This chapter examines the links between biodiversity and worldwide patterns of zoonotic disease outbreaks. We find that biodiversity appears to be a major contributing factor determining the diversity of human infectious diseases, and that zoonotic disease outbreaks should be considered with the indices of human development and biodiversity loss. Increasing population and wealth (i.e., GDP) both threaten biodiversity and favour epidemics, leading us to conduct an analysis showing the deleterious impacts of development (and globalization) on health. Our results support this premise in contrast to most studies showing generally negative effects of biodiversity reduction on the spread of infectious diseases. Biodiversity has a complex relationship with human infectious diseases, serving both as a source of pathogens and as a regulating factor, keeping the incidence down.