Detection of dengue virus serotypes in Aedes larvae: a multi-location study from Bhubaneswar, India, suggestive of vertical transmission

Dengue virus (DENV), primarily spread by Aedes mosquitoes, remains a significant public health concern in India. This study focused on Bhubaneswar, Odisha, India aiming to detect DENV serotypes in Aedes larvae to gain early insights into viral circulation. A total of 8,257 larvae were collected from 60 locations, pooled (n = 390) and screened for dengue using real-time-PCR (pan-dengue assay). Serotyping was carried out using serotype-specific RT-PCR targeting DENV-1 to DENV-4. Overall, 60 pools tested positive for DENV. DENV-1 emerged as the dominant serotype across both winter and rainy seasons. DENV-2 appeared only during the rainy season, often in co-infections with DENV-1 in areas such as Bhagabatipur, Katani, and Dashpur. Higher viral loads were detected in Dashpur, BDA Colony, and Acharya Vihar. Persistent detection near locations like Kalinga Hospital and evidence of vertical (transovarial) transmission further emphasize the ongoing risk. The emergence of adult Aedes from larvae confirmed vector species identity. These findings underscore the value of larval molecular surveillance in identifying transmission hotspots and timing interventions. Integrating such data with public health efforts can significantly enhance dengue outbreak prediction and vector control in urban settings.