Conclusion
Toward the end of the second millennium, in 1994, two books were published that both warned of a “coming plague” apocalypse. The Pulitzer-prize-winning author Laurie Garrett, after chronicling over a dozen frightful diseases that were “newly emerging” in a “world out of balance,” declared in her last chapter that our microbe predators now had the advantage over their macro hosts and would emerge victorious unless we changed our environmentally destructive ways.1 Similarly, Richard Preston, in his best-selling book The Hot Zone, which tells the story of an outbreak of Ebola and Marburg hemorrhagic fevers in central subSaharan Africa and at an army research lab in Reston, Virginia (which served as the inspiration for the 1995 film Outbreak), concluded in his final pages that “the earth is mounting an immune response against the human species.” By this he means that, as humans are destroying ecological environments such as the tropical rainforest, so does the earth, in a kind of role reversal, attempt “to rid itself of an infection by the human parasite” with the emergence of deadly new diseases, particularly the worldwide plague of AIDS.2 Continuing this theme, a new study relates our heightened disease environment specifically to the loss of biodiversity and natural habitat destruction, which increases our exposure to exotic pathogens by “homogenizing” or spreading them around the world, where they displace complex local species varieties.3 Such biodiversity loss would also deprive us of potential cures such as new antibiotic drugs that are desperately needed now more than ever, with the advent of hospital-raised “superbugs” such as methicillin-resistant staphylococcus aureus (MRSA) as well as drug-resistant strains of established diseases like tuberculosis and malaria.
A good example of the consequences of our habitat encroachment is the sudden appearance of the deadly Hendra virus in Australia in 1994, around the same time as Ebola was wreaking havoc in Africa. In both cases, it seems these never-before-seen diseases were the result of destruction of or intrusion upon bat habitat, which allowed for once exotic pathogens harbored in a remote host environment to homogenize and jump species. Perhaps this is simply the Gaia effect, whereby mother nature on a global scale is simply correcting the imbalance of an exploding human population, which as of 2010 is approaching seven billion.4 The last time there was a major correction was during the Black Death in the late Middle Ages; since population has been growing largely unchecked ever since, it could be argued we are overdue for another one.But in addition to failing to respect the boundaries of the wildlife ecosystem, which is an especially big problem because it is estimated that 60 percent of all diseases crossover from animals to humans, there are other large-scale factors at work, both environmental and otherwise, that will affect our epidemiological history: global warming, poverty, warfare, and so forth. It seems we are locked in a never-ending war with microbes, a war that has gone on ever since humans began altering their natural surroundings for their own purposes with the advent of agriculture and settled communities at the start of the Neolithic era some twelve thousand years ago. In some scholars' schema, this was but the “first transition” to a new disease ecology, in which humans now had to live with a far greater prevalence and virulence of disease in their lives; a “second transition” is understood to have occurred with the advent of the agricultural and industrial revolutions during the eighteenth and nineteenth centuries, when populations, at least in the West, commenced a rapid expansion and began concentrating in urban environments as well as establishing colonies of themselves around the world, all of which were made possible by the more efficient production of food and creation of wealth and factory employment in the cities. The “third transition” currently under way is the product of globalization of disease environments, as already mentioned.
But whereas most texts portray the emergence of so many new diseases since the 1980s and 1990s (such as AIDS, Ebola, mad cow's disease, Lyme disease, Legionnaire's disease, hantavirus pulmonary syndrome, SARS, and avian flu, to name just a few) as well as the reemergence of some old ones (such as tuberculosis, malaria, yellow fever, schistosomiasis, cholera) as being an unprecedented and alarmingly new phenomenon, it could actually be argued that all this is really just a natural extension of some ancient forces going back thousands of years, which include changing modes of subsistence, shifting populations, environmental disruptions, social inequalities, and so on. We are simply entering a new stage in our age-old struggle with disease, one that now combines the worst of both prior transitions: more contact with new disease environments and greater ease and speed of their spread among large numbers of people around the globe—nor ought all of these transitions be necessarily accompanied by a worsening of human health across the board. During the second transition, for instance, incidences of tuberculosis, smallpox, and cholera began to dramatically decline, helped partly but not exclusively by new medical advances, such as vaccination and the germ theory, although such benefits came considerably later to the developing world.5At this point, we should remind ourselves that the germ of many of these ideas goes back to a notion first advanced by the historian William McNeill in Plagues and Peoples, and which has informed disease studies ever since: humans are “macroparasites” on their environments in a way that is analogous, and yet also mutually dependent upon, the relationship that “microparasites,” or disease microbes, have with us. Even should we be successful in our medical fight against disease, McNeill argues that this would only be a temporary victory, as the “galloping increases” in human population as a result would then put enormous pressures on our food supply and other resources that inevitably need to be corrected, a kind of global neo-Malthusianism.6 Although the rate of population growth seems to have slowed in recent years, estimates are that the world's population will reach eight to nine billion people by 2050 and nine to ten billion by the end of the twenty-first century, unless unforeseen catastrophic pandemics (or any number of other natural or man-made disasters) intervene.7 The chance that we will self-impose limits or even reverse reproduction of our numbers seems remote.
(Communist China's “one-child” policy has so far had limited success.) Therefore, it seems assured that disease will play an inevitable part of human history for the foreseeable future.The main themes of our future history with disease are ones that I identified already in the first chapter on plague. Travel, which now exists in the form of relatively cheap airfare that makes possible the reaching of almost every corner of the globe from almost any other within a day, will continue to spread disease just as Mongol trade routes spread the Black Death, although the process has been speeded up so much that exotic diseases once confined to remote places are now practically in our backyard. The winners and losers of disease will continue to fall along the fault lines of wealthier countries mainly in the West—which are better able to weather the storms of pandemics and, with their pharmaceutical conglomerates, might even economically benefit from them—and poorer nations in the third world of Africa, Asia, and Latin America, which will bear the brunt of most disease mortalities, as India did, for example, during the Third Pandemic of plague and the 1918—1919 influenza outbreak. And medicine will find its limits in successfully preventing and treating infectious diseases, especially in this day and age with the emergence of so many new ills on nearly a daily basis.
Nevertheless, I mentioned in the introduction that I personally am more hopeful, optimistic, sanguine, or however you wish to call it, than probably most other authors about humans' future at the hands of disease.8 Perhaps this is partly because I live in Vermont, where over the course of little more than a century, deforestation and biodiversity loss have actually been reversed, to the point where today 80 percent of the state is carpeted with trees, whereas in 1880 only 20 percent was, and many wild animal species—such as moose, whitetail deer, black bear, and turkey—have been reintroduced to the state and are now quite commonly sighted.
But the principal reason for my positive outlook goes back to one of the main theses I identified at the start of this book: humans have proven throughout history their power to alter the course of epidemics and pandemics, simply through their cultural conceptions about disease. To my mind, too many histories of disease still focus on the biomedical fight against microbes with our impressive and continually evolving technologies, such as genetic engineering. But the even faster evolution of microbes means that the dream of a “gorillacillin” superdrug to match the superbugs is probably unrealistic.9 It is likely then that we will forever have to fall back on our own cultural devices as at least some part of our future response to disease. This is why the history of that response such as we have been tracing in this book is so important and instructive. The SARS outbreak in 2003 is a good example of how a pandemic in the making was successfully contained, despite the fearfully fast pace of its spread, using tried and true methods of quarantine and information sharing among countries (after initial efforts at suppression in China); we perhaps benefited from our heightened state of readiness toward global terrorism. (In the event, the SARS scare was over in just a few months, but the stakes involved were demonstrated by the fact that in that brief time over eight thousand people in thirty-seven countries were infected, of whom eight hundred died.) And yet, I cannot help feeling that the focus in too many books with disease bioterrorism is rather overblown, given that most diseases through their natural modes of dissemination are terrifying enough.10 It should be of some comfort to us that humanity was able to survive even the horrors of the plague, with its average mortality of 50 to 60 percent during the medieval Black Death. Europe's low- grade quarantines are still thought to have had some effect in helping to eventually end the plague by the eighteenth century, and our ancestors' widespread belief in the afterlife may have helped psychologically “inoculate” them against the mass death due to disease. The British physician John Snow demonstrated how good old-fashioned detective work could provide the tools for tracing and conquering cholera in the mid-nineteenth century, well before the germ theory heralded our modern biological approach to disease. Some of our current difficulties, such as multi-drug-resistant tuberculosis or new strains of avian flu, are entirely of our own making, whether by not taking the prescribed course of antibiotics or by mishandling our mass consumption of domestic poultry, and only behavioral changes will correct them. If a current disease like AIDS remains beyond our biomedical ability to cure it, then perhaps we should approach it as primarily a function of poverty, as the former South African president and AIDS denier, Thabo Mbeki, has argued. Only, the poverty we need to channel our ingenuity into combating is the poverty of third world sufferers to afford antiretroviral therapies by which they can still be functioning members of society, or the poverty of their economic ability to change risky social behaviors that are responsible for ever more people contracting the disease. Certainly, the decline of tuberculosis even before the age of antibiotics seems to support such an approach. We may have to resign ourselves to making our own cultural peace with our own, new plagues, such as AIDS.The other main thesis I have tried to emphasize in this book is to take a comparative approach to the study of plagues, which can draw out both the commonalities and distinctive features among different diseases. Plague and cholera, for example, acquired the reputation of being particularly horrible diseases to die from, owing to the suddenness of their onslaught and the revolting nature of their symptoms. Societies responded to the uniquely terrifying aspects of these diseases with fevered campaigns against filth or hysterical accusations of poisoning. Tuberculosis and influenza, on the other hand, perhaps bred a certain degree of complacency as a result of the slow, latent progress the disease could take in the body or the relative mildness and ephemeral nature of the symptoms. The shock was then all the greater when fulminant forms of these diseases took hold, defying normal expectations to the point that perhaps societies simply denied their existence or else stigmatized and shunned their sufferers. Today, this denial or complacency has a real impact with the low completion rates of antibiotic treatments or low participation in vaccination programs, which only helps increase the virulence and propagation of these diseases. Smallpox demonstrated how a disease could wreak terrible havoc in a “virgin soil” population but also how other societies that were immune or less affected by the disease could use it as both a cultural and biological weapon. AIDS, much like syphilis in the past, has become a metaphor for all sorts of moral and ethical stigmas attached to a disease spread primarily (but in the case of AIDS not exclusively) by socially unacceptable behaviors, such as promiscuous heterosexual and homosexual intercourse and intravenous drug use.11 Yet, some would argue instead that this moral and sexual dimension to AIDS has blinded us to its underlying causes in poverty and that our ethical obligation is to combat such causes, rather than attempt to change “risky” social behaviors such as by encouraging greater condom use or sexual abstinence, especially in countries that have a cultural aversion to them.12
I have chosen all these diseases for discussion in this book because of the many, particular lessons they have to teach. And yet these are lessons that, despite their particularity, can nonetheless be applied broadly to other diseases, both now and in the future, that happen to come our way. Let us hope we can learn to be sufficient pupils of disease.