Ehrlichiosis and Anaplasmosis 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 Prevention Key Points More Information Topic Resources Ixodes scapularis Deer tick Deer ticks Ehrlichiosis and anaplasmosis are caused by rickettsial-like bacteria.