Resurgence and molecular epidemiology of dengue virus serotype 4 amid the COVID-19 pandemic in Thailand.

Authors

Lilian Bosibori Obaga, Tharathip Boondouylan, Warinya Nuwong, Navin Horthongkham, Kamol Suwannakarn, Pravech Ajawatanawong, Pravarit Athiprayoon, Atsadang Boonmee, Nattaya Tanlieng, Khanate Sayasit, Chutikarn Chaimayo

Published in

Journal of clinical virology : the official publication of the Pan American Society for Clinical Virology. Volume 186. Pages 106004. Sep 15, 2026. Epub Sep 15, 2026.

Abstract

Dengue virus serotype 4 (DENV4) co-circulates with other serotypes in Thailand, a hyperendemic setting characterized by cyclical shifts in serotype predominance. During the COVID-19 pandemic, related public health interventions may have influenced dengue detection, transmission and epidemiological dynamics.
A total of 413 dengue NS1/PCR-positive samples collected from 2018 to 2024 at a tertiary hospital in Bangkok were serotyped using a real-time PCR DENV1-4 subtyping assay. Forty-seven DENV4-positive samples (Ct < 32) underwent whole-genome sequencing using the ATOPlex DENV1-4 panel on the DNBSEQ-G99RS platform. Sequencing reads were processed using CLC Genomics Workbench, followed by phylogenetic, mutation, codon-based selection-pressure, and epitope-mapping analyses.
DENV4 was identified in 18.2% (75/413) of samples, with 48% of cases requiring hospitalization. Detection increased markedly from 11.8% (22/186) during 2018-2021-23.3% (53/227) during 2022-2024 (proportion ratio, 1.97; p = 0.0025). Among the 47 whole-genome-sequenced samples, most strains clustered within genotype I lineage 4I_A.3 and showed lineage-associated non-synonymous substitutions. NS1-A90T, NS2A-L113F, and NS3-F523Y appeared exclusively during 2022-2024 (p < 0.001), whereas NS2A-L113F, NS5-G223S, and NS5-Q631R showed concordant positive-selection signals by FEL and MEME.
This hospital-based study highlights an increase in DENV4 detection in Bangkok during 2022-2024 compared with 2018-2021, accompanied by predominance of lineage 4I_A.3 distinct from Malaysian and Indonesian strains reported during a similar period. These findings support integrated clinical and genomic surveillance to monitor DENV serotype and genotype dynamics and inform public health and vaccine strategies.

PMID:
42753459
Bibliographic data and abstract were imported from PubMed on 18 Sep 2026.

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