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Context: Dengue virus (DENV) causes acute febrile illness in tropical and subtropical countries. In India there is a steady increase in incidence since 1950s which could be attributed to emergence of new serotype or lineage\clade shifts in circulating DENV. Aims: We aimed to perform molecular characterisation and phylogenetic analysis on samples from the recent outbreak (August–October 2017). Settings and Design: Retrospective epidemiological analysis of dengue outbreak. Subjects and Methods: Samples positive for non-steroidal 1 antigen by enzyme-linked immunosorbent assay (n = 147) were included. The study was approved by our institute ethics committee (JIP/IEC/2018/496). Five hundred and eleven base pair of capsid and pre-membrane encoding genes (CprM) region was amplified using Lanciotti primers, followed by second round of polymerase chain reaction using serotype specific primers. Samples which were positive by second round (n = 68) were sequenced and genotyped using Basic Local Alignment Search Tool analysis and phylogenetic tree was constructed by MEGA7 software. Results: Phylogenetic analysis of CprM sequences identified all 4 serotypes in circulation during this outbreak. We observed both single (n = 50) and concurrent infections (n = 18), with DENV4 as the major contributor (64%). Within Genotype I of DENV4 we observed a distinct new clade (Clade E) which was 2.6% ± 0.9%–5.5% ± 1.1% divergent from the other clades. Among the concurrent infection, DENV 4 and DENV 2 combination was observed to form the majority (77.8%). Conclusions: Overall this study documents the emergence of DENV4 as the major serotype in circulation, replacing DENV1, 2 and 3 which had been previously reported from Tamil Nadu and Puducherry. This substantiates the need for continuous monitoring in endemic countries like India, where such data may impact the formulation of vaccine policy for dengue.
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Occult hepatitis B infection (OBI) is a cause of concern while screening the blood donors to prevent transfusion-related transmission of infection. This study was conducted to assess the prevalence of OBI using total anti-HBc by ELISA and DNA detection by real time polymerase chain reaction (PCR). The samples included were negative for HBs Ag by ELISA. Out of 1102 samples tested, 156 were positive for total anti-hepatitis B core antigen and 52/156 by real-time PCR. Overall, the prevalence was found to be 4.71% (52/1102). The results indicate that nucleic acid-based testing should be an essential part of screening procedure to prevent missing of OBI.
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Background: Human metapneumovirus (HMPV), discovered in the 21st century, has emerged as an important cause of influenza‑like illness in children and adults causing mild upper respiratory tract infection to severe bronchiolitis and community‑associated pneumonia. The aim of this study was to determine the prevalence of HMPV in the Union Territory of Puducherry, India, as part of National Influenza Surveillance Programme. Materials and Methods: From November 2011 to December 2013, a total of 447 nasopharyngeal samples were collected from patients with acute respiratory infections and tested for HMPV RNA by real‑time polymerase chain reaction. Results: HMPV was identified in 23/447 (5%) samples with 11/23 in the age group of 14–30 years. Most of the HMPV infections were mild with no fatalities. Two patients were co‑infected with the respiratory syncytial virus and one with influenza B virus. The seasonal distribution showed increasing HMPV infection cases in rainy months except for a peak in summer of 2012. Phylogenetic analysis based on the sequences of the nucleoprotein gene of one HMPV strain showed a high degree of sequence identity with Indian strains obtained during 2006 and 2011. Conclusion: This study shows that HMPV infection is more common in adults than in children. Sequence homology suggests the circulation of closely related HMPV strains within the country.
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Respiratory syncytial virus (RSV) is a significant cause of contagious acute respiratory infections in children and older adults. Since there are contradictory reports regarding the efficacy of different methods to detect RSV, we evaluated the performance of the conventional PCR versus real‑time PCR in 222 patients with acute respiratory infections (ARI) recruited between January 2012 and March 2013. Conventional PCR had a very poor sensitivity of 40% (95% CI: 19.2-63.9%) and failed to detect RSV in respiratory samples with low viral load. Thus, it may be prudent to replace it with real‑time PCR to achieve precise diagnosis.