries like the later discovery of penicillin. One just happened to be dealing with a fungus that produced the right compound to impede the growth of that particular bacterium at the time.

Yes, but it's fair to say, too, that Jenna was building on an established folklore. I mean, there was, in the 18th century farming community, it was quite well known that cowpox would prevent smallpox. And there are all sorts of folk practices that exist before Jenna put the science, well, not put the science around it, but demonstrated to the satisfaction of the scientific community that this worked. So discovery in discovery, it's an intelligent appreciation of something that's already known in the local community.

When did the idea of public health in the community, that emerged about this time too, didn't it? And what formed it? So when did it emerge and what drove it? The idea of public health in the community really emerges in the first half of the 19th century. Traditionally it said that it's been driven by the arrival of cholera in Europe. From India. from India, but in fact we can see that there was a great deal of concern in the community, both in France and in Britain at that time, about fevers in general,

which is one of the consequences of rapid urbanisation in England as a result of the Industrial Revolution, and that at this period is typhoid and typhus, which are endemic in the community, and which have been observed in hospital patients to be on the increase in the community, and they're indigenous. Collar is an invader. It doesn't belong in Britain. And it comes, it visits Europe, it goes away again.

But it's concern about the indigenous fevers and the increase there that is what really drives the public health movement and the attempt to begin to get grips with disease, infectious disease in the community. Is the drive in the mid-nighteenth century, let's call it that, and just for the sake of ease at this particular point? Is that a mixture of philosophy and self-examination?

Philanthropy and self-preservation. Well, there are elements of that in it, but there's also a strong economic element there. If we go back to Edwin Chadwick, who was the individual who really started this movement in England, Chadwick was abenthamite, and he was interested in reducing the costs of disease on society. And that is one strong element.

element there. Philanthropy, yes, there are people who are interested in public health because it's obviously not good for the poor to be inflicted with disease which makes them dependent on the state, which makes them miserable. But individually, we can see too that, I mean, if you look at the novels of Dickens, for instance, it's quite clear that, that, that, that, the, the middle classes did think about the poor as carriers of disease. I mean, there's a wonderful passage in Bleak House where Dickens described the great slum, Tom All Alone's, which seethes and festers in the heart of London. And, you know, there's nothing about Tom All Alone's that doesn't, not a wickedness of his committing,

not a something or other, that doesn't travel right the way through the ranks of society from the lowest of the low to the highest of the high. And that's a sort of image of a, contagion and disease seeping from poverty and neglect and insanitary conditions right through to affect all classes of society. So there is that sense that of individual preservation, perhaps if we do something about this, the rest of us won't suffer as seriously we might do otherwise.

But it wasn't only structures, it was daily habits, wasn't it? The idea of washing one's hands, a typhoid Mary in New York, as a woman who cooked in a New York restaurant. That comes much later. That comes much later. And spitting, because spitting could also carry diseases, is that later? Well, this is the outcome of the bacteriological revolution of the work of Pasteur and Koch that we were talking about earlier. Can you just tell people why spitting wasn't such a good thing?

Spitting is... Even when I was young, I mean, you spat, didn't you? Yes. Well, there was a whole culture of spitting. It was a male culture of spitting. How far could you spit? How large was your gompb, you know? But this is Chris's department, because that was tuberculosis.

You just cleaned that off pretty good. People would be interested. Why was it tuberculosis? Why was spitting tuberculosis? Well, tuberculosis was a devastating disease and it was still causing something like 70,000 deaths a year in this country in 1900. It's infectious.

And the bacteriologists can demonstrate that the tuberculal bacillus, the disease-causing organism, is transmitted in spittal. and they also think they demonstrate that once a spit dries, the tuberculosis organism is disseminated in dust in the streets and elsewhere. So it becomes important to discourage people from spitting because that's one way that tuberculosis can infect other individuals in the community.

But I think it's likely to be a minor route of transmission, ironically, although so much emphasis was put on not spitting, in fact, most of transmission from tuberculosis, was probably by people coughing into the atmosphere and the aerosol droplets carrying the bacteria to other people who would then inhale them directly. It's rather unlikely that much tuberculosis

was being picked up through direct contact with spit. Right, well, we've cleared that up. Can I just... Right. Do you think we'll... Have we ever successfully defeated a disease? I love you. You people.

I think people in... Well, the classic one, of course, though it's being questioned now for different reasons, is smallpox, which got rid of completely from the world so that there were no cases of smallpox after the very late 1970s, the last person in the world.

And that was just intensive thing. It was a combination of, first of all, mass vaccination. to try and reduce the number of cases. But that wasn't making too much headway in the last few parts of the world like Africa and so on. And they brought in Bill Fagie, who was working in the field there, brought in the idea of when you had one of these residual,

limited number of cases, you put a watch on and you vaccinate anyone who came near that person with utter ruthlessness almost. And that finally got rid of the last few cases. and that methodology managed to get rid of it. But smallpox is unusual because there aren't carriers. That is to say, there aren't people wandering around carrying smallpox, baccars.

So how might it come back then? Why are we hearing that it might come back then? Well, there are a few bottles of it in various places, probably rather more places than it's supposed to still be. And there has been the suggestion that it might be used for bioterrorism. and prepared in the right way. It could be quite devastating. So that that's a sort of deliberate act.

You envisaged the possibility of a disease-free world? Is that possible at all? It's a fantasy? No, is the short answer. We're never going to be living in a disease-free world. The world is full of organisms trying to make a living off each other. That's where disease comes from. It's many different manifestations of that ecological fact. We're never going to get rid of disease per se.

We could get rid of a few more than we have done so far. The next big one on the list is polio, which is now close to eradication through a gigantic effort by WHO and various other organisations working together. And then when polio has been cleared up, there's talk of doing the same for measles as well, but that'll be a much more challenging problem. And, Heidi, do you think the West response to disease has changed. Do you think that we now seem in this country to live largely in a disease-free

area, do you think that that means that we're complacent about disease or over-alarmed when new diseases come up? We've been extremely fortunate in the West in the last 50 years. Since polio immunisation was introduced in the 1950s and all the other childhood immunisations, we've to a large extent lost our knowledge, our consciousness, our understanding of what it's like to be affected with infectious disease. And that, I think, has been a great change in the last 50 years. And it's one, we may be living in a fool's paradise. The situation could easily change.

I think in the 1970s. Well, I'm afraid we have to go out now. awfully sorry. Thank you all very much. And thank you very much for listening. We hope you've enjoyed this Radio 4 podcast. You can find hundreds of other programs about history, science and philosophy at BBC.com. forward slash radio 4