Objectives: Nipah virus (NiV) causes deadly outbreaks in Bangladesh, with a fatality rate of 71%. Two sublineages, NiV-BD 1 and NiV-BD 2, have been identified. This study aimed to characterize their epidemiologic and clinical diversity.
Methods: This study analyzed 21 new (2016-2023) and 17 previously (2012-2015) reported NiV genome sequences and compared sublineages using descriptive and bivariate analysis.
Results: The median age of sequenced cases was 17 years (Interquartile Range (IQR): 9-30), 66% were male. Raw date palm sap consumption was main transmission pathway (92%). NiV-BD 2 showed a broader geographic distribution, including the southern region. The sublineages did not differ significantly in age, sex, or transmission modes. Both sublineages presented with fever, altered mental status, and unconsciousness. Respiratory distress was more frequent in NiV-BD 2 (23 of 29 cases), whereas hospitalization was longer for NiV-BD 1 (median: 3 days; IQR: 1-23). The overall mortality was 84%, with no significant difference between sublineages. Phylogenetic analysis demonstrated that NiV-BD 1 and NiV-BD 2 formed distinct clusters with 98.72-99.25% nucleotide and 99.98-99.99% amino acid identity. The structural nucleoprotein and matrix proteins remained conserved across sublineages.
Conclusions: This study highlights genetic, spatio-temporal, and clinical variation between sublineages, emphasizing continuous genomic surveillance to inform future vaccine and therapeutic strategies.
Keywords: Bangladesh; Genetic diversity; Nipah strain; Nipah virus.
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