The changing assessments of John Snow's and William Farr's cholera studies

This article describes the epidemiological studies of cholera by two major British investigators of the mid-nineteenth century, John Snow and William Farr, and it asks why the assessments of their results by contemporaries was the reverse of our assessment today. In the 1840s and 1850s Farr's work was considered definitive, while Snow's was regarded as ingenious but flawed. Although Snow's conclusions ran contrary to the exceptations of his contemporaries, the major reservations about his cholera studies concerned his bold use of analogy, his thoroughgoing reductionism, and his willingness to ignore what seemed to be contrary evidence. Farr's electic use of current theories, his reliance multiple causation, and his discovery of a mathematical law to describe the outbreak in London in 1849 was much more convincing to his contemporaries. A major change in thinking about disease causation was needed before Snow's work could be widely accepted. William Farr's later studies contributed to that acceptance.     

John Snow: the first hired gun?

The 1854 English cholera outbreak led to reform of Victorian public health legislation, including the Nuisances Removal and Diseases Prevention Act. The reforms threatened the closure of many factories whose fumes were considered hazardous to the public's health. The second witness to appear before the Parliamentary committee considering the reforms was Dr. John Snow. Snow testified on behalf of the manufacturers threatened by the reforms. He stated that the fumes from such establishments were not hazardous. He contended that the workers in these factories did not become ill as a result of their exposures, and therefore these fumes could not be a hazard to the general public's health. Snow also presented data from the 1854 cholera outbreak as the basis for his belief that epidemic diseases were transmitted by water, not air. Although the data concerned cholera, Snow extended the inference to all epidemic diseases. When the committee's report was published, The Lancet chastised Snow in a stinging editorial. Parliament subsequently revised the bill in favor of the manufacturers and passed it into law. The implications of this particular episode in the history of epidemiology are discussed.     

Our sense of Snow: the myth of John Snow in medical geography

In 1854, Dr. John Snow identified the Broad Street pump as the source of an intense cholera outbreak by plotting the location of cholera deaths on a dot-map. He had the pump handle removed and the outbreak ended...or so one version of the story goes. In medical geography, the story of Snow and the Broad Street cholera outbreak is a common example of the discipline in action. While authors in other health-related disciplines focus on Snow's "shoe-leather epidemiology", his development of a water-borne theory of cholera transmission, and/or his pioneering role in anaesthesia, it is the dot-map that makes him a hero in medical geography. The story forms part of our disciplinary identity. Geographers have helped to shape the Snow narrative: the map has become part of the myth. Many of the published accounts of Snow are accompanied by versions of the map, but which map did Snow use? What happens to the meaning of our story when the determinative use of the map is challenged? In his book On the Mode of Communication of Cholera (2nd ed., John Churchill, London, 1855), Snow did not write that he used a map to identify the source of the outbreak. The map that accompanies his text shows cholera deaths in Golden Square (the subdistrict of London's Soho district where the outbreak occurred) from August 19 to September 30, a period much longer than the intense outbreak. What happens to the meaning of the myth when the causal connection between the pump's disengagement and the end of the outbreak is examined? Snow's data and text do not support this link but show that the number of cholera deaths was abating before the handle was removed. With the drama of the pump handle being questioned and the map, our artifact, occupying a more illustrative than central role, what is our sense of Snow?     

运用标点地图法寻找霍乱流行真相:约翰·斯诺

约翰·斯诺(John Snow,1813-1858),是麻醉医学和流行病学界举足轻重的人物。他通过调查证明霍乱经患者粪便污染的水传播,首次提出霍乱的防治措施,阻止了19世纪英国霍乱蔓延。1854年,他对伦敦索霍区霍乱暴发的调查创造性地使用了对比分析,使现场调查在医学研究中具有独特的意义。"霍乱流行图"的绘制也使标点地图法成为流行病学一项基本研究方法,斯诺也因此被誉为"流行病学之父"。     

Who made John Snow a hero?

This paper describes how and why John Snow's investigation of the transmission of cholera grew into an epidemiologic classic. The evolution of the interpretation of the work of John Snow was first studied in depth in the Dutch medical literature, and thereafter traced more superficially in the bacteriologic, hygienic, and epidemiologic literature of Germany, the United Kingdom, and the United States. From the oral tradition of teaching, as well as from the written sources, it is concluded that US epidemiologist W. H. Frost was responsible for the revival of the work of John Snow in the 1930s. Besides the obvious and enjoyable clarity of thinking and reasoning, epidemiologically and medically, of the writings of John Snow, his example well suited epidemiology of the 1930s since his convictions came very close to the bacteriologic paradigm of the day.     

The changing assessments of John Snow's and William Farr's cholera studies

Summary This article describes the epidemiological studies of cholera by two major British investigators of the mid-nineteenth century, John Snow and William Farr, and it asks why the assessments of their results by contemporaries was the reverse of our assessment today. In the 1840s and 1850s Farr's work was considered definitive, while Snow's was regarded as ingenious but flawed. Although Snow's conclusions ran contrary to the exceptations of his contemporaries, the major reservations about his cholera studies concerned his bold use of analogy, his thoroughgoing reductionism, and his willingness to ignore what seemed to be contrary evidence. Farr's electic use of current theories, his reliance multiple causation, and his discovery of a mathematical law to describe the outbreak in London in 1849 was much more convincing to his contemporaries. A major change in thinking about disease causation was needed before Snow's work could be widely accepted. William Farr's later studies contributed to that acceptance.

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Das sich wandelnde Verständnis der Cholera-Studien von John Snow und William Farr

Zusammenfassung Dieser Artikel befasst sich mit den epidemiologischen Cholera-Studien von zwei bedeutenden Britischen Forschern der Mitte des 19. Jahrhunderts, John Snow und William Farr. Es wird hinterfragt warum deren Zeitgenossen die Studienresultate entgegengesetzt beurteilten als wir dies heute tun. In den 1840er- und 50er-Jahren wurde die Arbeit von Farr als massgeblich betrachtet, während die Arbeit von Snow zwar als originell, aber fehlerhaft galt. Auch wenn die Schlussfolgerungen von Snow den Erwartungen seiner Zeitgenossen widersprachen, die grössten Bedenken im Hinblick auf seine Cholera-Studien galten der gewagten Verwendung von Analogien, seinem extremen Reduktionsismus und seiner Neigung zu ignorieren, was ein Beweis des Gegenteils schien. Farrs selektiver Gebrauch bestehender Theorien, sein vertrauensvolles mehrfaches Kausalprinzip und seine Entdeckung eines mathematischen Zusammenhangs zur Beschreibung des Cholera-Ausbruchs in London 1849, hatten grössere Überzeugungskraft auf seine Zeigenossen. Es war zunächst notwendig, dass sich das Verständnis über die Verusachung von Krankheiten grundsätzlich änderte, bevor Snows Arbeit überhaupt akzeptiert werden konnte. William Farrs spätere Studien trugen dazu bei.

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Evolution historique de l'appréciation des études sur le choléra de John Snow et de William Farr

Résumé Cet article décrit des études épidémiologiques sur le choléra menées par deux importants chercheurs britanniques du milieu du 19^ème siècle, John Snow et William Farr. Il s'interroge sur les raisons pour lesquelles leurs contemporains apprécièrent leurs résultats de façon inverse à notre appréciation contemporaine. Au curs des années 1840 et 1850, les travaux de Farr furent considérés comme définitifs, alors que ceux de Snow étaient jugés ingénieux mais biaisés. Bien que les conclusions de Snow allaient à l'opposé des attentes de ses contemporains, les principales réserves par rapport à ses études sur le choléra provenaient de ses analogies périlleuses, de son réductionnisme implacable et de sa tendance à ignorer les faits qui contredisaient sa théorie. Ses contemporains étaient beaucoup plus convaincus par l'utilisation éclectique, par Farr, des théories en vogue, son acceptation de l'existence de causes multiples et sa découverte d'une loi mathématique qui décrivait l'épidémie de Londres en 1849. Il fallait que se produise un changement majeur dans le raisonnement causal en médecine pour que les travaux de Snow puissent être largement acceptés. Les dernières études de William Farr ont contribé à la reconnaissance de Snow.

     

现场流行病学 第一讲 现场流行病学及中国现场流行病学培训项目

一、现场流行病学概论1 .现场流行病学产生的背景 :流行病学起源于现场 ,从Snow的对霍乱调查开始 ,人类的流行病学工作一直围绕着“到现场去解决现实的公共卫生问题”这一主线 ,离开了现场 ,流行病学家的灵感和流行病学的成就都无从谈起。明确流行病学研究的主战场在现场这一点至关重要。临床医师不去门诊、病房和手术室就会无所事事 ,流行病学医师不深入现场也会一事无成。现场是疾病和卫生事件实际发生的地方 ,是一切病因线索的来源。不深入现场或不认真调查研究 ,就不能获得充分、准确的信息 ,也很难提出符合实际情况的疾病控制对策和措…     

Outbreak of cholera in Ibadan, Nigeria

The changing epidemiology of cholera in Ibadan, Nigeria, has become a public health challenge, and outbreaks of the disease have been occurring with increasing frequency since the first outbreak in modern times in 1970. In this outbreak, 1384 persons were seen, diagnosed and treated for the disease at the cholera unit, Ibadan from January to December 1996. The outbreak lasted for a whole year. No child under one year was seen. The age adjusted case fatality rate was 5.3%. Diarrhoea and vomiting were the most common combination of symptoms present in 97.3% of all cases, followed by diarrhoea, vomiting and dehydration (84.3%). The median number of days spent on admission was only 2 days. Cholera cases were clustered within the densely populated and poorly planned areas of the city. Though significantly more cases were seen during the rainy season than during the dry season (p < 0.01), the deaths were not seasonally related (p = 0.67). Contamination of otherwise potable sources of water, late presentation to the cholera treatment unit and low levels of knowledge about diseases need to be addressed in order to effectively control this disease in the community. Progress should also be made towards developing a suitable vaccine for the control of this internationally important public health disease so that the responsibility of its control is not left entirely to individuals and communities, particularly in developing countries.     

Pioneers in infection control: John Snow, Henry Whitehead, the Broad Street pump, and the beginnings of geographical epidemiology

John Snow was one of the founders of epidemiology. Already convinced of the value of pure water, he analysed the distribution of cholera cases in the 1848 epidemic in relation to the purity of the water supply in London. His hypothesis that cholera was spread by contaminated water was tested by the 'Broad Street' epidemic of 1854. Snow quickly traced the water used in the houses affected by cholera to the pump in Broad Street, and persuaded the parish council to remove the handle. The epidemic subsided. The council did not really believe Snow, so the curate, Henry Whitehead, set out to repeat Snow's work, albeit at a more leisurely pace as the epidemic had subsided. He located 700 deaths within a 250-yard radius and showed that use of water from the Broad Street pump was strongly correlated with death from cholera. This surprised him as he had drunk water from the pump himself during the outbreak. Thus 'geographical epidemiology' began, although it was some years before Snow's observations were generally accepted.     

The coronavirus (COVID-19) pandemic's impact on mental health

Throughout the world, the public is being informed about the physical effects of SARS-CoV-2 infection and steps to take to prevent exposure to the coronavirus and manage symptoms of COVID-19 if they appear. However, the effects of this pandemic on one's mental health have not been studied at length and are still not known. As all efforts are focused on understanding the epidemiology, clinical features, transmission patterns, and management of the COVID-19 outbreak, there has been very little concern expressed over the effects on one's mental health and on strategies to prevent stigmatization. People's behavior may greatly affect the pandemic's dynamic by altering the severity, transmission, disease flow, and repercussions. The present situation requires raising awareness in public, which can be helpful to deal with this calamity. This perspective article provides a detailed overview of the effects of the COVID-19 outbreak on the mental health of people.     

Public perception of urban companion animals during the COVID-19 outbreak in China

This paper responds to the increasing concern regarding the role of non-human life in shaping urban space by exploring the public perception of urban companion animals during the coronavirus disease 2019 (COVID-19) outbreak in China. We argue that the public's perception of urban companion animals during emerging infectious disease outbreaks is related to medical and life science issues and reflects the political, economic, and emotional struggles involved in human-animal multispecies cohabitation. We find that the public has mainly followed and reconstructed medical discourses about the risk of companion animal-to-human transmission and discussed sustainable ethical animal practices in urban public health emergency management during the COVID-19 outbreak. Concerns regarding the risk of companion animal-related infection reflect the increasing prominence of more-than-human families, the pet industry, and multispecies leisure conflicts in public space in Chinese cities. The public's attention to animal ethics has prompted Chinese policy makers to adopt a more morally acceptable model for urban public health emergency management that can be sustained and supported by responsible non-governmental organizations and ethical urban residents.     

The Singapore Field Epidemiology Service: Insights Into Outbreak Management

Field epidemiology involves the implementation of quick and targeted public health interventions with the aid of epidemiological methods. In this article, we share our practical experiences in outbreak management and in safeguarding the population against novel diseases. Given that cities represent the financial nexuses of the global economy, global health security necessitates the safeguard of cities against epidemic diseases. Singapore''s public health landscape has undergone a systemic and irreversible shift with global connectivity, rapid urbanization, ecological change, increased affluence, as well as shifting demographic patterns over the past two decades. Concomitantly, the threat of epidemics, ranging from severe acute respiratory syndrome and influenza A (H1N1) to the resurgence of vector-borne diseases as well as the rise of modern lifestyle-related outbreaks, have worsened difficulties in safeguarding public health amidst much elusiveness and unpredictability. One critical factor that has helped the country overcome these innate and man-made public health vulnerabilities is the development of a resilient field epidemiology service, which includes our enhancement of surveillance and response capacities for outbreak management, and investment in public health leadership. We offer herein the Singapore story as a case study in meeting the challenges of disease control in our modern built environment.     

Appraising outbreak investigation skills in a public health emergency: an examination based on an actual event.

The purpose of this article is to provide a method of appraising skills in surveillance, assessment, and public health emergency investigation by using an examination based on an actual outbreak occurrence. This article presents an examination that uses a problem-based approach that works sequentially through the steps of an outbreak investigation to assess the investigation skills of individual students. Designed for graduate public heath students enrolled in a course in infectious disease epidemiology at East Carolina University, the examination can be used to appraise the outbreak investigation skills of medical students or practitioners.     

Outbreak investigations--a perspective.

Outbreak investigations, an important and challenging component of epidemiology and public health, can help identify the source of ongoing outbreaks and prevent additional cases. Even when an outbreak is over, a thorough epidemiologic and environmental investigation often can increase our knowledge of a given disease and prevent future outbreaks. Finally, outbreak investigations provide epidemiologic training and foster cooperation between the clinical and public health communities.     

John Snow, the broad street pump and modern epidemiology

John Snow was a genius in epidemiology. His achievement was to evolve an elegant, internally and externally consistent theory which concerned the mechanisms and processes involved in every aspect of the subject he had chosen to study. In order to do this he did not restrict himself to any method. He used all skills available to himself and his colleagues. He published his theory, and practical suggestions for the prevention of cholera arising out it, both internally in medical meetings and to the medical press, and to the public in the form of pamphlets and in reports addressed to the appropriate authority. This surely should be the objective of all epidemiological work.     

Cholera, canals, and contagion: Rediscovering Dr. Beck's report

Cholera first appeared in North America (in Montreal and Quebec) in 1832 and spread rapidly across the eastern half of the continent. The dispatch of American disease control experts to Lower Canada in anticipation of cholera's spread implies that medical professionals expected spread, possibly from contagion, even though the notion that cholera was contagious was disparaged in medical writings of the time, and would be until John Snow's landmark work in London in the 1850s. Snow's insights derived largely from his observations on spatial and temporal patterns of cholera cases. We discuss a document from the 1832 epidemic, the report of Dr. Lewis Beck to New York's Governor Throop, which anticipates Snow in presenting geospatial data that imply cholera's contagiousness. Beck shows that the movements of immigrants along the newly completed New York state canal system resulted in sequential cholera outbreaks along the canal's path. Although aware of the degree to which this suggested contagion, Beck argues strenuously against the contagiousness of cholera. We explore the social context of early nineteenth-century medicine that probably led Beck to disbelieve his own observations, and to favor a medical model inconsistent with his data. Themes that emerge from our inquiry include belief in disease as a physical manifestation of defective morality, stigmatization of the poor and immigrant groups, and reluctance to overturn prevailing medical models that themselves reflected the economic position of medical practitioners. We show that these themes continue to serve as obstacles to innovation in medical and public health practice today.     

Paradigms in epidemiology textbooks: in the footsteps of Thomas Kuhn.

This article attempts to contribute to the debate on the future of epidemiology by combining Thomas Kuhn's ideas on scientific paradigms with the author's observations on some epidemiology textbooks. The author's interpretations were based on his readings of Kuhn's The Structure of Scientific Revolutions, epidemiology textbooks, and papers on the future of epidemiology. Thomas Kuhn's view is that sciences mostly work with a single paradigm driven by exemplars of successful work, and that proposals for paradigm change are resisted. Sciences that are maturing or changing do not have a dominant paradigm. Epidemiology textbooks showed diversity in their concepts, content, and approach. Most exemplars related to etiologic research rather than public health practice. One key focus of the recent controversy regarding the role of epidemiology has been the increasing inability of epidemiology to solve socially based public health problems. Kuhn's views help explain the polarization of views expressed. Kuhn's philosophy of science offers insights into controversies such as whether a paradigm shift is needed or imminent and the gap between epidemiology and public health practice. Interaction between science philosophers, epidemiologists, and public health practitioners may be valuable.     

Networks and tuberculosis: an undetected community outbreak involving public places

After decades of decline in developed countries, there was a resurgence of tuberculosis in the mid-1980s accompanied by increased recognition that this infectious disease has long remained a major public health problem at the global level. New methods from molecular biology, in particular DNA 'fingerprinting' (of Mycobacterium tuberculosis), made it clear that current transmission and recent infection (in contrast to reactivation of earlier, latent infection) were much more significant than previously believed. Studies of tuberculosis outbreaks using these new tools pointed to complex networks through which infection was spreading and highlighted the need for new approaches to outbreak investigation and disease control. In the study reported here a new approach--combining methods from molecular biology, epidemiology and network analysis--was used to examine an outbreak of tuberculosis in Houston, Texas. Initial investigation using conventional strategies revealed few contacts among 37 patients with identical (six-band) DNA (IS6110-based) fingerprints but subsequent research uncovered over 40 places (including many gay bars) to which patients in this outbreak could be linked. Network methods were used to reconstruct an outbreak network and to quantify the relative importance (here, 'betweenness' centrality) of different actors (persons and places) playing a role in the outbreak. The multidisciplinary work provides the basis for a new approach to outbreak investigation and disease control.     

Short course training in epidemiology and biostatistics for graduate and undergraduate public health professionals.

The University of South Florida has developed short courses of 2 to 3 days in epidemiology and biostatistics geared to public health workers. A key focus is providing skills which will assist local and State public health units to assess their status and measure progress with respect to achieving their explicitly stated health objectives for the year 2000. The courses were developed after the identification of the training needs in health departments and other public health settings. The training objectives were (a) to enhance the biostatistics skills of professionals involved in the analysis of health data; (b) to reinforce basic knowledge of epidemiologic methods and its practical applications in public health settings, including measures of disease frequency and association, epidemic outbreak investigations, and the identification and use of surveillance data; and (c) to demonstrate the application of the risk factor approach to select the interventions needed to reach health objectives for year 2000 and how to evaluate such interventions. A total of 43 students have taken this course series. Professional staff in health departments cannot always enroll in formal training in epidemiology and biostatistics because of time limitations or a lack of a bachelor''s degree. However, the need exists. An alternative to such training could be the short course program described in this paper.