Masqueraders Around Disaster: Clinical Features of Scrub Typhus in Fukushima, Japan

Abstract

Abstract Background Scrub typhus (ST) is endemic in Fukushima, with the largest number of cases reported in Japan from 2006 to 2011. Although ST is highly treatable, its atypical clinical presentation impedes diagnosis, causing delays in treatment. Methods We review the clinical features of ST in adults from 2008 to 2017 at Ohta Nishinouchi General Hospital in Fukushima, Japan. Results Fifty-five cases (serotype Karp 24, Irie/Kawasaki 21, Hirano/Kuroki 10) of ST were confirmed via serology based on elevated IgM and IgG and polymerase chain reaction positivity of eschar samples. The mean age was 69 years old, and 64% were female. The case fatality rate was 1.8% (1/55). Approximately 70% of cases (38/55) were not diagnosed as ST upon the initial clinic visit. Inappropriate use of antibiotics was identified in 22% of the cases (12/55). In terms of atypical clinical features, the fever, rash, and eschar triad were absent in 31% of cases (17/55). Approximately 11% of cases presented without eschar (6/55, Karp: 1, Irie/Kawasaki: 1, Hirano/Kuroki: 4). Moreover, severe complications were observed in association with Hirano/Kuroki, with shock and disseminated intravascular coagulation in 7% of cases (4/55), Thus, while 53% of cases presented with the typical triad (29/55), unusual complications and atypical features occurred in 40% (22/55). The fatality rate was 1.8% (1/55). Conclusions The diagnosis of ST becomes clinically challenging in the absence of typical features. In Fukushima, an endemic area of ST, an atypical presentation involving multi-system disease is common.