Scrub Typhus and Molecular Characterization of <i>Orientia tsutsugamushi</i> from Central Nepal

oleh: Rajendra Gautam, Keshab Parajuli, Mythili Tadepalli, Stephen Graves, John Stenos, Jeevan Bahadur Sherchand

Format: Article
Diterbitkan: MDPI AG 2021-04-01

Deskripsi

Scrub typhus is a vector-borne, acute febrile illness caused by <i>Orientia tsutsugamushi</i>. Scrub typhus continues to be an important but neglected tropical disease in Nepal. Information on this pathogen in Nepal is limited to serological surveys with little information available on molecular methods to detect <i>O. tsutsugamushi</i>. Limited information exists on the genetic diversity of this pathogen. A total of 282 blood samples were obtained from patients with suspected scrub typhus from central Nepal and 84 (30%) were positive for <i>O. tsutsugamushi</i> by 16S rRNA qPCR. Positive samples were further subjected to 56 kDa and 47 kDa molecular typing and molecularly compared to other <i>O. tsutsugamushi</i> strains. Phylogenetic analysis revealed that Nepalese <i>O. tsutsugamushi</i> strains largely cluster together and cluster away from other <i>O. tsutsugamushi</i> strains from Asia and elsewhere. One exception was the sample of Nepal_1, with its partial 56 kDa sequence clustering more closely with non-Nepalese <i>O. tsutsugamushi</i> 56 kDa sequences, potentially indicating that homologous recombination may influence the genetic diversity of strains in this region. Knowledge on the circulating strains in Nepal is important to the development of diagnostic tests and vaccines to support public health measures to control scrub typhus in this country.