Bangladesh’s 2023 Dengue outbreak – age/gender-related disparity in morbidity and mortality and geographic variability of epidemic burdens

Bangladesh is currently grappling to control its most devastating dengue fever outbreak recorded since the dengue virus (DENV) reappeared in the country in 2000 [1, 2, 3]. Although dengue is endemic in Bangladesh, the current dengue surge is unusual in terms of case burden and mortality, seasonality, and the early sharp increase [[1]]. Between 1 January and 25 August 2023, a total of 110,224 DENV infections including 528 deaths (case fatality ratio [CFR]: 0.48%) were recorded [[2]]. The reported number of dengue cases and deaths this year so far is already the highest ever recorded in the country, while the numbers are continuing to rise [1, 2, 3]. The Bangladesh Ministry of Health and Family Welfare's Management Information System (MIS) provides daily reports on cases, deaths, and the district-wise distribution of DENV infections [[2]]. Analyses of data from inpatient records and geographic coordinates of residence locations between 1 January and 17 August 2023 highlight four important findings that require further epidemic investigation: First, approximately half of the cases (n=52,656) were recorded in the capital city Dhaka, and 86% of them were located within a 2-km radius of hospitals, raising concern about the high density of DENV patients in the proximity of the hospitals (Fig. 1). Second, although 62% of the cases are males, 58% of the deaths are females indicating a higher risk of mortality among females. Third, we identified a possible age-specific disparity in morbidity and mortality indicating more severe infections in the older age group. People ≥30 years old accounted for 38% of cases and 64% of deaths in 2023. Fourth, out of 528 deaths, 391 (74%) were recorded among the patients hospitalized in the capital city, Dhaka (Fig. 2)

Bangladesh's 2023 Dengue outbreak – age/gender-related disparity in morbidity and mortality and geographic variability of epidemic burdens

Bangladesh is currently grappling to control its most devastating dengue fever outbreak recorded since the dengue virus (DENV) reappeared in the country in 2000 [1, 2, 3]. Although dengue is endemic in Bangladesh, the current dengue surge is unusual in terms of case burden and mortality, seasonality, and the early sharp increase [[1]]. Between 1 January and 25 August 2023, a total of 110,224 DENV infections including 528 deaths (case fatality ratio [CFR]: 0.48%) were recorded [[2]]. The reported number of dengue cases and deaths this year so far is already the highest ever recorded in the country, while the numbers are continuing to rise [1, 2, 3]. The Bangladesh Ministry of Health and Family Welfare's Management Information System (MIS) provides daily reports on cases, deaths, and the district-wise distribution of DENV infections [[2]]. Analyses of data from inpatient records and geographic coordinates of residence locations between 1 January and 17 August 2023 highlight four important findings that require further epidemic investigation: First, approximately half of the cases (n=52,656) were recorded in the capital city Dhaka, and 86% of them were located within a 2-km radius of hospitals, raising concern about the high density of DENV patients in the proximity of the hospitals (Fig. 1). Second, although 62% of the cases are males, 58% of the deaths are females indicating a higher risk of mortality among females. Third, we identified a possible age-specific disparity in morbidity and mortality indicating more severe infections in the older age group. People ≥30 years old accounted for 38% of cases and 64% of deaths in 2023. Fourth, out of 528 deaths, 391 (74%) were recorded among the patients hospitalized in the capital city, Dhaka (Fig. 2)

Shifting Geographical Transmission Patterns: Characterizing the 2023 Fatal Dengue Outbreak in Bangladesh

In 2023, Bangladesh experienced its largest and deadliest outbreak of Dengue virus (DENV), reporting the highest-ever recorded annual cases and deaths. We aimed to characterize the geographical transmission of the DENV in Bangladesh. From 1 Jan – 31 Dec 2023, we extracted and analyzed daily data on dengue cases and deaths from the national Management Information System (MIS). We performed a generalized linear mixed model to identify the associations between division-wise daily dengue counts and various geographical and meteorological covariates. The number of Dengue cases reported in 2023 was 1.3 times higher than the total number recorded in the past 23 years (321,179 vs. 244,246), with twice as many deaths than the total fatalities recorded in the past 23 years (1705 vs. 849). Of the 1705 deaths in 2023, 67.4% (n=1015) expired within one day after hospital admission. The divisions southern to Dhaka had a higher dengue incidence/1000 population (2.30 vs. 0.50, p<0,0.01), and higher mean annual temperatures (27.46 vs. 26.54 °C) than the northern divisions. The average daily temperature (IRR: 1.13, 95% CI: 1.11-1.14), urban and rural population ratio of the divisions (IRR: 1.04, 95% CI: 1.03-1.04), showed a positive, and rainfall (IRR: 0.99, 95% CI: 0.98-0.99) showed a negative association with dengue cases in each division. We observed a major geographical shift of Dengue cases from the capital city Dhaka to different districts of Bangladesh with a higher incidence of dengue in the southern division of Bangladesh, influenced by temperature and urbanization