The urban health transition hypothesis: empirical evidence of an avian influenza Kuznets curve in Vietnam?

A landscape planning agenda for global health security: Learning from the history of HIV/AIDS and pandemic influenza

This paper considers the role of landscape planning and design in the context of a growing need for research and policy recommendations associated with Emerging Infectious Diseases (EIDs), of which COVID-19 is the most recent. Beginning with a definition of EIDs and their origins within the context of landscape planning, the paper then argues that planning and design scholars and practitioners should begin by seeing the importance of a "global urban ecosystem" (GUE) comprised of rapidly transforming metropolitan and regional "patches" connected through "corridors" of relatively unregulated global transportation and mobility networks. It then revisits the history of the two prior global pandemics of HIV/AIDS and pandemic influenza to establish the importance of a landscape planning perspective at the intersection of wildlife, livestock, and globally connected human communities. The essay concludes by arguing that this GUE concept can facilitate creative planning and design by adapting concepts established in other patch and corridor networks like urban transit systems to the ongoing risk of future pandemic EIDs.

Disentangling associations between vegetation greenness and dengue in a Latin American city: Findings and challenges

Being a Re-Emerging Infectious Disease, dengue causes 390 million cases globally and is prevalent in many urban areas in South America. Understanding the fine-scale relationships between dengue incidence and environmental and socioeconomic factors can guide improved disease prevention strategies. This ecological study examines the association between dengue incidence and satellite-based vegetation greenness in 3826 census tracts nested in 474 neighborhoods in Belo Horizonte, Brazil, during the 2010 dengue epidemic. To reduce potential bias in the estimated dengue-greenness association, we adjusted for socioeconomic vulnerability, population density, building height and density, land cover composition, elevation, weather patterns, and neighborhood random effects. We found that vegetation greenness was negatively associated with dengue incidence in a univariate model, and this association attenuated after controlling for additional covariates. The dengue-greenness association was modified by socioeconomic vulnerability: while a positive association was observed in the least vulnerable census tracts, the association was negative in the most vulnerable areas. Using greenness as a proxy for vegetation quality, our results show the potential of vegetation management in reducing dengue incidence, particularly in socioeconomically vulnerable areas. We also discuss the role of water infrastructure, sanitation services, and tree cover in lowering dengue risk.

Emerging infectious disease, the household built environment characteristics, and urban planning: Evidence on avian influenza in Vietnam

Recent concerns with pandemic outbreaks of human disease and their origins in animal populations have ignited concerns regarding connections between Emerging Infectious Diseases (EID) and development. As disasters, health, and infectious disease become part of planning concern (Matthew & McDonald, 2007), greater focus on household infrastructure and EID disease outbreaks among poultry is warranted. Following Spencer (2013), this study examines the relationship between the mix of household-scale water supplies, sanitation systems, and construction materials, and Highly Pathogenic Avian Influenza (HPAI) among poultry in a developing country: Vietnam. Findings of our multivariate logistic regressions suggest that a non-linear, Kuznets-shaped urban transition (Spencer, 2013) has an independent effect on the outbreak of HPAI, especially as it relates to household-level sanitation infrastructure. We conclude that the Kuznets-shape development of household infrastructure characteristics in Vietnam play a significant role in explaining where poultry outbreaks occur. Using secondary data from the Census of Population and Housing, and the Agricultural Census at the District and Commune levels for the country of Vietnam, we performed logistic regression to test the relationship between outbreaks of HPAI in poultry and newly-developed "coherence indices" (Spencer, 2013) of household water supply, sanitation, and construction materials that measure nonlinear, transitional development. Results show that district-scale coherence indices are negatively and independently correlated with HPAI outbreaks, especially for sanitation. Findings also suggest that community-scale coherence of urban infrastructures is a powerful tool for predicting where HPAI poultry outbreaks are likely to occur, thereby providing health planners new tools for efficient surveillance.

Perceived Risk of Avian Influenza and Urbanization in Northern Vietnam

Highly pathogenic avian influenza (HPAI) is an important public health concern because of potential for widespread morbidity and mortality in humans and poultry and associated devastating economic losses. We examined how perceptions of the risk of HPAI in poultry vary across communes/wards in the north of Vietnam at different levels of urbanization (rural, peri-urban, urban). Analyses of questionnaire responses from 1081 poultry raisers suggested that the perceived risk of HPAI in poultry was highest in peri-urban and rural settings. We also found that perceived risk was higher when respondents rated settings in which they did not live and that the process of change is related to perceived risk. Compared with others, respondents in peri-urban areas reported less disease management planning; respondents in rural areas reported less ability to separate infected poultry. These findings are consistent with, and add to, the limited previous research on the perceived risk of HPAI in poultry in developing countries. What is new in the present findings is that we describe how urbanization is related to people's perceptions of and ability to respond appropriately to variations in their environment. In particular, the inability to respond is not necessarily because of an inability to perceive change. Rather, rapid and extensive change poses different challenges for poultry management as communes move from rural to peri-urban to urban settings. Our results suggest that health promotion campaigns should address the perceptions and needs of poultry raisers in different settings.

Evidence for the Convergence Model: The Emergence of Highly Pathogenic Avian Influenza (H5N1) in Viet Nam

Building on a series of ground breaking reviews that first defined and drew attention to emerging infectious diseases (EID), the 'convergence model' was proposed to explain the multifactorial causality of disease emergence. The model broadly hypothesizes disease emergence is driven by the co-incidence of genetic, physical environmental, ecological, and social factors. We developed and tested a model of the emergence of highly pathogenic avian influenza (HPAI) H5N1 based on suspected convergence factors that are mainly associated with land-use change. Building on previous geospatial statistical studies that identified natural and human risk factors associated with urbanization, we added new factors to test whether causal mechanisms and pathogenic landscapes could be more specifically identified. Our findings suggest that urbanization spatially combines risk factors to produce particular types of peri-urban landscapes with significantly higher HPAI H5N1 emergence risk. The work highlights that peri-urban areas of Viet Nam have higher levels of chicken densities, duck and geese flock size diversities, and fraction of land under rice or aquaculture than rural and urban areas. We also found that land-use diversity, a surrogate measure for potential mixing of host populations and other factors that likely influence viral transmission, significantly improves the model's predictability. Similarly, landscapes where intensive and extensive forms of poultry production overlap were found at greater risk. These results support the convergence hypothesis in general and demonstrate the potential to improve EID prevention and control by combing geospatial monitoring of these factors along with pathogen surveillance programs.

An exploration of how perceptions of the risk of avian influenza in poultry relate to urbanization in Vietnam

This research examined how perceptions of outbreaks of highly pathogenic avian influenza (HPAI) subtype H5N1 in poultry are related to urbanization. Via in-depth interviews with village leaders, household farmers, and large farm operators in modern, transitional, and traditional communes in the north of Vietnam, we explored behaviors, attitudes, cultural values, and traditions that might amplify or attenuate HPAI outbreaks. We also explored conceptualizations of urbanization and its impacts on animal husbandry and disease outbreaks. Qualitative theme analyses identified the key impacts, factors related to HPAI outbreaks, and disease prevention and management strategies. The analyses also highlighted how urbanization improves some aspects of life (e.g., food security, family wealth and health, more employment opportunities, and improved infrastructure), but simultaneously poses significant challenges for poultry farming and disease management. Awareness of qualitative aspects of HPAI risk perceptions and behaviors and how they vary with urbanization processes may help to improve the prevention and management of emerging infectious diseases.

A Conceptual Framework for Analyzing Social-Ecological Models of Emerging Infectious Diseases

Unraveling mechanisms underlying new and reemerging infectious diseases (EID) requires exploring complex interactions within and among coupled natural and human (CNH) systems. To address this difficult scientific problem, we need to understand how transformations in social-ecological systems caused by multifaceted interactions with anthropogenic environmental changes such as urbanization, agricultural transformations, and natural habitat alterations, produce feedbacks that affect natural communities and ultimately their pathogens, animal host, and human populations. Focusing on the complex interactions among natural and human systems at diverse spatial, temporal, and organizational scales, we describe the development of a framework for analyzing social-ecological models, to understand how these systems function and the processes through which these systems interact with each other to influence disease outbreaks. To address multi-scale issues within the framework, we draw upon multiple social science theories and methods (e.g., environmental economics, geography, decision and risk science, urban and regional development, and spatial information science). We posit that the framework helps to identify potential vulnerabilities of CNH systems to disturbances, describing important elements as a starting point for the development and testing of more general CNH systems. We also posit that transformations in the elements and how they relate to each other are key in determining the robustness of CNH systems. Given the importance and difficulty of research on social-ecological systems, we recommend a carefully considered theoretical rationale and a model-guided methodological approach. We conclude that no single theory or method is sufficient to explain complex phenomena such as EID and the relationships between factors influencing disease outbreaks. Integrated approaches are arguably the best way to provide an in-depth description and analysis of a complex problem.