Entomological Investigation of Dengue Outbreak in Raigarh, Central India: Dominance of Aedes albopictus as the Primary Vector

Background & objectives: Dengue outbreaks pose a significant public health threat in Raigarh City, Central India. During the 2023–2024 rainy season, there was a marked rise in febrile cases resembling dengue across urban areas. In response, ICMR-NIMR, in collaboration with local health authorities, initiated entomological surveillance campaign. This effort aimed to identify dengue vectors and implement rapid intervention strategies to mitigate disease transmission. Methods: An entomological survey was conducted in 16 wards of the Raigarh city. The study incorporated epidemiological data spanning nine years (2016–2024), along with a detailed month-wise analysis of dengue cases reported in 2023 and 2024. Vector density was assessed with House Index (HI), Container Index (CI), and Breteau Index (BI), to identify high-risk areas and predominant vector species. Results: A total of 2,080 water-holding containers were identified across 622 surveyed properties, for vector breeding. Among these, 67 (35%) were routinely used household containers, while 124 (65%) were disposable items. Larval collections yielded 986 Aedes specimens, including 104 pupae, with Aedes albopictus accounting for 85% of the total, followed by Aedes aegypti (8%) and Aedes vittatus (5%). The entomological indices reflected a critical vector proliferation scenario, with an HI of 17.35%, CI of 7%, and BI of 24.49. Interpretation & conclusion: Targeted entomological surveillance, community awareness programs with interventions have contributed to a notable reduction in dengue case incidence. The findings establish Aedes albopictus as the predominant dengue vector in the region, alongside Aedes aegypti .