Molecular serotyping of dengue virus in villages of Daman District, India: predominance of DENV-2 and comparison with regional and international surveillance studies

Abstract

Background: Dengue virus (DENV) is endemic in India, with all four serotypes (DENV-1–4) co-circulating nationwide[1]. Serotype surveillance is essential because the dominant serotype affects outbreak dynamics and risk of severe disease. This study reports molecular serotyping of DENV-positive cases from villages in Daman District (Western India) and compares the local serotype distribution with recent regional and international data.

Objectives: To determine DENV serotype frequencies among dengue-positive patients from multiple villages in Daman District, and to contextualize these findings by comparison with recent serotype surveillance studies (Burkina Faso, Ghana, Nigeria, Kerala [India], Dhaka [Bangladesh], Mexico).

Methods: Serum samples from 513 dengue-positive patients (diagnosed by NS1 antigen or molecular assays) were collected from 15 villages in Daman District. Viral RNA was extracted and serotype was determined by RT-PCR with type-specific primers and gel electrophoresis or multiplex RT-qPCR. Clinical signs (fever, headache, arthralgia, myalgia, retro-orbital pain, rash) were tabulated by serotype. Descriptive summaries of serotype counts were generated, and results were compared qualitatively with published serotyping reports from other regions.

Results: Among 513 serotyped cases, DENV-2 was overwhelmingly predominant (430/513; 83.8%), followed by DENV-3 (52/513; 10.1%) and mixed DENV-2 + DENV-3 infections (28/513; 5.5%). DENV-1 (2/513; 0.39%) and DENV-4 (1/513; 0.19%) were exceedingly rare. These distributions are summarized in Table 1. Consistent with serotype frequencies, DENV-2 cases accounted for most recorded symptoms: for example, 169 of 204 fever episodes and 112 of 136 headaches were in DENV-2 patients (Table 2). Other symptoms (arthralgia, myalgia, retro-orbital pain, rash) were infrequent across all serotypes. By contrast, published surveillance studies from Burkina Faso and Mexico during 2023 found DENV-3 as the dominant serotype[2][3], and a Kerala (India) study found DENV-2 predominance (49%) with co-circulation of all four serotypes[4].

Conclusions: In Daman District, DENV-2 is the overwhelmingly dominant serotype, with co-circulating DENV-3 and occasional mixed infections. The near absence of DENV-1 and DENV-4 suggests limited local diversity. This pattern matches recent findings from Kerala, India[4] and parts of South Asia (DENV-2 dominance), but contrasts with West African (Burkina Faso[2]) and Mexican data[3] where DENV-3 predominated. The presence of mixed DENV-2/DENV-3 infections imply risk for secondary heterologous infection and severe dengue. These results underscore regional heterogeneity in DENV serotype circulation and the importance of ongoing local surveillance.