Figure 1.
Framework for the classification of drivers of human exposure to animal pathogens (interspecies barrier).
See text for more details.
Table 1.
Drivers for overcoming the interspecies barrier.
Figure 2.
Examples of sets of drivers and ecological processes implicated in the emergence of zoonotic pathogens in humans.
(A) Emergence of Sin Nombre virus in the Four Corners area of the United States in 1993 was attributed to population growth of the rodent reservoir (Peromyscus maniculatus) following increases in food resources (mast) associated with El Niño-Southern Oscillation events [16]. (B) Emergence of Borrelia burgdorferi in the eastern US in 1974 was attributed to population growth and range expansion of white-tailed-deer (Odocoileus virginianus) and black-legged-tick (Ixodes scapularis) vector populations following increase in suitable habitat due to reforestation and management encouraging high deer densities [17]. (C) Emergence of Ebola virus in the Democratic Republic of Congo (formerly Zaire) in 1976 was attributed to increases in interspecies contact between humans and primates following increases in bushmeat hunting and encroachment into undisturbed habitats [18]. (D) Emergence of enteric pathogenic Escherichia coli at the human-animal interface was attributed to increased direct and indirect human-animal contact following changes in the food chain and in water quality, often due to the intensification of livestock production [19].