By Mayo Clinic Staff. Tularemia is a rare infectious disease that typically attacks the skin, eyes, lymph nodes and lungs. Tularemia â also called rabbit fever or deer fly fever â is caused by the bacterium Francisella tularensis. The disease mainly affects mammals, especially rodents, rabbits and hares, although it can also infect birds, sheep, and domestic animals, such as dogs, cats and hamsters. Tularemia spreads to humans through several routes, including insect bites and direct exposure to an infected animal. Highly contagious and potentially fatal, tularemia usually can be treated effectively with specific antibiotics if diagnosed early.