Inactivation of biological threat agents with nonionizing radiation

The terrorist attack in September 2001, with the dissemination of Bacillus anthracis spores in letters sent through the U.S. Postal Service, brought home the reality of bioterrorism. These attacks have heightened concerns about future largescale aerosol attacks with powders of B. anthracis spores and other pathogens that cause smallpox, pneumonic plague, tularemia, and viral hemorrhagic fevers, as well as toxins such as botulinum toxin, ricin or Staphylococcus enterotoxin B. Means to prevent the use of these agents, and to manage the consequences of their use, have become a high priority. One of the tools that can play a role in disease prevention and consequence management is nonionizing radiation in the form of germicidal short-wavelength ultraviolet (UV) light. This article presents background information on the pathogen Bacillus anthracis, the causative agent for anthrax, and its susceptibility to killing by germicidal UV. The results of two experimental studies are also presented that examine UV inactivation of B. anthracis vegetative cells and spores, and spores of closely related Bacillus species, in suspension, dried on surfaces, and as free-flowing powders.