Francisella tularensis: Causative Agent of Tularemia and Biothreat Agent

The bacterium Francisella tularensis subspecies tularensis (also designated F. tularensis type A) is a potential biological warfare agent, classified as Tier 1 Select Agent by the US Centers for Disease Control and Prevention (CDC). F. tularensis, one of the most infectious and virulent bacteria known, is responsible for tularemia, a zoonosis transmitted to humans through animal bites, contact with animals, contaminated body fluids or feces, or by consumption of foods of animal origin. Inhalation of a low dose of F. tularensis type A is sufficient to cause a human disease with an associated lethality that may reach 30–60% if untreated. F. tularensis adapts to various and extreme environments.