Francisella tularensis is a pathogenic species of Gram-negative, aerobe, rod-shaped coccobacillus. It is the causative agent of tularemia, the pneumonic form of which is often lethal without treatment. It spreads easily by aerosol and has high virulence making this a Tier 1 Select Agent by the U.S. government. In nature this strain can survive for several weeks at low temperatures in animal carcasses, soil, and water.