Introduction: microbes, networks, knowledge-disease ecology and emerging infectious diseases in time of COVID-19.

This is an introduction to the topical collection Microbes, Networks, Knowledge: Disease Ecology in the twentieth Century, based on a workshop held at Queen Mary, University London on July 6-7 2016. More than twenty years ago, historian of science and medicine Andrew Mendelsohn asked, "Where did the modern, ecological understanding of epidemic disease come from?" Moving beyond Mendelsohn's answer, this collection of new essays considers the global history of disease ecology in the past century and shows how epidemics and pandemics have made "microbes complex".

'Tipping the Balance': Karl Friedrich Meyer, Latent Infections, and the Birth of Modern Ideas of Disease Ecology.

The Swiss-born medical researcher Karl Friedrich Meyer (1884-1974) is best known as a 'microbe hunter' who pioneered investigations into diseases at the intersection of animal and human health in California in the 1920s and 1930s. In particular, historians have singled out Meyer's 1931 Ludwig Hektoen Lecture in which he described the animal kingdom as a 'reservoir of disease' as a forerunner of 'one medicine' approaches to emerging zoonoses. In so doing, however, historians risk overlooking Meyer's other intellectual contributions. Developed in a series of papers from the mid-1930s onwards, these were ordered around the concept of latent infections and sought to link microbial behavior to broader bio-ecological, environmental, and social factors that impact hostpathogen interactions. In this respect Meyer-like the comparative pathologist Theobald Smith and the immunologist Frank Macfarlane Burnet-can be seen as a pioneer of modern ideas of disease ecology. However, while Burnet's and Smith's contributions to this scientific field have been widely acknowledged, Meyer's have been largely ignored. Drawing on Meyer's published writings and private correspondence, this paper aims to correct that lacuna while contributing to a reorientation of the historiography of bacteriological epidemiology. In particular I trace Meyer's intellectual exchanges with Smith, Burnet and the animal ecologist Charles Elton, over brucellosis, psittacosis and plague-exchanges that not only showed how environmental and ecological conditions could 'tip the balance' in favor of parasites but which transformed Meyer thinking about resistance to infection and disease.

Imagining pandemics now, and then: a century of medical failure.

Ever since the devastating 1918-1919 influenza pandemic, policy makers have employed mathematical models to predict the course of epidemics and pandemics in an effort to mitigate their worst impacts. But while Britain has long been a pioneer of predictive epidemiology and disease modellers occupied influential positions on key committees that advised the government on its response to the coronavirus pandemic, as in 1918 Britain mounted one of the least effective responses to Covid-19 of any country in the world. Arguing that this 'failure of expertise' was the result of medical and political complacency and over-reliance on disease models predicated on influenza, this paper uses the lens of medical history to show how medical attitudes to Covid-19 mirrored those of the English medical profession in 1918. Rather than putting our faith in preventive medicine and statistical technologies to predict the course of epidemics and dictate suppressive measures in future, I argue we need to cultivate more profound forms of imaginative engagement with infectious disease outbreaks that take account of the long history of quarantines and the lived experiences of pandemics. A useful starting point would be to recognize that while measures such as the R° may be useful for calculating the reproductive rate of a virus, they can never capture the full risks of pandemics or their social complexity.

René Dubos, tuberculosis, and the "ecological facets of virulence".

Reflecting on his scientific career toward the end of his life, the French-educated medical researcher René Dubos presented his flowering as an ecological thinker as a story of linear progression-the inevitable product of the intellectual seeds planted in his youth. But how much store should we set by Dubos's account of his ecological journey? Resisting retrospective biographical readings, this paper seeks to relate the development of Dubos's ecological ideas to his experimental practices and his career as a laboratory researcher. In particular, I focus on Dubos's studies of tuberculosis at the Rockefeller Institute in the period 1944-1956-studies which began with an inquiry into the tubercle bacillus and the physiochemical determinants of virulence, but which soon encompassed a wider investigation of the influence of environmental forces and host-parasite interactions on susceptibility and resistance to infection in animal models. At the same time, through a close reading of Dubos's scientific papers and correspondence, I show how he both drew on and distinguished his ecological ideas from those of other medical researchers such as Theobald Smith, Frank Macfarlane Burnet, and Frank Fenner. However, whereas Burnet and Fenner tended to view ecological interactions at the level of populations, Dubos focused on the interface of hosts and parasites in the physiological environments of individuals. The result was that although Dubos never fully engaged with the science of ecology, he was able to incorporate ecological ideas into his thought and practices, and relate them to his holistic views on health and the natural harmony of man and his environment.

Between Securitisation and Neglect: Managing Ebola at the Borders of Global Health.

In 2014 the World Health Organization (WHO) was widely criticised for failing to anticipate that an outbreak of Ebola in a remote forested region of south-eastern Guinea would trigger a public health emergency of international concern (pheic). In explaining the WHO's failure, critics have pointed to structural restraints on the United Nations organisation and a leadership 'vacuum' in Geneva, among other factors. This paper takes a different approach. Drawing on internal WHO documents and interviews with key actors in the epidemic response, I argue that the WHO's failure is better understood as a consequence of Ebola's shifting medical identity and of triage systems for managing emerging infectious disease (EID) risks. Focusing on the discursive and non-discursive practices that produced Ebola as a 'problem' for global health security, I argue that by 2014 Ebola was no longer regarded as a paradigmatic EID and potential biothreat so much as a neglected tropical disease. The result was to relegate Ebola to the fringes of biosecurity concerns just at the moment when the virus was crossing international borders in West Africa and triggering large urban outbreaks for the first time. Ebola's fluctuating medical identity also helps explain the prominence of fear and rumours during the epidemic and social resistance to Ebola control measures. Contrasting the WHO's delay over declaring a pheic in 2014, with its rapid declaration of pheics in relation to H1N1 swine flu in 2009 and polio in 2014, I conclude that such 'missed alarms' may be an inescapable consequence of pandemic preparedness systems that seek to rationalise responses to the emergence of new diseases.

Regulating the 1918-19 pandemic: flu, stoicism and the Northcliffe press.

Social historians have argued that the reason the 1918­19 'Spanish' influenza left so few traces in public memory is that it was 'overshadowed' by the First World War, hence its historiographical characterisation as the 'forgotten' pandemic. This paper argues that such an approach tends to overlook the crucial role played by wartime propaganda. Instead, I put emotion words, emotives and metaphors at the heart of my analysis in an attempt to understand the interplay between propaganda and biopolitical discourses that aimed to regulate civilian responses to the pandemic. Drawing on the letters of Wilfred Owen, the diaries of the cultural historian Caroline Playne and the reporting in the Northcliffe press, I argue that the stoicism exhibited by Owen and amplified in the columns of The Times and the Daily Mail is best viewed as a performance, an emotional style that reflected the politicisation of 'dread' in war as an emotion with the potential to undermine civilian morale. This was especially the case during the final year of the conflict when war-weariness set in, leading to the stricter policing of negative emotions. As a protean disease that could present as alternately benign and plague-like, the Spanish flu both drew on these discourses and subverted them, disrupting medical efforts to use the dread of foreign pathogens as an instrument of biopower. The result was that, as dread increasingly became attached to influenza, it destabilised medical attempts to regulate the civilian response to the pandemic, undermining Owen's and the Northcliffe press's emotives of stoicism.