Overview of Rickettsial and Related Infections By William A Petri, Jr, MD, PhD, University of Virginia School of Medicine Reviewed / Revised Mar 2022 | Modified Sep 2022 View Patient Education Symptoms and Signs Diagnosis Treatment Key Points Topic Resources Meningococcemia Measles (Macular Rash) Rubella Rocky Mountain Spotted Fever Scrub Typhus Diseases Caused by Rickettsia... Rickettsial diseases (rickettsioses) and related diseases (anaplasmosis, ehrlichiosis, Q fever, scrub typhus) are caused by a group of gram-negative, obligately intracellular coccobacilli.