Medicine
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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty
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Item Potential use of IGR Pyriproxifen for control of dengue vector Aedes albopictus(Sri Lanka College of Microbiologists, 1999) Gunawardene, Y.I.N.S.; de Silva, N.R.; Abeyewickreme, W.Dengue Fever (DF) Dengue Haernorrhagic Fever (DHF) is now a significant problem in Sri Lanka. The incidence of DHF has increased cyclically since the first recognized outbreak in 1989. Of the 203 suspected DHF cases recorded in 1989, 87 were confirmed and 26 deaths were reported. By 1997, 5882 clinical cases, 1558 serologically confirmed cases and over 300 deaths have been reported. Without an effective vaccine against dengue, and considering the clinical difficulty in managing DHF cases, vector control has become an important com¬ponent in the integrated attempts for dengue con¬trol. Aedes aegypti and Aedes albopictus not only transmit dengue but are also a nuisance and cause annoyance by their day biting behaviour. In this study an attempt was made to control Ae. albopictus by exploiting its oviposition behaviour, us¬ing an Insect Growth Regulator (IGR), Pyriproxifen. The IGR is known to interfere with the synthesis and deposition of chitin in insects and thereby prevent growth and development. Different concentrations of the IGR (0.01 g/1 -0.08g/1) were tested against Ae.albopictus, in laboratory experiments. The most effective larvisidal concentration of Pyriproxifen for Ae.albopictus was determined to be 0.03g/1. Field trials were also carried out to determine the feasi¬bility of employing used automobile tyres contain¬ing Pyriproxifen as ovitraps against Ae.albopictus. Tyres containing water were treated with Pyriproxifen (0.03g/1) and the emergence of adults was recorded. Pyriproxifen at a concentration of 0.03g/1 was found to inhibit the emergence of adult Aedes mosquitoes up to 6 weeks.Item An Entomological study to plan intervention for prevention of dengue in Gampaha district, Sri Lanka(Elsevier, 2008) Abeyewickreme, W.; Hapangama, H.A.D.C.; Weerasinghe, I.; Hapugoda, M.D.; Gunawardene, Y.I.N.S.; Gunawardena, N.K.; Wickremasinghe, A.R.BACKGROUND: Dengue is the most common and fastest spreading human arbo viral disease worldwide. Most control efforts are based not on insecticides but on suppression of vectors by reducing the number of larval breeding habitats. METHODS: Total of 2000 houses in the District of Gampaha in the Western Province which had the second highest transmission of dengue in 2006 was selected using grid sampling technique, based on disease incidences during 2003—2006. Mosquito surveillance was carried out from 0900 hrs to 1400 hrs during June-August, 2007. Larval and pupal surveillances were carried out indoors and outdoors using standard larval surveillance techniques. RESULTS: The House, Container and Breteau indices for Aedes larvae were 49.3%, 26.1% and 26.9% respectively. The common breeding places for Aedes species were discarded containers 27.1% (559/2064), unused bowls 16.2% (334/2064), plant axils 11.7% (242/2064), water storing barrels 11.4% (236/2064) and coconut shells 5.4%(111/2064). Most productive container types for larvae were tyres (44.3%), plant axils (37.6%), ceramic jars (36.6%), discarded containers (29.5%) and fish tanks (25.0%). Most productive container types for pupae were discarded containers (13.4%), fish tanks (10.4%), unused bowls (8.38%), ceramic jars (7.31%) and coconut shells (6.3%). Aedes albopictus (larvae-85.3%, pupae-80.4%) was the most predominant vector in the district. Earthen pots, plant axils, discarded containers and buckets were the main sources for Aedes albopictus while tyres, barrels, tanks and bowls were for Aedes aegypti. Further, mixed breeding was observed in water storage containers and tyres. CONCLUSION: Discarded small bowls/containers were the key containers with the highest pupal index. Natural breeding habitats such plant axils may also significantly contribute to pupal production. Therefore an integrated control effort to include community level awareness programmes, improved solid waste management for small containers and efforts to prevent breeding in plants is suggested for prevention of dengue in the district. © 2008 Elsevier Inc.