Genetic processes facilitating pathogen emergence

The goal of biosecurity is to minimize the risk of introduction and transmission of infectious diseases to people, animals, and plants. This is achieved by accurately identifying pathogens and instituting appropriate methods to prevent their introduction, reemergence, and/or spread. However, disease is dynamic, and biosecurity needs to continually change to keep pace as pathogens evolve. As described in this chapter, a basic understanding of evolution is central in considering how genetic changes and their associated phenotypes can alter the disease presentation of pathogens. In addition, evolution leaves a trail of genetic information that can be leveraged to inform biosecurity because the spatiotemporal patterns of these past changes provide clues as to how the pathogen might be spreading. This chapter aims to provide insights into how various genetic alterations occur, the background on how these are informative for biosecurity, and illustrations of applications to real-world examples. Evolution underlies the abilities of pathogens to adapt, emerge, and to cause epidemics.