Cause
Tularemia is caused by the bacterium called Francisella tularensis. This bacterium is found naturally in small mammals such as rabbits, rodents, and hares, as well as the bugs that feed on these animals. The bacterium can survive for weeks at low temperatures in water, moist soil, hay, straw, or decaying animal carcasses. F. tularensis has two subspecies.
- Type A is common in North America and may be highly virulent (potent) in humans and animals.
- Type B probably causes all human tularemia in Europe and Asia.