Expanding disease ecology even more: One Health, politics and place. Response to commentaries on Michael Emch and Varun Goel’s ‘Disease ecology in health and medical geography: History, progress, and innovations’

Our paper describes the development of the disease ecology tradition of health and medical geography including some key themes and a few recent innovations. The four commentaries by a distinguished set of scholars add more background to this tradition and offer many useful opinions about productive areas of inquiry that this tradition has and should focus on. Our paper does not provide history, themes and areas of innovation to the entire subdiscipline of health and medical geography but is specifically devoted to disease ecology; and because of our expertise, it focuses mainly on infectious disease ecology. This tradition started with studies of infectious disease ecology almost a century ago, but the breadth of the field has expanded substantially in both infectious and non-communicable disease research as well as health and healthcare. We focus on disease ecology and not health, although one could argue that these cannot be separated. One of us (Michael Emch) writes this while on sabbatical studying infectious diseases at the Faculty of Public Health at Mahidol University in Bangkok, Thailand just six kilometres from the hospital where Jacques May began his explorations in disease ecology in 1932. As Mayer points out in his commentary, ‘his basic concepts added much at the time’ but ‘research has far transcended May and it was – and continues to be – important to progress beyond the past intellectual history of the field’ (Mayer, 2025). This paper and these fine commentaries attempt to bring this scholarly tradition forward. In his commentary, Mayer asks whether the field of health and medical geography should extend beyond the discipline of geography. He advocates for a more inclusive approach to which we wholeheartedly agree. John Hunter championed this inclusive approach in the 1960s and 1970s as the field of medical geography and the tradition of disease ecology within the subdiscipline developed in the United States (US). He believed that the integrative perspective of geography and all the questions and methodologies of geography's various traditions are useful for studying health and disease (Hunter, 1974). Even though our brief review of the disease ecology literature mostly focuses on the work of geographers, our field cannot be separated from cognate disciplines that focus on health. Disciplinary lines are always arbitrary, and debates about the delineation of our discipline and subdiscipline will continue as they have with these commentaries. One of the strengths of geography is that it fosters interdisciplinary and inter-subdisciplinary scholarship. As Mayer states, our subdiscipline is ‘firmly within the health and public health sciences’, which is why many health and medical geographers hold faculty appointments in health sciences. Mayer suggests that our subdiscipline is particularly well-suited to conduct studies that fall into the interdisciplinary fields of One Health and EcoHealth. Oppong and Messenger's commentary also mentions One Health and EcoHealth as areas of growth for geographic disease ecology, as well as the new interdisciplinary field of Planetary Health (Oppong & Messenger, 2025). We agree; and given how complementary these fields are to the disease ecology tradition of health and medical geography, we have actively undertaken research and collaborations that span across these interdisciplinary fields. For example, although we framed our swine influenza case study as a landscape genetics disease ecology study in our paper, one of the study's major goals, as framed to the US National Science Foundation (NSF) is to help build and expand One Health theory. Mayer highlights that while fields such as One Health have created new avenues of research in the health sciences, factors such as the role of social structure, human behaviour, culture and political and economic power are often ignored. In our previous study on H5N1 avian influenza in Vietnam, our current swine flu study and our new study on H5N1 in the US, we examine those factors by collaborating with an interdisciplinary team of veterinarians, virologists and computational biologists. We echo Mayer's call for more involvement in these fields, and our own experience suggests that health and medical geographers can uniquely leverage their holistic interdisciplinary lens to contribute to theoretical and methodological advancements in these fields. In her commentary, McLafferty states that place and politics should have a more prominent role in contemporary disease ecology studies and adds that most quantitative and empirical disease ecology studies often do not acknowledge political ecology of health and disease literature that relies strongly on qualitative and critical approaches (McLafferty, 2025). As Hunter wrote so many decades ago, all approaches are needed to fully understand the geographies of health and disease. McLafferty gives a contemporary example of how politics can influence health as new leaders in the US are presently changing health policy, restricting access to public health data (e.g., Demographic and Health Surveys), and cutting funding for research and programmes. Policy shifts and funding cuts have been dramatic as we write this in 2025 and have affected populations in the US and globally such as a 20 per cent US cut to future federal government allocations to the Supplemental Nutrition Assistance Program which provides monthly funding to low-income households for groceries. Another example is the abrupt 90-day pause of funding on 25 January 2025, for the President's Emergency Plan for AIDS Relief (PEPFAR), which provides services for more than 20 million people worldwide. While the funding was eventually restored in July 2025, the disruption has already led to an estimated 118 960 adult and 12 663 child deaths as of October 2025 (Nichols et al., 2025; PEPFAR Program Impact Tracker, 2025). McLaffterty's point that politics and economics are essential to understanding disease ecologies is painfully obvious as we write this. You cannot understand the ecology of HIV-AIDS at present without considering these funding and programme cuts in the ecology of this disease. Funding cuts to research programmes on diseases will also influence the ecology of diseases. McLafferty emphasizes that this present political climate is a stark reminder of the embeddedness or our work within social and political systems. Our research is rooted in these systems just as disease ecologists in Nazi Germany were embedded in the state goals of empire-building and German racialized nationalism. Our paper mentioned ‘environmental justice’ as an area of innovation and expansion for disease ecology studies that focus on political and economic factors that comprise the underlying structural determinants of health and disease and unequal distributions of environmental burdens. An NSF Directive on 18 April 2025 led to the termination of hundreds of awards that had already been funded that are ‘not aligned with program goals or agency priorities’ including research grants that are focused on ‘environmental justice’ (NSF Directive, 2025). Additionally, the US Environmental Protection Agency Environmental Justice Office was recently shut down and many grants to communities aimed to mitigate unequal distributions of environmental burdens have been cut. As these large-scale cuts and changing political climate shape data reliability, access and availability, we echo McLafferty's call for disease ecologists to apply critical lenses to studying health outcomes. We can also use contemporary approaches such as big data and associated methods to substitute or complement previously available data. Oppong and Messenger mention more historical literature on early disease mapping endeavours that we did not include in the review that are an important part of the history of the disease ecology tradition. They also argue that the disease ecology tradition should describe how environment constrains human behaviours and determines relationships between composition and context, something that Melinda Meade discussed in her seminal paper on human ecology. This theoretical area is also part of the interdisciplinary neighbourhoods and health tradition, which many health and medical geographers have contributed and is described elsewhere (e.g., Emch, Root & Carrel, 2017). Oppong and Messenger also critique existing disease ecology studies, including our Bangladesh case study, and describe challenges with obtaining individual-level data, incorporating structural and political processes, and explaining complex overlapping causes. However, we believe that many of these obstacles can be overcome when geographers engage in interdisciplinary collaborations with other health-related disciplines. Our Bangladesh study – which is part of a long-standing collaboration – is a case in point. By supporting and working with a large network of community health workers and leveraging an existing health and demographic surveillance system, we utilize an existing infrastructure to collect rich individual-level data. Additionally, although spatial Bayesian models, as used in our case study, cannot explain all underlying structural, political and economic factors driving the effectiveness of the intervention, they can be used as a starting point to further investigate where intervention effectiveness may potentially be limited by those structural, political and economic factors. In fact, as more sophisticated quantitative models and rich individual and ecological data sources become available, health and medical geographers are uniquely positioned to leverage their diverse theoretical and methodological expertise and build interdisciplinary teams to address limitations such as incorporating place dynamics and politics as mentioned by both McLafferty, and Oppong and Messenger. Additionally, as echoed by Oppong and Messenger, disease ecologies are complex and cannot be fully explained by linear, causal narratives. To explain the complex causal linkages between several factors and effectiveness of arsenic mitigation interventions, it would be impossible to include every variable related to the effectiveness of the intervention. Hence, our approach has been to incrementally understand the full story of the ecology of the drinking water and the groundwater arsenic problem in Bangladesh through multiple analyses over many years with teams of epidemiologists, environmental microbiologists, geologists and economists, including the narrow example we offer as part of our review paper (e.g., Emch, 1999; Escamilla et al., 2013, Goel et al., 2019, 2023, 2025; Wu et al., 2016). In Paul's commentary, (he has also studied the groundwater arsenic problem in Bangladesh – e.g., Paul & De, 2000; Paul, 2004) he nicely describes more details about the context of this problem in rural Bangladesh and highlights some of our case study findings, namely that deep tubewells are associated with lower diarrheal disease incidence and that the odds vary over space (Paul, 2025). Oppong and Messenger offer another critique of the approach of using landscape genetics to understand geographic drivers of the evolution of pathogens and question whether this approach ‘could help prevent or help limit its spread particularly given the long complex relationship of humans and viruses.’ Very few studies investigate how non-individual level contextual variables such as farming practices or environmental context are involved with evolution and transmission of influenza viruses. This methodological approach is just one that geographers use to conduct disease ecology studies; there are many others that geographic disease ecologists can use. The common theme of all the commentaries is that there are many theoretical and methodological approaches that the tradition of disease ecology—and health and medical geography in general—should include. We concur that a wide range of geographic theories and approaches should be embraced, as well as engagements with interdisciplinary fields such as One Health and collaborations with scholars in other disciplines who also contribute to the larger field of public health.