anthrax, a much more serious disease. But the most lethal manifestation of anthrax is caused by inhalation of spores, causing a severe disease that is often fatal. Inhalational anthrax is generally rare and is mainly observed in individuals who work with animal skins. Inhalational anthrax in individuals not likely to have suffered occupational exposure, however, can be a sign of a biological attack with B. anthracis spores.
When appropriately prepared, anthrax spores are premier agents for biological warfare and bioterrorism because they can be produced in prodigious quantities in a form that can be aerosolized and inhaled. These factors, plus the high mortality associated with inhalational anthrax, make B. anthracis a serious military and bioterrorism threat. For these reasons, the appearance of B. anthracis in the 2001 mailings launched a major public health and criminal investigation.