Tularemia is a potentially serious illness that occurs naturally in the United States. It is caused by the bacterium Francisella tularensis that is found in animals (especially rodents, rabbits, and hares). Symptoms of tularemia could include: sudden fever, chills, headaches, diarrhea, muscle aches, joint pain, dry cough and progressive weakness. People can also catch pneumonia and develop chest pain, bloody sputum and can have trouble breathing and even sometimes stop breathing. Other symptoms of tularemia depend on how a person was exposed to the tularemia bacteria. These symptoms can include ulcers on the skin or mouth, swollen and painful lymph glands, swollen and painful eyes, and a sore throat.