Outbreak of scrub typhus in Puducherry & Tamil Nadu during cooler months

Abstract

Background & objectives:The southern part of India has witnessed an increase in scrub typhus (ST) during the past ten years. ST outbreaks occurred during winter months but at intervals of one to three years. With only a few reports of ST in Puducherry, this study was undertaken to look for the persistence of ST cases in Puducherry and Tamil Nadu in the winter months.Methods:During relatively cooler months of September, 2012 to March, 2013, a total of 45 patients with fever and clinical suspicion of ST and who provided both acute and convalescent blood samples were included. Total WBC, platelet counts, serum creatinine, liver enzymes levels and a rapid immunochromatographic test (RICT) for ST were first done. Paired serum samples were analysed by two specific tests - ST IgM and IgG ELISA- and a non-specific, but widely used Weil-Felix (WF) test.Results:Of the 45 patients, 21 adults and seven children were confirmed as ST based on clinical and laboratory findings, and positivity in specific serological test(s). Setting ST IgM and IgG ELISA as reference, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for RICT were 91.67, 85.71 per cent; 90.48, 100 per cent; 91.67, 100 per cent and 90.48, 80.95 per cent, respectively. Similarly, for WF the values were 83.33, 75 per cent; 95.24, 100 per cent; 95.24, 100 per cent and 83.33, 70.83 per cent, respectively.Interpretation & conclusions:ST continues to persist in the cooler months in Puducherry and neighbouring Tamil Nadu with fever and myalgia as prominent features. None of the tests evaluated in this study was found to be ideal, but ST IgM/IgG ELISA was useful for batch testing and the non-specific WF test can be used in resource poor settings.

Clinical and demographic study of scrub typhus in a tertiary care teaching hospital in Puducherry during 2015-2018

“…A study by Vivekanandan et al, found eschar in only 46% of patients with scrub typhus, whereas a study by Patricia et al, reported eschar in 21%. 6,8 In this present study, eschar was found in 22.9% of the patients, correlating with findings of Patricia et al 6 Thrombocytopenia, was observed in 28% of the patients which was comparable with the reports by Stephen S et al 9 Scrub typhus can produce severe complications, especially when the diagnosis and treatment is delayed. 8 Acute respiratory distress syndrome (ARDS) was the most common complication reported in this study.…”

Abundance & distribution of trombiculid mites & Orientia tsutsugamushi, the vectors & pathogen of scrub typhus in rodents & shrews collected from Puducherry & Tamil Nadu, India

“…Recently, outbreaks of scrub typhus have been reported all over India including southern States67. It has emerged as an important cause of febrile illness in Puducherry and adjoining areas of Tamil Nadu, and confirmed cases have been reported every year8. However, no information is available on the occurrence of the causative agent of the disease, O. tsutsugamushi , on the host animals such as rodents and shrews and its vectors.…”

Validation of Geno-Sen's scrub typhus real time polymerase chain reaction kit by its comparison with a serological ELISA Test

“…Scrub typhus (ST) caused by Orientia tsutsugamushi and transmitted by the chigger mites was once considered a disease of the shrub jungle/war and confined to “Tsutsugamushi triangle.”[ 1 ] Now ST is spreading across the world with more endemic foci being identified in India, where ST is an emerging infectious disease and reported from almost every state. [ 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 ] A few minor ST epidemics have occurred in Southern India, with the diagnosis mostly based on the serological evidence along with clinical presentation. [ 2 3 4 5 6 8 9 10 11 12 13 14 15 18 20 23 24 25 ] Application of molecular techniques for diagnosing ST has been reported by very few Indian researchers in the recent past.…”

“…[ 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 ] A few minor ST epidemics have occurred in Southern India, with the diagnosis mostly based on the serological evidence along with clinical presentation. [ 2 3 4 5 6 8 9 10 11 12 13 14 15 18 20 23 24 25 ] Application of molecular techniques for diagnosing ST has been reported by very few Indian researchers in the recent past. [ 7 16 19 21 22 ] In this study, we compare ST patients' IgM antibody response in enzyme-linked immunosorbent assay (ELISA) and presence of O. tsutsugamushi 56-kDa type-specific gene in real time polymerase chain reaction (PCR) quantitative PCR (qPCR), using a commercial kit, which has become available in India only recently and being validated for the first time.…”