Comparison of chest radiographic findings between severe fever with thrombocytopenia syndrome and scrub typhus Single center observational cross-sectional study in South Korea

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by SFTS virus (SFTSV) which involves multiple organ systems, including lungs. However, there is limited data on lung involvement of SFTS. Therefore, the present study investigated the chest radiographic findings of SFTS, including computed tomography (CT), and compared these with those of scrub typhus, which is the most common tick-borne illness in South Korea and share risk factors and occur in similar settings. Medical records of patients with confirmed SFTS and scrub typhus in a tertiary hospital in Seoul (South Korea), between January 2014 and June 2018, were reviewed. Initial chest radiography and CT were reviewed by 2 experienced radiologists. A total of 39 patients with SFTS and 101 patients with scrub typhus were analyzed. All patients except 3 patients with scrub typhus in both groups received chest radiography. Cardiomegaly (90%) and patchy consolidation with ground glass opacity (GGO) pattern (31%) were more common in SFTS group than scrub typhus group (20%, P<.001 and 2%, P<.001, respectively). About half of each group received chest CT. Consolidation (29%) and pericardial effusion (24%) were more common in SFTS group than scrub typhus group (6%, P=.02 and 4%, P=.008, respectively). Interstitial thickening in chest radiography (58%) and chest CT (65%) was more frequent in scrub typhus group than SFTS group (18%, P<.001 and 19%, P<.001, respectively). Cardiomegaly with/without pericardial effusion and patchy consolidation with GGO pattern were more frequent in SFTS group, whereas interstitial thickening was more frequent in scrub typhus group. These findings will assist the early differentiation of SFTS from scrub typhus.