The book presents the current state of rickettsial infections: spotted typhus, tick-borne spotted fever, Q fever, and ehrlichiosis. In the context of globalization, ecological imbalance, and climate change, rickettsioses have become diseases that threaten humanity. They are spreading to new areas where they did not previously exist. New, previously unknown rickettsial infections with new causative agents have been discovered. According to the World Health Organization, rickettsial infections are a permanent problem that requires the combined efforts of specialists from around the world to solve. The book is written in Bulgarian and English and brings together the works of some of the best rickettsiologists from around the world.