Molecular epidemiology of scrub typhus in Taiwan during 2006–2016

Abstract

Scrub typhus is the most common endemic vector-borne disease in Taiwan. We identified a total of 4,857 laboratory-confirmed cases during 2006–2016 with hyperendemic foci on offshore islands, including Penghu (778 cases, 16.0%) and Kinmen (716 cases, 14.7%), and eastern Taiwan, including Taitung (628 cases, 12.9%) and Hualien (508 cases, 10.5%). Scrub typhus cases occur year-round throughout Taiwan, with a summer peak in June and July. A total of 545 O. tsutsugamushi isolates were successfully obtained from patients infected in diverse geographic areas, including Taiwan and three offshore islands, and the complete open reading frame of the 56 kDa type-specific antigen gene (tsa56) sequence of these isolates was examined. High phylogenetic diversity was found in these isolates, which could be grouped into 36 distinct sequence types. Most isolates belonged to the Karp (49.9%; 272/545), followed by the TW-22 (17.8%; 97/454) and Kawasaki (14.7%; 80/545) genotypes. In conclusion, our data indicate the widespread presence of tsa56 genotypes closely related to Thailand and Korean strains and the presence of the unique endemic strains TW-12, TW-22, TW-29, and TW-36 in Taiwan.

Molecular Detection of Multiple Genotypes of Orientia tsutsugamushi Causing Scrub Typhus in Febrile Patients from Theni District, South India

“…However, only two Karp-related sequences (ON156000-VCRC and ON156001-VCRC) showed 100% query coverage and percentage identity with the Ot GroEL DNA sequence from Japan. The higher sequence homology we obtained with the Ot sequence submitted from S. Korea, China, Japan, and the United Kingdom could possibly explain the trafficking of pathogens from this country to southern India, probably through migratory birds [ 21 , 22 ], but needs further confirmation.…”