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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 Gene flow patterns among Aedes aegypti (Diptera: Culicidae) populations in Sri Lanka(MDPI AG, 2020) Fernando, H.S.D.; Hapugoda, M.; Perera, R.; Black Iv, W.C.; de Silva, B.G.D.N.K.ABSTRACT:In Sri Lanka, dengue is the most serious arboviral disease. Recent increases in dengue cases suggest a higher infection rate and spread of the disease to new areas. The present study explores gene flow patterns of Ae. aegypti, the main vector of dengue disease, among 10 collection sites including major ports and inland cities using variations at 11 microsatellite loci. Discriminant analysis of principal components (DAPC) and k-means clustering estimated eight genetic clusters. Analysis of Molecular Variance (AMOVA) estimated equal variances among cities and among collections in Colombo, Sri Lanka. Significant evidence, although weak, was detected for isolation by distance. Analysis of gene flow rates and directions using MIGRATE-n indicated that populations throughout the island served as a source of immigrants for Colombo with abundant gene flow among major commercial cities in Sri Lanka, which appear to receive migrant mosquitoes from throughout Sri Lanka. The observed patterns probably arise through human movement of Ae. aegypti during commerce from throughout Sri Lanka into Colombo increasing the risk of spread. The patterns uncovered in this study are significant for global health as Sri Lanka is situated along a key international shipping route. KEYWORDS: Aedes aegypti; Sri Lanka; gene flow patterns; population structure.Item First report of V1016G and S989P knockdown resistant (kdr) mutations in pyrethroid-resistant Sri Lankan Aedes aegypti mosquitoes(BioMed Central, 2018) Fernando, S.D.; Hapugoda, M.; Perera, R.; Saavedra-Rodriguez, K.; Black WC 4th; de Silva, N.K.; ; ;BACKGROUND: Dengue is a serious arboviral disease in Sri Lanka with a large number of dengue fever (DF) cases every year. Control of the primary vector Aedes aegypti depends upon larval habitat source reduction and insecticide application. However, increases in the number of reported cases suggest the inefficiency of current control strategies and the possibility of resistance to currently used insecticides. Early detection of mutations in the voltage-gated sodium channel (vgsc) gene that confer knockdown resistance (kdr) to pyrethroid insecticides is important in resistance management in vector populations. RESULTS: Resistance to pyrethroid insecticides was detected in the three populations studied. Polymerase chain reaction was used to detect the presence of two kdr mutations F1534C and V1016G. During this process a S989P mutation was also detected in pyrethroid-resistant Ae. aegypti populations. These mutations were found to be widespread and frequent in the collections studied. CONCLUSIONS: To our knowledge, this study reveals for the first time the presence of V1016G and S989P mutant alleles in the vgsc of Sri Lankan Ae. aegypti populations. The spread of the mutant alleles throughout the country poses a threat of increased resistance to pyrethroids. Long-term insecticide applications and indiscriminate use of pyrethroids has led to the evolution of resistance. More strategic and diverse strategies, including novel insecticides with new modes of action and community participation, should be engaged for Ae. aegypti control.Item A Preliminary study of genetic estimates of population structure of Aedes aegypti populations in three districts, Sri Lanka(Sri Lanka Association for the Advancement of Science, 2014) Fernando, H.S.D; Hapugoda, M.D.; de Silva, B.G.D.N.K.