Circulation of DENV-3 Genotype 3 during 2017 to 2018 in Delhi: A Single-Center Hospital-Based Study

Introduction  Delhi is hyperendemic for dengue virus (DENV) where all the four DENV have previously been reported. A constant vigilance of circulating DENV serotypes is important in surveillance, since the introduction of a new variant to areas affected by preexisting serotypes constitutes a risk factor for dengue hemorrhagic fever and dengue shock syndrome.

Objectives  This retrospective study was performed with an objective to determine the circulating serotype and genotype of DENV in acute phase blood samples of patients who have reported to a tertiary liver care hospital in New Delhi during the last 2 years (2017–2018).

Methods  The data of clinician-initiated testing for dengue nonstructural protein 1 (NS1) antigen (Ag) was searched in the institutional hospital information system. The serum sample of dengue NS1 Ag-positive cases confirmed by enzyme-linked immunosorbent assay (ELISA; PANBIO, Gyeonggi-do, ROK) and a fever duration of less than 5 days were retrieved from the laboratory archive. The DENV serotyping on these sample was performed by reverse transcriptase polymerase chain reaction (RT-PCR). Sequencing and phylogenetic analysis was done for the capsid premembrane (CprM) region to determine the genotype.

Results  A total of 440 acute-phase samples were received. Twenty one (4.77%) were positive for dengue NS1 Ag with a mean age of 35.1 years and male-to-female ratio of 1.1:1. Eight cases (38.09%) were positive by dengue RT-PCR and all belonged to DENV-3 serotypes. Phylogenetic tree analysis revealed DENV-3 clustered to genotype III with 100% homology with 2008 Indian subcontinent strain.

Conclusion  This study revealed circulation of DENV-3, genotype III in Delhi from 2017 to 2018, similar to the 2008 viral type. Virological surveillance is an important exercise to be done for viral infections with public threat and outbreak potential.

Epidemiology and challenges of dengue surveillance in the WHO South-East Asia Region

Dengue poses a significant health and economic burden in the WHO South-East Asia Region. Approaches for control need to be aligned with current knowledge on the epidemiology of dengue in the region. Such knowledge will ensure improved targeting of interventions to reduce dengue incidence and its socioeconomic impact. This review was undertaken to describe the contemporary epidemiology of dengue and critically analyse the existing surveillance strategies in the region. Over recent decades, dengue incidence has continued to increase with geographical expansion. The region has now become hyper-endemic for multiple dengue virus serotypes/genotypes. Every epidemic cycle was associated with a change of predominant serotype/genotype and this was often associated with severe disease with intense transmission. Classical larval indices are widely used in vector surveillance and adult mosquito samplings are not implemented as a part of routine surveillance. Further, there is a lack of integration of entomological and disease surveillance systems, often leading to inaction or delays in dengue prevention and control. Disease surveillance does not capture all cases, resulting in under-reporting, and has thus failed to adequately represent the true burden of disease in the region. Possible solutions include incorporating adult mosquito sampling into routine vector surveillance, the establishment of laboratory-based sentinel surveillance, integrated vector and dengue disease surveillance and climate-based early warning systems using available technologies like mobile apps.

Genetic characterization of dengue virus serotype 2 isolated from dengue fever outbreaks in eastern Uttar Pradesh and western Bihar, India

Dengue (DEN) is the most common cause of mosquito-borne endemic viral diseases in the tropical and subtropical countries. DEN outbreaks associated with multiple dengue virus (DV) serotypes have been regularly reported in different parts of India. This study was done during DEN outbreaks in 2015 to 2016 in UP and Bihar where DEN-2 was found as the only prevalent serotype. DV-2 was the only serotype amplified in serotype-specific reverse-transcription polymerase chain reaction from sera of 210 (65.21%) out of 322 DV NS1 antigen-positive patients. Further genetic analysis based on full-length envelope (E) protein sequence derived from patient's sera as well as DV isolate showed the circulation of lineages I and III of DV-2 cosmopolitan genotype during 2015 and lineage II during 2016. Finally, the phylogenetic analysis using the E gene sequence revealed that these DV-2 strains have a close genetic relationship with the recently reported DV-2 genotypes from DEN outbreaks reported from different parts of north India. These results showed the circulation of cosmopolitan genotype of DV-2 in eastern Uttar Pradesh and western Bihar, India. The genetic database generated on circulating DV strains in this study will be useful as reference for disease surveillance and strengthening laboratory diagnosis protocols.

Genotype replacement of dengue virus type 3 and clade replacement of dengue virus type 2 genotype Cosmopolitan in Dhaka, Bangladesh in 2017

Dengue is a mosquito-borne disease that has spread to >100 countries and is caused by the dengue virus (DENV), which belongs to the Flavivirus genus of the family Flaviviridae. DENV comprises 4 serotypes (DENV-1 to -4), and each serotype is further divided into distinct genotypes. In India, it is reported that all 4 serotypes of DENV co-circulate. Although Bangladesh is a neighboring country of India, very few reports have published DENV sequence data for the country, especially after 2012. To understand the current distribution of DENV genotypes in Bangladesh, we determined the nucleotide sequences of envelope regions obtained from 58 DENV-positive patients diagnosed at Apollo Hospitals Dhaka during the period between September 2017 and February 2018. We found 5 DENV-1, 47 DENV-2, and 6 DENV-3 serotypes. A phylogenetic analysis of the obtained viral sequences revealed that DENV-3 genotype I was present instead of DENV-3 genotype II, which was predominant in Bangladesh between 2000 and 2009. Furthermore, we found two distinct lineages of the Cosmopolitan genotype of DENV-2, one of which was closely related to strains from Southeast Asia and has never been reported previously in Bangladesh. These results indicated that DENVs in Bangladesh have increased in genotypic diversity and suggest that the DENV genotypic shift observed in other Asian countries also might have been taking place in Bangladesh.

Cosmopolitan A1 lineage of dengue virus serotype 2 is circulating in Pakistan: A study from 2017 dengue viral outbreak

Dengue viral infection has become a challenge in tropical and subtropical countries where dengue virus is endemic. Its epidemics are occurring at higher rates amid its circulation throughout the year. Since the first documented outbreak in Pakistan in 1994, this region has reported many sporadic cases and epidemics. There is availability of small scale demographic and epidemiological studies on dengue viral infection in Pakistan. The year 2017 witnessed a huge dengue outbreak in Peshawar city of Pakistan with 69 deaths and 24 807 laboratory-confirmed cases. We suspect that the circulation of a different lineage or genotype could be responsible for the enhanced number of infected patients in Pakistan's 2017 outbreak since previous studies have already described this phenomenon in other countries. For this, we collected 1447 suspected blood samples and their epidemiological data. After serotyping through polymerase chain reaction nine samples of Dengue virus2 (DENV2) were randomly selected and were subjected to Sanger's sequencing for genotyping analysis. The mean distance, genetic diversity, and phylogenetic analysis were carried out using K2 model. The phylogenetic analysis split Pakistani isolates into two lineages, the sequences from 2017 outbreak in Peshawar grouped within A1 lineage of cosmopolitan genotype (IV) of DENV2. The difference in distance, genetic diversity, and amino acids composition strongly back the results that the new lineage is circulating in the region. This is significant as Pakistan is struggling to control dengue epidemics which have caused much loss in both monetary and health sectors.

Infectious uveitis: an Asian perspective

Several intraocular infections can present with protean manifestations posing major diagnostic and management challenges. Infections such as tuberculosis, dengue and chikungunya fever have continued to remain major endemic diseases that are associated with uveitis in the Asia Pacific region. These entities often require a high index of clinical suspicion and laboratory analysis including assays of ocular fluids and/or tissues for confirmation of the diagnosis. Infectious uveitis caused by tuberculosis, dengue and chikungunya can present with characteristic clinical features and imaging findings on ancillary investigations; that may provide clue to the early diagnosis. Use of modern imaging modalities such as enhanced-depth imaging optical coherence tomography, optical coherence tomography angiography and ultra-wide field fundus photography greatly aid in the evaluation of these conditions. In the current review, we have discussed the epidemiology, clinical phenotypes, imaging characteristics, diagnosis and management of uveitis caused by tuberculosis, dengue and chikungunya.

Co-circulation of all the four dengue virus serotypes and detection of a novel clade of DENV-4 (genotype I) virus in Pune, India during 2016 season

Dengue is the most common mosquito-borne viral infection in tropical and sub-tropical countries. In recent years, India has reported increased incidences of concurrent infection with multiple serotypes of dengue viruses (DENV). In the present study, we have characterized DENV circulating during a single season of 2016 in Pune, India. A total of 64 serum samples from NS1 ELISA positive dengue patients were used for PCR amplification of CprM region of the viral genome and sequencing. Phylogenetic analysis documented circulation of all the four DENV serotypes with predominance of DENV-2 (40.6%). DENV genotyping classified DENV-1 to Genotype V, DENV-2 to Genotype IV, DENV-3 to Genotype III and DENV-4 to Genotype I. Further analysis revealed emergence of a novel clade (D) of genotype I of DENV-4. Subsequent isolation of three DENV-4 viruses in cell culture followed by complete genome sequence analysis confirmed this observation. Additionally, a new genotype within serotype-4 with >6.7% sequence variation from other genotypes was identified. This first report of significant co-circulation of all the four serotypes in a single outbreak in Pune reconfirms need for molecular monitoring of DENV.