IDR Team Summary 1

How do ecosystem services affect infectious and chronic diseases?

CHALLENGE SUMMARY

Many attributes of ecosystems directly affect human health (Millennium Assessment 2005). For example, biodiversity may have implications for infectious disease transmission and for the availability of biopharmaceuticals; air quality affects mortality and morbidity from respiratory and cardiovascular diseases; wetlands affect the availability and quality of drinking water; wildlands can provide environments for disease vectors; climate can affect food production, the transmission of infectious diseases as well as mortality and morbidity from chronic diseases; and natural disasters can affect both physical and mental health in profound way. Substantial health and health ecology work documents these and other linkages between human health and ecosystems broadly defined (e.g., McMichael et al. 2003; Tzoulas et al. 2007).

In some cases, the same ecosystem may contribute differentially to more than one health issue. Wetlands filter water but may also provide habitat for mosquitoes transmitting malaria. Historically, society has weighed the tradeoffs of these services and disservices, opting to manipulate the ecosystem to get rid of the disservice. For instance, the development of Washington, D.C. was enhanced by the draining of malaria infested wetlands (Foggy Bottom) along the Potomac. Such decisions were relatively easy to make at the time because overall stress on ecosystems were sufficiently small so that the tradeoffs in question, in this case water filtration, did not affect the supply of quality water to the capital.

The situation today has changed in at least three ways. First, the combined stressors on all ecosystems—resulting in human modified ecosystems



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IDR Team Summary 1 How do ecosystem services affect infectious and chronic diseases? CHALLENGE SUMMARY Many attributes of ecosystems directly affect human health (Millennium Assessment 2005). For example, biodiversity may have implications for infec- tious disease transmission and for the availability of biopharmaceuticals; air quality affects mortality and morbidity from respiratory and cardiovascular diseases; wetlands affect the availability and quality of drinking water; wild- lands can provide environments for disease vectors; climate can affect food production, the transmission of infectious diseases as well as mortality and morbidity from chronic diseases; and natural disasters can affect both physi- cal and mental health in profound way. Substantial health and health ecology work documents these and other linkages between human health and eco- systems broadly defined (e.g., McMichael et al. 2003; Tzoulas et al. 2007). In some cases, the same ecosystem may contribute differentially to more than one health issue. Wetlands filter water but may also provide habi- tat for mosquitoes transmitting malaria. Historically, society has weighed the tradeoffs of these services and disservices, opting to manipulate the ecosystem to get rid of the disservice. For instance, the development of Washington, D.C. was enhanced by the draining of malaria infested wet- lands (Foggy Bottom) along the Potomac. Such decisions were relatively easy to make at the time because overall stress on ecosystems were suffi- ciently small so that the tradeoffs in question, in this case water filtration, did not affect the supply of quality water to the capital. The situation today has changed in at least three ways. First, the com- bined stressors on all ecosystems—resulting in human modified ecosystems 7

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8 ECOSYSTEM SERVICES and landscapes—is such that multiple, interacting ecosystem services are stressed simultaneously. Second, the worldwide cumulative effect of these stressors promises to alter the earth system with human health consequences (e.g., climate change and movement toward the poles and high elevation for tropical diseases). Third, the features of ecosystems that are believed to be relevant to health are much broader than previously thought and are likely to affect not only infectious diseases but also the most common chronic diseases. For example, ecosystem services that are directly related to human health include food production, water supply and quality, air quality, as well as other aspects of the human-environment interface related to the ways in which human settlements are built, organized, and linked to their natural environments. The challenge is to understand the overall impact of ecosystems on infectious and chronic diseases broadly defined, as well as the consequences of changes in ecosystems—not only on overall rates of morbidity, but also on health inequalities by place and person. Key Questions • What are the relevant aspects of human health that would be im- portant to measure? • What kinds of features of ecosystems are likely to be most important to human health over the next few decades? • What are the key outstanding questions in understanding the links between ecosystems and chronic and infectious diseases? • What kinds of methodologic approaches (measures, studies, and analytical approaches) are necessary to understand and predict ecosystems effects on chronic and infectious diseases? • Can measure be developed to capture the overall human health consequences of changes in multiple ecosystem services? Reading Brook RD and Brook JR. A road forward to improve public health. Circulation 2011;123:1705- 1708. Butler CD and Friel S. Time to regenerate: ecosystems and health promotion. PLoS Med 2006;3(10):e394. Keesing F, Belden LK, Daszak P, Dobson A, Harvell D, Holt RD, Hudson P, Jolles A, Jones KE, Mitchell CE, Myers SS, Bogich T, and Ostfeld RS. Impacts of biodiversity on the emergence and transmission of infectious diseases. Nature 2010;468:647-652.

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9 IDR TEAM SUMMARY 1 McMichael AJ, Campbell-Lendrum DH, Gorvalan CF, Ebi KL, Githeko AK, Scheraga JD, Woodward A, eds. Climate change and human health. World Health Organization: Geneva, 2003. Millennium Assessment. Ecosystems and human well-being: health synthesis. Island Press: Washington, D.C., 2005. Tzoulas K, Korpela K, Venn S, Yli-Pelkonen V, Kazmierczak A, Niemela J, and James P. Promoting ecosystem and human health in urban areas using green infrastructure: A literature review. Landscape and Urban Planning 2007;81:167-178. IDR TEAM MEMBERS • Joshua N. Adkins, Pacific Northwest National Laboratory • Brian F. Allan, University of Illinois Urbana-Champaign • Kate A. Brauman, University of Minnesota • Francis L. de los Reyes, North Carolina State University • James L. Garrison, Purdue University • Tony Goldberg, University of Wisconsin-Madison • Diana S. Grigsby-Toussaint, University of Illinois at Urbana-Champaign • Taylor H. Ricketts, University of Vermont • Laura Smith, University of Georgia • Beth A. Winkelstein, University of Pennsylvnia IDR TEAM SUMMARY Laura Smith, NAKFI Science Writing Scholar University of Georgia IDR Team 1 was asked to determine how ecosystem services affect the transmission of infectious and chronic diseases. While the services that eco- systems provide are thought of primarily in relation to the sustainability of the food supply or the effects of climate change, they also play an important role in the regulation of disease. Human interference in the environment— intentional or not—can change patterns of disease. It is generally accepted, for example, that the degradation of ecosystems facilitates the emergence of infectious diseases. If we can better understand how ecosystem services are linked to specific diseases, then we can also predict how human alteration of the environment might affect human health. IDR Team 1 tackled the challenge by considering what knowledge exists on the subject, then pinpointing areas that would benefit from future research. What the team discovered is that the key to a better understanding

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10 ECOSYSTEM SERVICES of the relationship between ecosystem services and disease may be a fusion of existing knowledge from disciplines such as epidemiology, ecology, and microbiology to form a common research framework. To establish this framework, the team proposed a conceptual article to review existing lit- erature, identify gaps in knowledge, and outline how to demonstrate direct links between ecosystem services and human health. Finding the Link The majority of the group’s time was spent exploring examples of diseases thought to be linked to ecosystem services. The team thought about every- thing from changes in land use, its effects on water resources and possible con- nections to water-borne diseases like cholera, but also considered the effects of green space and recreation on important indices as mental health and obesity. The “aha” moment The struggle to explain linkages among diseases and ecosystem ser- vices resulted in two major conclusions. One is that, though many diseases have potential links to the environment, some are more directly linked than others. The diseases more strongly correlated with ecosystem services should be easier to control through improvements to the ecosystem or by monitoring the way humans alter the environment. The team decided that these diseases would prove the most beneficial to study further. For example, it may be more productive to focus improvement efforts on air quality to reduce asthma rather than spending time and money on a disease with a more tenuous connection to ecosystem services that may be better addressed in other ways. The other conclusion was that infectious diseases are more obviously linked to ecosystem services than chronic diseases. While the team did come up with some examples of chronic diseases that could be related to certain ecosystem services—like some cancers caused by toxins—the relationships were less defined and spurred more debate than those involving vectors, for example. Establishing a test Given the large number of diseases that could be understood to have links to ecosystem services, the team developed a “test” to determine if a

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11 IDR TEAM SUMMARY 1 disease is directly or indirectly linked to a specific ecosystem service. The test asks two questions: 1. Does a change in an ecosystem lead to a change in a health-related outcome? 2. Can this relationship be linked to a specific function that the eco- system provides? If the answer to both questions is yes, then the disease in question is considered to be directly related to ecosystem services. The team used the ex- ample of trees next to a roadway capturing particulate matter from vehicles in sufficient quantity to reduce the incidence of asthma in nearby communities. If the answer to one or both questions is no, then the disease is more likely to be indirectly linked to ecosystem services. For example, polio has re-emerged because of a decrease in vaccinations, related to both social and political reasons; although polio likely has some links to the environment— it is transmitted via food or water and outbreaks are common in over- crowded urban areas—improvements in ecosystem services are unlikely to affect future polio infection rates. A spectrum of diseases After some debate, it was decided that the diseases would be divided into infectious and non-infectious disease categories, and that they would fall along a gradient in terms of how directly they are related to ecosystem services. Infectious diseases that have very clear, direct relationships with eco- system services include zoonoses with the potential to become pandemic (i.e.; influenza), vector-borne diseases (i.e.; Lyme disease), and water-borne diseases (i.e.; cholera). Those that are less clearly related to ecosystems in- clude food-borne, airborne, and sexually transmitted diseases. Within the chronic disease category, respiratory illness related to par- ticulates are considered more strongly linked to ecosystem services, followed by nutritional illnesses, mental health, immune disorders, cardiovascular disease, cancers and reproductive disorders. Meshing models At first, the team attempted to create its own basic model for assessing the relationships between human-led change in the environment, ecosystem

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12 ECOSYSTEM SERVICES services and disease-related outcomes. However, a quick Google search re- vealed that existing ecological approaches used for diseases like Lyme disease already seemed to contain some of the same elements team members were trying to fit into a new model. The team concluded that adapting existing modeling approaches from disease ecology and epidemiology, as well as other related fields, to make them more relevant to ecosystem services research is a sound approach. These models may help in understanding the webs of causation that occur among ecosystem services, human use of the environment, and disease. In fact, as the team pointed out, several biomedical disciplines (micro- biology, epidemiology, immunology, etc.) already conduct research relevant to ecosystem services, but don’t necessarily make the connection between specific ecosystem services and health outcomes. Bringing experts from these disciplines together may be the key to launching future research geared specifically toward understanding the links between ecosystem services and disease. Next Steps To work toward the establishment of an ecosystem services model, or a common framework, the team proposed a conceptual review article looking back at previous research and outlining how to identify and define linkages among certain diseases and ecosystem services. A review of the existing lit- erature should reveal specific diseases that can be used as cases demonstrat- ing strong links to ecosystem services. A basic research question that would need to be answered using the resulting framework is “how do changes in the ecosystem affect ecosystems services, and subsequently human health?” The answer to that research question is crucial for affecting substantive change in ecosystem management practices on a policy level. The research article is an important step toward understanding how ecosystem services, and our own actions, can affect human health outcomes. Not only would such an article help create a framework from which to study such relation- ships, but it would also serve as a tool for policy change. If specific diseases can be shown to have direct linkages to ecosystem services, then it will be easier to show policy-makers the benefits of ecosystem management by providing them with concrete evidence and even financial incentives for maintaining the relevant ecosystems. A last element of the team’s plan was to begin a “call to arms” for researchers in all of the fields that deal with ecosystem services, whether it’s ecology or urban planning, to work together

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13 IDR TEAM SUMMARY 1 to improve human health through ecosystem management. Through ad- vertisements, podcasts, journals and other avenues, experts in every related discipline need to be made aware of the health component of ecosystem services and the possibility of working together to improve human health worldwide.

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