Epidemiological Characterisation of the Record 2023 Dengue Epidemic in Bangladesh: An 8-Year National Surveillance Analysis (2018–2025)

Bangladesh experienced its largest dengue epidemic on record in 2023, with 321,017 admitted cases — a 31.6-fold increase from the 2018 baseline and a national incidence of 189.6 per 100,000 population. This study presents a retrospective descriptive epidemiological analysis of national dengue surveillance data from the DGHS HEOC Dengue Dashboard, covering 2018–2025. We characterise the 8-year temporal trend, seasonal pattern (monthly and weekly, 2023–2025), and division-level geographic distribution of admitted dengue cases in Bangladesh. Key findings: (1) Bangladesh dengue increased 31.6-fold from 2018 to 2023; (2) the COVID-19 lockdown in 2020 caused a 97.5% reduction in reported cases, demonstrating the sensitivity of hospital-based surveillance to healthcare-seeking behaviour; (3) more than 83% of annual dengue burden occurs during the monsoon season (June–October); (4) post-2023 cases stabilised at a new elevated baseline (~102,000/year), 10-fold above the 2018 level; (5) Barishal division carries the highest per-capita incidence despite having the smallest population. Data source: DGHS HEOC Dengue Dynamic Dashboard (publicly available government surveillance data, accessed June 2026). All analysis code and extracted datasets are available at: https://github.com/khalilurrrahmanridoykhan/bangladesh-dengue-2018-2025