Eschar Investigations in Scrub Typhus

Overview

This is an observational study of patients with scrub typhus (rapid diagnostic test/quantitative polymerase chain reaction (RDT/qPCR) positive) and an inoculation eschar present on examination, recruited from Chiangrai Prachanukroh Hospital, North of Thailand. In this study, we aim to: * Investigate relevant pathogen dissemination dynamics, early innate immune response, and pathogen-host interactions in scrub typhus using a minimal set of easily accessible samples; the inoculation eschar (crust or biopsy), whole blood and - where possible - a lymph node fine-needle aspiration (FNA). * Determine the potential use of the inoculation eschar for improving early diagnostics and assessing the diversity of human pathogenic strains; by evaluating non-invasive swabs and scrapings, as well as biopsies for molecular diagnostics templates. * Dissect the underlying patho-biology associated with the inoculation eschar and in a subgroup, including the draining lymph node; by defining the spectrum of infected cells via microscopy and double-immune labeling; by determining cytokine and RNA gene expression profiles in blood peripheral blood mononuclear cell (PBMCs) and eschar samples. Data sharing: No future analysis or study of legacy data/specimens including data sharing for purposes not specified in the protocol will be done without seeking further regulatory (EC/IRB) approval * Any requests for data sharing will be considered by MORU's data sharing committee * Any data subsequently shared will be anonymised and will not include personal identifiers

Scrub typhus patients will be recruited into the scrub typhus patient (EXP) arm of the study. There will be 3 sub-groups: * EXPa (n=12) will have blood and non-invasive eschar samples collected (consent to study, declined biopsy). * EXPb (n=12) will have blood, non-invasive eschar samples, and an eschar biopsy collected (consent to study, draining lymph node (LN) inaccessible). * EXPc (n=12) will have blood, non-invasive eschar samples, eschar biopsy, and LN FNA collected (consent to study, draining LN accessible). Samples will be collected at baseline (all) and 2 weeks (blood only). Control participants will be recruited into the scrub typhus control. \- EXC (n=12) are healthy individuals, attending hospital for elective/minor surgery or treatment of minor skin injury, and normally reside in a scrub typhus endemic region. Blood and a skin sample will be collected at baseline only.