In a collaborative study involving USAMRIID and the National Institute of Allergy and Infectious Diseases (NIAID), investigators demonstrated that postexposure vaccination can shorten the duration of antibiotic treatment required to protect against inhalational anthrax. The findings, which appear in this week's online edition of Proceedings of the National Academy of Sciences, could have important implications for public health management of anthrax bioterrorism events.

Anthrax is caused by the spore-forming bacterium Bacillus anthracis, and causes three types of disease--cutaneous, gastrointestinal, and inhalational--depending upon the route of exposure. Inhalational anthrax--the type likely to occur following a bioterrorist attack--is difficult to diagnose early, and despite antibiotic therapy, has a high fatality rate. In addition, because anthrax spores can remain in the body for extended periods, antibiotic treatment is typically recommended for 60 days or more following exposure.

As noted by the authors, following the 2001 anthrax attacks in the United States, approximately 10,000 people were offered 60 days of antibiotic therapy to prevent inhalational anthrax. Adverse events associated with this regimen--including diarrhea, nausea, vomiting, and dizziness--were commonly reported. More importantly, only about 44 percent of people completed the whole 60-day course. Thus, minimizing the duration of postexposure antibiotic treatment could be crucial to a successful defense against a large-scale anthrax attack.

In the study, two groups of rhesus macaques were exposed to very high amounts of anthrax spores by aerosol. Both groups were then given c
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Contact: Caree Vander Linden
Caree.Vanderlinden@us.army.mil
301-619-2285
US Army Medical Research Institute of Infectious Diseases
1-May-2006