pl. n. (sing. rickettsia)
a group of very small nonmotile spherical or rodlike parasitic bacteria that cannot reproduce outside the bodies of their hosts. Rickettsiae infect arthropods (ticks, mites, etc.), through whom they can be transmitted to mammals (including humans), in which they can cause severe illness. The species Rickettsia akari causes rickettsial pox, R. conorii, R. prowazekii, R. tsutsugamushi, and R. typhi cause different forms of typhus, R. rickettsii causes Rocky Mountain spotted fever, and Coxiella burnetii causes Q fever.
• rickettsial adj.
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rick·ett·siae (rĭ-ketґse-e) plural of rickettsia.Medical dictionary. 2011.