Genotypic and epidemiological analysis of Orientale tsutsugamushi infection in Guangzhou, 2012–2016

Objective To analyze the genotypic and epidemiological characteristics of Orientia tsutsugamushi infection in Guangzhou from 2012 to 2016.

Methods Whole blood samples were collected from the clinical diagnosed patients. 56kDa type-specific antigen gene segment of O. tsutsugamushi was amplified by using nested-polymerase chain reaction. Sequences were analyzed by alignment with GenBank and the phylogenetic tree was established by using software MGEA 5.0.

Results A total of 220 samples were detected to be positive (24.3%) from 906 samples, including 138 strains of Karp, 29 strains of Kato, 39 strains of Gilliam, 13 strains of TA763 and 1 strains of uncertain genotype. Two incidence peaks were observed, one was during May - June and another one was during September - October. The cases mainly occurred in rural areas of Conghua and Zengcheng.

Conclusion The incidence of scrub typhus in Guangzhou was in increase and the genotypes of O. tsutsugamushi showed diversity, but Karp was predominant. It is necessary to strengthen the molecular epidemiology surveillance for O. tsutsugamushi in Guangzhou.