The Many Faces of Emerging and Re-emerging Infectious Disease.

The emergence of disease threats can take many forms, from the adaptation of a traditionally zoonotic pathogen for efficient spread in humans, to the development of antibiotic resistance in well-known pathogens, to the creation of new niches for established disease through social and societal changes. In this commentary, the authors explore these various facets of disease emergence through the lens of the papers included in this issue of Epidemiologic Reviews. The authors explore multiple aspects of emergence, and the ways in which emergent pathogens can be controlled with the limited tools available. In doing so they put the papers in this issue in the context of the broader research agenda around understanding and combatting emergent pathogens.