Acute respiratory distress syndrome associated with scrub typhus: diffuse alveolar damage without pulmonary vasculitis

Pathologic findings of scrub typhus have been characterized by vasculitis of the microvasculature of the involved organ resulting from a direct invasion by Orientia tsutsugamushi. We experienced a case of acute respiratory distress syndrome (ARDS) associated with scrub typhus. The case was proven by eschar and high titer of serum IgM antibody (positive at 1:1280). Open lung biopsy showed diffuse alveolar damage (DAD) in the organizing stage without evidence of vasculitis. Immunofluorescent antibody staining and polymerase chain reaction for O. tsutsugamushi failed to demonstrate the organism in the lung tissue. The patient expired due to progressive respiratory failure despite doxycycline therapy. Immunologic mechanism, without direct invasion of the organism, may participate in the pathogenesis of ARDS associated with scrub typhus.