Unusual genotypic distribution of Orientia tsutsugamushi strains causing human infections on Jeju Island

We investigated the clinical characteristics and serologic types of tsutsugamushi disease on the largest island of South Korea. There were 141 patients with tsutsugamushi disease at Jeju National University Hospital and Seogwipo Medical Center between November of 2003 and December of 2012. Median age of patients was 61 years, and 59% were women. The major clinical manifestations were fever (80.5%) and skin rash (55.7%), with eschars evident in 75.8% of the patients. Genotype analysis of Orientia tsutsugamushi was conducted in 33 specimens. The genotype was identified as Boryong type in 17 of 33 patients and Taguchi type in 15 of 33 patients. In our study, although the Taguchi genotype is rarely reported in the endemic area, it was common on Jeju Island. This genotype may be associated with mild and moderate forms of tsutsugamushi disease.