Fig. 2.

A decision tree applying a new framework for emergence. We redefined EID events as: 1. EIDs: those that increase in impact or increase in geographic range. 2. Emerging pathogens (EPs): those that have undergone recent evolutionary change, are entering detected in the human population for the first time, a pathogen has significantly changed its pathology or clinical presentation, or are newly discovered and show evidence that their presence in a human host causes clinical illness. 3. Novel potential pathogens (NPPs): those that are characterized by recent evolutionary change, are entering detected in the human population for the first time, or are newly discovered, but and show no evidence that their presence in a human host causes clinical illness. 4. Submerging infectious disease or pathogen: those that are receding in impact due to human intervention or through natural means.