Edifications on Indirect IgM ELISA and Immunofluorescence assay (IFA) of scrub typhus in humans and erudition of Orientia tsutsugamushi in the vector of cohabiting rodents

Scrub typhus is a vector-borne disease caused by Orientia tsutsugamushi, propagated into humans by the bite of infected mite belonging to genus Leptotrombodium. The present study was conducted in the Nagpur region of central India aiming towards a survey of cohabiting rodents and their potential vectors for the presence of Orientia tsutsugamushi by PCR method. The study also emphasizes serological diagnosis of the disease by employing indirect IgM ELISA and IFA amongst the human cases of pyrexia of unknown origin. Indirect IgM ELISA recorded 39.69% (31/92) seropositive patients, further processing of ELISA positive samples for IFA revealed 67.74 % (21/31) positivity for Boryong, Gilliam, Karp, and Kato serotypes. A total of 50 rodents were trapped from the cohabit areas of the patients. Three different types of rodents were identified; among which, Rattus bandicoot was highest. From these rodents, 164 vectors viz mites, lice, and fleas were collected. The highest chiggar index was recorded for Ornithonyssus biscotti mites (3.4). This study prompts a detailed analysis of different species of rodents and vectors in the said endemic region.