In light of the complexity of the factors involved, this lack of preparedness should perhaps not be surprising. As explained by the infectious disease ecology described here, zoonotic disease emergence involves biological processes operating on the scale of molecules and cells to that of coupled, regional scale human-natural systems. The latter involve political economic factors and policies driving regional environmental change, spreading geographically across the globe. It is this process of globalization-its ecological underpinnings and consequences-to which the current EID global trend of zoonotic disease emergance can be largely attributed.