Spatiotemporal epidemiology of dengue fever across all 64 districts of Bangladesh: a retrospective ecological analysis of reported hospital admissions

Abstract

Bangladesh has experienced increasingly widespread dengue activity, with hospital admissions reported beyond the historical concentration in Dhaka. District-level evidence is needed to support preparedness, but nationwide-analyses combining temporal patterns, population-standardised reported admission rates, and spatial clustering remain limited. We conducted a retrospective ecological spatiotemporal analysis of reported dengue hospital admissions across all 64 districts of Bangladesh using daily Directorate General of Health Services Health Emergency Operations Centre reports from 1 January 2022 to 31 December 2025. The analytical dataset contained 93,504 district-day observations after imputing 19 missing dates using district-wise linear interpolation. Annual reported admission rates per 100,000 population were computed using district mid-year population projections from the 2022 census. Temporal patterns were assessed descriptively, with exploratory Seasonal Mann-Kendall assessment and Benjamini-Hochberg false-discovery-rate correction. Spatial clustering was evaluated using Global Moran’s I, Local Indicators of Spatial Association (LISA), and Getis-Ord Gi* under queen-contiguity weights, with K-nearest-neighbour (k = 6) sensitivity analysis. Additional sensitivity analyses examined the impact of missing-date handling. DGHS yearly totals reported 62,382 dengue admissions in 2022, 321,017 in 2023, 101,214 in 2024, and 102,861 in 2025. Corresponding totals in the interpolated dataset were 62,034, 320,943, 100,803, and 102,929, respectively, reflecting minor differences attributable to interpolation of missing dates. Reported admissions increased sharply from 2022 to 2023, declined substantially in 2024, and remained stable in 2025. Dhaka district’s share of national admissions fell from 63.5% to 31.5% between 2022 and 2025, while Barishal Division’s share increased from 5.1% to 21.1%. In 2025, Barguna recorded the highest reported admission rate (959.5 per 100,000 population). Spatial autocorrelation was strongest from 2023 onward, with weak positive autocorrelation detected in 2022. Dhaka was not identified as a statistically significant LISA or Gi* hotspot core, unlike spatially coherent southern clusters emerging 2023 onwards. Reported dengue hospital admissions show an apparent redistribution beyond Dhaka, with repeated concentration in several southern districts after 2023. Because the analysis is based on hospital-reported admissions, a study-period of four years, and facility-location rather than residence-location data, the findings should be interpreted as suggestive evidence of changing dengue-admission patterns.