Dengue Virus Serotype 2 Cosmopolitan C Genotype Reemerges with a New Subclade in Southwest Region of Bangladesh

In 2023, the Dengue virus (DENV) outbreak infected over 0.3 million cases and 1500 deaths in Bangladesh. Although the the serotype and genotype data were unavailable. Our study conducted serotyping and genomic surveillance in four districts of Southwest Bangladesh between September and October 2023. The surveillance data from 2019 to 2023 extracted from the Directorate General of Health Services in Bangladesh indicated a significant increase of Dengue infections in 2023, particularly during September-November. The two-layered hypothesis examination confirmed that, despite endemic months, 2023 dengue outbreak had a higher morbidity rate compared to previous years (2019-2022) in Southwest of Bangladesh. Serotyping and E gene sequence analysis of 25 randomly selected positive samples reveals that DENV-2 was the sole serotype circulating in this region during the study period. Genomic analysis exposed a new subclade of DENV-2, classified under Cosmopolitan genotype within C clade, distinct from previous years Bangladeshi variants until 2022. This subclade, possibly migrating from India, might be emerged during COVID-19 pandemic years and exhibited higher morbidity rates, thus challenging our existing mitigation strategies. This investigation provides valuable insights for public health interventions and underscores the importance of continuous genomic surveillance in managing Dengue outbreaks. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study was supported by the Jashore University of Science and Technology grant no: 23-FoBST-06 though University Grant Commission, Bangladesh. Funding source has no role for design, collection the data, analysis and approval of manuscript. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study was approved by the ethical review committee (ERC) of Jashore University of Science and Technology (JUST), Bangladesh (ERC no: ERC/FBST/JUST/2021-62), and all experiments were performed in the Genome Center, JUST according to the relevant guidelines and regulations I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes