Urban Hyperendemicity and Emerging Coastal Per‐Capita Risk of Dengue in Bangladesh, 2021–2025: A Nationwide Spatiotemporal Ecological Analysis

Abstract

Background Dengue has shifted from Dhaka‐centric to nationwide in Bangladesh. Aim To quantify spatiotemporal patterns and identify high‐risk clusters across all 64 districts from 2021 to 2025, and, extending previous reports with data from 2025, this study aims to observe an ongoing shift in per‐capita risk hotspots. Methods Retrospective ecological study of the Directorate General of Health Services (DGHS) aggregate yearly data on suspected and laboratory‐confirmed dengue admissions (n = 637,626 cases). Incidence per 100,000 population was calculated using 2022 census projections with 1.12% annual growth. Global (Moran’s I) and local (Getis‐Ord Gi∗) spatial autocorrelation and prospective space–time scan statistics (SaTScan) were applied. Results National incidence: 76.4/100,000/year. 2025 rate‐adjusted Moran’s I = 0.328 (p = 0.001). Raw‐case hotspots: Greater Dhaka; population‐adjusted hotspots: Jhalokathi, Barguna (coastal). High‐rate space–time cluster (2024–2025): Dhaka, Manikganj (RR = 3.13, p = 0.001). Dhaka O/E = 4.31 (RR = 6.38). Two low‐rate clusters (north, southeast). Conclusion Urban hyperendemicity, characterized by a high case volume, coupled with the emerging coastal per‐capita risk, necessitates tailored interventions. Intensive vector control is essential in Dhaka, while early‐warning surveillance should be implemented in coastal districts.