Breeding habitats of Aedes aegypti Linnaeus and Acalbopictus Skuse in a dengue transmission area in Kandy, Sri Lanka

Abstract

Breeding habitats of Ae.aegypti and Ae.albopictus were studied from July 2002 to August 2003 in Kandy District, Sri Lanka. Den­ gue fever (DF) and dengue haemorrhagic fever (DHF) cases were identified and details of pa­ tients were collected in consultation with Regional Epidemiologist, Kandy. Entomological investi­ gations were carried out around 347 DF/DHF cases in 120 study sites, covering an area of 100. m radius around each case and including a mini­ mum of 100 houses per site. All possible breed­ ing places were examined, Aedes larvae were col­ lected in labelled containers using pipetting, dip­ ping and siphoning techniques. Larvae were iden­ tified in the laboratory. 884 containers positive for Ae.aegypti and Ae.albopicus were encountered around 12,470 houses. The majority (51.36%) of positive con­ tainers for Aedes breeding were the water stor­ age tanks and barrels. Water storage containers have constituted 66.66% breeding habitats of Ae.aegypti. Other important containers positive for Aedes breeding were tyres (11.88%), discarded plastic containers (11.31%), earthen pots (10.07%), and metal ware (3.17%). For all types of containers (except for roof gutters), number of containers positive for Ae.albopictus was higher than that for Ae.aegypti. In spite of mechanical and biological larval con­ trol measures, 10.01%water storage containers were found positive for Aedes breeding. This in­ dicates that mechanical and biological measures alone are not sufficient for preventing Aedes breeding and the necessity of a supplementary chemical method for Aedes larval control in water storage containers in the study area. Furthermore, effective garbage collection and proper disposal by the local government bodies, commitment of individuals and communities in source reduction, and law enforcement against occupants of premises with Aedes mosquito breeding are necessary for DF and DHF control in the Kandy District.