Epidemics in Western Society Since 1600

HIST 234 - Lecture 15 - Tropical Medicine as a Discipline

Chapter 1. Tropical Medicine [00:00:00]

Professor Frank Snowden: Okay, well let’s begin. And, as you know, in our class one of the topics, or themes, that we’re considering is intellectual history. And lurking in the background, of course, is the big question of medicine itself and what it is. What is medical science? What does it mean to have a medical science? Well, this morning we’ll be considering that. Is medical science purely the technical application of neutral knowledge? Or should we think of it as a cultural institution, also, built by dominant social groups in society, that in some way may reflect their worldview, sometimes may embody their prejudices, and may promote their interests? And at least we should ask the question, if we accept the biomedical paradigm of disease, what are the implications of that acceptance? What are the costs? What are we giving up?

So, that’s the big issue. And today what I’d like to do is to look at a subset of the bigger problem, and this is the medical specialization that’s known as “tropical medicine.” It emerged in the 1890s, in a period, that is, of — it gained rapidly enormous prestige and influence, and is still a major subfield in medicine. The discipline thus far has undergone three periods in its history. The first is the one that we’re going to be concentrating on this morning, and that’s the period from roughly the 1890s until more or less the First World War. That marks the real heyday of tropical medicine, the time when it was the cutting edge of medical science, when it made a series of major discoveries, and served the most obvious political purposes.

It was followed in its history by a second period, that lasts more or less from World War I until the 1970s, the next half-century of tropical medicine. And during this period the discipline loses a lot of its scientific momentum. Tropical medicine came to be confined essentially to parasitology, and at this period, the dynamism in medical science moved instead to microbiology and such offshoots as immunology, and that boosted such major developments as antibiotics and a series of effective vaccines, and that attracted the lion’s share of research funds. So, tropical medicine, in the period from the First World War to the 1970s, made relatively few major, major discoveries.

Then, after World War II, and accelerating from the 1970s, we see a third phase, ushered in by such things as decolonization and a new attention to public health in the Third World, and with it a new influx of research funds through the World Health Organization and powerful foundations like the Rockefeller and MacArthur Foundations. Well, what I want to do this morning is to look critically at tropical medicine. And by that I don’t mean for or against. What I want to do instead is to look at why it arose as a discipline when it did. What interests did it serve? What were its implications? And I’m going to argue that tropical medicine, and particularly in this formative early period before the First World War, was clearly socially constructed.

This is a period that coincides with the high tide of colonial expansion, the age of the scramble for Africa. And tropical medicine gave expression to an imperial view of the world, and it marked the relationship, in medical terms, between Western Europe, on the one hand, and Asia and Africa on the other, and between the United States and Latin America. As a discipline, it served as a major instrument also in promoting European expansion overseas, and American hegemony in the Americas. In its applications, and in the policies it promoted, tropical medicine was not only value-neutral science; it was also an instrument of power, and we need to bear that in mind.

Chapter 2. Background: Diseases of the Tropics [00:05:48]

Now, the emergence of tropical medicine marked a transition, a transformation, from something that had preceded it, and that I hope won’t be confusing. But from the middle of the eighteenth century, more or less, until the closing decade of the nineteenth century, there had been an older tradition that can be summarized under the label of “diseases of the tropics.” And there were a couple of classic statements of this older tradition. One was a work, an important work, by James Lind, an eighteenth-century physician, who wrote “An Essay on Diseases Incidental to Europeans in Hot Climates,” and this was built on the experience of Europeans in the West Indies. And then there was another work by James Johnson called “The Influence of Tropical Climates on European Constitutions,” built on the experience of Europeans in India.

What these works, and other ones of their kind, meant in the expression “diseases of the tropics” was something particular. They meant that in the colonial world — in, that is, the area of hot climate, as it was expressed at the time — Europeans were subject to special diseases as challenges, that arose as a result of conditions peculiar to warm climates, and to the resulting conditions of temperature, humidity and local ecology. Under those conditions, the diseases that would afflict Europeans were not, however, different in nature from those familiar at home. The diseases of hot countries were heightened in their virulence, perhaps, and the constitutions of white people were now subjected to new and unfamiliar stresses that made them peculiarly vulnerable in these climates to disease. But the issue was simply — in the era, should we say, of diseases of the tropics — was simply one of degree, rather than kind.

The diseases of the tropics were simply intense variants of familiar disease processes. And there was an educational corollary to that, which was that physicians who had studied general medicine, in European medical schools, were fully equipped to treat the entire spectrum of human diseases wherever they occurred. Diseases of the tropics weren’t a special category. They were simply heightened versions of familiar maladies. In other words, the concept of diseases of the tropics presupposed a universality of a single medical discipline that viewed the diseases of the tropical world as posing problems of degree, but not of a thoroughly different kind.

We should also say that this idea of diseases of the tropics already did have embodied in it some troubling and important questions that had to do with a colonial or imperial and racial view of the world. European bodies, the concept presupposed, were different in some way from those of Asians and Africans. They weren’t intended for the conditions prevailing in the colonies, and so the question was, were the tropics in fact inhabitable for Europeans? You can see this in expressions like “darkest Africa,” “teeming Asia” — those imply dangerous places — and even more the expression of “the white man’s grave.”

And, so, the question was whether settling in the tropics was going to be possible. Was it simply that Europeans needed a period of seasoning — another term of the time — or acclimatization, after which they’d be stress-hardy and able to survive in these new settings? Physicians who dealt with diseases of the tropics thought of themselves as performing an indispensable service, one that was useful to European states, and especially to explorers, travelers, settlers, colonial administrators, and of course sailors and soldiers. The service was to provide assistance and advice during the time of acclimatization, advice on exercise, diet, clothing and housing; in short, everything that new arrivals would need to protect themselves from the rigors of the new environment. But the 1890s marked a transition to something different — from this view of diseases of the tropics, to something that sounds subtly different, but was profoundly so, and that is tropical diseases and tropical medicine.

Chapter 3. Transition to Tropical Diseases and Tropical Medicine: Medical Factors [00:11:53]

Now, what was implied in this transition, this transformation? It was a vision of the world in which Asia and Africa, for Europeans, or possibly Latin America, for U.S. citizens, were conceived in a really charged fashion as harboring disease that were conceptually different from other diseases, that could not be treated by physicians who had graduated from European medical schools unless they had undergone special postgraduate training. And the implication too was a different form of hygiene. And there was a work that was a foundational text for this new medical specialty, one of the most influential medical works of the whole of the nineteenth century, and one that had enormous influence on the relations of the metropolitan powers to their colonial dependencies. This work was by this man, a British physician named Patrick Manson, who came to be known as the father of tropical medicine.

The work that caused the stir was called — it’s an enormous, fat volume — entitled Tropical Diseases: A Manual for the Diseases of Warm Climates. And it was written in 1898, which isn’t an accident. And it wasn’t also an accident that the father of tropical medicine was British, or that Britain became the world center of the new discipline, Britain at the time being the world’s leading imperial power. Now, what were the background conditions that promoted the emergence of this whole new medical sub-discipline? A first, as we said, was Britain’s position as a great colonial power. There were others, as well, that lay behind this new medical specialism. One was something we’ve already dealt with, and that is the germ theory of disease and the triumph of contagionism over anticontagionism.

The germ theory had a number of possible implications. One was the idea, as we’ve seen, of clinching the concept of disease specificity. And tropical medicine was built on the premise that some diseases lurking in Africa and Asian now needed new classifications, belonging in special categories, and that to understand them — and here was another of its implications — you needed physicians who were trained at special institutions, and had a specialized curriculum, and that they could be dealt with by specific special remedies and measures of hygiene that were different from those that had been successful in bringing about a mortality revolution in Europe.

As you’ll remember when we examined the theories of Max van Pettenkofer, the germ theory marked the end of an alternative approach to medicine, one that had flourished at mid-century, particularly in continental Europe, but was intellectually vanquished by the laboratory methods of bacteriology, and later parasitology. This was the idea of social medicine, associated with a radical German physician, Rudolf Virchow. For social medicine, medicine was a collective enterprise in which it was important for physicians to treat not only individual patients, but society as a whole, dealing with issues of sanitary conditions, poverty, nutrition, social justice. Well, the germ theory of disease was a setback for social medicine, and I’m going to argue that tropical medicine went even a step further in the turn from that direction. It argued that in the tropical world the chief problem — and we’re talking with the period down to World War I — the chief problem was to preserve the health of European settlers.

As a discipline, until much later in its life, tropical medicine largely ignored the general health of indigenous societies. This also came to mean something somewhat sinister, when the logic was applied to the global north and south, and black/white relationships. It seemed to suggest that the bodies of Africans and teeming Asians were medically dangerous, that they were the reservoirs for diseases that posed serious new threats for Europeans. And there was an implication, a possible strategy for hygiene, and that was that perhaps the best way forward was for Europeans and indigenous peoples to be segregated in their housing arrangements, that Europeans should live in the tropical world in special enclaves where the latest prophylactic measures would be applied. Whereas natives, or indigenous peoples, could be left as they had been found.

Alternatively, if you read some of the literature produced by works of European writers such as Somerset Maugham, you’d see that the Europeans were advised to take to the hills during the dangerous summer months, leaving dangerous natives behind. But we shouldn’t forget that tropical medicine, at the turn of the century, was also where the scientific action and excitement in medical science were taking place. Beyond the germ theory of disease, tropical medicine embodied the various latest developments, and above all the new science of parasitology. And it attracted some of the leading figures, indeed, in the development of microbiology to enter this new discipline. This was true, for example, of Robert Koch, who came, made a voyage, to Italy to study parasitology in the form of malaria, and then set off for the colonial world. Pasteur at this time had just died, but his institute saw affiliates or satellite institutes set up at Saigon, at Tunis, Algiers, in the 1890s, all preaching the new discipline of tropical medicine. And Pasteur’s most famous and able disciple, Émile Roux, became a specialist in this new discipline.

To understand it, we need to remember two major breakthroughs. The first was by Patrick Manson in 1883. At that time, he discovered something that was radically new. He was dealing with the disease of elephantiasis, and he found that the filarial worm that causes it is transmitted by mosquitoes; the first example of a vector borne disease transmission. This was epoch-making in that respect. And it was also a movement from bacteria or — though it wasn’t known at the time — viruses, to more complex life forms, the interaction of humans with biologically more sophisticated protozoa or helminths or worms, and with insect vectors. Diseases could now be seen to be part of a much more complicated process, and with complicated life forms.

Then there was, following this, the establishment of the mosquito theory of transmission for malaria, which took place during the end of the decade of the 1890s, with two figures, who were working independently of each other, but in 1898 established that malaria was a parasitical disease, transmitted by certain species of mosquitoes. So, malaria — which is a disease that we’ll be dealing with after the spring break — was of decisive importance in the establishment of tropical medicine, and malaria was the disease that was at its heart and its center.

The two people were in Italy — and we’ll be coming back to this in a couple of weeks, when we resume classes — in Italy there was Giovanni Battista Grassi, who made a very elegant demonstration, and a very convincing one, that human malaria was transmitted by mosquitoes. And he did so by experiments in which he introduced just one variable in the exposure, during the warm summer months, of large populations to biting insects. He protected, by screening, or later by chemical means, select groups of people, while everyone around them was falling ill of malaria. They lived in exactly the same conditions as those around them, except for one variable; that they weren’t subject to the bites of flying insects. And thereby he established that it was indeed insects, mosquitoes, and certain types of mosquitoes; we’ll be returning to that. Not all mosquitoes, just anophelene mosquitoes, and certain species of them, that transmitted the disease of malaria.

At the same time, Ronald Ross, a British physician in India, was working instead with malaria among the avian — that is, birds — avian malaria, where he demonstrated that it too was transmitted by the bites of mosquitoes. And he argued, by analogy, that human malaria was probably transmitted by mosquitoes as well. Now, this was the age of a ferocious imperial rivalry, and Ross was the first British scientist to discover the pathogen of a major disease, and he became a national icon, the British answer to Pasteur or Koch. He won the Nobel Prize, and along with Manson became one of two decisive figures in the founding of the discipline of tropical medicine.

It was quite interesting that there was an extraordinary collaboration between Manson and Ross in India, where Ross wrote home what he was finding under his microscope in India, and sent that back to Manson, who worked with him in suggesting new directions for his research, and pushed him forward. So, in many ways the discovery of the transmission of malaria belonged to Manson as well as Ross. Well, in any case, malaria became the template, the ideal type of tropical diseases. And in Manson’s great work malaria occupies the largest amount of space in the volume; the reasons being that it was a perfectly vector-transmitted disease, a perfect parasitic disease. The plasmodium that causes it, as we’ll see in a couple of weeks, lives in a closed cycle, and never exists free in the environment. Human beings don’t happen upon it, and the plasmodium has an extremely complicated lifecycle in both man and mosquito. And the involvement of the mosquito also is scientifically complicated; in other words, it was useful and important that Grassi was a naturalist, was well as a physician.

Parasitology was scientifically interesting, and intellectually so. To study malariology, one needed to be a physician, but also an entomologist, a naturalist, and to have a knowledge of the basic sciences. So, in 1898, for a whole generation, parasitology replaced bacteriology as the cutting edge of medical science, and it became the foundation of this new discipline, the rising discipline of tropical medicine. Well, if that’s how it emerges, what is the new discipline? Manson defined tropical medicine in his great work. For him, it was a special discipline, with diseases of an area defined by geography and warm climate. Diseases there, he said, were unlike the diseases of the temperate zone, and they require therefore a special medical discipline to deal with them, and they require physicians who are specially trained in post-graduate institutes. For that reason, tropical medicine emerged outside of established medical schools, because it presupposed that physicians needed a special curriculum and training to deal with diseases that were conceptually different.

For example, in 1898, in association with Joseph Chamberlain, the secretary of state for the colonies — and you can see the role of the state in the promotion of this new discipline, which was seen as important for the promotion of imperial interests — and with the collaboration of Patrick Manson — there was founded the London School of Tropical Medicine, with the specific intention of training colonial medical officers in a new medical discipline; or very closely associated was the Liverpool School of Tropical Medicine. Another idea that Manson said was essential to the new discipline was that tropical diseases were caused not usually by bacteria but by more complex biological agents, with complex lifecycles — protozoa and helmets — and that they were transmitted by insect vectors, like mosquitoes or the tsetse fly.

Malaria had pride of place. It was the ideal type to illustrate this, and it’s the first disease that Manson discusses in his work, and the disease he discusses at greatest length. There were others of this type, like trypanosomiasis, which was African sleeping sickness, which was caused by a parasite also that multiplies in the human bloodstream and causes skin eruptions, anemia, chronic fever, debilitation, lethargy and perhaps coma and death. It was transmitted by the tsetse fly. Or there was schistosomiasis, caused by worms, with the snail as its alternative host. Or leishmaniasis, or yellow fever — a viral infection, it was later discovered — transmitted by a certain species of mosquito.

Well, so far, if you were reading Manson’s work, you would’ve found the diseases I’ve just mentioned would be the ones that you would’ve encountered, and there was a kind of logical coherence to what they were. Diseases of places with warm climates, transmitted by mosquitoes, caused not by bacteria but rather by more complex life forms. But Manson then goes on. And what we see then is something of a grab bag of diseases, that don’t seem to have much of a scientific connecting link. He mentions certain infectious bacterial diseases, some of them very familiar to you already: bubonic plague, Asiatic cholera. He adds leprosy. He then moves on to certain nutritional diseases: pellagra, which is caused by a deficiency of niacin, if your diet consists not of wheat, but exclusively of corn; or beriberi, or certain fungal diseases. And he even calls heatstroke a tropical disease.

Chapter 4. Institutional Factors [00:31:09]

Another background factor was institutional. Should we call it the institutionalization of this new medical discipline? That is, it coincides with the high point of European expansion. And this wasn’t just a coincidence. It was an important instrument in the domination of Africa and India, for instance, as important as gun powder, enabling settlers to run mines and plantations, traders to travel, administrators to govern, missionaries to preach, and soldiers to perform their duties. For this reason, tropical medicine rapidly attracts governmental backing, certainly in the British case, and institutional support and assistance, from powerful economic interests, with concerns in the tropical world. So, these institutions — in Britain we’ve already talked about the London School of Tropical Medicine, the Liverpool School of Tropical Medicine, the Royal Society of Tropical Medicine and Hygiene. And it’s embedded in a new major journal, The Journal of Tropical Medicine and Hygiene, founded in 1895.

In France, we see the Pasteur Institute; in the United States, such institutions as Johns Hopkins, the Rockefeller Institute — and in particular its International Health Division — the American Academy of Tropical Medicine, the American Society of Tropical Medicine. And in the U.S., there were a couple of distinctive features. One was the association of tropical medicine with the military, and its leading figures, Walter Reed and William Gorgas, were in fact Army officers. And it was in the Western hemisphere too that yellow fever replaced malaria as the quintessential tropical disease. Some of the institutional links can be seen in specific cases. An example that’s recently been studied, somewhat intensively, is the relationship of the Harvard Department of Tropical Medicine to the colonial establishment of American power in Liberia, and in particular the Firestone rubber plantations. And one can see there the clear role of tropical medicine in promoting, if we like, the expansion of company interests to extract resources from Liberia. This was an important illustration of the uses that tropical medicine could be put to.

Chapter 5. Implications of Tropical Medicine [00:34:15]

Well, what were some — if that’s what tropical medicine was as a discipline — what were some of its implications, the implications of the worldview that it suggested? One is that Africa, Asia and Latin America had something in common. This was an artificial construction of European imagination. They were seen as reservoirs of diseases that threatened Europe; Europe protected by the ramparts of civilization and medical science. So, tropical medicine embodied, down to a later period — certainly in this period down to the First World War — a Eurocentric worldview. It was initially not responsive to specific locations, as the tropics were artificially constructed as some single homogeneous place. The natives of the tropics were also conceptualized as somehow dangerous, harboring a vast array of lethal and highly contagious diseases.

Another implication was that tropical medicine was concerned, in the early decades of the new century, primarily overwhelmingly, with the help of Europeans — settlers, administrators, missionaries and soldiers. There was little concern for the health of the indigenous population. Indeed, the medical problems of the colonial world that received attention were those that threatened Europeans, not the health problems of the indigenous population. There was little attention to the social and economic determinants of what we might today call Third World problems of health, such as poverty, labor conditions, malnutrition. And there was a neglect of major diseases that were often the major health problems of the local population; say dysentery or gonorrhea, pneumonia, tuberculosis.

In recent years, in fact, the blindness of the past has even resulted in new international attention to a group of diseases, termed neglected tropical diseases, that cause large-scale suffering such as poverty, low productivity, poor pregnancy outcomes, but that for decades received little funding or attention from policymakers. More ironically, a major issue, not considered after World War I, as I said, was the impact of colonialism itself on the inhabitants of the tropical world; that is, there was no attention to the way in which colonialism itself contributed to environmental degradation; or promoted labor mobility in unsanitary conditions; the way in which it promoted unplanned urbanization, low educational attainment and poverty.

In fact, this period, the first period of tropical medicine, from 1890 to just after the First World War, was a time, one of the times, of the greatest epidemiological disasters in the tropical world, with virgin soil epidemics, like smallpox and measles, and the impact of what was called constructive imperialism. Railroads, roads, trade, the transportation revolution, all enabled a pandemic of bubonic plague, from the 1890s to 1920, and epidemic influenza, in 1918 and ‘19, to occur in the tropical world as well. Colonial wars, the involvement of the colonies in the two world wars, had major disease impacts. So did the ecological impact of railroads, factories, mines and plantations, and the recruitment of migrant labor. So, just as in the case that we examined at greater length in your reading of North America, disease played an important part in European expansion.

Another implication was public health policy. In Europe and North America, hygiene had given rise to a broad-gauge sanitarian movement; one that reformed urban living conditions through what we might call — and introducing a new jargon into our course — horizontal programs of public health; that is, improvements that dealt with living conditions across a broad spectrum of diseases. We’ve seen that in the sanitary movement. In the tropics, instead, metropolitan powers applied a different vision of what was called vertical hygiene, or tropical hygiene. Now, vertical campaigns of public health targeted instead single diseases, and they were designed to protect, above all, Europeans against the most menacing epidemics. That was tropical hygiene, then; something different from what was practiced at the same time in Europe, was one of the implications.

Another implication was a new prestige and authority for physicians. Ross and Koch, for example, now became advisors to metropolitan governments, as did Manson. It meant also — another implication was perhaps what we might call selective historical amnesia. Many of the diseases identified as tropical had only recently been present in Europe, and they weren’t eradicated by temperature, but by broad social and economic improvements. Malaria itself had been a European disease, as you know, bubonic plague and cholera also. And then tropical medicine was clearly an instrument of cultural and ideological hegemony. It was a justification and rationale for colonialism.

Europeans felt that they had health and civilization to offer, and that medicine was a means of winning acceptance of the colonial presence. So, tropical medicine provided a narrative of European progress, rationality and civilization overcoming ignorance, superstition, darkness and the witchcraft of natives. Patrick Manson was very explicit in his vision of the relationship of medicine and empire. In a simple sentence he declared, “I believe in the colonization of the world by the white race.” Well, that was the early period of tropical medicine, between 1890, more or less, and just at a period after the First World War.

Later we see a transformation in the discipline. And I don’t want to argue that it’s the same today as it was at the eve of the First World War. Radical changes in tropical medicine came through a number of influences. One was the Second World War itself, which was in part — and although there were deep contradictions involved in it — it was in part, at least, a war against racialism. The discipline was affected by decolonization, also by the rise of American hegemony after World War II, with new priorities. It was influenced by globalization as an explicit idea, and its implications that we all live in a single disease environment, and that what happens in distant parts of the world are also vitally important for the entire world population. And then there was — what was very important also was a transformation in funding.

Because of those factors, around and during the 1970s, The World Health Organization introduced a major new emphasis on tropical diseases, and with it, in 1975, a major new research project. The same happened with the Rockefeller Foundation in the 1970s, and then the MacArthur Foundation thereafterwards. And this meant a new dynamism scientifically for the discipline of tropical medicine, and also with that a major attention, reversing an earlier trend, with an emphasis on global health programs that would be applicable everywhere, and that would include major attention to the health of the population of indigenous peoples in areas that had been neglected by an earlier phase of tropical medicine.

And, so, the entire discipline, if we like, was transformed after World War II, and became something that no longer embodied a colonial position, and no longer embodied the idea that it was the bodies of Europeans that deserved privileged protection, rather than the health of indigenous peoples in other parts of the world. So, tropical medicine was a very important instrument of colonial power in the period down to the First World War, and it was slowly transformed in the inter-war period, and radically so after World War II. I hope you’ll bear that in mind as you think about the issue of what are the implications of medical science; and what are its implications for the kinds of society and the world that we live in?

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