Understanding how and where pathogens emerge: Preparedness and response for zoonotic diseases

This chapter covers emerging zoonotic diseases, with a focus on the current understanding of how and where zoonotic pathogens circulate, their pathways to emergence, potential for sustained human-to-human transmission, and gaps in our knowledge. The first cluster of infections among people may be recognized well after a zoonotic pathogen has spilled over from its primary animal host to other intermediate hosts or directly to people. The collection and use of "pre-outbreak" information improve global health security through better preparedness for infectious disease threats, particularly when up-to-date information is promptly shared by an interlinked, global early surveillance and warning system that can provide timely signals for response to zoonotic threats at the earliest stage of emergence. The chapter also discusses actions to bolster preparedness and response to emerging and re-emerging infectious diseases (EID), which can aid policymakers, scientists, health systems, businesses, and communities to reduce the frequency and impact of zoonotic pathogen spillover (spillover is defined as the transmission of a microbe from one species to another and includes animal-to-animal, animal-to human, and human-to-animal transmission). Recommendations on how countries and the international community can improve prevention, detection, and response to future epidemic and pandemic threats are included.