Rickettsia parkeri (abbreviated R. parkeri) is a Gram-negative intracellular bacterium. R. parkeri causes mild spotted fever disease in humans, (sometimes referred to as American tick bite fever), characterized by headache, rash, fever, and an eschar at the site of tick attachment. It is transmitted via tick bite and found mainly in the Western Hemisphere. Doxycycline and chloramphenicol are the most common drugs of choice for reducing the symptoms associated with disease caused by R. parkeri.