any of a group of very small rod-shaped bacteria that live in biting arthropods (as ticks and mites) and cause disease in vertebrate hosts; they cause typhus and other febrile diseases in human beings
造句
用作名詞(n.)
It is caused by Rickettsia rickettsii and spread by ticks of the genus Dermacentor. 該病由立克次氏體引起，由革蜱屬的蜱類傳播。