Bioterrorism is defined as the unlawful use of living microorganisms or toxins to cause death or disease in humans, animals, or plants for political, religious, or ideological goals. Biological agents are ranked based on their potential public health impacts including morbidity, mortality, delivery potential, public perception of fear and disruption, and preparedness needs. Category A agents are considered critical as they can easily spread between people, cause high mortality, have major public health impacts, induce public panic and disruption, and require special preparedness actions.