Temporal and Spatial Distribution of Dengue Case Fatality Rates in Bangladesh: A Retrospective Investigation.

Abstract

Dengue remains a significant public health challenge in Bangladesh, with considerable variation in disease burden and mortality. This study aimed to assess how dengue case fatality rates (CFRs) had varied across months, seasons, and geographic regions of Bangladesh. A retrospective observational study was conducted from January 2021 to December 2025 using surveillance data obtained from the Directorate General of Health Services, Bangladesh (DGHS). Descriptive statistical analyses were performed to estimate dengue CFR. Univariate and multivariable logistic regression analyses were conducted to evaluate the association between the studied variables and dengue CFR. Seasonal and trend components of the data were examined through LOESS-based decomposition to understand underlying time-series patterns. Over the past 5 years, a total of 6,15,991 dengue cases and 3,079 deaths, with an overall CFR of 0.49%, were recorded. The year-wise highest CFR was recorded in 2024 (0.56%; 95% CI: 0.52-0.62). The month-wise and season-wise mean CFRs were recorded highest in February (1.21%) and winter (0.74%), respectively, while the division-wise highest mean CFR was recorded in Dhaka (0.60%). In addition, the month of February (AOR = 3.09; 95% CI 1.59-5.38; p < 0.001) and the winter season (OR = 1.61; 95% CI 1.41-1.82; p < 0.001) had significantly higher odds for dengue CFR. Compared to Dhaka, most of the other divisions had significantly (p < 0.001) lower odds for dengue CFR. The year 2024 had significantly (p < 0.001) higher odds for dengue CFR compared to most other years under study. This present study identified the critical time and high-risk areas in Bangladesh, underscoring the need for public health interventions and enhanced surveillance systems.