Background & objectives: Dengue is a vector-borne febrile disease caused by the dengue virus, having four serotypes, viz. DENV-1 to 4. Dengue serotyping is an in-vitro RT-PCR based assay that allows specific detection of dengue serotypes from the serum samples of the patients. The purpose of this study was to identify emerging and circulating single and concurrent serotypes in Malda district during 2023–2024. Methods: Dengue NS1 and IgM ELISA were performed on 1445 suspected dengue patients. Serum samples from NS1 ELISA-positive dengue patients were processed for the RT-PCR test. Dengue viral RNA was extracted from serum of the patients. Per sample, a two-tube multiplex RT-PCR assay was used for differential diagnosis of serotypes. Data statistically analysed using the GraphPad Prism (version 8.0.2) and Microsoft Excel 2016. Results: A total of 1185 (82.01 %) samples were found to be dengue viral RNA positive. Among the single infections, DENV-2 was the most prevalent (73.23 % in 2023 and 69.01 % in 2024) serotype during the study years. In addition, both DENV-2 and DENV-3 were the prevalent (65.22 % in 2023 and 51.55 % in 2024) concurrent serotypes. DENV-4 was found rare (0.40% in 2023 and 0.76 % in 2024) among single serotypes. Interpretation & conclusion: This study revealed that DENV-2 was the predominant single serotype circulating in the district of Malda. A higher prevalence of concurrent serotype infection was found for DENV-2 and DENV-3. The emerging trend and changing pattern of dengue serotypes indicate that this district is becoming a dengue-endemic area.
Sarkar et al. (2026) studied this question.