Scrub typhus: radiological and clinical findings

Abstract

Objectives: To describe the radiological and clinical findings of scrub typhus. We retrospectively analysed the radiographic, thin-section CT and clinical features of scrub typhus.

Methods: The study included 75 consecutive patients (median age = 47 years, range = 18-81 years) with scrub typhus. Plain chest radiographs were obtained in all 75 patients and 19 underwent thin-section CT within 6 days of initial radiography. The radiographic and thin-section CT findings were retrospectively analysed by three radiologists.

Results: Most common clinical symptoms were fever (73/75, 98%), myalgia (61/75, 81%) and headache (60/75%, 80%). Rash (59/75, 79%) and eschar (56/75, 75%) were the most common signs. Radiography showed abnormalities in 54/75 (72%) patients. The most frequent findings were parenchymal abnormalities (53/75, 71%) with lower lung predilection including bilateral reticulonodular opacities (30/75, 40%), ground-glass opacity (19/75, 25%), consolidation (19/75, 25%), septal lines (27/75, 36%) and hilar lymph node enlargement (19/75, 25%). Thin-section CT (n = 19) showed ground-glass opacity (17/19, 89%) predominantly in the lower zones. Bronchial wall thickening (11/19, 58%), centrilobular nodules (9/19, 47%) and interlobular septal thickening (9/19, 47%) were less frequent findings.

Conclusions: Scrub typhus is an acute febrile illness characterized by eschar, which usually has a limited course without serious complication. Diffuse bilateral reticulonodular opacities with lower lung predominance was the most frequent radiographic finding. Chest radiography and thin-section CT show pulmonary interstitial disease which may have a component of pulmonary oedema secondary to cardiac dysfunction.