The Need for Geographic Location Specific Optical Density Cut-offs for IgM ELISA Serology to Diagnose Scrub Typhus in Children

摘要

We read with interest the article on detection of immunoglobulin M and immunoglobulin G antibodies against Orientia tsutsugamushi for scrub typhus (ST) diagnosis by Gupte, et al. [1]. This study was done to estimate the regional cut-off of optical density (OD) values of serum IgM antibodies by ELISA for the diagnosis of ST. Authors had successfully determined regional cut off of OD value for IgM antibodies, which will be utilized in diagnosing ST in that area. This study has shed light into one of the most obvious pitfalls in diagnosing ST by serology (IgM ELISA) i.e., using an inaccurate, arbitrary OD value cut off for diagnosis. This has serious implications that are applicable beyond the study population.