Emergence of dengue virus 4 as the predominant serotype during the outbreak of 2017 in South India.

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.

The prevalence of occult hepatitis B infection among the blood donors in a tertiary care hospital, Puducherry.

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.

Cryptosporidiosis: A mini review.

Cryptosporidium spp. was first described in mice in 1907. The first human case was reported in an acquired immune deficiency syndrome patient after which it gained importance. It is one of the emerging protozoan parasites according to the Centre of Disease Control and Prevention. The special structure which is present in them such as rhoptries and micronemes are responsible for their virulence and pathogenicity. They can be transmitted from animals, human to human, water, food, and tends to cause waterborne outbreaks. The clinical manifestation in immunocompetent patient is self-limiting when compared to immunocompromised individual where it causes chronic diarrhea not responding to treatment. Hence, it is necessary to diagnose them early to prevent any complication in these patients. There are many investigations currently available such as stool microscopy after Sheather's concentration technique, rapid test targeting specific antigen, molecular methods, and imaging techniques.

Detection of Cryptosporidium in stool samples of immunocompromised patients.

INTRODUCTION: Cryptosporidium species is the most common opportunistic enteric parasite encountered in the immunocompromised patients. Considering the need to diagnose them early relies mostly on rapid tests such as antigen detection by immunochromatographic test (ICT), ELISA, and microscopy. However, the sensitivity and specificity varies with different methods and different kits used. This study was conducted to determine the intestinal parasitic profile in immunocompromised patients and to assess the diagnostic accuracy of the ICT using ImmunoCard STAT kit in detecting Cryptosporidium spp. MATERIALS AND METHODS: The patients in this study were divided into two groups: one group was immunocompromised patients (n = 73) and the other was nonimmunocompromised individuals (n = 73). Stool microscopy, ICT, and polymerase chain reaction (PCR) were carried out for all stool samples. RESULTS: Totally, 4 (5.4%) of 73 patients of the study group were positive for Cryptosporidium. The species detected were Cryptosporidium parvum and Cryptosporidium hominis. PCR was taken as gold standard in the current study. PCR detected Cryptosporidium in four samples while ICT in two samples and microscopy in one sample. CONCLUSION: Cryptosporidium was found to be the most common enteric parasite in the immunocompromised patients studied, followed by Cystoisospora, Entamoeba histolytica, and Strongyloides stercoralis. Although the ICT is a rapid test, it was less sensitive and more expensive in comparison to the PCR; hence, its utility appears to be limited in our setting.