The most typical signs and symptoms of rickettsial diseases include: fever, headache, nausea, vomiting, muscle aches, rashes, swollen lymph glands, abdominal pain, hypotension, and difficulty breathing. Commonly, a small hard black sore (clinically known as an eschar) tends to appear at the bite site where the infection started. In more severe cases, respiratory distress, acute renal failure, brain damage, or mortality may occur.