Abstract

Scrub typhus, caused by the proteobacterium, Orientia tsutsugamushi, is re-emerging in several regions of Asia, particularly in India. Severity of infection and clinical presentations are known to vary with the infecting prototype/genotype. Hence genotypic characterization and distribution of various genotypes is of clinical and epidemiological importance. One hundred and forty five suspected scrub typhus cases, reporting to a tertiary care centre in Puducherry, India were investigated for O. tsutsugamushi specific IgM antibodies by ELISA out of which, 135 (93%) were positive. Most cases occurred post-monsoon, peaking in September, and there was a preponderance in young adults. Forty samples tested positive by Nested PCR based on 56kDa gene of O. tsutsugamushi and amplicons from PCR positive samples were sequenced. Phylogenetic tree constructed using 35 sequences (from nt 20 to nt 130) obtained in the study, along with those retrieved from NCBI site, formed two major branches; one comprising 15 sequences from this study, which aligned with Karp genotype, and the other containing 6 sequences which aligned with a sequence from Vellore, India. The second major branch had 12 sequences, which formed an independent group from the Gilliam prototype. Analysis of association of clinical manifestations with genotypes obtained in the present study showed that the sequences that formed an independent group, were associated with a wide spectrum of clinical manifestations involving multiple organs and more severe manifestations like ARDS and hypotension. The sequences, which branched with Karp prototype were associated with hepatitis, meningitis and Multi-organ disorder syndrome (MODS). The present study thus indicated that different genotypes of O. tsutsugamushi occur in southern regions of India, which were associated with various clinical manifestations. Studies on the occurrence of genotypes will help in development of diagnostic methods and vaccines to curtail the infection.

Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.