Centaurus

Quantitative assessments of when infectious disease outbreaks end are crucial, as resources targeted towards outbreak responses typically remain in place until outbreaks are declared over. Recent improvements and innovations in mathematical approaches for determining when outbreaks end provide public health authorities with more confidence when making end-of-outbreak declarations. Although quantitative analyses of outbreaks have a long history, more complex mathematical and statistical methodologies for analysing outbreak data were developed early in the 20th century and continue to be refined. Historically, such methodologies focused primarily on factors affecting the early and middle phases of an outbreak, with less attention given to determining how and when outbreaks end. This review discusses mathematical modelling methods from the last 20 years that have been developed for determining the ends of infectious disease outbreaks, and considers factors that affect the accuracy of such determinations. When disease surveillance systems provide timely and representative data to inform models, the timings of end-of-outbreak declarations can be fine-tuned to allow outbreaks to be declared over quickly and with a low risk of being incorrect. Premature declarations that outbreaks are over can undermine earlier achievements in disease control and may result in a resurgence of cases, but unnecessary delays in declaring outbreaks over can cause significant economic and social harm. Appropriate declarations that balance the benefits of relaxing control measures against the risk of a surge in cases allow public health resources to be conserved (and economic and social pressures to be reduced) while limiting the potential for additional transmission.

At the Centre for Ecological and Evolutionary Synthesis (CEES, University of Oslo), a group of biologists has been working for decades to disentangle the complex mechanisms of plague epizootics and epidemics in places where extant wild rodent reservoirs are present. These questions have been approached through ecological and climatic studies, mathematic modeling, as well as genomics and epidemiology. In 2013-2018, the Centre hosted the ERC-project MedPlag, which explored past pandemics through the lenses of additional disciplines, like archaeogenomics (ancient DNA), anthropology, archaeology, and evolution, always against the background of historical information. Here, we reflect on the end of plague in Europe based on the most recent studies on plague carried out in these different disciplines.

In the 17th century, English plague-tract writers began replicating a practice begun some decades earlier by their French and Italian counterparts: creating local histories to better describe the disease and explain how best to manage it. After the great London outbreak of 1665, however, plague deaths often went unrecorded and English tract-writing declined significantly. Without local epidemics to record or historicize, the authors became remote spectators of plague elsewhere, their own outbreaks perhaps now seemingly safe in the past. When plague raged in Marseille in 1720, the disease generated fear but was in some ways a bygone event to English tract-writers. Marketing their tracts as historical accounts, a number of English authors likened the Marseille plague to the epidemics that were forming part of England's social memory. By repeatedly hailing 1665 as the last time plague had raged in London, some writers emphasized England's long plague-free status, pointing to the success of past efforts to contain the disease and also, in some cases, denying that plague could ever have been endemic in the kingdom. They did not downplay the threat that the Marseille outbreak posed should it spread; indeed, concern that plague might devastate English cities once again is at times palpable in the tracts. However, for numerous writers, plague had become an imported foreign threat, one that could be mitigated with appropriate measures, not one that arose domestically. They pointed specifically to the Ottoman Empire, describing it as disease-ridden and the source of their own plagues-historically and, potentially, in the future. In other words, 18th-century English tract-writers relegated their plague epidemics to the past by both firmly historicizing them and making the disease definitively foreign. Plague had not come to an end, but it was no longer their plague.

The great plague in London in 1665 was the last in a series of epidemics that had begun with the Black Death in the 14th century. Plagues continued elsewhere in Europe into the 18th century, but after 1679 no cases of plague were reported in England at all. The disease seemed to have disappeared. How could that be explained? The purpose of this paper is to discover when contemporaries began to think that plague had gone for good, and why they thought that had happened. The paper falls into two parts. The first concentrates on the decade of the 1720s, when plague was expected to come from Marseilles and never arrived. In the space of a few months there was fierce and concentrated public debate about a new Quarantine Act to be enforced if an epidemic developed, much of it arguing that the Act was unnecessary because plague was plainly not contagious at all. It depended wholly on local environments, and in England they had been improving ever since the Great Fire of London. The second part of the paper takes the story forward into the later 18th century, when there was no longer much dispute that plague was indeed contagious, but it was confidently supposed that England now enjoyed the double protection of further environmental improvement at home combined with effective quarantine of shipping abroad, especially in the Mediterranean. Over the century, contending explanations for plague were debated, interpretations of the past disputed and sometimes falsified, and expectations and ambitions for the future remodelled, because one epidemic threat had disappeared for good.

The politics of epidemics in Chinese history not only involves competing interpretations about the meanings of disease, but also includes dynamic tensions between socio-political factors and the participants involved in emergency responses. This article examines three cases-the plague epidemic of 1949, the cholera epidemic of 1961-1965, and the meningitis epidemic of 1966-1967-to reveal the entangling political, technological, and epidemiological factors involved in ending epidemics in the People's Republic of China, while also illustrating the difficulty of charting the end of an epidemic when data on disease prevalence and disease control are collected, reported, framed, and archived by political authorities.

This article explores the question of how malaria “ends” in Myanmar, since malaria has been categorized both as an epidemic and as being endemic on seemingly countless occasions. The example of malaria reveals some of the limitations of understanding a disease within a single category of experience, such as an “epidemic.” In the case of malaria, epidemic is a shifting term that is best understood as being the point at which health authorities decide to intervene in the disease, rather than as a clear and absolute measure of the scale or intensity of the threat. The identification of malaria as epidemic may thus be better understood as a political choice rather than as a precisely defined medical category. This article thus discusses what it means to end malaria in Myanmar, what kind of ending has been envisaged, and by whom. As this article demonstrates, policy makers have at various points aimed for the “elimination,” “eradication,” and “control” of malaria. Unlike the local population, who seem to have a rather nonchalant attitude toward malaria since malaria has long been familiar to them, international partners and the government have been shaping the narrative toward elimination with the aim of obtaining the World Health Organization's malaria-free certificate. Despite a number of political, social, and environmental obstacles, they believe that elimination can be achieved by 2030. However, unexpected political events such as the military coup in 2021, as well as the emergence of another pandemic, demonstrates that the “end” of malaria is a fragile concept.

This article examines how chikungunya virus disease is epidemiologically and politically invisible in Brazil, unlike other diseases related to the Aedes Aegypti mosquito, such as Zika, dengue, and yellow fever. It demonstrates the intricacy of identifying the presence of chikungunya, as its effects are generally materialised in pain, which is difficult to measure and quantify, and thus is invisible to medical and state bureaucracy. As with other chronic diseases, chikungunya transforms identities and social relations among those affected. By analysing the situation in Natal, in Northeast Brazil, and considering epidemics as social, economic, and political narratives as well as biomedical phenomena, the article asks how chikungunya might end when it has not even officially started.

Studying national and local contexts is essential for understanding the ending of epidemics and related policy responses. This article examines HIV/AIDS in the 1980s and 1990s and swine flu in 2009-2010 in the UK as comparative “tracer epidemics” to understand the multiplicity of endings from the perspective of the contemporary history of policy. Such endings can include: the political ending, changes in definition away from epidemic, the medical end, different endings for different “risk groups,” local endings, and media endings. This multiplicity of endings throws light on the nature of political and institutional structures and their change over time.

In this article, I address some infectious diseases that never really “ended,” even though their morbidity, their social impact, and their public visibility have faded away: AIDS, syphilis, and measles. I will use data from different projects I have conducted on each of those epidemics: HIV/AIDS at the doctoral training level in the 1990s, with a geographical focus on Brazil and the United States; syphilis in the context of a 2010 project on the social history of health in Lisbon in the late 19th and early 20th centuries; and measles as part of my current project on labor migration in the 19th century, with a focus on epidemic outbreaks in migrant ships from Madeira to Hawaii.

This article discusses a paradox in the modern history of tuberculosis: its eradication has been seen as imminent ever since it was defined as a condition with a necessary bacterial cause in 1882, but, to date, has failed to arrive. The unwavering belief in an imminent end to tuberculosis mostly illustrates the degree to which modernity trusts in pharmaceutical interventions, whether in the form of Koch's tuberculin cure of 1890, the BCG vaccine of the mid-20th century, or global health control programs that prioritize mass-treatment campaigns with antibiotics and chemotherapies. These visions of pharmaceutical-based solutions have not only failed to eradicate tuberculosis, but can often distract attention away from the social causes of the epidemic, such as poor housing and nutrition.

Skeletons drawn from archaeological contexts provide a fund of data for assessing disease in general and timing of epidemics in particular in past societies. The bioarchaeological record presents an especially important perspective on timing of some of the world's most catastrophic diseases, such as leprosy, tuberculosis, plague (Black Death), and treponematosis. Application of new developments in paleogenomics and paleogenetics presents new opportunities to document ancient pathogens' DNA (for example, Black Death), track their history, and assess their beginning and end points. Paleopathological documentation of disease terminus is complex, in part owing to circumstances where past communities experienced overlapping epidemics, such as leprosy and plague. For most settings, these syndemics-whereby there is an interaction between two or more epidemic diseases-both exacerbate and enhance the burden of morbidity in a community or region. Fundamental to understanding the severity and duration of epidemics is the consideration of multiple factors that simultaneously influence the severity and duration of the specific infectious diseases in a community or region, including poor oral health, under-nutrition, iron deficiency anemia, and elevated parasite load. In our view, comprehending the beginning, the middle, and the end of epidemics requires understanding the wider context of syndemics, the multiple challenging circumstances that undermine health and community stability, and how biosocial factors differentially affect the immune competence of individuals. This article provides several examples of the application of bioarchaeology and syndemics theory in achieving an understanding of how epidemics end. Pathogens continue to circulate, even after what appears to be the end. In effect, then, there is no “end,” just evolution of opportunistic pathogens and our ability (or not) to mitigate them.

Pre-existing medical conditions and co-infections are common to all human populations, although the natures of the pre-existing conditions and the types of co-infections vary. For these reasons, among others, the arrival of a highly infectious pathogenic agent may differentially affect the disease burden in different sub-populations, as a function of varying combinations of endemic disease, chronic disease, genetic or epigenetic vulnerabilities, compromised immunological status, and socially determined risk exposure. The disease burden may also vary considerably by age cohort and socio-economic status. The social consequences of infection, the medical sequelae, and the paths of recovery from infection may also vary, according to these variables. As a result, different sub-populations may have different experiences of a disease process, including when and how an epidemic comes to an end.

This essay suggests that historians' engagement with path-breaking biological and medical anthropological research will allow new approaches to understanding disease processes that will enrich the study of epidemics and their endings. It is organized in three sections. The first discusses some general approaches to and assumptions about epidemics that are used by many historians. The second introduces new perspectives on the study of historical epidemics opened up by the medical anthropological concept of syndemic disease interactions and by an engagement with biological scientific perspectives. It briefly discusses two rural epidemics-one of anemia caused by the syndemic interaction of hookworm and malaria co-infections in early 20th-century British Malaya, and the other of rebound infections caused by the loss of acquired immunity to falciparum malaria in mid-20th-century Liberia-that illustrate, respectively, the utility of the concept of syndemic disease interactions and the centrality of immunological status in understanding epidemic outbreaks in these discrete populations. The third section addresses some of the research considerations involved in moving beyond the single pathogen model of epidemic disease.

To answer how epidemics end, one must ask two intersecting but separate questions: first, how particular waves of epidemics end, whether of yellow fever, cholera, plague; and second, how epidemic diseases become eradicated-either through scientific intervention, as with smallpox in the 1970s, or simply by disappearing for reasons that remain mysterious, as with the Second Plague Pandemic from ca. 1347. This article challenges two general notions on how epidemics end. First, individual waves of plagues in European municipalities or regional states did not just fade into the sunset. By the late 16th century, their ends were celebrated with artistic displays, musical and poetic performances, ex-voto gifts, and bangs ranging from tambourines to military salutes. Second, the five-century Second Pandemic of plague-that is, the disease-did not end with declarations or scripted performances, but with another sort of bang. Instead of the usual assumption that epidemic diseases decline gradually over time, progressively inflicting lighter loads of virulence and mortality, the last significant plague outbreaks in most regions in Europe returned to heights of mortality not seen since the Black Death of 1347-1351. Finally, this article adds an obvious but rarely mentioned variable for understanding epidemic endings. Before widespread vaccination, the characteristics of these disappearances depended on the type of disease.

Smallpox's devastating impact on Indigenous Peoples of the Americas figures prominently in the historical literature. But when did this horrific experience end? Historians have not noticed, and there are good reasons why they have not, at least for Indigenous Peoples of the United States. Between 1898 and 1903, federal agents and tribal officials enforced quarantines, isolated infected individuals, and vaccinated communities in response to a nation-wide epidemic. Smallpox consequently disappeared. But the evidence we can use to identify this ending leads us in directions other than acknowledging a significant historical milestone. Federal agents detailed efforts to erase Indigenous cultures and described ongoing health problems not related to smallpox, making the passage of the old scourge less significant. Stories that Indigenous Peoples produced after eradication, moreover, contained no celebration of smallpox's demise. These stories instead refer to the disease's arrival as the beginning of colonial trauma that had yet to come to its own end.

During the COVID-19 epidemic, the name of the 19th-century English physician John Snow (1813-1858) has cropped up to a surprising extent, notably in connection with the severe cholera epidemic of 1854 in the district of Golden Square, London. It is repeatedly stated that Snow brought this epidemic of waterborne disease to an end by removing the handle of the Broad Street pump. It is also widely known that this story is a myth. Nonetheless, the Broad Street pump story as told by Snow's close friend Benjamin Ward Richardson remains embedded, partly, it is argued, because of its appeal to areas of the cultural consciousness. In America, Snow and his work on the epidemiology of cholera, including the Broad Street pump story, achieved a serious status which has endured, in one form or another, to the present day. In contrast to Britain, the heroic age of public health in America coincided with the optimism of the bacteriological revolution and higher hopes for medical science. However, this rapidly changing environment exacerbated differences of opinion as to what the small and emergent specialty of epidemiology should look like, what its project was, and where it should be based. Different versions of Snow's persona came to represent basic and often conflicting conceptions of epidemiology and the status (or lack of it) of its practitioners. For many, consciously or otherwise, the removal of the Broad Street pump handle remained an individualistic triumph, a single human intervention which resembled modern medicine in providing a “cure.”

In 1943, Allied forces in recently liberated Naples were confronted with an outbreak of louse-borne typhus. The established Anglo-American narrative of that epidemic is a triumphant story of effective action that controlled the disease with unprecedented speed and success, aided by the pioneering use of the pesticide DDT. Rather than retell that tale, this article discusses why the outbreak and its ending are largely absent from Italian accounts of wartime Naples. Drawing on Italian sources and contemporary Allied ones, it argues that this absence speaks powerfully to the realities of life for Neapolitans at the time. These realities included the likelihood that the epidemic left most people unscathed, and the presence of additional challenges that made survival in the city perilous. Illustrating how tangled events (and even non-events) can be fashioned into simplistic but meaningful frameworks according to the perspective and priorities of the observer, the article also demonstrates how methods (in this case, delousing with insecticide) that were later proclaimed as crucial in ending an epidemic can be viewed very differently by populations required to comply with them, especially when the disease's dangers seem remote.

“An epidemic has a dramaturgic form,” wrote Charles Rosenberg in 1989, “Epidemics start at a moment in time, proceed on a stage limited in space and duration, following a plot line of increasing and revelatory tension, move to a crisis of individual and collective character, then drift towards closure.” Rosenberg's dramaturgic description has become an important starting point for critical studies of epidemic endings (Vargha, 2016; Greene & Vargha, 2020; Charters & Heitman, 2021) that, rightly, criticize this structure for its neatness and its linearity. In this article, I want to nuance these criticisms by distinguishing between the term Rosenberg uses, “closure,” and its implicature, “ending.” I aim to show how many of the complications ensuing between the different forms of ending imagined may well be resolved by assessing whether they bring closure or not.