The historical epidemiology of global disease challenges

Abstract

In response to the spread of Ebola virus disease in west Africa, global public health agencies have scrambled to organise teams to staunch the spiral of infections and have urged researchers in medical anthropology, disaster management, ethics, and other social science fields to formulate ideas for intervention as quickly as possible. The epidemic is by far the worst of the Ebola outbreaks on record that date back to 1976. Yet, it is only one of several deadly viral pathogens—such as yellow fever, dengue, and influenza—that have repeatedly scourged populations in west Africa. How do the past and present Ebola outbreaks compare with other viral epidemics? What efforts were made to contain previous outbreaks and how did these efforts fare? How did local populations respond to and interpret these interventions? How did they understand the causes of the outbreaks?We do not have robust answers to all these questions. In part, this is because the subject area of historical epidemiology—on the cusp of the fields of the history of medicine and epidemiology—has been claimed by neither of these disciplines. Historians of medicine and public health have mostly paid scant attention to the historical study of viral disease control efforts and their epidemiological consequences. Most medical historians tend to focus their research efforts on the social history of disease in developed nations. Epidemiologists are deeply involved in the analysis of viral outbreaks, focusing principally on dynamic modelling. The twain rarely meet. One consequence is that physicians and public health specialists do not usually draw lessons from the historical record of disease control efforts. This can sometimes result in poor policy decisions.The lack of integration of current health policy with the epidemiological past is not restricted to viral epidemics. Consider the case of malaria. In 2007, global health donors rushed to commit to a programme for the eradication of malaria. This commitment was not based upon an assessment of past experiences with malaria control and eradication. As a result, some experiences were repeated. Global donors deployed dichlorodiphenyltrichloroethane and other synthetic insecticides during the 21st century in west African regions where a similar array of insecticides had been deployed during the mid-20th century WHO-led Malaria Eradication Program. The synthetic insecticides once again produced resistance in the Anopheles mosquito vectors. The USA was the major funder for the Malaria Eradication Program, and after it reduced its contributions in the mid-1960s, the global campaign sputtered to a halt. A similarly eerie echo of the past is found in the financial vicissitudes that beset the contemporary global malaria campaign. The financial commitments pledged early in the 21st century are faltering largely because of the ongoing global economic recession that began in 2008. In the mid-20th century, the Malaria Eradication Program substantially reduced malaria mortality and morbidity, but in some areas, after the commitment to malaria control and eradication waned, malaria rebounded savagely. Echoing this experience, in the 21st century large successes have again been achieved in reducing the burden of malaria. But with declining resources, and without the creation of dedicated malaria control services in tropical Africa, it is possible that the experience of the vicious rebound of malaria, too, might be repeated in some places.These potential risks can be made visible through the prism of historical epidemiology. Historical epidemiology is the study of the impacts of efforts to control disease over time and the ways in which interventions have transformed patterns of disease and influenced disease transmission. It integrates ecological, social, economic, and political processes with pathogenic processes, human responses, and the effects of global health interventions. The historical epidemiology of contemporary disease challenges, a newly emerging field, is fundamentally multidisciplinary in approach, drawing on social science and biomedical knowledge to explore the historical records of disease control. Its remit is concerned with change over time and with the contexts in which diseases emerge. Historical epidemiology has the promise of developing as a fundamental resource for global public health.This subject area is at present largely missing from the curricula of schools of public health. Most schools do not have historians of medicine on staff and do not teach the history of public health interventions. Indeed, even in many of the leading schools that specialise in global health and tropical medicine there are few, if any, historians of tropical medicine or global public health, and few, if any, resources devoted to the historical epidemiology of global disease challenges. A central reason is that historical epidemiology is uncomfortably multidisciplinary in methods and approach. The disciplinary biases of many graduate programmes discourage multidisciplinary training. Few epidemiologists have trained in the historical sciences and few historians of medicine in epidemiology.To illustrate the logic of historical approaches to disease control, an analogy from the field of foreign policy is apt. There is no doubt that the quantitative modelling of political negotiations and interstate warfare is of considerable value. Yet it would be nearly unimaginable for foreign policy initiatives to be undertaken without historical contextualisation or knowledge of the local cultural context. Foreign policy analysts, irrespective of their political perspectives, would agree that our understandings of the current crisis in Ukraine must be framed in the historical contexts of Russian empire, Soviet expansionism, and post-Soviet revanchism. By contrast, the global public health community operates largely in an ahistorical mode, taking cues from evidence-based practices and mathematical models that use data removed from social contexts that are held to be universally applicable. The models generally assume that interventions can be rolled out without regard to cultural context and historical experience.How to remedy this situation? There are two prime orders of business. The first is within the academy. It is time to encourage historians of medicine to undertake research that has a direct bearing on contemporary disease challenges and epidemiologists and global public health specialists to open their departmental doors to medical historians and medical anthropologists to facilitate multidisciplinarity. It is well past time to move beyond triumphalist historical narratives of global public health. The eradication of smallpox is rightly celebrated in the global public health community, and for some global health donors it remains the gold standard of intervention. Yet smallpox eradication, important and laudable, has deflected attention from the empirical knowledge that can be gleaned from partially successful or failed interventions and used to inform future interventions. This is particularly true with regard to lethal viruses. We know little, for example, about the long history of yellow fever outbreaks and interventions in tropical Africa, and yet it seems likely that the historical epidemiology of yellow fever, a mosquito-borne viral haemorrhagic disease, could yield insights that would be useful to inform efforts to control other haemorrhagic fevers across the subcontinent.The second order of business is to encourage transparency among global health donors and to improve the historical conservation of global health intervention data. The global health community—and the individual states with responsibilities for their populations' public health—need to collect and preserve records of what has happened in the course of contemporary control programmes. This must necessarily involve records of failures, problems, obstacles, and glitches. This is made difficult by the donor culture of programme evaluation that pays scant regard to social, political, and cultural dimensions of interventions and by the exclusive valorisation of positive data for publication. It is time to appreciate that there is a great deal to be learned from partial success and failure that can improve future interventions.The emerging field of the historical epidemiology of contemporary disease challenges has the potential to integrate a number of disparate fields of knowledge. It will depend upon the conservation and accessibility of the records of public health interventions—including the grey literature of public health services, global health donors, and non-governmental health organisations. WHO, for example, has an extensive archive that a new generation of historians is beginning to consult. The Bill & Melinda Gates Foundation, one of the most important of global health actors, has made a commitment to archiving materials of historical importance. Other institutions engaged in global public health work would do well to follow suit. It would be short-sighted to neglect the long and informative record of the past in the belief that new approaches and technologies will necessarily prove determinative in the future. Ignorance of the epidemiological past precludes its lessons from being learned and thereby constitutes a public health risk. In response to the spread of Ebola virus disease in west Africa, global public health agencies have scrambled to organise teams to staunch the spiral of infections and have urged researchers in medical anthropology, disaster management, ethics, and other social science fields to formulate ideas for intervention as quickly as possible. The epidemic is by far the worst of the Ebola outbreaks on record that date back to 1976. Yet, it is only one of several deadly viral pathogens—such as yellow fever, dengue, and influenza—that have repeatedly scourged populations in west Africa. How do the past and present Ebola outbreaks compare with other viral epidemics? What efforts were made to contain previous outbreaks and how did these efforts fare? How did local populations respond to and interpret these interventions? How did they understand the causes of the outbreaks? We do not have robust answers to all these questions. In part, this is because the subject area of historical epidemiology—on the cusp of the fields of the history of medicine and epidemiology—has been claimed by neither of these disciplines. Historians of medicine and public health have mostly paid scant attention to the historical study of viral disease control efforts and their epidemiological consequences. Most medical historians tend to focus their research efforts on the social history of disease in developed nations. Epidemiologists are deeply involved in the analysis of viral outbreaks, focusing principally on dynamic modelling. The twain rarely meet. One consequence is that physicians and public health specialists do not usually draw lessons from the historical record of disease control efforts. This can sometimes result in poor policy decisions. The lack of integration of current health policy with the epidemiological past is not restricted to viral epidemics. Consider the case of malaria. In 2007, global health donors rushed to commit to a programme for the eradication of malaria. This commitment was not based upon an assessment of past experiences with malaria control and eradication. As a result, some experiences were repeated. Global donors deployed dichlorodiphenyltrichloroethane and other synthetic insecticides during the 21st century in west African regions where a similar array of insecticides had been deployed during the mid-20th century WHO-led Malaria Eradication Program. The synthetic insecticides once again produced resistance in the Anopheles mosquito vectors. The USA was the major funder for the Malaria Eradication Program, and after it reduced its contributions in the mid-1960s, the global campaign sputtered to a halt. A similarly eerie echo of the past is found in the financial vicissitudes that beset the contemporary global malaria campaign. The financial commitments pledged early in the 21st century are faltering largely because of the ongoing global economic recession that began in 2008. In the mid-20th century, the Malaria Eradication Program substantially reduced malaria mortality and morbidity, but in some areas, after the commitment to malaria control and eradication waned, malaria rebounded savagely. Echoing this experience, in the 21st century large successes have again been achieved in reducing the burden of malaria. But with declining resources, and without the creation of dedicated malaria control services in tropical Africa, it is possible that the experience of the vicious rebound of malaria, too, might be repeated in some places. These potential risks can be made visible through the prism of historical epidemiology. Historical epidemiology is the study of the impacts of efforts to control disease over time and the ways in which interventions have transformed patterns of disease and influenced disease transmission. It integrates ecological, social, economic, and political processes with pathogenic processes, human responses, and the effects of global health interventions. The historical epidemiology of contemporary disease challenges, a newly emerging field, is fundamentally multidisciplinary in approach, drawing on social science and biomedical knowledge to explore the historical records of disease control. Its remit is concerned with change over time and with the contexts in which diseases emerge. Historical epidemiology has the promise of developing as a fundamental resource for global public health. This subject area is at present largely missing from the curricula of schools of public health. Most schools do not have historians of medicine on staff and do not teach the history of public health interventions. Indeed, even in many of the leading schools that specialise in global health and tropical medicine there are few, if any, historians of tropical medicine or global public health, and few, if any, resources devoted to the historical epidemiology of global disease challenges. A central reason is that historical epidemiology is uncomfortably multidisciplinary in methods and approach. The disciplinary biases of many graduate programmes discourage multidisciplinary training. Few epidemiologists have trained in the historical sciences and few historians of medicine in epidemiology. To illustrate the logic of historical approaches to disease control, an analogy from the field of foreign policy is apt. There is no doubt that the quantitative modelling of political negotiations and interstate warfare is of considerable value. Yet it would be nearly unimaginable for foreign policy initiatives to be undertaken without historical contextualisation or knowledge of the local cultural context. Foreign policy analysts, irrespective of their political perspectives, would agree that our understandings of the current crisis in Ukraine must be framed in the historical contexts of Russian empire, Soviet expansionism, and post-Soviet revanchism. By contrast, the global public health community operates largely in an ahistorical mode, taking cues from evidence-based practices and mathematical models that use data removed from social contexts that are held to be universally applicable. The models generally assume that interventions can be rolled out without regard to cultural context and historical experience. How to remedy this situation? There are two prime orders of business. The first is within the academy. It is time to encourage historians of medicine to undertake research that has a direct bearing on contemporary disease challenges and epidemiologists and global public health specialists to open their departmental doors to medical historians and medical anthropologists to facilitate multidisciplinarity. It is well past time to move beyond triumphalist historical narratives of global public health. The eradication of smallpox is rightly celebrated in the global public health community, and for some global health donors it remains the gold standard of intervention. Yet smallpox eradication, important and laudable, has deflected attention from the empirical knowledge that can be gleaned from partially successful or failed interventions and used to inform future interventions. This is particularly true with regard to lethal viruses. We know little, for example, about the long history of yellow fever outbreaks and interventions in tropical Africa, and yet it seems likely that the historical epidemiology of yellow fever, a mosquito-borne viral haemorrhagic disease, could yield insights that would be useful to inform efforts to control other haemorrhagic fevers across the subcontinent. The second order of business is to encourage transparency among global health donors and to improve the historical conservation of global health intervention data. The global health community—and the individual states with responsibilities for their populations' public health—need to collect and preserve records of what has happened in the course of contemporary control programmes. This must necessarily involve records of failures, problems, obstacles, and glitches. This is made difficult by the donor culture of programme evaluation that pays scant regard to social, political, and cultural dimensions of interventions and by the exclusive valorisation of positive data for publication. It is time to appreciate that there is a great deal to be learned from partial success and failure that can improve future interventions. The emerging field of the historical epidemiology of contemporary disease challenges has the potential to integrate a number of disparate fields of knowledge. It will depend upon the conservation and accessibility of the records of public health interventions—including the grey literature of public health services, global health donors, and non-governmental health organisations. WHO, for example, has an extensive archive that a new generation of historians is beginning to consult. The Bill & Melinda Gates Foundation, one of the most important of global health actors, has made a commitment to archiving materials of historical importance. Other institutions engaged in global public health work would do well to follow suit. It would be short-sighted to neglect the long and informative record of the past in the belief that new approaches and technologies will necessarily prove determinative in the future. Ignorance of the epidemiological past precludes its lessons from being learned and thereby constitutes a public health risk.