Genotypic identification of Orientia tsutsugamushi strains causing scrub typhus disease in southern Sri Lanka

Abstract

Scrub typhus (ST) is a febrile illness in human caused by intracellular bacterium Orientia tsutsugamushi (OT). OT is transmitted to humans via a chigger bite leaving an eschar at the bite site. High genotypic diversity of OT is a major obstacle in developing diagnostics and vaccines. Little is known regarding OT genotypes in Sri Lanka (SL). Present study determined the OT genotypes in Southern Province, SL. A total of 13 eschars, 4 peripheral blood cell samples (PBCs) and 5 blood clots (BCs) were collected from 22 clinically suspected ST patients between 2018 and 2020. Specimens were stored in RNAlater at -80 oC prior to analysis and DNA was extracted with DNeasy Blood and Tissue DNA extraction kit (Qiagen). Partial tsa56 gene locus (483bp) was amplified by nested Polymerase Chain Reaction (PCR), and sequenced.