Entomological Investigation during an Outbreak of Dengue in 2018 in Bilaspur District, Himachal Pradesh

Abstract

Background: Post dengue outbreak in July 2018, an entomological survey was undertaken in the Bilaspur district of Himachal Pradesh in India, to identify risk factors for Aedes breeding and subsequently suggest mitigation measures to control the epidemic situation. Method: In view of the clustering of dengue cases, three wards of Diara primary health centre and surrounding villages were selected for the survey. Hand catch method was used to collect adult vectors resting indoors, whereas immature stages of vectors were collected from containers using a ladle. Man-hour density and other vital entomological indices were calculated using the standard methods. Results: An alarming Breteau Index (129), as well as a very high House Index (75), Container Index (32) and Pupal Index (120) were observed during the survey, indicating a dengue outbreak situation. Aedes aegypti and Aedes albopictus, vectors of dengue, were collected from the affected region with man-hour density ranging between 1 and 6.4. Plastic containers and syntax tanks were the major containers observed in households to store water due to irregular water supply. Interpretation & Conclusion: The population was hesitant to discard the stored water due to scarcity and irregular water supply. Plastic containers were the most productive for Aedes breeding. Community knowledge, attitude and practices towards the severity of dengue, its prevention and control were low. The present study recommends that the dengue control strategy should focus on keeping water supply and plastic containers in mind and the community should be mobilised to keep water containers covered properly, or source reduction should be done.