Emergent infectious diseases (EIDs) are conditions caused by pathogenic microorganisms or parasites that have recently appeared or reappeared in human or animal populations. Typically, EID agents have begun to change the range of their infection, spread through new vectors or the movement of preexisting vectors, rely on shifts in patterns of host susceptibility, or have only recently been identified as the causes of existing diseases. This includes reemerging disease agents once thought to have been eradicated, but that have returned in resistant strains, or as a result of disintegrating public health infrastructure. Emergent diseases have tremendous impact on human health, and the health of pets and livestock. Furthermore, they pose a threat to biodiversity because many wild animal species are also at risk.

Science and Origins

An emerging infection can be caused by such viral agents as Ebola virus, HIV, or the SARS-associated corona-virus...