An occurrence or imminent threat of an illness or health condition that (1) is believed to be caused by any of the following: (a) Bioterrorism; (b) Appearance of a novel or previously controlled or eradicated infectious agent or biological toxin; (c) Natural disaster; (d) Chemical attack or accidental release; (e) Nuclear attack or accident; and (2) poses a high probability of any of the following harms occurring in a large number of the affected population: (a) Death; (b) Serious or long-term disability; (c) Widespread exposure to infectious or toxic agent posing significant risk of substantial future harm (the center for Law and the Public's Health at Georgetown and Johns Hopkins Universities)