Spillover and emerging infectious diseases

Abstract

Abstract Emerging infectious diseases occur when pathogens spread to new hosts or new geographic areas, or when an existing infectious disease suddenly becomes more prevalent or severe. This chapter introduces the processes involved with disease emergence, starting with spillover events, where pathogens jump into unusual hosts. This includes zoonotic pathogens that are transmitted from animals to humans. After spillover to a new host species, a pathogen may dead-end without further transmission. Alternatively, the pathogen might be transmitted further, causing outbreaks that eventually fade out or that erupt into full-blown pandemics. Combining approaches from epidemiology and disease ecology can provide insights into how, why, and when pathogen spillover events occur.