Why Be Concerned About Anthrax
Inhalational anthrax is the most lethal form of anthrax disease, with fatality rates reaching up to 90%, depending on whether aggressive treatment is provided soon enough after exposure7. Because of their small size, anthrax spores can be easily aerosolized, inhaled, and enter through the lower respiratory mucosa in humans. A single breath of anthrax may contain enough spores to cause disease. Accordingly, aerosolized anthrax spores are the form most likely to be used in an anthrax bioterrorism attack.
In the fall of 2001, there were 11 cases of inhalational anthrax following the intentional spread of anthrax spores through the United States Postal Service. The case fatality rate among these individuals with inhalational anthrax disease was 45% (5/11), even with the administration of multiple antibiotics and aggressive, intensive care.
In a report published by World Health Organization (WHO) consultants it was estimated that in just three days following the release of 50 kg of anthrax spores along a 2-km area upwind of a city with a population of 500,000, approximately 125,000 infections would occur, with about 95,000 of these cases resulting in death8. Compared to similar scenarios of the release of other bioterrorism agents, this predicted number of deaths possible after an anthrax attack is substantially higher. It has also been predicted that an aerial release of anthrax spores along a 100-km line under ideal meteorologic conditions could result in a lethality rate of 50% as far as 160 km downwind9.
7Anthrax Fact Sheet. Centers for Disease Control and Prevention.
8Report of a WHO group of consultants. Health aspects of chemical and biological weapons. Geneva: World Health Organization; 1970. p. 97-9.
9Science Applications International Corporation. Effectiveness of medical intervention against battlefield levels of Bacillus anthracis. 1993.
