Abstract
Emerging infectious diseases are diseases that are either new, are newly recognized, or are increasing in prevalence in new areas. Resurgent diseases are also usually grouped in this category, as is antimicrobial resistance. These diseases have been given formal recognition in the past two decades, although a historical outlook demonstrates that the phenomenon has probably been persistent, although largely undetected, through recorded history. Emergence has accelerated recently, driven by factors such as demographic change, land use change, increased rapidity and frequency of intercontinental transportation, and other mostly social trends. Continued infectious disease emergence poses, and will continue to pose, significant challenges for public health and for basic science.