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Dengue virus (DENV) is one of the most significant mosquito-borne diseases in Nepal. In 2023, DENV outbreaks began in Eastern Nepal, near the border with India, and rapidly spread nationwide. The study aims to describe the outbreak's epidemiological pattern, laboratory characteristics, DENV serotypes, and genotypes. A hospital-based cross-sectional study was conducted in four hospitals in Jhapa, Eastern Nepal, in 2023. Acute serum samples were obtained from dengue suspected patients within 7 days of illness and subjected to virus isolation, conventional and real-time polymerase chain reaction (RT-PCR), and phylogenetic analysis. Out of 60 samples, 42 (70 %), 11 (18.3 %) and 7 (11.7 %) were primary, secondary and non-dengue infection, respectively. Among 53 dengue confirmed patients, 46 (86.7 %) were positive for NS1 and 12 (22.6 %) were positive for both NS1 and IgM. Out of 42 dengue isolates, a new clade of the cosmopolitan genotype of DENV-2 was the most prevalent (28, 66.7 %), followed by genotype III of DENV-3 (11, 26.2 %) and genotype V of DENV-1 (3, 7.1 %). Genotype III of DENV-3 was first introduced in 2022-2023 in Nepal. Phylogenetic analysis of the E gene revealed the DENV-2 isolates from Nepal had 98 % homologous nucleotide similarity with the strains from India and Bangladesh. To our knowledge, this is the first report of circulating serotypes and genotypes of DENV in Jhapa. Integrating molecular findings into the dengue control plan can enhance surveillance efforts, monitor disease trends, and implement proactive measures to reduce the burden of dengue and prevent fatalities in future outbreaks., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In 2023, Nepal faced its second largest dengue outbreak ever, following a record-breaking number of dengue cases in 2022, characterized by the expansion of infections into areas of higher altitudes. However, the characteristics of the 2023 circulating dengue virus (DENV) and the vector density remain poorly understood. Therefore, we performed DENV serotyping, clinical and laboratory assessment, and entomological analysis of the 2023 outbreak in central Nepal. A total of 396 fever cases in Dhading hospital suspected of being DENV positive were enrolled, and blood samples were collected and tested by different techniques including PCR. Of these, 278 (70.2%) had confirmed DENV infection. Multiple serotypes (DENV-1, -2, and -3) were detected. DENV-2 (97.5%) re-emerged after six years in Dhading while DENV-3 was identified for the first time. Dengue inpatients had significantly higher frequency of anorexia, myalgia, rash, diarrhea, nausea, vomiting, abdominal pain, and thrombocytopenia ( p < 0.05). In this area, Aedes mosquitoes largely predominated (90.7%) with the majority being A. aegypti (60.7%). We also found high levels of Aedes index (20.0%) and container index (16.7%). We confirmed multiple DENV serotype circulation with serotype re-emergence and new serotype introduction, and high vector density in 2023. These findings call for the urgent initiation and scaling up of DENV molecular surveillance in human and mosquito populations for dengue control and prevention in Nepal.

Myanmar is an endemic country for arboviruses, and outbreaks occur frequently. A cross-sectional analytical study was conducted during the peak season of the chikungunya virus (CHIKV) outbreak in 2019. A total of 201 patients with acute febrile illness who were admitted to the 550-bedded Mandalay Children Hospital in Myanmar were enrolled in the study, and virus isolation, serological tests, and molecular tests for the dengue virus (DENV) and CHIKV were performed for all samples. Out of 201 patients, 71 (35.3%) were only DENV-infected, 30 (14.9%) were only CHIKV-infected and 59 (29.4%) were coinfected with DENV and CHIKV. The viremia levels of the DENV- and CHIKV- mono-infected groups were significantly higher than those of the group coinfected with DENV and CHIKV. Genotype I of DENV-1, genotypes I and III of DENV-3, genotype I of DENV-4 and the East/Central/South African genotype of CHIKV were co-circulating during the study period. Two novel epistatic mutations of CHIKV (E1:K211E and E2:V264A) were noted. This study highlighted that there were many coinfection cases during the outbreak and that the co-circulation of both viruses in DENV-endemic regions warrants effective monitoring of these emerging pathogens via comprehensive surveillance to facilitate the implementation of effective control measures., Competing Interests: Declaration of competing interest The authors declared that there was no conflict of interests., (Copyright © 2023. Published by Elsevier Masson SAS.)

The largest dengue outbreak in the history of Nepal occurred in 2022, with a significant number of casualties. It affected all 77 districts, with the nation's capital, Kathmandu (altitude 1300 m), being the hardest hit. However, the molecular epidemiology of this outbreak, including the dengue virus (DENV) serotype(s) responsible for this epidemic, remain unknown. Here, we report the epidemic trends, clinico-laboratory features, and virus serotypes and their viral load profiles that are associated with this outbreak in Nepal. Dengue-suspected febrile patients were investigated by routine laboratory, serological, and molecular tools, including a real-time quantitative polymerase chain reaction (qRT-PCR). Of the 538 dengue-suspected patients enrolled, 401 (74.5%) were diagnosed with dengue. Among these dengue cases, 129 (32.2%) patients who required hospital admission had significant associations with myalgia, rash, diarrhea, retro-orbital pain, bleeding, and abdominal pain. DENV-1, -2, and -3 were identified during the 2022 epidemic, with a predominance of DENV-1 (57.1%) and DENV-3 (32.1%), exhibiting a new serotype addition. We found that multiple serotypes circulated in 2022, with a higher frequency of hospitalizations, more severe dengue, and more deaths than in the past. Therefore, precise mapping of dengue and other related infections through integrated disease surveillance, evaluation of the dynamics of population-level immunity and virus evolution should be the urgent plans of action for evidence-based policy-making for dengue control and prevention in the country.

Competing Interests: We declare no competing interests.

Dengue virus (DENV) is one of the most prevalent neglected tropical diseases, with half of the world's population at risk of infection. In Nepal, DENV was first reported in 2004, and its prevalence is increasing every year. The present study aimed to obtain and characterize the full-length genome sequence of DENV from the 2017 outbreak. Hospital-based surveillance was conducted in two provinces of Nepal during the outbreak. Acute-phase serum samples were collected from 141 clinically suspected dengue patients after the rainy season. By serological and molecular techniques, 37 (26.9%) and 49 (34.8%), respectively, were confirmed as dengue patients. The cosmopolitan genotype of DENV-2 was isolated from 27 laboratory-confirmed dengue patients. Genomic analysis showed many amino acid substitutions distributed mainly among the E, NS3, and NS5 genes. Phylogenetic analyses of the whole genome sequence revealed two clades (Asian and Indian) among DENV-2 isolates from Nepal. The DENV isolates from hilly and Terai areas were similar to Asian and Indian strains, respectively. Further genomic study on different DENV serotypes is warranted to understand DENV epidemics in Nepal, where there are limited scientific resources and infrastructure.

Background: Dengue cases have been continuously reported in Nepal, including some large outbreaks, since its first introduction in 2004. The disease is now expanding towards newer locations above 1400 m high, especially the country's capital city, Kathmandu. In 2019, >14,000 dengue cases including six deaths were reported. This study was aimed at the detection and molecular characterization of dengue virus (DENV) in dengue patients., Methods: A total of 451 patients were enrolled in this study. Demographic, clinical and laboratory information was collected from dengue patients. Dengue infection was confirmed by antibody/antigen detection assays followed by RT-PCR analysis., Results: The DENV patients showed fever, body ache, headache, myalgia, retro-orbital pain and arthralgia. The platelets were decreased, serum liver enzymes were increased and leucopenia was seen. Out of 195 patients, 111 (57.0%) were positive for DENV RNA by consensus PCR. We found DENV-2, 70 (63.1%) as the predominant serotype responsible for the 2019 outbreak, while DENV-3 was detected in two patients., Conclusion: Our findings suggest that DENV-2 was the major serotype causing the 2019 massive outbreak in Nepal. This information will help in disease control programs to understand the molecular epidemiology and its changing trend., (© The Author(s) 2020. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene.)

Coronavirus disease 2019 (COVID-19) pandemic has caused significant impact on the health care system. As a consequence, diagnosis and treatment of vector borne diseases including dengue has been equally affected. Nepal is no exception to this, where COVID-19 cases is exponentially increased and all resources are concentrated on its prevention, control and management. Dengue, one of the major vector-borne diseases in Nepal, is apparently overlooked despite approaching the peak season of the disease. The aim of this paper is to describe the double burden of COVID-19 and dengue in Nepal, particularly highlighting the co-circulation and possible coinfections. This has posed higher risk of increased severity, more severe cases and deaths in Nepal. Moreover, potential misdiagnosis of these viral diseases may lead to delayed or, inappropriate treatment and poor allocation of resources.

In this study, we aim to assess the association of dengue viremia with dengue severity. The study protocol was developed and registered in PROSPERO (CRD42016039864). We searched nine databases to find potential papers. Studies meeting the inclusion criteria were included. We, based our analysis on three outcomes which are disease severity, dengue serotype and disease infection type. Thirty studies with 3316 patients were included. Our analysis revealed that viremia is significantly higher in dengue hemorrhagic fever patients than dengue fever in days 5 to 6. Regarding the serotype of dengue, the maximum viremia titre of serotype 1 was significantly higher than serotype 3 and the viremia in dengue serotype 2 was significantly higher than serotype 4 in days 2 to 4. However, comparison of the daily viremia level between the primary and secondary dengue infection revealed that secondary infection was significantly higher than the primary infection on seventh day and on the eighth day. Viremia is strongly associated with disease severity and type of infection which gave viremia a high indicative power to be used as a clinical predictor. Dengue serotype is also associated with viral load with higher viremia in DENV-2/1., (© 2020 John Wiley & Sons, Ltd.)

Background: The protective or pathogenic role of T lymphocytes during the acute phase of dengue virus (DENV) infection has not been fully understood despite its importance in immunity and vaccine development. Objectives: This study aimed to clarify the kinetics of T lymphocyte subsets during the clinical course of acute dengue patients. Study design: In this hospital-based cohort study, 59 eligible Vietnamese dengue patients were recruited and admitted. They were investigated and monitored for T cell subsets and a panel of clinical and laboratory parameters every day until discharged and at post-discharge from the hospital. Results: We described for the first time the kinetics of T cell response during the clinical course of DENV infection. Severe cases showed significantly lower levels of effector CD8 + T cells compared to mild cases at day -1 ( p = 0.017) and day 0 ( p = 0.033) of defervescence. After defervescence, these cell counts in severe cases increased rapidly to equalize with the levels of mild cases. Our results also showed a decline in total CD4 + T, Th1, Th1/17 cells during febrile phase of dengue patients compared to normal controls or convalescent phase. On the other hand, Th2 cells increased during DENV infection until convalescent phase. Cytokines such as interferon-γ, IL-12p70, IL-5, IL-23, IL-17A showed tendency to decrease on day 0 and 1 compared with convalescence and only IL-5 showed significance indicating the production during acute phase was not systemic. Conclusion: With a rigorous study design, we uncovered the kinetics of T cells in natural DENV infection. Decreased number of effector CD8 + T cells in the early phase of infection and subsequent increment after defervescence day probably associated with the T cell migration in DENV infection., (Copyright © 2020 Manh, Weiss, Thuong, Mizukami, Dumre, Luong, Thanh, Thang, Huu, Phuc, Nhung, Mai, Truong, Ngu, Quoc, Ha, Ton, An, Halhouli, Quynh, Kamel, Karbwang, Huong, Huy and Hirayama.)

Dengue virus (DENV) infection remains a major public health concern in many parts of the world, including Southeast Asia and the Americas. Sri Lanka experienced its largest dengue outbreak in 2017. Neurological symptoms associated with DENV infection have increasingly been reported in both children and adults. Here, we characterize DENV type 2 (DENV-2) strains, which were isolated from cerebrospinal fluid (CSF) and/or serum of patients with dengue encephalitis. Acute serum and CSF samples from each patient were subjected to dengue-specific non-structural protein 1 (NS1) antigen test, IgM and IgG enzyme-linked immunosorbent assay (ELISA), virus isolation, conventional and real-time polymerase chain reaction (PCR), and next-generation sequencing (NGS). Among the 5 dengue encephalitis patients examined, 4 recovered and 1 died. DENV-2 strains were isolated from serum and/or CSF samples of 3 patients. The highest viral genome levels were detected in the CSF and serum of the patient who succumbed to the illness. A phylogenetic tree revealed that the DENV-2 isolates belonged to a new clade of cosmopolitan genotype and were genetically close to strains identified in China, South Korea, Singapore, Malaysia, Thailand, and the Philippines. According to the NGS analysis, greater frequencies of nonsynonymous and synonymous mutations per gene were identified in the nonstructural genes. The full genomes of serum- and CSF-derived DENV-2 from the same patient shared 99.7% similarity, indicating that the virus spread across the blood-brain barrier. This is the first report to describe neurotropic DENV-2 using whole-genome analysis and to provide the clinical, immunological, and virological characteristics of dengue encephalitis patients during a severe dengue outbreak in Sri Lanka in 2017., Competing Interests: The authors have declared that no competing interests exist.

Dengue virus (DENV) infection is a major cause of morbidity and mortality in Vietnam, and the incidence is higher and more consistent in the southern part of the country. This study investigated the circulation of DENV serotypes, viremia levels, immunological status, and cytokine levels, with disease severities among children infected in 2017 in Ho Chi Minh City, Southern Vietnam. Acute and convalescent serum samples were collected from clinically diagnosed dengue children. They were confirmed to have DENV infection by NS1 antigen, IgM and IgG ELISAs, virus isolation, and conventional and real-time RT-PCR. Measurement of 10 cytokine levels was performed in the serum samples. All the children were dengue IgM positive; 28% and 72% of them had primary and secondary DENV infections, respectively, whereas 54% of those with secondary infection were children with dengue with warning signs and with severe dengue. Any or mixed infection of the four serotypes of DENV RNA was detected in 58 children. Twenty DENV strains (DENV-1 = 16 and DENV-4 = 4) were isolated. Levels of IFN-γ, TNF-α, MCP-1, IL-10, and IL-6 were significantly higher in severe dengue cases. We report the predominance of DENV-1 over other serotypes in the 2017 dengue outbreak in Southern Vietnam. Our data showed that cytokine expressions were correlated with dengue pathogenesis and may help in identifying an effective therapeutic strategy.

Background: Sri Lanka experienced its largest dengue outbreak in 2017 with more than 185,000 dengue cases including at least 250 fatalities., Objectives: Our study aimed to characterize the clinical, immunological and virological features of confirmed dengue patients in Sri Lanka during the outbreak in 2017 when unusual manifestations of severe dengue were observed., Study Design: Sera from 295 patients who were admitted to Teaching Hospital Kandy, Kandy, Sri Lanka between March 2017- January 2018 were subjected to NS1 antigen, IgM and IgG ELISAs, virus isolation, conventional and real time RT-PCR and next generation sequencing., Results: Primary and secondary infections were detected in 48.5 % and 51.5 % of the study population, respectively. Two hundred twenty five DENV strains were isolated (219 DENV-2, one DENV-3, two DENV-4, two mixed infections of DENV-2 and -3 and one mixed infection of DENV-2 and -4). Unusual and severe manifestations such as encephalitis, encephalopathy, liver failure, kidney failure, myocarditis, Guillain-Barré syndrome and multi-organ failure were noted in 44 dengue patients with 11 deaths. The viraemia levels in patients with primary infection and unusual manifestations were significantly higher compared to those in patients with secondary infection. A new clade of DENV-2 Cosmopolitan genotype strains was observed with the strains closely related to those from China, Malaysia, Indonesia, Singapore and Taiwan., Conclusions: The new clade of DENV-2 cosmopolitan genotype observed in Sri Lanka in 2017 caused an unprecedented, severe dengue outbreak. The emergence of DENV-3 and DENV-4 in the 2017 outbreak might cause future outbreaks in Sri Lanka., Competing Interests: Declaration of Competing Interest The authors declare that they have no competing interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

We report on the changing epidemiology of two important flaviviruses in Nepal: Japanese encephalitis (JE) and dengue viruses. Morbidity and mortality in Nepal is in the thousands since JE was introduced in 1978. Nepal launched an extensive laboratory-based JE surveillance in 2004. Nepal experienced a remarkable reduction in disease burden after mass immunizations from 2005 to 2010, when 2,040 JE infections and 205 JE-related deaths were confirmed. With its emergence in 2006, dengue has become a significant challenge in the country, highlighted by a sudden outbreak in 2010 that resulted in 359 confirmed dengue infections. Currently, both viruses cocirculate in Nepal. Here, we document the remarkable expansion of dengue in Nepal, which urgently requires national surveillance to refine the burden and make recommendations regarding control and prevention programs. We believe that the use of existing JE surveillance network for integrated dengue surveillance may represent the most appropriate alternative.