Determination of a cut-off value for the serological diagnosis of scrub typhus by detecting anti-Orientia tsutsugamushi immunoglobulin M

Background & objectives: The diagnosis of scrub typhus (ST) is usually done using enzyme-linked immunosorbent assay (ELISA) due to its ease of performance and reading objectivity. The cut-off value for ELISA needs to be calculated for each geographical location as it depends on zonal endemicity of the disease. This study was, therefore, undertaken to calculate the pan-India cut-off for anti-Orientia tsutsugamushi (OT) immunoglobulin M (IgM) by ELISA. Methods: Samples from cases (cases of ST) and controls (voluntary, consenting, healthy adults) were collected by a network of 29 laboratories across India and tested for anti-OT IgM by immunofluorescence assay (IFA), the considered gold standard test. These samples were retested by ELISA for anti-OT IgM and their optical densities (ODs) were used for cut-off estimation by receiver operating characteristic (ROC) curve. Results: Anti-OT IgM ELISA ODs from 273 controls and 136 cases were used for the cut-off estimation. The ODs of the anti-OT IgM ELISA on healthy individuals and those of confirmed ST cases ranged from 0.1 to 0.75 and 0.5 to 4.718, respectively. ROC curve-based cut-off for ELISA was calculated as 0.554 at a sensitivity of 95.2 per cent and specificity of 95.1 per cent. A value of >1 was noted to have a specificity of 100 per cent in diagnosing ST. Interpretation & conclusions: The cut-off calculated for India was similar to the previous cut-off that was used until now.

Neutralization assays for SARS-CoV-2: Implications for assessment of protective efficacy of COVID-19 vaccines

The WHO emergency use-listed (EUL) COVID-19 vaccines were developed against early strains of SARS-CoV-2. With the emergence of SARS-CoV-2 variants of concern (VOCs) - Alpha, Beta, Gamma, Delta and Omicron, it is necessary to assess the neutralizing activity of these vaccines against the VOCs. PubMed and preprint platforms were searched for literature on neutralizing activity of serum from WHO EUL vaccine recipients, against the VOCs, using appropriate search terms till November 30, 2021. Our search yielded 91 studies meeting the inclusion criteria. The analysis revealed a drop of 0-8.9-fold against Alpha variant, 0.3-42.4-fold against Beta variant, 0-13.8-fold against Gamma variant and 1.35-20-fold against Delta variant in neutralization titres of serum from the WHO EUL COVID-19 vaccine recipients, as compared to early SARS-CoV-2 isolates. The wide range of variability was due to differences in the choice of virus strains selected for neutralization assays (pseudovirus or live virus), timing of serum sample collection after the final dose of vaccine (day 0 to 8 months) and sample size (ranging from 5 to 470 vaccinees). The reasons for this variation have been discussed and the possible way forward to have uniformity across neutralization assays in different laboratories have been described, which will generate reliable data. Though in vitro neutralization studies are a valuable tool to estimate the performance of vaccines against the backdrop of emerging variants, the results must be interpreted with caution and corroborated with field-effectiveness studies.

Inter-laboratory testing as a strategy for external quality assessment for qualitative detection of SARS-CoV-2 by real-time RT-PCR testing in India

To implement the strategy of test, track and treat to tackle the ongoing COVID-19 pandemic, the number of real-time RT-PCR–based testing laboratories was increased for diagnosis of SARS-CoV-2 in the country. To ensure reliability of the laboratory results, the Indian Council of Medical Research initiated external quality assessment (EQA) by deploying inter-laboratory quality control (ILQC) activity for these laboratories by nominating 34 quality control (QC) laboratories. This report presents the results of this activity for a period of September 2020 till November 2020. A total of 597 laboratories participated in this activity and 86 per cent of these scored ?90 per cent concordance with QC laboratories. This ILQC activity showcased India’s preparedness in quality diagnosis of SARS-CoV-2.

Normative Data of Optimally Placed Endotracheal Tube by Point-of-care Ultrasound in Neonates

Objective: To derive normative data of the distance betweenoptimally placed endotracheal tube tip and arch of aorta byultrasound in neonates across different weight and gestation.Design: Cross-sectional study.Setting: Tertiary care neonatal intensive care unit from April 2015to May 2016.Participants: All neonates requiring endotracheal intubation wereeligible for the study.Methods: During intubation, insertional length was determinedusing weight-based formula. The distance between endotrachealtube tip and arch of aorta was measured by ultrasound.Endotracheal tube position was confirmed by chest radiograph.Results: Out of 133 enrolled infants, 101 (75.9%) had optimallyplaced endotracheal tubes. The mean (SD) distance betweenendotracheal tube tip and arch of aorta by ultrasound was 0.78(0.21) cm in infants <1500 g and 1.04 (0.32) cm in infants ≥1500 g.The regression equation to estimate insertional length fromweight, crown heel length (CHL), occipito-frontal circumference(OFC), nasal tragus length (NTL) and sternal length (SL) wereWt(kg)+4.95, 0.15×CHL(cm)+0.57, 0.22×OFC(cm)+0.49, 0.82×NTL(cm)+1.24 and 0.75×SL(cm)+2.26, respectively.Conclusion: Our study reports normative data of the distancebetween optimally placed endotracheal tube tip and arch of aortaby ultrasound in neonates. The distance between endotrachealtube tip and arch of aorta increases with increase in weight andgestation. Insertional length correlates strongly with all theanthropometric parameters

Critical decision of operability in congenital heart disease patient with severe pulmonary hypertension.

Repair of congenital heart disease in the presence of high pulmonary pressure has always been a contentious issue. Pulmonary vascular resistance (PVR) is considered important for establishing operability in these patients. However, PVR estimation is not always accurate and cannot solely be relied upon to make critical decision of operability. Clinical examination, chest X‑ray, and echocardiography are also important indicators of pulmonary vascular disease. Knowledge of pits and falls of each investigation is important for appropriate management in these patients. We present a case report of successfully operated, 6‑year‑old child with anomalous origin of the right pulmonary artery from aorta, deemed inoperable on the basis of PVR estimation.