Distribution and breeding sites of potential dengue vectors in Kandy and Nuwara Eliya districts of Sri Lanka

Entomological investigations were con­ ducted in 26 urban and semi urban areas in Kandy and Nuwara Eliya districts to determine the distribution and breeding sites of potential vectors of dengue, viz., Aedes aegypti Linnaeus and Aedes albopictus Skuse in these areas. Aedes larval surveys were carried out around suspected/ serologically positive dengue fever (DF)/ dengue haemorrhagic fever (DHF) cases in dengue transmission areas, and, in bus depots, government institutions and tyre shops (high risk places for Aedes breeding) in DF/ DHF non transmission areas. Aedes aegypti and Ae. albopictus were not encountered in the Nuwara Eliya town (altitude 1900 m). But, either Ae. albopictus or Ae. aegypti and Ae. albopictus were encountered in all the other localities (elevation 100 -1300 m). The majority (96%) of breeding sites of Ae. aegypti and Ae. albopictus comprised of water storage containers, discarded receptacles and tyres. Breeding sites of Ae. aegypti and Ae. albopictus differed from one locality to another as well as from one time period to another. This study shows that the areas situated below 1300 m elevation in Kandy and Nuwara Eliya districts are receptive for dengue transmission. Strengthening of DF/ DHF surveillance and control measures in these areas is an urgent need to reduce morbidity and mortality, and the spatial distribution of DF/DHF in the two districts. Since, the breeding sites differed from one period of time to another and from one locality to another, dengue control measures should be planned based on local and current entomological information.