Historians have devoted considerable attention to public health over the past decade.ⁱ Infectious diseases, in particular, have been studied in medical histories, but also in historical studies of law, migration and politics. Indeed, one historian has recently observed, “Today, nobody is surprised when diseases and illnesses are discussed as slippery, ambiguous, complex entities constructed and framed historically taking into consideration the individual and the collective as well as the sociocultural and the biological”.1 What historians find unsurprising may, however, open up new ways of thinking for epidemiologists, public health officials and policy-makers, many of whom find the past intriguing but do not necessarily think historically about public health.

Above all, thinking historically involves the contextualisation of events, agents and practices, looking for contingencies and continuities as much as for change. It is not an exercise that draws on the past simply to link it, or contrast it to the present. At a popular level, as well as in scholarly public health literature, attempts to connect past to present typically produce one of two conclusions: infectious diseases of our time are unnervingly novel; or, more commonly, current disease outbreaks are repetitions of previous epidemics. In the first line of thinking, every mutated virus, form of transmission, cure or prevention technique represents a definitive break from the past. For example, recent concern over the threat of bioterrorism has prompted many political commentators to present the issue as extraordinary, calling for unprecedented measures of preparedness and prevention. Yet historians who study public health remind us that similar claims were made in the Cold War era and even in the 1930s, when biological warfare plans were brewing in Asia and the West.2 3

The second objective, searching for the precedents of alarming current public health problems, is also popular, especially with journalists and non-medical commentators, whose preoccupations are more gothic than historical. Whenever a new epidemic of infectious diseases emerges, the dark past is summoned up in chilling detail. Historic events lead to the apocalyptic question: could this outbreak, this disease, be the final great plague? Some invocations of the past are clearly misleading and often inaccurate. Historic public health crises regularly feature in popular medical histories that loosely deploy terms like “plague” generically, or refer to the Black Death in superficial ways. Unscholarly but enormously popular books, such as Killer germs, load their works with the gravitas of doomsday projections and net millions of buyers in the process.4 This is scare-mongering masquerading as history, and publishers, especially, indulge.

Recently, the global influenza pandemic of 1918–9 has provided a popular cautionary tale for the threat of severe acute respiratory syndrome (SARS) and the imminent danger of avian flu. Not only could the next pandemic be equally devastating, we are constantly reminded, but newly mobile populations make the threat even greater. For instance, in a popular magazine story about Toronto’s (mis)handling of the 2003 SARS outbreak, the layout of 1918 flu imagery is strategic. Framed by wartime sepia-toned pictures of masked medical personnel and sheeted corpses, the text leaps to the present: “2003 was just a dress rehearsal for the inevitable pandemic … The only question is how many will die.”5 Every time the 1918–9 influenza pandemic is replayed, it retains and gains cultural purchase. And while there is certainly no reason to think that we have somehow escaped the dangers of large-scale acute epidemics in the present, this rhetorical strategy of historical referencing has little analytical weight.

This is not to suggest that connecting the past to the present necessarily raises more alarm than awareness, or that distinguishing newer disease threats from older infections inevitably underwrites calls for greater restrictions on human liberties. Drawing selectively on historical evidence can lead to both of these conclusions, but thinking historically about public health and its management across time and cultures greatly enriches our analytical capacity. Because historians are trained “to find roots, antecedents and precedents, continuities and discontinuities”, Alan Brandt argues, the field of public health history can and ought to enhance the “post hoc process of policy assessment and evaluation” (p462).6 Historical-mindedness entails searching for differences as well as similarities between past and present, not presupposing one or the other. It also requires fine-grained empirical work in different geographic, national and local contexts. For example, from the moment AIDS appeared as a disease and an acronym, historians drew cautionary parallels between the public health and clinical response to HIV/AIDS and historical discriminatory responses to people with so-called venereal diseases, and, to a lesser extent, leprosy. At the same time, important distinctions became evident, not so much in the nature of the diseases or their transmission as in the political, cultural and social milieux in which transmissible disease has been managed, represented and resisted.7 8

In this study we assess recent work on the history of infectious disease management to highlight how historians have conceived of public health within and beyond the framework of medical history. Taken together, this work illuminates persistent and changing elements of infectious disease management, which are less apparent at close temporal range. Whether or not they make explicit links to the present, historically minded studies of public health confirm that past practices inhere in current perceptions and policies, which, like their antecedents, unfold amidst shifting amalgams of politics, culture, law and economics, in addition to increasingly sophisticated medical expertise. More significantly, it is difficult and even misconceived to explain past health policy decisions or practices purely in medical or epidemiological terms. To do so ignores evidence that they were rarely, in any historical context, designed solely on medical grounds.

There are, nevertheless, notable themes and consistencies in the history of infectious disease control. Here we consider three: restrictions on movement and contact, the powers and contestation of medicolegal authority, and the constitution of national borders and identities. By assessing the questions that historians have posed and the evidence that they have uncovered across a range of jurisdictions and periods, we outline how history can best be brought to bear on contemporary public health issues. Political and social history, not just medical history, have established that each of these factors interacts and operates under conditions—including changing legal structures, economic systems, migration regulations, state forms and religious doctrines—that shift over time and between geographical contexts. Thinking historically thus provides neither a formula for fear nor a primer on policy, but an opportunity for grounded, critical reflection.

MOVEMENT, CONTACT AND THEIR REGULATION

The continuities of the control of infectious diseases across wide periods presents the strongest case for explicit historical inquiry into contemporary public health. While historians are usually driven to search for change over time, there is considerable historical evidence of similarities in the spatial and segregating management of infectious disease from one century to another. This theme is less evident in the history of clinical medicine and therapeutics, in which radically unfamiliar therapies, such as bloodletting, cold baths, poultices, purging, form the standard stuff of antiquarian medical history: the curiosity shop of strange and ghastly outmoded treatments. By contrast, historians of public health have established that “old” systems of preventing and minimising the spread of infectious disease are recognisable because they have persisted, in modified form, especially with respect to acute disease.

Spatial strategies of disease control have always been signal features of public health. Agents and agencies in the present and the past have faced the same challenges: how to prevent direct and indirect contact between people who should be separated in some fashion, and how to stop, redirect or at best minimise human flow as well as the flow of animals and goods. The dangers of contact implied in the terms “infectious”, “communicable”, or the older “contagious” disease have repeatedly led to the imposition of segregation in its various forms—isolation, quarantine and household confinement. Thus, for example, the immediate response to SARS-infected individuals and suspected SARS “hotspots” in Asia and Canada in 2003 was fundamentally the same as the European response to cholera in 1831: surveillance, isolation, quarantine, border control. Another example is the isolation and disinfection of mail: instituted after the anthrax scare in late 2001, it has direct precedents in the screening, inspection and disinfection of letters in earlier centuries. Despite major conceptual shifts in aetiology, and notwithstanding the different cultural and political reception of these regulatory measures, they would have been broadly familiar to a public health agent in Marseilles in the 1760s, a quarantine officer in Hong Kong in the 1870s or a League of Nations Epidemic Commission officer in Poland in the 1920s. Put another way, past preventive health practices remain recognisable, even after public health arenas and authorities change. Overall, there is much more continuity of practice in the field of public infectious disease management than in other fields of biomedicine and clinical practice.

The spatialised practice of surveillance and separation has been implemented at all social and political levels, from the isolation of individuals to the separation of nations. The person considered to be the conduit of disease has frequently found herself isolated, as in the removal of women to “lock hospitals” under 19th-century contagious diseases legislation enacted in Hong Kong, the Straits Settlements, India, Queensland, Britain and elsewhere.9 At another level, families and households have been segregated in their homes, a common response in the acute disease management of smallpox, cholera and plague in earlier times, as with SARS in 2003. Urban spaces—sometimes streets, and sometimes whole cities—have been quarantined and all exit and entry points strictly policed. Behind these urban cordons sanitaires, a long associated history of major “disinfection” programmes, slum clearances and new housing policy developed simultaneously.10 11 And, finally, whole nations have been segregated, or have isolated themselves from contact, through emergency measures of quarantine, while certain individuals and groups have been excluded over longer periods through immigration restrictions, to be discussed below. It is this wide social reach of infectious disease management that has attracted not just medical historians, but urban historians, historians of migration, historical geographers and, as we shall see, historians of nationalism and internationalism.

Thinking historically about infectious disease is largely a matter of attending closely to earlier understandings of public health. Past epidemiologists left ample evidence to confirm that they conceived of disease management as a political enterprise, particularly at moments when human movement suddenly increased and brought with it a higher risk of transmission. Certain holidays and religious movements, for example, caused as much anxiety among public health officials in the past as they do today. In particular, the annual Muslim pilgrimage to Mecca has drawn historians’ attention precisely because it inspired intense epidemiological scrutiny in the past.12 Health regulation of people travelling to Mecca exercised both Ottoman and European authorities, and increasingly so over the 19th century. Many familiar practices were implemented there: quarantine camps, screening, disinfection stations, queues for inspection, and health documentation. The pilgrimage routes and Mecca itself were understood geopolitically as the hinge between “East” and “West”, the locus and means by which cholera, especially, might annually enter Europe. Furthermore, concern over this mass movement coloured international relations, as the question of health and disease rendered negotiation between European powers and the Sultan tense but necessary. There were many such early manifestations of “pre-emption” doctrines in this context, which allowed European powers to rationalise their own (public health) interventions in other sovereign territories on the basis of the incapacity of that other state to do so effectively. Such pre-emptive strikes aimed to prevent the spread of infectious disease generally but arose from efforts to protect the populace within Europe’s boundaries.13

Indeed, historians of imperialism have contributed significantly to the historical analysis of public health, in the same way that medical historians have enriched histories of “empire”. The historical literature on colonialism, infectious disease and public health management is now very considerable indeed. In addition to Muslim pilgrimages, for instance, two other mass movements—the migration of Europeans to “the new world” and the Chinese global diaspora, emerging from the middle of the 19th century—inspired similar programmes of public health that linked medicine to politics, law, culture and economics. That infectious diseases accompanied early European traders, missionaries and the military is now a standard argument in many imperial histories: epidemics often mapped directly along lines of trade and commercial exchange.14 However, the reverse is also the case: devastating numbers of Europeans died in “the tropics” from the early modern period onward, a concern that produced the discipline and institutions of tropical medicine. At the same time, the growing global authority of Europeans to manage movement meant that the flow of Europeans differed from the flow of Muslims to Mecca. Only certain Europeans became subject to laws that inspected, detained or deported persons on public health grounds, as the screening practices at Ellis Island, New York, illustrate.15 16 In contrast, English-speaking people moving around the world were never managed in public health terms en masse or because of their Englishness. Nothing could provide a starker contrast than the global history of infectious disease regulation and the Chinese diaspora. In concert with the formation of new kinds of territory-based nations, a major manifestation of the public health effort to separate people in order to contain infectious disease was the string of Chinese Exclusion Acts and Immigration Restriction Acts of the late 19th and early 20th centuries. As we discuss below, each of these Acts had public health clauses and public health rationales but carried with them political and economic interests and culturally coded notions of fitness.

AUTHORITY, LAW AND THE STATE

The mechanisms necessary to implement restrictions on human movement have historically developed in tandem with, and as part of, state formation.17 Unlike clinical medicine and therapeutics, regulating public health is and has been tied historically to questions of governance, authority and sovereignty. Determining how to deal with infectious disease entails forging relationships among state, society and the individual—a relationship whose character differs in, for instance, autocracies, religious states and democratic polities. This explains why specialists in political economy, law, political science and philosophy have frequently drawn on public health history to instantiate their arguments. Based on a study of disease management in San Francisco’s Chinatown, Nayan Shah argues: “Public health reform is far more than the instruments to suppress epidemic illness and enhance human vitality. It promotes a strategy of governance and citizenship with its own ethical and knowledge formations” (p258).18 This is evident in the best scholarship in public health history, which works equally as histories of government, politics and the state. George Rosen’s unsurpassed History of public health, for example, argues that Western public health systems developed within and drove the development of mercantilist and administrative government, political economy, liberalism and socialism from the early modern period through the 20th century.19 This is the analytical depth that popular histories of epidemics lack when they sever the history of public health from the history of political economy and social policy.

Analysts of state power have often selected public health regimes as historical case studies; accordingly, the questions they have asked have as much to do with government as medicine: what actions have states, citizens and non-citizens in the past considered appropriate and inappropriate, legitimate or illegitimate, to prevent the spread of disease? how has infectious disease management tested the limit of legal powers and concepts, such as habeas corpus in the common law tradition? how has coercion figured in programmes to prevent acute disease and how was this defended or resisted? As in the current context, so in the past: management of infectious disease entails weighing the risks and costs of individual freedoms against public safety. But the weighing of individuals has differed radically between categories of people and was often based on criteria other than disease status.

People already marginalised on the grounds of their race, class, gender or religion have been seen historically more as risks than as being at risk, with the result that governing authories have managed them primarily as “sources” instead of sufferers. The historical record indicates how persistently sex workers, poor children, Chinese, Jews and indigenous people have been targeted as the most likely infected and thus most in need of segregation. For example, in Australia, policies for the management of leprosy by the National Health and Medical Research Council as late as 1956 recommended isolation, but only for so-called full-blooded natives. This pronouncement followed a generation of elaborate legal requirements to prove infection and to enforce detention on the nation’s “leper colonies”, but according to distinct racial categories: “white”, “half-caste”, “full-blood”, “Chinese” and so forth. Another manifestation of this racially skewed (and medically ineffective) preventive measure was the West Australian “leper line”, the result of a statute that did not in fact regulate the movement of people with leprosy but did regulate more broadly the north–south movement of Aboriginal people in that state.20 In another instance, the implementation of both Britain’s and Hong Kong’s 19th-century Contagious Diseases Acts relied on the police surveillance and detention of women as the conduits of disease, not men, who also spread syphilis and gonorrhoea. As Löwy has put it, public health always invites the question “who or what is to be controlled?”21 The historical record is clear: more often than not, the answer was determined by who was controllable.

If historians have uncovered such dubious practices in the history of public health, they have also unearthed evidence that politically as well as scientifically suspect policies have been challenged in the past. Individuals have voiced objections by citing microbiological and epidemiological evidence and by asserting the values of human liberty. The very officials charged with controlling infectious disease have sometimes questioned the misuse and abuse of public health powers to regulate movement and compulsorily to detain, inspect and treat. For example, a lone doctor drew attention to the absurdity of the Australian race-based regulatory practices: “[I]t is illogical for the blacks only to be examined” (cited in Bashford, p98).20 Organisational protest is easier to trace. The Contagious Diseases Acts, for example, prompted one of the most prolonged and influential campaigns in the history of liberal ideas and politics, deeply determining and limiting the authority of the state over the bodies of individuals for many generations in Britain. The medical and legal arguments that the Acts were both “a hygienic mistake” and that they “remove every guarantee of personal security which the law has established and held sacred” eventually held sway.22

In British history, vaccination is the only public health issue that rivalled the significance of the Contagious Diseases Acts in shaping a politics of health and of liberal subjects, for it too inspired public debate over compulsion and state authority. Nadja Durbach, for example, looked at mid-19th-century smallpox vaccination campaigns in industrialising England and found that they became politicised in class terms. Like the Contagious Diseases Acts, vaccination programmes brought state power into the “private” familial and domestic sphere and inspired many to argue for alternative techniques of prevention.23 In a different context, David Arnold traced how British authorities and Indian populations clashed in the 19th century over public health measures. British experts, and indeed British law, insisted on vaccination rather than indigenous practices of variolation. Attempts to make vaccination compulsory, and in the process to render variolation illegal, gave rise to anti-imperial campaigns of resistance, as well as countless local disruptions.24

Rather than seeking to evaluate the validity of compulsory vaccination, these historians analyse the full range and context of the debates it inspired between supporters of vaccination and their opponents. Approaching the problem in this way highlights the wider point that the politics of infectious disease prevention is not a new phenomenon imposed on the past by historians, but an issue that was clearly apparent to historical actors themselves. Compulsory vaccination was not politicised by, say, working-class groups or Indian nationalists (or, indeed, by latter-day historians); rather, all stakeholders in the debate, not least the advocates of compulsion, understood public health to be naturally and necessarily a political field. Acknowledging that smallpox vaccination was the most important life-saving intervention of modern public health does not, therefore, preclude acknowledging its inherent class- and race-based politics; rather, good history calls for it.

Determining how to manage the asymptomatic carrier is another public health objective with historically variable political and legal implications. The “carrier” appeared as a problem for governments once new microbiological systems and laboratories of diagnosis became both possible and widely available. One trajectory in public health around the turn of the 19th century was away from problematising the disease status of areas (a town, a city, streets, countries) and towards a greater concern for the disease status of individuals. Judith Waltzer Leavitt’s study of the asymptomatic Mary Mallon (“typhoid Mary”) in New York City from 1907 to 1910 and from 1915 to 1938 is an illustrative case.25 What New York public health officials and bacteriologists learnt from this extraordinary episode of apprehension, diagnosis and prolonged detention was, first, that such detention was logistically impossible en masse, even if it had been deemed legal for Mallon. Second, and as a result, health authorities toiled at alternatives—various treatment protocols and prevention measures in the community.25 Here we see the close connection between medical history and criminal justice history. The Typhoid Mary episode was just one in a tangled history of unwitting or even intentional infectious disease transmission, and their definition through legal determinations of criminal responsibility. Preventive health measures and criminal sanctions have been remarkably ambiguous in the past.26

The compulsory isolation of the healthy carrier is in essence an exercise in pre-emption. The danger of misuse is constant, partly because of the authority invested in certain powers to segregate and move people and partly because the public benefit in doing so can appear so clear and evident. Consequently, democratic regimes that rely on public consensus have proven as capable of imposing grossly segregative measures as have dictatorships. Indeed it was health segregation (often with the best intention) that preceded and led to subsequent racial segregation in numerous historical contexts. Historian of Nazi health policy Robert Proctor has explored what he calls the medicalisation of antisemitism and shown how the first interventions of the Nazi occupiers on Polish Jews were preventive health measures: quarantine regulations passed and imposed ostensibly to prevent typhoid fever. This regulation, this preventive quarantine, became the first legal measure towards the Warsaw ghetto, after which Nazi authorities used the concept of quarantine “to confine, transport, and deport individuals throughout the war”.27 While studies such as Paul Weindling’s intricately researched book Epidemics and genocide in Eastern Europe deal with extreme moments of 20th-century history,28 describing them as wholly exceptional runs the risk of misunderstanding what public health has been and done in the past. The point is that managing infectious disease holds a particular potential for misuse in these ways, not that this necessarily materialises.

NATIONALISM AND INFECTIOUS DISEASE

Closely connected to the political and legal dimensions of public health has been historical work that links infectious disease management to the emergence of nationalism over the 19th and 20th centuries. Historians have examined this connection by tracing the development of medicolegal border control, the implementation of public health campaigns associated with notions of modernity, and programmes that fused health promotion, individual conduct and citizenship. In one sense, it is important to acknowledge the effectiveness of these practices from the point of view of microbial history. For example, rigid quarantine practices in Australia (coupled with its geographical isolation) helped to prevent cholera from reaching Australian shores and the Australian population. Considering the circuits of global maritime connection in which Australia was situated, this was a remarkable achievement. Nonetheless, that public health success story leaves out the related story of nation-building in which it was implicated.

One of the principal means of expressing the abstract notion of sovereignty has been through national medicolegal border control and the tight administrative connection between quarantine and immigration regulations.29 30 Many national governments have legitimately sought to prevent the spread of disease by inspecting people before entry, or on entry, or indeed, as with the United Kingdom, after entry. “Infectious disease” or “loathsome disease” clauses appear in almost all immigration laws of the 19th century and first half of the 20th century, starting with the wave of Chinese Exclusion Acts around the 1880s. Conversely, various public health laws have stipulated powers of exclusion or deportation of infected migrants. Considerable legal, medical and political effort has gone into medicolegal border control—certainly on the basis of disease prevention but rarely on that basis alone. In other words, it is evident that disease and quarantine laws, as well as the “infectious disease” clauses in immigration laws, have formed rationales for shaping national populations in desired ways, as well as shaping distinctive nationalisms.

Historians, unlike most epidemiologists, focus on the wider sources and effects of measures designed to protect national health, and consider them at least as important as their medical features, and often more intriguing. What else, aside from objectives of infection prevention, produces specific health and immigration regulations in specific historical moments, such as during economic or military crises, or at the point of nation formation? Public health historians have also shown that regulations governing the health of people seeking entry and/or citizenship shift over time, though not always in ways that make sense in purely epidemiological or even microbiological terms. Borders demarcate jurisdictions, but cultural historians emphasise their capacity to symbolise “the nation” and its vulnerabilities both to disease and to outsiders. Only through a wider social, political and cultural frame of reference can the full meaning of exclusionary infectious disease controls be appreciated.

Adopting new public health measures has been one means through which several non-Western nations have asserted a specifically modern national identity. Historian Susan Burns, for example, shows that Japanese authorities pursued and implemented Western public health measures insistently as a key component of its modernisation programme after the Meiji Restoration of 1868. “[T]he public health system that began to take form in the 1870s and 1880s was organised around the principles of policing and confinement ... [T]he formation of public health policy was ... implicated in the pursuit of national prestige” (p108).31 In the case of leprosy management, she shows how public policy shifted quickly from support for the religiously-identified “wandering lepers” to a new, Western-inspired system of notification and segregation. By 1931, a “lifetime confinement” law committed people with leprosy to segregation until their death, a law repealed only by 1996, and one that has subsequently prompted hundreds of suits for compensation.31

Chinese authorities borrowed from Western public health models in the same period, to minimise and contain disease and also to manage populations in “modern” ways for national political ends. In Hygienic modernity, Ruth Rogaski analysed the shift in meaning of weisheng (“hygiene” or literally “guarding life”) from a Chinese cosmology to one encompassing “state power, scientific standards of progress, the cleanliness of bodies, and the fitness of races”.32 Weisheng, she argued, was and is “a central part of contemporary China’s struggle to achieve what seems to be an ever-elusive state of modernity”.32 Her analysis confirms weisheng’s political significance, where variously Chinese, Japanese and British physician–bureaucrats increasingly tied individual hygienic conduct to issues of national health and fitness.

By the 20th century, health propaganda was a feature of public health transnationally. Public health departments sprang up all over the world and instituted education programmes and campaigns to combat infectious disease. Such campaigns were often inherited from philanthropic groups with class-based interests. Attempting to inculcate habits at the most minute and everyday level in the largest number of individuals in their population, campaigns ranged from hand-washing exhortations to “don’t spit” warnings, to all manner of sexual hygiene practices (including promoting abstinence). This was the flip side of the coercive public health of segregation and containment. For bureaucrats and epidemiologists alike, connecting healthy habits to national fitness and nationalism was the governing aim of much 20th-century public health, an ideal soundly reasoned and often proudly declared.

Examining connections between the management of individual conduct, overt nationalism and health is now common in historical analyses of public health history. In large part, this line of inquiry responds directly to the historical record: quite simply, it is impossible to ignore, especially in the early- to mid-20th-century phase of hypernationalism around the globe. It is no coincidence that this early-20th-century moment was also the era in which national public health departments and bureaucracies first emerged: for example, Tianjin held the first native-administered municipal department of health in China in 1902; the Australian Department of Health was established in 1921; the French established a Ministry of Hygiene in 1920. Public health practitioners in that period were deeply schooled in thinking about public health’s wider implications. As we have seen, in China, weisheng was promoted as part of a modern nationalism. In Britain, hand-washing and a new culture of outdoor activities for children were part of the programme to maintain national and imperial greatness, as well as to resist disease. In New Zealand, “physical culture” and “domestic hygiene” made for good citizenship as well as tuberculosis-resistant young adults. In National Socialist Germany, as in post-revolutionary Mexico, public health and national duties were conflated in the strong encouragement to reproduce fit, healthy babies.33 In the USA, Chinese community leaders responded avidly to the health and hygiene measures and norms that would “earn” them inclusion in the US civic body. Altogether, this transnational commitment to an explicit “political hygiene” is one of the more remarkable trends of 20th-century world history. It certainly reduced infectious disease morbidity, but it simultaneously produced scripts for national fitness and national identities. The most thorough understanding and explanation of the significance of this trend has emerged less from narrowly focused medical history than from histories of “governance”, which analyse the relation between national government and self-government, between health and citizenship.

CONCLUSIONS: THE USABLE PAST?

What we have sketched here is a précis for more historically minded thinking about infectious disease and human flow. Historical contributions to public health problems such as these are richer when they are not driven by the imperative to respond to policy-makers’ requests to provide “the” history of “the” issue. Historians reject this approach, Brandt explains, because the “very presumption that there is a particular, explicit, and objective history that simply can be produced at will for policy purposes distorts both historical methodology and analysis” (p466).6 If policy-makers look to historians for clear answers, they are likely to be disappointed. Alternatively, if they are receptive to information that may have been forgotten, and, more importantly, if they are receptive to the wide-framed thinking that historians bring to bear on the history of infectious diseases, historically informed analysis will prove its value. The most important questions about the precedents for current approaches to prevention and treatment of infection are as likely to come from immigration or legal histories, we suggest, as from expressly medical histories. Above all, the historian’s intellectual commitment to explore and analyse context can provide a corrective to narrowly biomedical accounts of public health history.

Historical mindedness complements epidemiology. If epidemiologists study trends in morbidity and mortality for particular kinds of diseases, historians remind us that long-term change does not lead inevitably towards a more enlightened present, even if public health and biomedicine have achieved great successes. Public health has always been entangled in questions of authority, coercion and freedom, as well as of the governance of people, their movement and conduct. There is nothing new about that. But the ways in which these questions are addressed in different jurisdictions and at different times depend on particular confluences of human movement and infectious disease and also on historically rooted practices and perceptions—whether or not we choose to acknowledge and analyse them.