Is the Social–Ecological Framework Useful in Understanding Infectious Diseases? The Case of HIV/AIDS

The extraordinary complexity of emerging infectious diseases calls for new paradigms and approaches to understand the casual mechanisms underlying pathogen emergence and to improve disease prevention. An attempt was made to foster interdisciplinary collaboration and stimulate transdisciplinary approaches to improve emerging infectious disease research during and subsequent to a meeting held in March 2005 as part of the US NIH Roadmap initiative “Research Teams of the Future.” The meeting drew on models and theories associated with the idea of humans and nature as interactive, complex systems. Of the three diseases chosen as case studies to represent the wide range of social and ecological emergence factors involved (dengue, leptospirosis, and HIV/AIDS), HIV/AIDS proved especially difficult. This Profile examines the meeting themes with a particular focus on the deliberations of a working group focused on HIV/AIDS. Attention is given to the challenges of bridging different disciplines and perspectives in applying a social-ecological framework to analyze HIV/AIDS and the benefits of reductionistic vs. holistic strategies in responding to the global HIV/AIDS pandemic. The issues raised point to opportunities to significantly deepen understanding of HIV/AIDS as a transdisciplinary problem. Disclaimer: The author is Director of the Research Program at the East–West Center and was chair of the HIV/AIDS mini-symposium. This Profile is based on the important contributions and efforts of all the members of the HIV/AIDS working group. All omissions or misrepresentations are the author’s.     

Emerging and Reemerging Infectious Diseases: Biocomplexity as an Interdisciplinary Paradigm

Understanding factors responsible for reemergence of diseases believed to have been controlled and outbreaks of previously unknown infectious diseases is one of the most difficult scientific problems facing society today. Significant knowledge gaps exist for even the most studied emerging infectious diseases. Coupled with failures in the response to the resurgence of infectious diseases, this lack of information is embedded in a simplistic view of pathogens and disconnected from a social and ecological context, and assumes a linear response of pathogens to environmental change. In fact, the natural reservoirs and transmission rates of most emerging infectious diseases primarily are affected by environmental factors, such as seasonality or meteorological events, typically producing nonlinear responses that are inherently unpredictable. A more realistic view of emerging infectious diseases requires a holistic perspective that incorporates social as well as physical, chemical, and biological dimensions of our planet’s systems. The notion of biocomplexity captures this depth and richness, and most importantly, the interactions of human and natural systems. This article provides a brief review and a synthesis of interdisciplinary approaches and insights employing the biocomplexity paradigm and offers a social–ecological approach for addressing and garnering an improved understanding of emerging infectious diseases. Drawing on findings from studies of cholera and other examples of emerging waterborne, zoonotic, and vectorborne diseases, a “blueprint” for the proposed interdisciplinary research framework is offered which integrates biological processes from the molecular level to that of communities and regional systems, incorporating public health infrastructure and climate aspects.     

Beyond Disciplinary Boundaries: Leptospirosis as a Model of Incorporating Transdisciplinary Approaches to Understand Infectious Disease Emergence

Leptospirosis is a zoonotic infectious disease of global significance. Political, economic, demographic, ecologic, and other anthropogenically driven environmental changes have fueled the reemergence of this disease in industrialized and developing countries, and in both urban and rural settings. We argue that conventional disciplinary, even interdisciplinary, research methods are not sufficient to elucidate the complex mechanisms and causal relationships among the myriad factors responsible for infectious disease emergence. To address the significant gaps in the field of leptospirosis, an integrated research agenda is needed to guide successful public health remediation of the disease. Based on both working group analysis of literature and newly obtained information, we describe cross-disciplinary collaborative approaches that allow a novel approach to understand leptospirosis emergence with regard to mountain-to-sea ecosystems in Hawai‘i and other region-specific ecosystems. Leptospirosis research is a model for how complementary disciplines in the social, cultural, ecological, and biomedical sciences can optimally interact towards a higher understanding of emerging infectious diseases.     

Development of Transdisciplinarity Among Students Placed with a Sustainability for Health Research Project

Transdisciplinary education on sustainability for health has been primarily developed in high-income countries, yet the need in countries with limited research and human resource investments remains urgent. Little empiric documentation of the facilitators and barriers to transdisciplinary learning in such countries has been described. We assessed transdisciplinary learning among students of different disciplines collaborating with an Ecuadorian sustainability for health research project. Six undergraduate students from four different disciplinary backgrounds were incorporated through work–study agreements with provincial university academic supervisors. Learning was fostered and monitored through participant observations by a field supervisor. Students’ learning was evaluated through subsequent in-depth interviews and visualization methods. Academic supervisor key informant and co-investigator observations aided triangulation. Qualitative data were analyzed using indicators of transdisciplinary thinking. Principal factors facilitating transdisciplinary learning were interaction with social actors, the integration of work with other disciplines, the use of alternative research techniques and methods, and the constant support of the field supervisor. Inhibiting factors included the existence of rigid academic rules, lack of training of the academic supervisors in diverse research methods, and social pressures to implement unidisciplinary foci. At the end of their link with the project, students had developed both cognitive outcomes and attitudinal values relevant to sustainable development for health. In countries with limited investments in research and human resources development, transdisciplinary approaches with social actors and engaged researchers can sensitize new professionals training in traditional academic contexts to the ecological–social–health problems faced by poor majorities and encourage their subsequent work on sustainability for human health.     

Chinese Social Media Reaction to Information about 42 Notifiable Infectious Diseases

This study aimed to identify what information triggered social media users’ responses regarding infectious diseases. Chinese microblogs in 2012 regarding 42 infectious diseases were obtained through a keyword search in the Weiboscope database. Qualitative content analysis was performed for the posts pertinent to each keyword of the day of the year with the highest daily count. Similar posts were grouped and coded. We identified five categories of information that increased microblog traffic pertaining to infectious diseases: news of an outbreak or a case; health education / information; alternative health information / Traditional Chinese Medicine; commercial advertisement / entertainment; and social issues. News unrelated to the specified infectious diseases also led to elevated microblog traffic. Our study showcases the diverse contexts from which increased social media traffic occur. Our results will facilitate better health communication as causes underlying increased social media traffic are revealed.     

A Model for Defining West Nile Virus Risk Perception Based on Ecology and Proximity

West Nile virus (WNV) has made considerable impact as an emerging infectious disease, spreading from coast to coast across North America since 1999. The disease has exhibited great spatial variability in North America, making an ecosystems approach to understanding the local human and vector ecology critical to prevention and control. This study underscores the importance of employing both personal prevention and community participatory approaches to create messages that have been adapted to the local ecology and are designed to reduce the risk of human infection with this mosquito-borne virus. As the virus spreads into new areas, underlying attitudes toward mosquitoes and the local perception of environment/ecology can affect the success of control and prevention measures. This work presents results from focus group discussions conducted in two Colorado counties in 2003, a year of significant WNV activity in the state. Issues addressed include residents’ assessment of risk and how this perception varied by age group and location, use or nonuse of repellents, and community attitudes toward mosquito control in areas with different ecologies and histories of mosquito-borne disease. The need to address individual components of personal prevention, to target prevention to specific audiences, and to disseminate prevention messages through local channels is discussed. The authors propose including aspects of ecology and disease proximity in understanding risk perception and addressing emerging diseases with a prominent ecological component.     

Evolution of virulence,environmental change,and the threat posed by emerging and chronic diseases

Assessments of future threats posed by infection have focused largely on zoonotic, acute disease, under the rubric “emerging diseases.” Evolutionary and epidemiological studies indicate, however, that particular aspects of infrastructure, such as protected water supplies, vector-proof housing, and health care facilities, protect against the emergence of zoonotic, acute infectious diseases. While attention in the global health community has focused on emerging diseases, there has been a concurrent, growing recognition that important chronic diseases, such as cancer, are often caused by infectious agents that are already widespread in human populations. For economically prosperous countries, the immediacy of this threat contrasts with their infrastructural protection from severe acute infectious disease. This reasoning leads to the conclusion that chronic infectious diseases pose a more significant threat to economically prosperous countries than zoonotic, acute infectious diseases. Research efforts directed at threats posed by infection may therefore be more effective overall if increased efforts are directed toward understanding and preventing infectious causes of chronic diseases across the spectrum of economic prosperity, as well as toward specific infrastructural improvements in less prosperous countries to protect against virulent, acute infectious diseases.     

Pathogeography: leveraging the biogeography of human infectious diseases for global health management

Biogeography is an implicit and fundamental component of almost every dimension of modern biology, from natural selection and speciation to invasive species and biodiversity management. However, biogeography has rarely been integrated into human or veterinary medicine nor routinely leveraged for global health management. Here we review the theory and application of biogeography to the research and management of human infectious diseases, an integration we refer to as ‘pathogeography’. Pathogeography represents a promising framework for understanding and decomposing the spatial distributions, diversity patterns and emergence risks of human infectious diseases into interpretable components of dynamic socio‐ecological systems. Analytical tools from biogeography are already helping to improve our understanding of individual infectious disease distributions and the processes that shape them in space and time. At higher levels of organization, biogeographical studies of diseases are rarer but increasing, improving our ability to describe and explain patterns that emerge at the level of disease communities (e.g. co‐occurrence, diversity patterns, biogeographic regionalisation). Even in a highly globalized world most human infectious diseases remain constrained in their geographic distributions by ecological barriers to the dispersal or establishment of their causal pathogens, reservoir hosts and/or vectors. These same processes underpin the spatial arrangement of other taxa, such as mammalian biodiversity, providing a strong empirical ‘prior’ with which to assess the potential distributions of infectious diseases when data on their occurrence is unavailable or limited. In the absence of quality data, generalized biogeographic patterns could provide the earliest (and in some cases the only) insights into the potential distributions of many poorly known or emerging, or as‐yet‐unknown, infectious disease risks. Encouraging more community ecologists and biogeographers to collaborate with health professionals (and vice versa) has the potential to improve our understanding of infectious disease systems and identify novel management strategies to improve local, global and planetary health.     

Complexity and Human Health: The Case for a Transdisciplinary Paradigm

Transdisciplinary thinking is an emerging philosophy underpinning health social science. We advance a definition of transdisciplinary thinking and link it with complexity theory. Complexity theory's concern with non-linear relationships, interactive causality and emergent properties of systems compels researchers to adopt a transdisciplinary perspective. We construct a generic framework for analyzing health processes from diverse disciplines and apply it to coronary heart disease in the Australian Coalfields. Insights from this analysis support our argument that transdisciplinary thinking maximizes understanding of the complexity of human health.     

Advances in microfluidic PCR for point-of-care infectious disease diagnostics

Global burdens from existing or emerging infectious diseases emphasize the need for point-of-care (POC) diagnostics to enhance timely recognition and intervention. Molecular approaches based on PCR methods have made significant inroads by improving detection time and accuracy but are still largely hampered by resource-intensive processing in centralized laboratories, thereby precluding their routine bedside- or field-use. Microfluidic technologies have enabled miniaturization of PCR processes onto a chip device with potential benefits including speed, cost, portability, throughput, and automation. In this review, we provide an overview of recent advances in microfluidic PCR technologies and discuss practical issues and perspectives related to implementing them into infectious disease diagnostics.     

Zoonotic Emerging Infectious Disease in Selected Countries in Southeast Asia: Insights from Ecohealth

Most emerging diseases of humans originate in animals, and zoonotic emerging infectious diseases (EIDs) threaten human, animal, and environment health. We report on a scoping study to assess actors, linkages, priorities, and needs related to management of these diseases from the perspective of key stakeholders in three countries in Southeast Asia. A comprehensive interview guide was developed and in-depth interviews completed with 21 key stakeholders in Vietnam, Lao People’s Democratic Republic, and Cambodia. We found numerous relevant actors with a predominance of public sector and medical disciplines. More capacity weaknesses than strengths were reported, with risk analysis and research skills most lacking. Social network analysis of information flows showed policy-makers were regarded as mainly information recipients, research institutes as more information providers, and universities as both. Veterinary and livestock disciplines emerged as an important “boundary-spanning” organization with linkages to both human health and rural development. Avian influenza was regarded as the most important zoonotic EID, perhaps reflecting the priority-setting influence of actors outside the region. Stakeholders reported a high awareness of the ecological and socioeconomic drivers of disease emergence and a demand for disease prioritization, epidemiological skills, and economic and qualitative studies. Evaluated from an ecohealth perspective, human health is weakly integrated with socioeconomics, linkages to policy are stronger than to communities, participation occurs mainly at lower levels, and equity considerations are not fully considered. However, stakeholders have awareness of ecological and social determinants of health, and a basis exists on which transdisciplinarity, equity, and participation can be strengthened.     

Toward Holistic Evaluation and Assessment: Linking Ecosystems and Human Well-Being for the Three Gorges Dam

A significant challenge exists in assessing the social and ecological impacts of development projects in a holistic and comprehensive manner. Our objective is to elucidate the linkages between ecological change and human well-being, and its importance in integrated assessment policy for development projects, using the Three Gorges Dam (China) as a case study. A collaborative research initiative was undertaken to review and synthesize published information on the ecological and human health effects of the Three Gorges Dam. Our synthesis suggests that the Three Gorges Dam has altered social–ecological dynamics of human health and ecosystem function in the Yangtze River basin with significant consequences for human well-being. Direct impacts to human well-being were grouped into four primary categories, including: (1) toxicological impacts; (2) shifting infectious disease dynamics; (3) natural hazards; and (4) social health. Social–ecological relationships were altered in complex ways, with both direct and indirect effects, positive and negative interactions, and chronic and acute impacts on human well-being. Our synthesis supports a comprehensive evaluation of development projects via integrated assessments of human and environmental consequences. This is probably best achieved through a coupled social–environmental impact assessment to ensure holistic and comprehensive analyses of expected costs and benefits. The role of research can thereby be to elucidate the linkages between ecosystems and human health to better inform the assessment process. A synthesis of the existing information on the Three Gorges suggests that this is best achieved through institutional collaboration and transdisciplinary integration of expertise.     

Within-species differences in primate social structure: evolution of plasticity and phylogenetic constraints

Primate socioecological studies have attempted to derive general frameworks using the average behavioural traits of species or genera to place them into categories. However, with the accumulation of primate studies, it is timely to place more emphasis on understanding within-species variation in social structure. In this review we have four objectives. First, we examine within-species variation in the potential determinants of social structure, including diet, demography, predation and infanticide, and document considerable variation. Second, we present case studies of within-species variation in social structure to illustrate the potential magnitude of this variation. For example, there are cases within a single interbreeding population where multi-male, uni-male, fission–fusion and monogamous groups are found. Third, by examining widespread primate lineages that occur in a variety of habitats, we note that there are differences in the magnitude of variation in social structures across different lineages and as a result we consider phylogenetic constraints on phenotypic variation in social structure. Finally, we reflect on the implications of extensive variation in social structure. We suggest that primate social structure will represent a combination of adaptation to present-day environment and phylogenetic inertia. To advance our understanding of the relative contribution of phylogeny versus ecology we propose two approaches. One approach is to compare groups in the same interbreeding population that inhabit different ecological conditions. Any differences that are found can be attributed to ecological differences, since phylogeny should not play a role within a single population. The second approach is to study distantly related species that have similar social structures to illustrate how similar ecological pressures might be operating to select for parallel social structures.     

Understanding Land Use, Livelihoods, and Health Transitions among Tibetan Nomads: A Case from Gangga Township, Dingri County, Tibetan Autonomous Region of China

Tibetan nomads in the Tibetan Autonomous Region of China have experienced profound transitions in recent decades with important implications for land use, livelihoods, and health development. The change from being traditional nomads to agropastoralists engaged in permanent agriculture, a sedentary village life (known as “sedentarization”), has been associated with a remarkable change in diet and lifestyle, decline in spatial mobility, increase in food production, and emerging infectious and noncommunicable diseases. The overarching response of the government has been to emphasize infrastructure and technological solutions. The local adaptation strategies of Tibetan nomads through maintaining balanced mobile herding, reindeer husbandry, as well as off-farm labor and trade could address both the cause of environmental degradation and improve the well-being of local people. Drawing on transdisciplinary, preliminary field work in Gangga Township of Dingri County in the foothills of Mt. Everest, we identify pertinent linkages between land use and health, and spatial and temporal mismatch of livelihoods and health care services, in the transition to sedentary village life. We suggest emerging imperatives in Ecohealth to help restore Tibetan livelihoods in transition to a sedentary lifestyle.     

Lurking in the shadows: emerging rodent infectious diseases

Rodent parvoviruses, Helicobacter spp., murine norovirus, and several other previously unknown infectious agents have emerged in laboratory rodents relatively recently. These agents have been discovered serendipitously or through active investigation of atypical serology results, cell culture contamination, unexpected histopathology, or previously unrecognized clinical disease syndromes. The potential research impact of these agents is not fully known. Infected rodents have demonstrated immunomodulation, tumor suppression, clinical disease (particularly in immunodeficient rodents), and histopathology. Perturbations of organismal and cellular physiology also likely occur. These agents posed unique challenges to laboratory animal resource programs once discovered; it was necessary to develop specific diagnostic assays and an understanding of their epidemiology and transmission routes before attempting eradication, and then evaluate eradication methods for efficacy. Even then management approaches varied significantly, from apathy to total exclusion, and such inconsistency has hindered the sharing and transfer of rodents among institutions, particularly for genetically modified rodent models that may not be readily available. As additional infectious agents are discovered in laboratory rodents in coming years, much of what researchers have learned from experiences with the recently identified pathogens will be applicable. This article provides an overview of the discovery, detection, and research impact of infectious agents recently identified in laboratory rodents. We also discuss emerging syndromes for which there is a suspected infectious etiology, and the unique challenges of managing newly emerging infectious agents.     

Spreading disease through social groupings in competition

Many animal populations live in social groups which avoid contact with other conspecific groups for at least part of the year. This may give rise to competition between groups for items such as shelter, land and mates. We couple intra-specific group competition with disease dynamics to investigate how infectious diseases may spread through population subgroups, particularly with reference to the contact rates between groups. Our model uses a nonlinear systems of ODEs for which steady-state analysis is carried out in the simplest two-group system. This indicates that coexistence of social groups is possible with the disease or that competitive exclusion occurs with one group dying out whilst the other retains disease. Moreover, we show that in certain circumstances the model can exhibit multistability and we discuss the ecological implications of this result in relation to contact between social groups.     

Examining the Links between Biodiversity and Human Health: An Interdisciplinary Research Initiative at the U.S. Environmental Protection Agency

Under the U.S. Environmental Protection Agency’s mission to protect human health and the environment, the agency seeks to conduct research on the structure and function of ecosystems and to improve our understanding of the processes that contribute to the sustained health of the nation’s ecosystems and the well-being of human populations. Changes in biodiversity can profoundly impact the ability of ecosystems to provide clean water, energy, food, recreation, and other services that contribute to human well-being. In addition, changes in biodiversity can affect the transmission of infectious disease to humans, particularly vectorborne diseases such as malaria and Lyme disease. The Environmental Protection Agency’s new initiative supports interdisciplinary research to characterize the mechanisms that link biodiversity and human health and to use this knowledge to develop integrative tools and approaches for quantifying and predicting these relationships. Research on these links can have an important impact on our view of biodiversity and how we manage resources to protect human and ecosystem health. Disclaimer: This work was funded in part under Grant #CX3-832328 with the American Association for the Advance of Science (AAAS). The views expressed do not necessarily reflect the views of the Environmental Protection Agency.     

Primate disease ecology in comparative and theoretical perspective

Infectious disease plays a major role in the lives of wild primates, and the past decade has witnessed significant strides in our understanding of primate disease ecology. In this review, I briefly describe some key findings from phylogenetic comparative approaches, focusing on analyses of parasite richness that use the Global Mammal Parasite Database. While these studies have provided new answers to fundamental questions, new questions have arisen, including questions about the underlying epidemiological mechanisms that produce the broader phylogenetic patterns. I discuss two examples in which theoretical models have given us new traction on these comparative questions. First, drawing on findings of a positive association between range use intensity and the richness of helminth parasites, we developed a spatially explicit agent-based model to investigate the underlying drivers of this pattern. From this model, we are gaining deeper understanding of how range use intensity results in greater exposure to parasites, thus producing higher prevalence in the simulated populations-and, plausibly, higher parasite richness in comparative analyses. Second, I show how a model of disease spread on social networks provides solid theoretical foundations for understanding the effects of sociality and group size on parasitism across primate species. This study further revealed that larger social groups are more subdivided, which should slow the spread of infectious diseases. This effect could offset the increased disease risk expected in larger social groups, which has yet to receive strong empirical support in our comparative analyses. In addition to these examples, I discuss the need for more meta-analyses of individual-level phenomena documented in the field, and for greater linkage between theoretical modeling and field research.     

Bioeconomic management of invasive vector-borne diseases

Invasive insects, arthropods, and other invertebrates are of concern due to the role some play in introducing and transmitting pathogens via a pathogen–vector relationship. Indeed, vector-borne diseases represent a significant portion of emerging diseases. We compare and contrast three strategic approaches to managing a vector-borne pathogen: conventional strategies based on disease ecology without regard to economic tradeoffs and cost-effective strategies based on a bioeconomic framework. Conventional strategies entail managing the vector population below a threshold value based on R ₀—the basic reproductive ratio of the pathogen, which measures a pathogen’s ability to invade uninfected systems. This does not account for post-infection dynamics, nor does it balance ecological and economic tradeoffs. Thresholds take on a more profound role under a bioeconomic paradigm: rather than unilaterally determining vector control choices, thresholds inform control choices and are influenced by them. Simulation results show cost-effective strategies can lower overall program costs and may be less sensitive to parameter estimation.