Meredith Barrett, PhD
How does an ecologist, who studied snails, lemurs and Andean spectacled bears, have anything to do with human population health?
As I have come to appreciate through my studies at the intersection of ecology, environmental science, biodiversity, wildlife biology and population health, these disciplines can add a unique perspective to understanding health challenges. My training as an ecologist primed me to think about populations, systems, and interactions, and allowed me to apply methods used in ecology towards unique health problems. I sincerely appreciate the opportunity to explore these intersections within the Robert Wood Johnson Foundation Health & Society Scholars Program at UCSF and UC Berkeley.
My work is motivated by an interest in how the environment affects health. Following this theme, I have worked on several studies investigating how environmental drivers influence geographic patterns of disease. Addressing the environmental drivers of disease is an essential population health strategy, and will be increasingly important as built and natural environments change rapidly due to increasing human pressures. I have explored these spatial dynamics in populations as diverse as lemurs in Madagascar, snails in Tanzania and (even) humans in Kentucky.
Despite my seemingly large disciplinary jump from ecology to population health, there have been recurrent and unifying themes across my work:
- Attempting to understand how the environment and environmental change influence health
- Using spatial frameworks to relate social and environmental drivers with health outcomes
- Taking a population level approach, regardless of the cohort focus (eg, lemurs, snails or humans)
- Applying ecological methods towards new health problems
Figure 1. Through the RWJF program, I have shifted from lemur populations to humans, from global issues of infectious disease to chronic disease in the US, and from primarily natural environments to built environments. It has been a fascinating transition.
Intersection of environment and health
So why study the environment and its effect on health? Fundamentally, the environment affects how people (and other species) live, thrive and interact.Â Hippocrates had this figured out back in 400 BC, but we’re just now catching up. With his classic “On Airs, Waters and [Places]](1),” the father of western medicine recognized that physicians should examine a patient’s environment in order to understand his health. Fast forward to the 21st century, when a growing body of literature (2) demonstrates that the majority of what drives our health doesn’t necessarily happen in the doctor’s clinic (3), but in our communities, in our air and water, and in our everyday lives.
The term environment encompasses many different contexts and scales, ranging from an individual’s home and neighborhood environments, to social and economic environments, to regional ecosystems, to the air that we breathe and the climate in which we exist (Figure 2) (4). The definition of environment can include both the built environment, such as urban systems, and more unmodified, natural ecosystems. And these different environments directly influence health. In fact, the World Health Organization estimates that 24% of the global burden of disease in humans is related to environmental factors (5).Â But the definition of health is also complex. According to the WHO, health is not defined merely by the absence of disease. Rather, health is a state of complete physical, mental and social well-being, which is directly influenced by the environments in which we live.
Previous work: environmental change driving disease patterns in Madagascar
In my previous research, I investigated how environmental change drove spatial patterns of human and lemur health in Madagascar (6, 7). Connections between human and ecosystem health are especially salient in Madagascar, where over 90% of the primary forest cover has been lost due to natural resource extraction, subsistence agriculture and cattle grazing. This degree of habitat loss has threatened much of Madagascar’s exceptional species diversity, and has undermined essential ecosystem functioning.
Madagascar’s habitat loss, high population growth rate and low standard of living has contributed to an increased risk of disease emergence among human populations. Globally, disease emergence rates have increased dramatically since the mid-20th century; 335 emerging infectious disease (EID) events have been identified in humans since 1940 and several rank as leading causes of mortality worldwide, with developing countries assuming a disproportionate burden (8, 9). More than 60% of these EID are zoonotic, and of those zoonoses, almost three quarters of them have originated in wildlife (8, 10, 11). I am still interested in how environmental change influences the risk of disease emergence from wildlife sources, and continue to work with human, wildlife and ecosystem health data to analyze these dynamics.
New work: leveraging novel health technologies to investigate geographic patterns of asthma
Â Now, I’m working as an ecologist with an interest in how both built and natural environments influence health. During the Health & Society Scholars program, I have been leveraging spatial frameworks to explore environmental drivers of asthma using novel health technologies.
Asthma inflicts a significant health and economic burden. Over 25 million people in the US suffer from asthma and the resulting economic burden totaled $56 billion in 2007. Racial, ethnic and socioeconomic disparities in asthma are of particular concern, with the heaviest burden in poor, urban communities that often are at highest risk for environmental exposure. Although a number of environmental triggers of asthma exacerbations have been identified, data limitations make it impossible to assess these triggers in real time or space.
New tools like GPS-enabled asthma inhalers from Asthmapolis are changing how we study asthma. With this technology, we can explore asthma exacerbations in real space and in real time. This type of temporal and georeferenced asthma data has never been available before, and allows researchers and clinicians to track symptoms and triggers and correlate them with air quality, traffic and other pollution sources.
In collaboration with my co-scholar, Olivier Humblet, and Asthmapolis, co-founded by Health & Society Scholar, David Van Sickle, we have participated in a research program built around the Asthma Innovation Project in Louisville, Kentucky. We worked to determine the spatial and temporal drivers of asthma exacerbations in real time and space. We hope our work will help to improve understanding of both individual and population-level environmental drivers of asthma, strengthen asthma surveillance, target interventions and plan for future asthma risk under changing development scenarios.
Transdisciplinary approaches to health: One Health
As a result of my winding path through ecology and health, I look at health through a very transdisciplinary lens and rely on collaboration. One great example of transdisciplinary collaboration is the One Health approach. This approach integrates knowledge from human and veterinary medicine, public health, and ecology to improve health outcomes for people, animals and ecosystems by informing health policy, expanding scientific understanding and improving health education (12-15). The use of this multifaceted perspective allows practitioners to work towards optimal health for people, domestic animals, wildlife, and the environment, concurrently, over multiple spatial and temporal scales. I see interesting overlaps between One Health and population health approaches, and have been exploring them through partnerships with the UC Global Health Institute, the North Carolina One Health Collaborative and the International Association for Ecology and Health.
Through my ecological training and previous wildlife field research I have come to appreciate the complexity of our interactions with each other, with our environments, and with other species. I thank the Robert Wood Johnson Foundation Health & Society Scholars program, as well as the faculty at UCSF and UCB, for acknowledging and creating a space for such non-traditional perspectives on health.
Meredith loves spending time outdoors biking, running and traveling. She grew up in Palo Alto and is excited to be back exploring her favorite spots in California. In 2009 she married her college sweetheart, Aaron Stoertz, on the shores of Lake Tahoe.
1. Hippocrates, Air, Waters and Places. (400 BC).
2. P. Braveman, S. Egerter, D. R. Williams, The Social Determinants of Health: Coming of Age. Annu. Rev. Public Health 32, 381 (2011).
3. M. A. Barrett, L. M. Gottlieb, P. A. Braveman, R. A. Hiatt, N. E. Adler, Health is more than health care: Pre-med curricula should incorporate the social determinants of health. Science (comment), (2012).
4. H. Barton, M. Grant, “The Determinants of Health and Well-being in our Neighbourhoods: The Health Impacts of the Built Environment” (Institute of Public Health in Ireland, Ireland, 2006).
5. A. Pruss-Ustun, C. Corvaan, “Preventing disease through healthy environments: Towards an estimate of the environmental burden of disease” (World Health Organization, Geneva, 2006).
6. M. A. Barrett, J. L. Brown, R. E. Junge, A. D. Yoder, Climate change, predictive modeling and lemur health: Assessing impacts of changing climate on health and conservation in Madagascar. Biological Conservation 157, 409 (2013).
7. R. E. Junge, M. A. Barrett, A. D. Yoder, Effects of anthropogenic disturbance on indri (Indri indri) health in Madagascar. Am. J. Primatol. 73, 632 (2011).
8. K. E. Jones et al., Global trends in emerging infectious diseases. Nature 451, 990 (Feb 21, 2008).
9. WHO, “Contributing to 'One World, One Health:' A strategic framework for reducing risks of infectious diseases at the animal-human-ecosystems interface” (World Health Organization, Food and Agriculture Organization, United Nations, United Nations Children Fund, The World Bank and World Organization for Animal Health, New York, 2008).
10. S. Cleaveland, M. K. Laurenson, L. H. Taylor, Diseases of humans and their domestic mammals: Pathogen characteristics, host range and the risk of emergence. Philos. Trans. R. Soc. B-Biol. Sc. 356, 991 (2001).
11. L. H. Taylor, S. M. Latham, M. E. J. Woolhouse, Risk factors for human disease emergence. Philos. Trans. R. Soc. B-Biol. Sc. 356, 983 (2001).
12. M. A. Barrett, S. A. Osofsky, in Jekel’s Epidemiology, Biostatistics, Public Health, and Preventive Medicine, D. L. Katz, J. G. Elmore, D. M. G. Wild, S. Lucan, Eds. (Elsevier Inc, Philadelphia, 2013), pp. 364-377.
13. M. A. Barrett, T. A. Bouley, A. H. Stoertz, R. W. Stoertz, Integrating a One Health approach in education to address global health and sustainability challenges. Front. Ecol. Environ. 9, 239 (2010).
14. J. Zinsstag, et al., Convergence of Ecohealth and One Health. EcoHealth 9, 371 (2012).
15. L. M. Gargano et al., Issues in the Development of a Research and Education Framework for One Health. Emerg. Infect. Dis. 19, (2013).