Tularemia is a zoonotic infection caused by the highly infectious bacterium Francisella tularensis. F. tularensis infections can occur via insect or tick bites, cutaneous contact with infected animal carcasses, ingestion of contaminated food and water, or inhalation of viable organisms. The type and severity of tularemia depends on the strain, dose, and route of infection. Cutaneous tularemia is the most common form of human disease, but is rarely fatal. Inhalation of F. tularensis results in respiratory or pneumonic tularemia and is most common in people in endemic areas who perform tasks that predispose them to infectious aerosols. Untreated respiratory forms of disease have mortality rates of >30%. The infectious dose of F. tularensis by the pulmonary route is as low as 10 microorganisms.