RICKETTSIA. RICKETTSIA Rickettsia are small, gram negative bacteria. They are parasites found in insects such as lice, fleas, and ticks. Rickettsia are responsible for a variety of spotted fevers and several types of typhus -- exanthematic typhus spread by lice, murine typhus spread by rat fleas or rat feces, and scrub typhus. These conditions which ravage various countries all have the same symptoms, including generalized vesicular rash resembling chicken pox, fever and chills, headaches whe