ABSTRACT
Despite the clear devastating effects of bioweapons on humans, animals, plants and the environment, some continued to build biological weapons or pursued research to construct the most lethal microbes/toxins. As the danger of their use is real, there is a clear need to identify microbial agents/ toxins that can be used as biological weapons, their mode of action and be prepared in the unfortunate event of a bioterror attack. Potentially any microbe or microbe-derived toxin capable of causing harm or human misery is a bioweapon agent. Among others, smallpox virus, anthrax and botulism toxins are considered the most significant bioweapons. To this end, the Centers for Disease Control and Prevention (CDC) in Atlanta, GA, USA published a list of critical biological agents in 2000 and divided them into three categories (Fig. 1). The most likely entry of these pathogens/toxins is inhalation into the lungs, ingestion of contaminated food or water or absorption of toxins through the skin presenting an easy mode of transmission to a large number of people. Of interest, the category A agents are most effectively transmitted via aerosols and are the most devastating bioweapons. In addition, our ability to genetically modify organisms may present serious consequences. For example, it is shown that genetic modification of mousepox virus can have fatal consequences for mice, which are normally resistant to this virus. Among category A, anthrax has gained the most attention in recent years. This is due to anthrax (Bacillus anthracis) spores enclosed in a letter and mailed to the US media and government officials in 2001 which resulted in several fatalities. The outcome confirmed the dangers of bioweapons but more importantly the simplicity in their use and dissemination. The potential of anthrax as a bioweapon is due to its ability to readily form spores which can be stored indefinitely and can survive in the dry air for several hours. They are Gram-positive bacteria and can cause serious gut (gastrointestinal anthrax) or skin infections (cutaneous anthrax) but if inhaled, they can produce inhalational anthrax with fatal consequences (mortality rate of more than 90%). The incubation period varies from a few hours to a few days. The clinical symptoms include fever, malaise, fatigue, respiratory failure, septicemia and finally death within 24 h (even with treatment). As anthrax is non-contagious in humans, their effects are limited to the applied area. In contrast, the smallpox virus is highly contagious and can result in global pandemics with a mortality risk of 30%. Bacillus anthracis is normally present in soil worldwide, and
there are approx. 200 - 2,000 annual cases of anthrax (mostly cutaneous). It is the inhalation of anthrax that is most associated with bioterror and has the potential of a bioweapon.
