|—n , pl -siae, -sias|
|any of a group of parasitic bacteria that live in the tissues of ticks, mites, and other arthropods, and cause disease when transmitted to man and other animals|
|[C20: named after Howard T. Ricketts (1871--1910), US pathologist]|
Rickettsia Rick·ett·si·a (rĭ-kět'sē-ə)
A genus of gram-negative bacteria that are carried as parasites by many ticks, fleas, and lice and cause diseases such as typhus, scrub typhus, and Rocky Mountain spotted fever.