ABSTRACT
Rickettsial infections are caused by fastidious, obligately intracellular bacteria which contain both DNA and RNA, multiply by binary fission, and are inhibited by antibiotics. The Q fever agent Coxiella burnetii is classified separately from the Rickettsia genus proper on the basis of several differences. Rocky Mountain spotted fever (RMSF) (caused by Rickettsia rickettsii), Q fever (Coxiella burnetti), endemic murine typhus (R. mooseri), epidemic/recrudescent typhus (R. prowa-zekii), and rickettsialpox (R. akari) are rickettsial diseases which occur in the US The lung pathology seen in RMSF is directly related to R. rickettsii infection of the pulmonary microcirculation and the attendant vasculitis. Walker et al. studied autopsy material from ten patients (age range 2.5 to 65 years) with fatal RMSF to elucidate the pathogenesis of pneumonitis in this disease. The distribution of interstitial pneumonitis correlated with areas of alveolar septal rick ettsial infection.
