It has been well understood for some time now that COVID-19 and its ensuing global pandemic are unprecedented events in our contemporary world. Not since the Influenza Pandemic of 1918 has global life been so drastically altered so quickly due to a viral outbreak.

In the century since 1918, countless individuals, organizations, and nations have striven to eradicate the unnumbered diseases, parasites, and structural barriers that cause unnecessary death, needless suffering, and the squandering of human potential.

Paul Farmer is one of those individuals. Chair of the Department of Global Health and Social Medicine at Harvard Medical School, Farmer is co-founder of Partners in Health, serves as a Special Advisor to the United Nations, and has authored several books on the topics of global health, human rights, and international cooperation.

Given our aforementioned collective moment in history and in honor of World Health Day, UC Press would like to bring renewed attention to these topics and Farmer’s role as a leading public figure.

The following is an excerpt from Infections and Inequalities: The Modern Plagues (2001), chapter 2, “Rethinking ‘Emerging Infectious Diseases.”

AIDS. Ebola. Flesh-eating bacteria. With newspaper and television re­ports rife with references to mysterious and lethal outbreaks caused by new (or newly virulent) pathogens, perhaps it’s safe to conclude that we’re living in a time of unprecedented popular interest in infectious dis­eases. Yet medical historians might be quick to discern, in this most recent wave of hysteria and genuine interest, but a small peak in that jagged line charting the course of popular concern with epidemic disease.

That’s not to say that there’s nothing new under the sun. This most re­cent surge of interest comes at a time when novel technologies can reveal a level of detail-about both pathogens and hosts-unimagined by our recent forebears. And this past decade has surely been one of the most eventful in the long history of the study of infectious diseases. There are multiple indices of these events, and also of the rate at which our knowl­edge base has grown. We have only to follow, for example, the sheer num­ber of relevant publications to perceive the explosive growth in this knowledge base. We have developed new methods of monitoring an­timicrobial resistance patterns. And we have new ways to promote the rapid sharing of information (and also, unfortunately, speculation and misinformation) through means such as the Internet that barely existed even ten years ago.

Then there are the microbes themselves. One of the most significant events of the past ten or fifteen years, and perhaps the most remarked upon, is the explosion of “emerging infectious diseases.” Some of these disorders-such as AIDS and Brazilian purpuric fever-can be regarded as genuinely new. Others were clinically identified some time ago but have newly identified etiologic agents or have again burst onto the scene in dramatic fashion. For example, the syndromes caused by Hantaan viruses have been known in Asia for centuries, but they now seem to be spreading beyond that continent as a result of ecological and economic transformations that increase contact between humans and rodents. The phenomenology of neuroborreliosis had been tackled long before the monikers “Lyme disease” and Borrelia burgdorferi were coined, and before suburban reforestation and golf courses complicated the equation by cre­ating an environment agreeable to both ticks and affluent humans. Hem­orrhagic fevers, including Ebola, were described long ago, and their etio­logic agents were in many cases identified in previous decades. Still other diseases grouped under the “emerging” rubric are ancient and well­-known foes that have somehow changed, either in pathogenicity or dis­tribution. Multidrug-resistant tuberculosis and invasive or necrotizing Group A streptococcal infection-the “flesh-eating bacteria” of the pop­ular press-are cases in point.

Popularizing the concept of” emerging infectious diseases” has helped to marshal a sense of urgency, notoriously difficult to arouse in large bu­reaucracies. Funds have been channeled, conferences convened, articles written, and a dedicated journal founded. The research and action pro­grams elaborated in response to the perceived emergence of new infec­tions have, by and large, been sound.

But the concept also carries complex symbolic burdens-as do some of the diseases most commonly associated with it. Such burdens have cer­tainly complicated and, in some instances, hampered the laying down of new knowledge. If certain populations have long been afflicted by these disorders, why are the diseases considered “new” or “emerging”? Is it simply because they have come to affect more visible-read, more “valu­able” -persons? This would seem to be an obvious question from the perspective of the Haitian or African poor.

In the emerging literature on emerging infectious diseases, some ques­tions are posed while others are not. A subtle and flexible understanding of emerging infections would be grounded in critical and reflexive study of how our knowledge develops. Units of analysis and key terms would be scrutinized and regularly redefined. These processes would include regular rethinking not only of methodologies and study design but also of the validity of causal inference, and they would allow reflection on the limits of human knowledge.

The study of such processes, loosely known as epistemology, often happens in retrospect. To their credit, however, many of the chief con­tributors to the growing literature on emerging infectious diseases, ac­customed to debate about microbial nomenclature, have shown excep­tional self-awareness in examining the epistemologic issues surrounding their work. Many are also thoroughly familiar with the multifactorial na­ture of disease emergence. In a 1995 review, one of the prime movers in the field (a virologist) noted that the emergence of a newly recognized or novel disease is rarely a purely virological event without identifiable causative co-factors: “Responsible factors include ecological changes, such as those due to agricultural or economic development or to anoma­lies in the climate; human demographic changes and behavior; travel and commerce; technology and industry; microbial adaptation and change; and breakdown of public health measures.” Similarly, the Institute of Medicine’s influential report on emerging infections does not even cate­gorize microbial threats by type of agent, but rather according to major factors held to be related to their emergence: “human demographics and behavior; technology and industry; economic development and land use; international travel and commerce; microbial adaptation and change; and breakdown of public health measures.”

Many students of emerging infectious diseases thus distinguish be­tween a host of phenomena directly related to human actions-ranging from improved laboratory techniques and scientific discovery to eco­nomic development, global warming, and failures of public health-and another set of phenomena, much less common and deriving more di­rectly from changes in the microbes themselves. Even in cases of micro­bial mutations, however, we often find signs that human actions have played a large role in enhancing pathogenicity or increasing resistance to antimicrobial agents. In one long list of emerging viral infections, for ex­ample, only the emergence of Rift Valley fever is attributed to a possible change in virulence or pathogenicity; and this cause is enumerated after other, social factors for which better evidence exists.

No need, then, to launch a campaign calling for a heightened aware­ness of the sociogenesis, or “anthropogenesis,” of disease emergence. Ironically, perhaps, some of the bench scientists involved in the field are both more likely to refer to a broad range of social factors and less likely to make immodest claims of causality about any one of them than are be­havioral scientists who study infectious diseases.

Yet a critical epistemology of emerging infectious diseases is still in the early stages of development. A key task of this endeavor is to take our ex­isting conceptual frameworks and ask, What is obscured in this way of conceptualizing disease? What is brought into relief?

For example, a first step in understanding the epistemologic dimen­sion of disease emergence involves, as Eckardt argues, developing” a cer­tain sensitivity to the terms we are used to.” When we think of “tropical diseases,” for instance, malaria comes quickly to mind. But not too long ago, malaria was a significant problem far from the tropics. Although there is imperfect overlap between malaria as currently defined and the malaria of the mid-nineteenth century, some medical historians agree with contemporary assessments that this illness “was the most important disease in the United States at that time.” In the Ohio River Valley, ac­cording to Daniel Drake’s 1850 study, thousands died in seasonal epi­demics. A million-odd soldiers were afflicted with malaria during the U.S. Civil War. During the second decade of the twentieth century, when the population of twelve southern states was about twenty-five million, the region saw an estimated one million cases of malaria per year. Malaria’s decline in this country was “due only in small part to measures aimed directly against it, but more to agricultural development and to other factors some of which are still not clear.”

One responsible factor that is clear enough, if little discussed in the lit­erature, is the reduction of poverty, including the development of im­proved housing, land drainage, mosquito repellents, nets, and electric fans-all of which have been (and remain) beyond the reach of those most at risk for malaria. In fact, many “tropical” diseases predominantly afflict the poor; the groups at risk for these diseases are often bounded more by socioeconomic status than by latitude. In Haiti, for example, my patients with malaria are almost exclusively those living in poverty. None have electricity; none take prophylaxis; many have lost kin to malaria. This aspect of disease emergence is thus obscured by an uncritical use of the term “tropical medicine,” which implies a geographic rather than a social topography.

Any modem practitioner dealing with infectious disease knows this well, even if he or she sits in a travel clinic in New England. Those who come in for malaria prophylaxis and to ask about appropriate vaccina­tions are students, professionals, and tourists. When practitioners are called into the emergency room for an imported case of malaria, however, we usually see a very different patient shuddering on a damp gurney. In Boston, at least, the patient with malaria is likely to have been born in an endemic region-Haiti, say, or West Africa-and to be working as a la­borer in the U.S. service economy. And that patient is also likely to tell us the diagnosis, for it will not be the first time that he or she has had malaria.

Similarly, the concept of “health transitions” is influential in what some have termed “the new public health” and also among sectors of the inter­national financial institutions that so often control development efforts. The “health transitions” model suggests that nation-states, as they de­velop, go through predictable epidemiologic transformations. Death due to infectious causes is gradually supplanted by death due to malignancies and complications of coronary artery disease; the latter deaths occur at a more advanced age, reflecting progress. Although it describes broad pat­terns now apparent throughout the world, the concept of national health transitions also masks other realities, including morbidity and mortality differentials within nationalities, which show that health conditions are often more tightly linked to local inequalities than to nationality.

For example, much was made of the fact that noncommunicable pathologies such as coronary artery disease and malignancies caused the majority of all world deaths in 1990. A very different picture emerges, however, when we compare causes of death among the wealthiest fifth of the world’s population to the afflictions that kill the poorest fifth: al­though only 8 percent of deaths among the world’s wealthiest were caused by infections or by maternal and perinatal mortality, fully 56 per­cent of all deaths among the poorest were caused by these pathologies, with infectious diseases at the head of the list. How do the variables of class and race fit into such paradigms? In Harlem, where age-specific mortality in several groups is higher than that in Bangladesh, leading causes of death are infectious diseases and violence.

The units of analysis are similarly up for grabs. When Surgeon General David Satcher, writing of emerging infectious diseases, reminds us that “the health of the individual is best ensured by maintaining or improv­ing the health of the entire community,” we should applaud his clear­sightedness. But we should also go on to ask, What constitutes “the entire community”? In a few instances-the 1994 outbreak of cryp­tosporidiosis in Milwaukee, say-the answer might be part of a city. In other instances, “community” may mean a village or a group of pas­sengers on an airplane. But the most common unit of analysis referred to in public health, the nation-state, is not all that meaningful to organ­isms such as dengue virus, Vibrio cholera 0139, HIV, penicillinase­-producing Neisseria gonorrhoeae, multidrug-resistant tuberculosis, and hepatitis B virus. Such organisms often proudly disregard political boundaries, even though a certain degree of “turbulence” in their dy­namics may be introduced at national borders. The dynamics of disease emergence are not captured in nation-by-nation analyses any more than the diseases are contained by national boundaries, which are themselves emerging entities. (Most of the world’s nations are, after all, twentieth­century creations, which might also give pause to those buying into the two-worlds myth.)

The limitations of these three important ways of viewing the health of populations-the concepts of tropical medicine, health transitions, and national health profiles-demonstrate that models and even assump­tions about infectious diseases need to be dynamic, systemic, and critical. That is, models with explanatory power must be able to track rapidly changing clinical, even molecular, phenomena and link them to the large-scale (often transnational) social forces that shape the contours of disease emergence. I refer here to questions less on the order of how pig­duck agriculture might be related to the antigenic shifts central to in­fluenza pandemics and more on the order of the following: Are World Banl< policies related to the spread of HIV, as some have recently claimed? What is the connection between international shipping prac­tices and the spread of cholera from Asia to South America and else­where in this hemisphere? How is genocide in Rwanda related to cholera in Zaire?

The study of anything said to be “emerging” tends to be dynamic. But the very notion of emergence in heterogeneous populations poses ana­lytic questions that are rarely tackled, even in modem epidemiology, which, as McMichael argues, “assigns a primary importance to studying interindividual variations in risk. By concentrating on these specific and presumed free-range individual behaviors, we thereby pay less attention to the underlying social-historical influences on behavioral choices, pat­terns, and population health.”

Systemic analyses of disease emergence are not hemmed in by political or administrative borders. New tools based on DNA analysis allow us to rethink comfortable conclusions regarding treatment for some but not for others. The notorious “W strain” of MDRTB, for example, spread quickly through New York City, but then moved on to Atlanta, Miami, and Den­ver. New data suggests that the W strain’s family tree has roots in Asia and Russia. If these are transnational pandemics, spread through shar­ing air, then surely responses must be transnational-although, thus far, such responses have been hobbled by short-sighted parochialism. Ge­netic subtyping of HIV leads to the same conclusions.

A critical (and self-critical) approach would ask how existing frame­works might limit our ability to discern trends that are related to the emer­gence of diseases. Not all social-production-of-disease theories are equally alive to the significance of how relative social and economic positioning­—inequality—affects the risk of infection. For example, neither poverty nor inequality appears as a “cause of emergence” in the self-described “cata­log” of emerging infections compiled by the Institute of Medicine.

Further, a critical approach would push the limits of existing academic politesse in order to ask more difficult and rarely raised questions, ques­tions that still need to be answered if we are to better understand disease emergence. Examples might include issues such as these: By what mech­anisms have international changes in agriculture shaped recent out­breaks of Argentine and Bolivian hemorrhagic fever, and how do these mechanisms derive from international trade agreements such as GAIT and NAFTA? How might institutional racism be related to both urban crime and the epidemics of multidrug-resistant tuberculosis registered in New York prisons? Does privatization of health services buttress social inequalities, increasing risk for certain infections-and poor outcomes ­among the poor of sub-Saharan Africa and Latin America? How do the colonial histories of Belgium and Germany, and the neocolonial histories of France and the United States, tie in to genocide in Rwanda-which was itself related to an epidemic of cholera? We can productively pose simi­lar questions about many of the diseases now held to be emerging, as a few examples will suggest.