Epidemiology and evolution of dengue outbreaks in Bangladesh (2020–2023)

Abstract

Objective: The aim of the study is to provide a comprehensive overview of the epidemiology and evolution of dengue virus (DV) in Bangladesh from 2020 to 2023. Methods: From January 1, 2020, to December 31, 2023, we analyzed the daily press releases on the dengue situation made public by the government. The published sequences from the period were then subjected to phylogenetic analysis, amino acid substitutions, evolutionary rate, and selection pressure analysis. Results: In Bangladesh, dengue fever usually peaks during the monsoon season. However, the increase in cases began considerably earlier, at the end of April 2023 and the disease had claimed 1705 lives, marking its highest annual death toll ever. Dhaka is the city most severely affected. The phylogenetic analysis revealed that the Bangladeshi DV-1 strains clustered far from any known genotype, indicating the circulation of a novel genotype, whereas the DV-3 strains clustered within the existing circulating genotype I. The DV-1 strains had a total of 107 amino acid alterations and two deletions, while the DV-3 strains had 17 alterations. The Bangladeshi DV-1 and DV-3 strains evolve rapidly. Additionally, selection pressure analysis revealed one positive selection site in DV-1 and three in DV-3, respectively, which require further research. Conclusions: The circulation of novel genotypes, a higher mutation rate, and positive selection of DV might result in the recent dengue outbreaks in the country. The study will help in the development of strategies to control outbreaks in Bangladesh and other nations with similar conditions in the future.