Land-Use Drivers of Infectious Disease Emergence

VOLUME 112 | NUMBER 10 | July 2004 • Environmental Health Perspectives Human-induced land use changes are the primary drivers of a range of infectious disease outbreaks and emergence events and also modifiers of the transmission of endemic infections (Patz et al. 2000). These land use changes include deforestation, road construction, agricultural encroachment, dam building, irrigation, coastal zone degradation, wetland modification, mining, the concentration or expansion of urban environments, and other activities. These changes in turn cause a cascade of factors that exacerbate infectious disease emergence, such as forest fragmentation, pathogen introduction, pollution, poverty, and human migration. These are important and complex issues that are understood only for a few diseases. For example, recent research has shown that forest fragmentation, urban sprawl, and biodiversity loss are linked to increased risk for Lyme disease in the northeastern United States (Schmidt and Ostfeld 2001). Expansion and changes in agricultural practices are intimately associated with the emergence of Nipah virus in Malaysia (Chua et al. 1999; Lam and Chua 2002), cryptosporidiosis in Europe and North America, and a range of food-borne illnesses globally (Rose et al. 2001). Road building is linked to the expansion of bushmeat consumption that may have played a key role in the early emergence of human immunodeficiency virus types 1 and 2 (Wolfe et al. 2000), and simian foamy virus has been found in bushmeat hunters (Wolfe et al. 2004). In recognition of the complexity of land use change and the risks and benefits to human health that it entails, a special colloquium titled “Unhealthy Landscapes: How Land Use Change Affects Health” was convened at the 2002 biennial meeting of the International Society for Ecosystem Health (6–11 June 2002, Washington, DC) to address this issue. The invited experts worked to establish consensus on the current state of science and identify key knowledge gaps underlying this issue. This article condenses the working group’s report and presents a new research and policy agenda for understanding land use change and its effects on human health. Specifically, we discuss land-use drivers or human activities that exacerbate infectious diseases; the land–water interface, common to many infectious disease life cycles; and conclusions and recommendations for research and training from the working group.