Natural and Anthropogenic Drivers of Viral Emergence

Emerging infectious diseases are causing outbreaks with loss of human and animal lives and may have large economic and societal impacts. There may be both natural and anthropogenic drivers behind the emergence of viral diseases. Zoonotic diseases are more commonly emerging, and because RNA viruses have an inherent tendency to change, they are overrepresented among emerging diseases. Apart from the naturally occurring changes in the pathogens, humans also contribute to disease emergence by contributing to changes in land use and climate, which in turn affects ecosystems and biodiversity. This chapter reviews the different mechanisms behind viral disease emergence, as well as presents a framework evaluating the spill-over of zoonotic diseases at the human-wildlife-livestock interfaces. The chapter starts with discussing viral evolution and moves towards global changes and the impact on diseases, with a particular focus on vector-borne viruses.