Surveillance for dengue vector mosquito in Kurunegala district, Sri Lanka

Abstract

BACKGROUND: Dengue vector surveillance is an important tool to determine the time and area/s to initiate control action. Our objective was to identify entomological risk factors with regard to transmission of dengue in a dengue hot-spot. METHODS: In the study 75 human dwellings in a dengue hot-spot in the District of Kurunegala was selected based on high disease incidence during 2000—2004, high Aedes as well as human population density and increased building activities. House to house mosquito surveillance was carried out from 08.00 am to 12.00 noon during May—August, 2007. Larvae and adult Aedes mosquitoes were collected indoors and outdoors using normal larval surveillance and human landing diurnal collection techniques respectively. Environmental and sociological data were obtained from households by interviewer administered questionnaires and observations. RESULTS: The house index for Aedes aegypti and Aedes albopictus ranged from 1.33%—6.60% and 2.67%—5.33% respectively. The Breatu index ranged between 23.67%—29.33% for Ae. aegypti and 1.33%—18% for Aedes albopictus. Man biting rates of 0.43—5.78 bites/man/hour were estimated for Ae. aegypti, while it ranged from 0.49—1.33 for Ae. albopictus. The most common breeding place for Aedes species was plastic baskets (16%, n = 12). More than half of the households (61%, n = 45) stored water in large cement tanks for their daily activities. Majority of the group (99%, n = 74) had a basic knowledge on dengue mosquito breeding places (97%, n = 73), their life cycle (95%, n = 71) and mode of transmission (99%, n = 74). Domestic waste of majority of households was carried away daily by the local authorities (n = 69). CONCLUSION: These results suggest that a vector control program should be adopted to reduce Aedes population levels below dengue transmission thresholds. Discarded containers of various types were identified as potential mosquitoes breeding habitats. Therefore, community must be educated on effective vector control measures to contain the transmission levels. © 2008 Elsevier Inc.