Abstract
Bangladesh is an endemic region of dengue fever and experienced an unprecedented large outbreak with more than 100,000 confirmed cases in 2019. To understand the prevalence of dengue antibody in patients and molecular epidemiological characteristics of dengue virus (DENV) in this outbreak, a total of 179 blood samples were collected from patients in 10 districts (seven divisions) covering nearly the whole country from August to December 2019. DENV NS-1 was detected in 162 samples, among which DENV-specific IgM was positive in 119 samples (73.5%), including 60.5% samples also positive for DENV-specific IgG. Sequencing of the partial C-prM gene and its phylogenetic analysis revealed predominance of DENV type 3 genotype I, accounting for 93% of samples examined. DENV-3 genotype III was identified in two samples from separate districts, and only one DENV-2 cosmopolitan genotype was found in the capital city, Dhaka. These findings suggest the predominance of DENV-3 genotype I and occurrence of DENV-3 genotype III, associated with increased incidence of recent secondary infection in Bangladesh in 2019.
Highlights
Dengue virus (DENV) infection is a mosquito-borne, acute systemic disease and has become one of the major public health problems worldwide in the last few decades, with Asia having the greatest disease burden [1]
Our present study indicates that DENV-3 became predominant, displacing other DENV serotypes in 2019, when an unexpected large outbreak occurred in Bangladesh
In western India, the dengue outbreak in 2017 was described as being associated with the replacement of dominant DENV-2 by emerging DENV-3 [22], which seems to be a similar situation to Bangladesh
Summary
Dengue virus (DENV) infection is a mosquito-borne, acute systemic disease and has become one of the major public health problems worldwide in the last few decades, with Asia having the greatest disease burden [1]. Following the observation of re-emergence of DENV-3, as well as predominance of DENV-2 in 2017 [10,11,12], a large outbreak of dengue involving more than 10,000 cases occurred in Dhaka, the capital city of Bangladesh, in 2018. This outbreak was caused by multiple viruses including a dominant DENV-2, along with DENV-1 and DENV-3 [8,10,12,13]. The present study was conducted to understand prevalence of secondary dengue infections and reveal genetic characteristics of DENV causing the outbreak, in all areas of Bangladesh. The results indicated a high rate of dengue reinfection, with predominantly DENV-3 genotype I, as well as the emergence of DENV-3 genotype III
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