risk. The primary goal of prepositioning is to increase the speed of MCM distribution and dispensing during a high-consequence biological incident.

In the event of an attack with aerosolized Bacillus anthracis (anthrax), administering oral antibiotics immediately following exposure has demonstrated the potential to save lives (Friedlander et al., 1993). Anthrax exists in vegetative and spore forms. The spore is an extremely hardy, dormant form of the bacterium; it can persist for decades in the environment. When a spore enters a live host, it transforms into its vegetative, disease-causing state. Once active, anthrax produces toxins that are lethal. Given its high lethality and potential ease of acquisition, production, and dissemination, the release of aerosolized anthrax is the type of high-consequence biological attack that is of most concern.

The Center for Biosecurity at the University of Pittsburgh Medical Center notes that anthrax is considered one of the most serious bioterrorism threats for the following reasons (UPMC Center for Biosecurity, 2007):

• widespread availability of starter cultures in culture collection banks around the world;

• widespread natural availability in endemic areas;

• wide commercial availability of equipment and techniques for mass production and aerosol dissemination;

• robustness of anthrax spores, making anthrax easier to weaponize for aerosol dissemination than other biological agents of concern;

• high fatality rate in untreated inhalational cases;

• relatively low infectious dose, based on nonhuman primate animal data;

• risk of antibiotic-resistant strains that exist in nature or that may be easily cultivated for use in an intentional release; and

• recent use of anthrax during the 2001 Amerithrax attacks.

During the 2001 Amerithrax attacks, the median incubation time for inhalational anthrax was 4 days (Jernigan et al., 2001). It is estimated that if oral antibiotics are not administered before the onset of clinical symptoms, the mortality rate, even in intensively treated cases, could potentially exceed 90 percent (UPMC Center for Biosecurity, 2007). In the few inhalational anthrax cases treated in 2001, intensive clinical treatment resulted in a mortality rate of 45 percent (Jernigan et al., 2001). Depending on the initial infective dose and when the exposure is detected, the effective window for antibiotic administration may be considerably less than 96 hours. As a matter of USG policy, current requirements have set the objective of delivery of oral antibiotics to potentially exposed individuals within 48 hours of the decision to do so (CDC, 2010a). Prepositioning can enable more rapid dispensing of oral antibiotics following an anthrax attack, thus increasing



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