Bacterial Zoonotic Pathogens as Bioterroristic Agents

Abstract

First reports on biological warfare date as early as the fourteenth century BC, while bioterrorism is a phenomenon of modern times. Bioterrorism means the deliberate release of viruses, bacteria, or other agents used to cause illness or death in people, animals, or plants. Infectious agents or their toxins, often known for long as the cause of classical infectious diseases may be used for bioterroristic purposes, but not all of them are equally suited as biological weapons.

Anthrax, caused by Bacillus (B.) anthracis, a gram-positive spore-forming rod, is a very long known animal disease with zoonotic potential. The ability to form endospores makes B. anthracis especially suitable for bioterroristic use as these endospores are highly resistant to environmental influences, disinfectants, heat, or radiation and can easily be aerosolized. B. anthracis possesses two main virulence factors, the anthrax toxin and the ability of capsule formation. Both virulence factors are plasmid-encoded. Human anthrax manifests itself as cutanaeous anthrax, alimentary anthrax, inhalational anthrax, and sometimes as injectional anthrax, especially in intravenous drug addicts.

Tularemia is a zoonosis with a broad host range. Wildlife animals are the main reservoir for humans. It is especially a disease of hares, rabbits, and other rodents. As humans are highly susceptible for tularemia, its agent, Francisella (F.) tularensis, which can be transmitted by arthropod vectors, by contact, by contaminated water or food, or even by aerosol, is supposed to have a bioterroristic potential, although no attempts of bioterroristic misuse have been known so far. While the most virulent subspecies F. tularensis ssp. tularensis is confined to North America, a less virulent subspecies, F. tularensis ssp. holartica, is widely distributed over the Northern hemisphere, predominantly over North America, Scandinavia, Russia, and Japan. Human tularemia is a febrile, inflammatory disease, which starts with unspecific symptoms like headache, growing pains, fever, chills, and weakness. The further course of disease depends on the agent’s virulence and its route of entry.