Scrub typhus: clinical, pathologic, and imaging findings.

Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi. The main pathologic change is focal or disseminated vasculitis caused by the destruction of endothelial cells and the perivascular infiltration of leukocytes. The diagnosis of scrub typhus is based on the patient's history of exposure, clinical features, and results of serologic testing. Regional and generalized lymphadenopathy is common. The pulmonary manifestations of scrub typhus include interstitial pneumonia, interstitial edema, and hemorrhage caused by vasculitis. Abdominal manifestations include splenomegaly, periportal edema, gallbladder wall thickening, and lymphadenopathy. Although the severity of scrub typhus varies considerably, involvement of the central nervous system is seen in almost all patients and can result in meningoencephalitis. A high degree of clinical suspicion and familiarity with the various radiologic manifestations of scrub typhus allow early diagnosis and timely initiation of appropriate therapy, and thereby may help reduce patient morbidity. Copyright RSNA, 2007.