Introduction

Why study disease? It’s not a very pleasant subject to contemplate. The pages of its history are full of suffering and death. Its comings and goings often seem arbitrary and simply inexplicable, the bane of most historians.

And yet... there is something about plagues that fascinates. For those with morbid minds, the spectacle of mass death is mesmerizing in its capacity to inspire fear, panic, viciousness, and cruelty. But for those of us who hold out some hope for humanity, there is also to be found—even in a time of plague—kindness, generosity, courage, and heroism. Truly, an epidemic tempers a society, subjecting it to trials either to which it must succumb or over which it must triumph. There is no middle ground with plague. It is the litmus test of civilizations.

Obviously, for our purposes, plagues and disease will be used interchangeably. Even though “plague” does refer to a specific disease,¹ which will be a main focus of this book, the origins of the term can be traced back to the Latin word plaga, meaning a “blow” or “wound.”² While in the classical context of the Latin lan­guage plague might be associated with a misfortune or disaster of some kind, it was not necessarily associated with disease; this only seems to have emerged dur­ing the late Roman Empire, when the Church issued a definitive Latin “Vulgate” edition of the Old and New Testaments, largely through the labors of St. Jerome, by 405 C.E. In this new context, plague naturally came to mean a “blow” from on high, such as when the Hebrew God struck down every firstborn male in Egypt, as recounted in the Book of Exodus. But this idea, if not the term, for plague was a common inheritance from the ancients, all of whom viewed disease as naturally emanating from the gods. Like the Hebrews, the Greeks could conceive of disease as a punishment or test for humans, with perhaps the most famous example being Apollo using his silver bow to rain down plague upon the Greeks, after Agamemnon had insulted his priest, Chryses, in the opening pages of Homer's epic poem The Iliad.

The history of disease, of course, is very old. It goes right back to the very begin­nings of humanity, when men and women first became aware of the pain and suffering caused by abnormal conditions, such as the invasion of their bodies by other organisms. Ever since they evolved from apes, humans were infected by the same diseases that afflicted their primate ancestors and that were caused by mi­crobes that originated and adapted to their hosts millions of years ago. Some of these “heirloom” infections include herpes, hepatitis, and yellow fever, all caused by viruses, as well as malaria, caused by a plasmodium. Later, when humans be­came hunters, other diseases passed to them from animals when they ate raw or partially cooked meats. For instance, Paleolithic man may have suffered from a variety of bacterial diseases, including anthrax, brucellosis, tularemia, and glanders, as a result of the microbes being present in the wild game they hunted.³

However, the opportunities for disease causation and spread are thought to have increased dramatically with the advent of settled agriculture at the dawn of the Neolithic period in c. 8000 B.C.E. Maintaining close and regular contact with domesticated animals, not to mention with other humans, as well as creating stagnant reservoir pools such as irrigation ditches and accumulating large amounts of human waste, perhaps within contaminating distance of drinking supplies, opened a new chapter in the disease history of humankind by allowing illnesses to become endemic, or perpetually present, in the artificial microbe pools thus created. Chronic diseases that could thrive even in small populations and that were associated with the new, man-made environments include tuberculosis, schistosomiasis, and typhoid fever. However, some “density-dependent” diseases, such as measles or smallpox, that may have originated in Neolithic man's new­found relationship with domesticated animals nonetheless had to wait until hu­man populations became large enough to sustain them, which could not have happened much before 3000 B.C.E.

Eventually, trade, war, migrations, and other activities that brought distant hu­man populations together were also to add to this disease environment, of which illnesses like plague and influenza were to be the primary beneficiaries. Early hu­mans also made efforts to counteract or compensate for disease-ridden conditions by designing sewer systems, imposing unclean food taboos, or setting up social barriers between disparate populations or “castes,” such as were distinctive features of ancient civilizations in India and Palestine (Hebrew culture). Yet, such efforts may have had mixed success. For example, the impressive sewer systems uncovered in the urban environments of Mohenjo-Daro and Harappa, part of the Indus River valley civilization in India dating to around 2600 B.C.E., even boasts individual household latrines connecting to the underground drains. It would seem obvious that this was part of an effort to contain waste contamination and protect freshwa­ter drinking supplies, but one should not discount the possibility that it was equally motivated by a desire to efficiently collect waste for use as fertilizer, in which case the likelihood of contracting disease would only increase.⁵

Toward the end of the Neolithic period, we begin to accumulate other evi­dence of the impact of disease upon human societies aside from the archaeo­logical. Our most valuable sources now become the written records that first make their appearance around 3000 B.C.E. Perhaps the earliest descriptions of and references to disease can be found in ancient Mesopotamian literature. The epic poem Gilgamesh, written down around 2000 B.C.E. but recounting events that apparently occurred several centuries earlier, tells of how the hero's friend, Enkidu, contracts a debilitating illness that confines him to his bed for twelve days until he dies.

From the almost equally ancient Egyptian culture comes the first recorded medical literature in history, the medical or surgical papyri, the oldest of which perhaps dates to the time of Imhotep in the 2600s B.C.E., even though the manuscript itself was not written down until about a thousand years later. In these medical papyri, Egyptian physicians describe both the medical conditions they are trying to treat—which as often as not are trauma instead of disease re­lated—and their remedies, which include both magical incantations and more “rational” techniques such as surgery and herbal recipes. Interpretation of these texts, however, is hampered by the still inexact knowledge of hieroglyphics and by the fact that the ancient Egyptian mind-set was quite unlike our modern outlook.⁶ In addition, Egyptian art, despite its often stylized representations, sometimes depicts spinal or limb abnormalities in statuary and relief carvings of its subjects, deformities that were possibly caused by disease.

Before leaving the second millennium, we should not omit the oracle bones dating from the Shang dynasty in China between c. 1500 and 1050 B.C.E. These contain, for their time, some quite remarkable conceptions of disease, centering around the chi, a logographic symbol depicting a man lying on a bed pierced by the arrow of disease. This obviously anticipates biblical and classical Greek references to “plague” in the sense of a blow sent down upon humans from on high, but in ancient Chinese culture, the notion of any higher power being responsible for disease seems to be absent, as the Chinese preferred to explain the origins of their civilization in purely humanistic terms going back to mighty ancestors. Instead, the disease agent is more rationally explained as due to a worm or insect of some kind, as in the li and ku symbols, perhaps referring to schistosomiasis. The ancient Chinese also identified diseases with fever or rash­like symptoms, such as malaria or scabies, and made more amorphous references to sensory, intestinal, and reproductive illnesses.⁸

In the last millennium before Christ, humankind entered a new era in writing about disease. References to disease epidemics multiply in the Bible, but its use of generalized terms such as “plague” make identification of specific illnesses diffi- cult.⁹ Fully half of the references to plague in the Bible occur in the first five books of the Old Testament, known collectively as the Torah or Pentateuch, which were composed over the course of half a millennium from the tenth to the fifth centu­ries B.C.E.

Moreover, the Bible perpetuates older conceptions of disease causation, namely, that the source of illnesses is to be attributed to a higher power. At roughly the same time, however, alternative explanations of disease began to emerge in other cultures in India, China, and Greece. Remarkably, all three proposed similar systems that located diseases' origins in humankind's natural environment and defined the disease condition within the body as resulting from an imbalance of its core elements. This was undoubtedly the beginning of a truly rational approach to disease and medicine, which used dietary and other health regimens to prevent illness and natural compounds, bleeding, and other, human- inspired techniques to cure it. But it is important to remember that these same ancient societies by no means abandoned religious or supernatural methods of healing, such as prayers and magical incantations, since desperate patients would have been willing to try any remedy that might work, and the two realms of religion and medicine were not seen as incompatible.¹²

Most influential for the West, of course, was the Greek medical tradition founded by Hippocrates of Cos (c. 460—377 B.C.E.). Along with the body of works attributed to him, known collectively as the “Hippocratic corpus,” Hip­pocrates and his circle of physicians advocated the humoral theory as an explana­tion of disease occurrences in the body, namely, that any given illness resulted when the four humors of the body—blood, phlegm, yellow bile (cholera), and black bile (melancholia)—were in a state of imbalance, a condition the Greeks called dyscrasia, literally, “bad mixture.” But readers should know that very simi­lar systems had also been proposed in ancient Indian and Chinese medicine. The Ayurvedic tradition, compiled around the sixth century B.C.E. as one of India's sacred Veda texts, states that human health is connected to the three dosas, or humors: these include Vayu, a dynamic, kinetic principle associated with air; Pitta, a thermal, explosive force identified with the sun; and Kapha, a cohesive principle that binds everything together. Balance of the dosas is to be maintained not only by diet and personal habits but also by mental attitudes and even social taboos that must be observed in accordance with the Hindu caste system.¹³

Likewise, ancient Chinese medicine, culminating in the Huangdi Nei Jing (The Yellow Emperor’s Classic of Medicine), dating to the first century B.C.E., proposed a sixfold classification system of diagnosis that, in its crudest, most simplified form, attempts to strike a balance between the two opposing yin-yang qualities of the body and explained illnesses as resulting from an imbalance in the body's qi, a nearly untranslatable term that seems to encompass everything that maintains life. Chinese medical tradition, going back to the Chou dynasty (1050—256 B.C.E.), also relates the advent of diseases to the four seasons and to any abnormalities in their cycle (such as cool spring weather in the summer or hot summer weather in the autumn). This is very similar to how works in the Hippocratic corpus, such as On Airs, Waters, and Places, explain disease. Like the Greeks, the Chinese also related the advent of disease to other factors including changes in the air and other aspects of the environment, excessive emotional states, and what the Greeks called bad regimen, such as overexertion, poor diet and hygiene, immoral behaviors such as drunkenness and sexual indulgence, and so on. But while the Greek miasmatic theory of bad air (the original malaria) allowed for the concept of contagion, or the direct spread of disease from person to person through the passing of the miasma, this never seems to have entered the classical Chinese medical tradition. And while the Greeks related their hu­mors to four basic elements of the universe, namely, air, water, earth, and fire, the Chinese tradition lists five: wood, fire, earth, metal, and water.¹⁴ Altogether, this ancient heritage identifies an impressive galaxy of diseases; judging from the symptoms described, the ancients likely suffered from cholera, malaria, mumps, measles, leprosy, erysipelas, dysentery, epilepsy, diphtheria, smallpox, tuberculo­sis, typhoid fever, cancer, influenza, beriberi, rickets, pneumonia, cirrhosis, asthma, arthritis... the list goes on and on.¹⁵

Nonetheless, the real history of disease could be said to have begun in 430-426 B.C.E., when a plague struck the city of Athens at the very start of the Pelopon­nesian War with its rival, Sparta. For it was the Plague of Athens that inspired the famous account of it by the Greek historian Thucydides as part of his History of the Peloponnesian War. Many would regard Thucydides’ brief but compelling narrative of the plague as the first example of historical writing about disease. This should be attributed to not only the rational, “enlightened” approach that he takes to disease (a path that was being concurrently blazed by the Hippocratics) but also the comprehensive way in which he discusses the plague’s impact, which he sees as affecting the entire body politic and not just the individual patient’s body.

Significantly, Thucydides states at the outset that he is eschewing all specula­tion about the plague’s origin or causes, perhaps because he has no wish to bring the gods into the discussion, as most other ancient authors would have been tempted to do. This rigorously scientific approach, while paralleling that in con­temporary Hippocratic medicine, was probably an entirely unrelated and inde­pendent phenomenon.¹⁶ Above all, Thucydides’ preoccupation with disease could be described as quintessentially historical: to describe it in such a way that could prove useful to successive generations of his readers. Consequently, Thucy­dides’ first order of business is to enumerate the characteristic symptoms of the disease, by means of which it can be readily identified by future sufferers; it is a task for which Thucydides was uniquely qualified, as he himself had contracted the disease and survived to tell the tale. These symptoms include a burning fever, inflammation of the throat and tongue, small pustules or ulcers on the skin, nauseating diarrhea and other discharges, and gangrene of the extremities, which, if they killed the victim, did so in about a week. Yet, despite this painstak­ing description, modern historians have endlessly debated exactly what kind of disease afflicted Athenians during the plague. While it assuredly was not the disease known as bubonic plague, since the characteristic symptom of the bubo is not present in Thucydides’ account, consensus opinion seems to have co­alesced around smallpox, although other candidates, including typhus, typhoid fever, measles, and anthrax, also have been proposed.¹⁷

But what elevates Thucydides’ narrative to far above the ordinary is his ensu­ing discussion of the social effects of the plague. In a profoundly perceptive analysis, Thucydides notes how the plague overturned the conventions of his society, whether these be in terms of funerary rites, religious observances, respect for the laws and morals, or even the obligations of family members to care for sick loved ones. It was Thucydides who first advanced the idea that people typi­cally respond to the threat of mass death from disease with a “live for the mo­ment” attitude as they await the imminent prospect of their own potential de­mise. As he puts it in a justly famous passage,

Men now coolly ventured on what they had formerly done in a corner and not just where they pleased, seeing the rapid transitions produced by persons in prosperity suddenly dying and those who before had nothing succeeding to their property. So they resolved to spend quickly and enjoy themselves, regarding their lives and riches as alike things of a day. Perseverance in what men called honor was popular with none, it was so uncertain whether they would be spared to attain the object; but it was settled that present enjoyment, and all that contributed to it, was both honorable and useful. Fear of gods or law of man there was none to restrain them. As for the first, they judged it to be just the same whether they worshipped them or not, as they saw all alike perishing; and for the last, no one expected to live to be brought to trial for his offences, but each felt that a far severer sentence had been already passed upon them all and hung ever over their heads, and before this fell it was only reasonable to enjoy life a little.¹⁸

However, it should be noted here that other Greek sources also record a more conservative reaction to the plague, one that reaffirmed the role of the gods in terms of being able to both cause and cure disease, as evidenced by the rising popularity of the healing cult of Asclepius, son of Apollo, in the decades follow­ing the Plague of Athens. Not surprisingly, this reactionary attitude receives al­most no mention from Thucydides.¹⁹

Perhaps the greatest contribution of Thucydides to the history of disease is his implied notion that a disease not only infects individuals but also makes all of society, an entire community, its victim. For a disease, he makes clear, not only affects people's health and well-being but also can determine the fate of large­scale events and situations, even if only in an indirect way. Although he doesn't say so explicitly, Thucydides does seem to suggest that the Plague of Athens al­tered the whole course of the Peloponnesian War, as indicated by his insertion of the narrative of the disease directly following his account of the funeral oration of Pericles that laid out Athenians' justification for fighting the war.²⁰ Whether the plague had longer-term effects, however, that resulted in the decline and ultimate fall of the Athenian empire by the end of the war in 404 is a subject that continues to be debated by historians.²¹

Somewhat later in his account, Thucydides does say that nothing did as much harm to the Athenian war effort as the plague: in purely military terms, the dis­ease wiped out 4,400 hoplites and 300 cavalrymen, who most likely represented roughly a third of available forces. Although Thucydides asserts that the plague's decimations among the general population are undiscoverable, modern calcula­tions—assuming a death rate commensurate with that among the army—yield figures in the tens of thousands.²² With its manpower thus sharply curtailed, Athens was severely hampered in terms of the scope of both land and sea opera­tions; it was not until more than a decade later, in 415, that the Athenians felt capable of launching the ill-fated Sicilian expedition.

But beyond mere numbers, the plague may also have affected how the Athe­nians fought the entire rest of the war, even though the disease occurred so early in the conflict.²³ Thucydides seems to credit the plague with inculcating a moral failing, or “lawlessness,” in the Athenian character, which was to show up later in the war in the form of ruthless and ultimately self-destructive policies, such as its brutal conduct toward the neutral island of Melos in 416, which in Thucy­dides' famous “dialogue” foreshadows inhumane treatment of Athens' own sol­diers when taken prisoner at Syracuse. Yet, it's hard to know if this is really the case, since Athens already revealed a ruthless streak early in its empire when it refused to allow the island of Naxos to secede from the Delian League in 467. Thucydides also notes that the plague was worldwide in its scope; for example, he states that it started in Ethiopia in sub-Saharan Africa and progressed from there northward and westward to Egypt and Libya and eastward to the Persian Empire. Therefore, in so many ways, Thucydides' history of the Plague of Athens provides a model for all other histories of disease that were to follow.²⁴

If we now shift our focus to modern historical writing about disease, it quickly becomes apparent that we have expanded considerably upon Thucy­dides' revolutionary rationality. In terms of the scope, importance, complexity, diversity, and a host of other factors to consider about disease, we have gone well beyond Thucydides' original speculations, even when following the basic lines of his thought. In the first place, whole books have now been devoted to the role that disease played in history, instead of the subject occupying but a minor part in the broader historical narrative. The traditional approach (some­times also called the “positivist” or “biological” school) of modern historical writing is to follow most ancient authors in treating disease as a discretely de­fined, exogenous, or foreign variable (now a microorganism rather than an ar­row from on high) that suddenly invades a population and wreaks havoc upon it. Taking their cue from Thucydides, who emphasizes how the death from plague of one man, Pericles, altered Athens' subsequent fortunes in the Pelo­ponnesian War, these writers stress the almost whimsical role that disease has played in dramatically changing the lives and course of historical personalities and events.²⁵ Aligned with this approach are those historians who chronicle humans' heroic struggle to medically “conquer” the biological enemy repre­sented by disease, a war that mankind, until recently, seemed to be winning as history progressed.²⁶

Then along came William McNeill's Plagues and Peoples in 1976, which some would consider as bringing about a seismic shift in historical studies of disease. McNeill himself claimed to be writing a new chapter in disease history, ascribing to epidemics an importance not previously found in historical surveys. Even though McNeill did pay homage to “antiquarians,” such as Hans Zinsser, for pointing out isolated disease incidents such as the Black Death that briefly com­manded the historical stage, such acknowledgments, he claimed, were rare and made historians uncomfortable because they did not fit in with their orderly views of the past.²⁷

By contrast, McNeill, a world historian who emphasizes cultural fusions among different civilizations that eventually led to Western dominance of the globe,²⁸ adapts this approach to disease in order to accord it a central place in world events. This is especially the case when new technologies or cultural devel­opments enable a disease to become “pandemic,” that is, to be communicated to distant lands far from its epicenter and thus have a dramatic impact on “virgin soil” populations with no prior exposure or immunity to it. McNeill's classic ex­ample of this, and the one that actually inspired his book, is the introduction of smallpox to the Americas in the early sixteenth century and the resulting horrific mortalities among Native American populations there; according to McNeill, smallpox by itself is sufficient to explain how conquistadors such as Hernan Cor­tes and Francisco Pizarro overcame overwhelming odds to swiftly conquer the once-mighty Aztec and Inca empires in Mexico and Peru.²⁹ In addition to such “transoceanic exchanges,” McNeill devotes another chapter to the role played by the Mongol Empire during the late Middle Ages in the dissemination of the Black Death, both east and west. His concluding chapter is perhaps his most conven­tional, tracing the now familiar success stories of modern medical science in conquering disease from the eighteenth to the twentieth centuries.

So far, nothing that McNeill has to say is exactly new; as a matter of fact, most of what is mentioned above could be fairly said to have been anticipated by the ancient historian Thucydides. For it was Thucydides who first pointed to the world scope of disease, to its devastating impact upon a population unprepared for it, and even to the central role disease could play in history. But I believe that McNeill has made two contributions to the history of disease that are important and unique.

In the first place, McNeill introduces the idea that disease can be a relative construct, not just a discrete biological entity. Although McNeill uses “macropar­asitism” to refer to one class of human beings living off the productive capacity of another class, one can also conceive of it in environmental terms, in which humans through their variegated behaviors alter their disease environment, which in turn adapts to their modifications, and so on in an unending war of mutual attrition; in many respects, this is comparable to how microparasites have adapted to their human and animal hosts, selectively evolving to neither kill them outright nor in turn be eliminated completely. In this way then, human beings can, in effect, create their own sense of just what is a disease. McNeill fully realizes that this can change “the very concept of disease,” making it entirely dependent on social and historical circumstances. As an example, nearsighted­ness and a “dull sense of smell” may be considered perfectly normal in today's society, but they would have been crippling debilities—indeed a disease—among Paleolithic hunters struggling to survive. However, McNeill rejects a completely relativist approach to disease, preferring to hold onto “a firm and universal nu­cleus to the concept of disease,” one in which “bodily disorder” mainly arises from “parasitic organisms.”³⁰

Despite McNeill's reservations, the relativist, or “social constructionist,” ap­proach, which increasingly viewed disease as an endogenous phenomenon arising solely out of factors intrinsic to the society or culture in which it occurs, became more popular among historians, particularly during the 1980s; for it was at that time that the emerging AIDS pandemic seemed to be a perfect illustration of how a disease can be a function of socially risky behaviors.³¹ Indeed, one historian in this school goes so far as to suggest, perhaps facetiously, that one day harmless skin freckles may be deemed unsightly enough to be classified as a disease, complete with a “National Institute of Freckle Research” devoted to eradicating them.³² However, if one goes to extremes with such an argument, one wonders what historical statements, if any, can be made about disease, if the very definition of the term is subject to such speculation. It seems that McNeill was right to insist upon a commonsense foundation from which to start a discussion.

McNeill's other contribution comes at the end of his book, where he specu­lates about the future of disease history. Despite the fact that Plagues and Peoples came out at the very same time that the World Health Organization was success­fully eradicating smallpox, and in stark contrast to traditional views of medical historians that foresaw an “end to epidemics,” McNeill concludes that infectious disease will remain an inseparable part of the history of humanity, indeed, for as long as humanity itself continues to exist. Ironically, he sees the very success of medical treatments of disease as only contributing to its perpetuation. A good example is the rash of polio infections that broke out among even the higher classes of American society in the mid-twentieth century, a circumstance attrib­utable, McNeill insists, to the higher standards of hygiene that wiped out minor infections among children, which earlier had conferred some immunity to more serious, full-blown infections.³³ In a new preface written in 1997 to take account of the current AIDS pandemic, McNeill maintained his pessimistic view of hu­mankind's ability to “conquer” disease, citing the worldwide AIDS crisis as just one more example of how the global transmission of disease was only accelerat­ing the biological evolution and adaptation of microorganisms to their hosts.³⁴ The efforts of humanity—the “macroparasite”—to wipe out disease were upset­ting the natural balance and, as recent disease history made clear, was only mak­ing things worse, not better. This gloomy perspective has been taken up by a host of far less restrained authors who peddle an alarmist, even apocalyptic, scenario where disease in the end conquers humankind, not the other way around.³⁵

On a very basic level, one can both agree and disagree with McNeill's thesis that disease has played a central role in human history. It seems an intuitive fact that most people who die a “natural death” do so as the result of some disease or other, rather than being blessed with the good fortune of dying of extreme old age, when the cells of the body simply cease to divide and function. In this re­gard, disease is almost as ubiquitous as death in terms of its presence and impor­tance in our everyday lives. Yet, one could also argue that the very fact that populations around the globe are increasing in number, and have done so at varying rates of propagation throughout history, prove that human fortunes are rarely dictated or limited by disease and its consequent mortality. Instead, one might counter that it is restrictions on reproductive capacity (aside from disease) that have played the greater role in the course of human development, such as the availability of food and other material resources that, from a Malthusian point of view, are forever locked with population in a struggle to achieve equi­librium or balance.³⁶ In a way, McNeill has sidestepped this whole conundrum by only focusing on large-scale, global pandemics of disease, whose mortalities posed extraordinary challenges to civilizations. His example, by necessity, will be followed in this book.

Nonetheless, even within McNeill's more specialized construct, his thesis has been attacked on two other fronts by revisionist scholars of disease. One group has made the case that disease does not act on its own when impacting human history; rather, it wreaks its devastation only in conjunction with other historical forces, such as the oppressive policies of colonialist/imperialist powers that inten­sify disease's morbidity and mortality.³⁷ This is true despite the fact that in some cases colonial powers believed they were acting in the best interests of their native subjects, such as by imposing Western standards of hygiene and medicine upon long-standing traditions of healing and customary responses to disease. Native resistance to high-handed health measures—such as hospitalization, isolation of contacts, disinfection, and quarantine—could effectively blunt their intended benefits. Given that, in some places, such as the Americas or the Pacific Islands, the sheer mortalities of imported diseases assuredly outweighed any medical blessings imperialism supposedly bestowed upon a conquered people, even when the benefits of modern medicine had material effect, imperialism could still amplify disease's impact since these same benefits also allowed Western soldiers and colonists to intrude longer and more deeply into previously inhospitable areas.³⁸ All this implies that McNeill had accorded an overmighty role to disease on the stage of history, which now should give way to a more nuanced, complex interplay with other factors.

Yet another contingent of historians besieged McNeill's edifice on the grounds that he was too consistently negative about the impacts of disease upon its victims. Instead, it could be argued that disease brought some benefits for certain elements of society, who might even welcome its arrival among them. This debate has been played out especially with respect to the Black Death in Europe during the late Middle Ages. McNeill claimed that the ravages of the Black Death, whose mortal­ity in Europe during its first outbreak in the mid-fourteenth century was as high as 50 percent on average, instilled a “fatalistic” or even “suicidal” mentality upon the collective consciousness of Europeans.³⁹ But more recent scholars of the Black Death have argued that it set in train necessary “transformations” in many areas of medieval society, including ushering in a more capitalistic-based economic system, new technologies such as the caravel and the printing press, a more empirical ap­proach to science and medicine, and even the Renaissance and Reformation with their greater emphasis on individual portraiture and piety.⁴⁰ Not even McNeill's classic case study of “virgin soil” American populations wiped out during the colo­nial period was immune from this argument, for some native groups, such as the Tlaxcala people of Mexico, actually benefited from the decimation of their rivals and overlords, chiefly the Mexica, on Lake Texcoco.

To take a more modern example of “always looking on the bright side” of disease, at least from a certain perspective, the ongoing AIDS pandemic is seen to have brought about a decline in risky social behaviors, such as sexual promis­cuity, that are believed to be major contributing factors to propagation and inci­dence of the disease. But inducing greater morality in human society is tradition­ally seen to be the exact opposite of disease's usual impact, going back to Thucydides.⁴¹ On a more prosaic level, AIDS has been a boon to Western phar­maceutical companies, which have been able to profit from antiretroviral drugs and “protease inhibitors” that inhibit full-blown symptoms of the disease almost indefinitely. AIDS has thus created a stable pool of captive customers for “Big Pharma's” products, which will remain the case for as long as a vaccine or cure for the disease remains elusive. Meanwhile, the disease has also created a very large and cheap pool of human “guinea pigs” for trial treatments for AIDS, since the expense of such treatments would otherwise be prohibitive to the vast major­ity of victims throughout the third world, which is now bearing the brunt of the global AIDS pandemic.

This brings us back to the question with which we opened this chapter: why study disease? Nearly every writer on the topic since Thucydides has clearly dem­onstrated that disease has had a big impact on human history, and—McNeill is surely right here—it will continue to do so for the foreseeable future. But what about the reverse—the impact that humans can have on disease? For I would ar­gue not only that disease has shaped the history of our predecessors but also that humans have been able to redirect its course and meaning in history. I am par­ticularly fascinated by those moments when civilizations around the world were severely impacted by a disease's mortality and morbidity, such that their very continued existence was in the balance. For it is at times such as these that human responses to disease assume their greatest importance. Yet, neither can such trials that test or temper a society occur without a very real biological disaster occurring among human populations and very often among the animals that live with them as well. While tribulations of the requisite magnitude or global scale may be rela­tively rare, they nonetheless will form the focus of this book. I hope to demon­strate from all this that humans can alter the extent to which they suffer from disease, even when this calamity seems to come, as the ancients truly believed, like a bolt from the blue. While some historians may not like studying disease for this very reason, in actual fact its course throughout human history has been far from arbitrary. Indeed, this is what makes disease such a fascinating topic of study. Un­like some other themes in history that have become trendy these days, such as the effects of climate change,⁴² disease has allowed humans to change their fate at its hands, instead of simply being subject to it. Even without the awesome power of modern technologies, men and women could have a relationship with disease that was not all one way. Humans have thus made their own history of disease even while it was also happening to them.

I thereby aim in this book to make a unique contribution to the study of disease, by explaining how humans have had the power to change how disease affects them simply through how they view disease. Although my approach does take a page from the relativist school of disease historians, I am not talking here merely about efforts to redefine the concept of disease but rather about the very practical effects that cultural attitudes toward disease can have in allowing a so­ciety to either succumb to or triumph over disease epidemics. These cultural responses to disease are even more important now that modern society has come to realize its limitations in terms of being able to medically cure or thwart chal­lenging new pandemics, such as AIDS. I also will seek in the following pages to go beyond the more obvious impacts humans can have on disease incidence, such as through medicine, imperialism, or bioterrorism, even though these in­evitably will be part of the story.⁴³

By no means do I claim to be opening up unheard of or unprecedented vistas in the history of disease. After all, it was Thucydides who first noticed how humans themselves could alter the course of a plague, such as by succumbing to despair at the very idea of getting the disease or by neglecting to nurse patients, thus hasten­ing or assuring their demise, even if he did not realize the larger implications of these observations.⁴⁴ We all know, instinctively, that psychosomatic disorders can happen, willing ourselves into suffering simply by dwelling upon it. (Medieval doctors rather poetically diagnosed psychosomatic disorders as “accidents of the soul.”) But I do claim to be expanding considerably upon this idea of humans' impact upon disease and to be addressing it in a more comprehensive way than ever before. Readers may also find that I am rather more hopeful than other recent writers about disease with regard to humankind's future in fighting epidemics.

Obviously, then, how a society or civilization perceives disease determines how it will respond to it, whether this be at the popular level or at the level of au­thoritative elites, and in terms of all the manifestations of the various social, economic, political, religious, or artistic aspects of this response. But at the same time, I also believe that what the disease is matters, in terms of establishing a clearly recognizable, biomedical identity.⁴⁵ Yet, the complexities of the historical evidence are such that some throw up their hands in despair of ever definitively identifying the epidemics of the past. Certain historians of disease now take the position that it is futile or even wrong to attempt to match up a historical epi­demic with a modern definition of a particular illness, on the grounds that the present “laboratory” understanding of disease based on the germ theory is so dif­ferent from how our distant ancestors approached their own, elusive “plagues.”⁴⁶

To my mind, this is nothing less than an intellectual cop-out, or perhaps de­featism, that is hardly justified by any supposed lack of concordance of symp­toms. On the contrary, in some cases, particularly as the evidence becomes much fuller beginning with the Black Death of the late Middle Ages, premodern doc­tors and other authorities writing on the subject are able to give quite convincing diagnoses of a given disease. The Moorish physician Ibn Khatima, who authored a plague treatise in February 1349, gives an impressive symptomology, complete with case studies, of the three forms of bubonic, pneumonic, and septicemic plague, while his predecessor, the ninth-century Persian doctor Muhammad ibn Zakariya al-Razi (known as Rhazes in the West), is able to clearly differentiate between smallpox and measles through a detailed analysis of their respective symptoms. And it was the sixteenth-century Venetian physician, Girolamo Fra- castoro, who was the first to name and identify syphilis, as well as typhus. But even when premodern observers describe symptoms that are fantastic or that little accord with the “scientific” diagnoses of nowadays, having an “objective” or “ontological” definition of disease may still be helpful in understanding how our ancestors approached the plagues of the past. For example, some medieval doc­tors describe the lymphatic swellings of bubonic plague as being red, yellow, green, or black in color, which they said signified the severity of the illness; the fact that modern observers of plague fail to notice this same phenomenon may indicate to some that medieval people were suffering from an entirely different disease.⁴⁷ But a detailed reading of medieval plague treatises reveals that actually what this tells us is that medieval doctors were here relying on ancient authority, in this case, the Prognostics of Hippocrates, rather than on their own, firsthand observations in order to make a prognosis of the disease. The lesson to take away from all this is not that the Black Death was a different disease from modern plague but rather that medieval doctors had radically different notions of how to diagnose and treat symptoms than their counterparts of today.

Completely abandoning the positivist or ontological definition would thus needlessly deprive us of a valuable tool in our effort to write the history of dis­ease. It may be obvious to say that each disease is unique, but what is less evident is that each disease has its own social/cultural dynamic in terms of how a society or civilization perceives and responds to it. This is no less a part of the “social construction” of disease than the relative values and norms of the culture upon whom the disease is acting. Together, both these forces could intersect to create some quite dramatic impacts in the course of the history of a pandemic. A good instance of this is how many late medieval doctors conceived of plague as a kind of “poison,” which seemed a product of both contemporary perceptions of the disease's progress in individual victims, as well as populations at large, and pre­conceived notions that were inherited from the ancients. Combined with the unprecedented mortality of the disease, this rather unique conceptualization of plague undoubtedly contributed to scapegoating tendencies that attributed the Black Death to a human cause, whereby Jews, witches, the poor, and other per­ceived enemies of society were believed to be deliberately spreading or prolong­ing an epidemic for their own nefarious purposes. To take a more modern ex­ample, AIDS was initially seen in the mid-1980s as a “gay plague” spread mainly by abrasive anal intercourse (gay-related immunodeficiency disease, or GRID), which led to homophobic responses in the workplace, among health insurers, and elsewhere. (At the present time, AIDS is primarily prevalent in sub-Saharan Africa, where it is spread overwhelmingly by heterosexual contact.) In both cases, we now know that these respective views of plague and AIDS were wrong, but this does not change the tragedy of their historical responses.

Likewise, a modern “laboratory” identification of a historical disease or pan­demic, even if only speculative, may help illuminate some of the outstanding questions and conundrums posed by it. Identifying the Black Death with plague, for instance, while still controversial, would explain why many late medieval outbreaks were associated by contemporaries particularly with women, children, or the poor, since these demographic groups were more likely to live in domestic conditions that ensured close contact with rats and fleas. It would also help us to understand the importance of trade to medieval society, since this is the medium through which plague is usually spread. Moreover, recent advances in biomo- lecular archaeology—which attempts to recover the genetic material of disease pathogens in human remains that have been preserved under optimal condi­tions, such as encapsulated dental pulp—seem to hold out some promise for positively identifying epidemics of the past in the laboratory just as definitively as modern occurrences of disease.⁴⁸

Readers should take note here that, as a consequence of all the above con­siderations, I deal in this book only with a “positivist” panoply of diseases, namely, those caused by the invasion of the human body by a known, identi­fied microorganism. I therefore leave out a host of noninfectious diseases, such as those caused by vitamin deficiencies or psychological disorders, that may appear in other surveys. I do this because, even though the latter diseases are certainly impacted by human behavior, at the same time, they lack some of the essential criteria for studying human responses to disease, such as, most obvi­ously, the nature of being infectious. In general, I have adopted three standards by which I have selected the diseases that are addressed in the chapters that follow: first, the disease must be, or at least must have been in the past, fatal for large numbers of victims, for there is nothing like the fear of death for eliciting a response from people. Second, the disease must have been, or still is, worldwide in its scope, in order to afford the opportunity to study contrast­ing responses to it among different cultures and societies. Third, the disease must have been exerting its virulence for a lengthy period of time, to observe evolving attitudes toward it.

In many ways, the topic of disease is ideally suited for a globally oriented world history textbook such as this one. Comparing how different civilizations throughout space and time have reacted to disease is perhaps the best means of recovering the lessons that disease has to teach. And these lessons have not always been learned or passed on, even by the best historians.⁴⁹ But by exploring the complex interactions, primarily in cultural terms, between disease and humans, a “new history” of disease that combines and integrates the positivist and relativ­ist approaches may be written, for which some historians have been calling.⁵⁰

I believe that understanding the many ways in which we, as humans with our almost infinite variations of societies and cultures, have coped with disease (or not, as the case may be) is one of the most important lessons of history. This is no mere academic exercise. It is nothing less than a matter of life or death.