Progression of dengue during an outbreak (2024) in Dhaka, Bangladesh: a hospital based longitudinal study

Background Bangladesh has experienced recurrent dengue outbreaks since 2000, driven by climatic changes and socio-demographic vulnerabilities. Limited evidence on circulating serotypes and immune diversity has hindered preparedness for severe dengue (SD). Identifying clinical and laboratory predictors of progression to severe dengue is key to strengthening outbreak response and clinical management. Methods A longitudinal cohort study was conducted in four hospitals in Dhaka between January and November 2024. Patients with confirmed dengue with warning signs were enrolled. Clinical data and blood samples were collected at enrollment, clinical deterioration/discharge, and convalescence (day 21 ± 7). Multivariable logistic regression identified factors associated with SD compared with dengue with warning signs (DWS). Associations were expressed as odds ratios (OR) with 95% confidence intervals (CIs) and p-values < 0.05 considered y significant. Findings Among 3135 dengue patients, 354 with warning signs were enrolled. 62 (17.5%) progressed to SD, including 2 deaths. Most of the patients (60%) were aged between 21 and 40 years, and 76% were male. Lethargy was more frequent in SD patients (29%) than DWS patients (11%). DEN-2 was the predominant serotype (90%). Multivariable logistic regression, adjusted for potential confounders, identified arthralgia (95% CI: 1.04–3.98), anorexia (95% CI: 1.40–11.7), lethargy (95% CI: 1.97–10.7), diabetes mellitus (95% CI: 1.01–6.17), pleural effusion (95% CI: 4.97–21.1) and prolonged APTT (95% CI: 1.02–1.08) as independent predictors for SD. Interpretation The findings show that a few simple and easily measurable indicators can support early risk assessment and guide timely hospital admission and clinical management. Funding United States Agency for International Development (USAID) under the Crisis Modifier Grant (GR-01909) in response to the dengue outbreak in Bangladesh.