The emergence of dengue in Bangladesh: epidemiology, challenges and future disease risk

Abstract

Dengue occurred sporadically in Bangladesh from 1964 until a large epidemic in 2000 established the virus. We trace dengue from the time it was first identified in Bangladesh and identify factors favourable to future dengue haemorrhagic fever epidemics. The epidemic in 2000 was likely due to introduction of a dengue virus strain from a nearby endemic country, probably Thailand. Cessation of dichlorodiphenyltrichloroethane (DDT) spraying, climatic, socio-demographic, and lifestyle factors also contributed to epidemic transmission. The largest number of cases was notified in 2002 and since then reported outbreaks have generally declined, although with increased notifications in alternate years. The apparent decline might be partially due to public awareness with consequent reduction in mosquito breeding and increased prevalence of immunity. However, passive hospital-based surveillance has changed with mandatory serological confirmation now required for case reporting. Further, a large number of cases remain undetected because only patients with severe dengue require hospitalisation. Thus, the reduction in notification numbers may be an artefact of the surveillance system. Indeed, population-based serological survey indicates that dengue transmission continues to be common. In the future, the absence of active interventions, unplanned urbanisation, environmental deterioration, increasing population mobility, and economic factors will heighten dengue risk. Projected increases in temperature and rainfall may exacerbate this.

Dengue seroprevalence, seroconversion and risk factors in Dhaka, Bangladesh

“…Based on molecular diagnostic testing of persons with acute disease, all four dengue serotypes have been found in circulation in recent years [19–21]. From 2000–2009, 91.0% of all reported dengue cases were from Dhaka making it the most endemic urban area of the country [22]. Cases of DF were clustered during the time periods: 2000–2002, 2003–2005, and 2006–2009, and Dhaka was the locality with ‘the most likely cluster for DF in all three periods’ [18].…”

Seasonal Distribution and Climatic Correlates of Dengue Disease in Dhaka, Bangladesh

“…1 It is estimated that about 400 million dengue infections occur each year in tropical and subtropical countries. 1,2 There are four DENV serotypes, and a primary infection usually results in mild disease; however, reinfection with a different DENV serotype is more likely to result in dengue hemorrhagic fever, a more severe disease manifestation. 2 Dengue incidence has been associated with variations in climate.…”

“…The first report of dengue in Bangladesh was in 1964. 1 Cases have been reported regularly in Dhaka, the capital of Bangladesh, since a large outbreak of dengue hemorrhagic fever in 2000 8 ; however, limited surveillance capabilities mean that we do not know if there exists year round transmission, nor which age groups are most affected by the disease. The objective of this study was to characterize the seasonality and age distribution of dengue cases and explore the climatic drivers of transmission.…”

Dengue coinfection in a case of enteric fever: a diagnostic and therapeutic dilemma

“…On the other hand, since 2000, regular outbreaks of dengue occur in Bangladesh. 15 To date, only several cases of coinfection by dengue and enteric fever are known. Both dengue and enteric fever are tropical diseases, and occur predominantly in monsoon season.…”