IPRC - 2015
Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/156
Browse
4 results
Search Results
Item Larvivorous Potential of Four Fish Species Against Dengue Vectors in The Kandy District of Sri Lanka(Faculty of Graduate Studies, University of Kelaniya, 2015) Kusumawathie, P.H.D.; Jayasooriya, G.A.J.S.K.; Gunathilaka, P.A.D.H.N.; Hapugoda, M.D.; Abeyewickreme, W.There is a growing concern on the effects of insecticides that are used for the control of mosquito vectors of human diseases. Introducing a self propagating predator into the vector breeding habitats may present continual biological control of vector population. In order to control dengue vectors, namely, Aedes aegypti (Linnaeus) and Aedes albopictus (Skuse) (Diptera: Culicidae), larval control is one of the major strategies. The objective of this study was to evaluate the larvivorous potential of fish species against dengue vectors. Four fish species, namely, Poecilia reticulata (guppy), Aplocheilus dayi (Udahandaya), Oreochromis niloticus (Tilapia) and Puntius bimaculatus were collected from natural breeding habitats. They were placed in fish stock cement tanks at the Regional Office of the Anti Malaria Campaign in Kandy till they were used for the study that was conducted from January – June 2015. In order to determine the larvivorous potential of the fish species, five fish of each species were placed in separate enamel trays containing de-chlorinated water and allowed to acclimatize for half an hour. Afterwards, a batch of 25 Ae. aegypti larvae was introduced to each tray and counted the number of larvae remaining after 5, 10, 30 minutes, 1 and 24 hours. When all 25 larvae are consumed, another batch of 25 larvae was introduced to those trays and this was continued till the study was completed. At the end of study period (24 hours), the number of larvae consumed per fish for each fish species was determined. This study was carried out in the laboratory with 6 replicates. The experiment was repeated for Ae. albopictus. Overall, Oreochromis niloticus, Poecilia reticulata, Aplocheilus dayi and Puntius bimaculatus consumed 97.6, 66.9, 49.3 and 47.5 Ae. aegypti and 98.4, 62.3, 51.2 and 45.4 Ae. albopictus larvae respectively. All four fish species showed larvivorous activity and Oreochromis niloticus showed the highest larvivorous potential followed by Poecilia reticulata. Since Ae. aegypti and Ae. albopictus breed in water storage containers such as cement tanks, barrels and ornamental ponds, the fish species that showed high larvivorous potential may be considered for dengue vector larval control in such containers. In order to achieve good community participation for the use of larvivorous fish for dengue vector control, effective health education is of utmost importance.Item Emerging Spatio-Temporal Trends in Dengue Incidence in Poojapitiya Medical Officer of Health (MOH), Central province, Sri Lanka(Faculty of Graduate Studies, University of Kelaniya, 2015) Udayanga, N.W.B.A.L.; Gunathilaka, P.A.D.H.N.; Iqbal, M.C.M.; Kusumawathie, P.H.D.; Abeyewickreme, W.Dengue has emerged as one of the major threats to the health sector of many countries including Sri Lanka, due to the increasing number of reported dengue cases over time. Therefore, a statistical and geo-informatics based analysis of the spatio-temporal trends in dengue distribution was carried out to identify recent spatial and temporal trends in dengue distribution patterns, while assessing the susceptibility of the population to dengue infection in the Poojapitiya Medical Officer of Health (MOH) area. Monthly records of reported dengue cases from 2009 to 2013 of the Poojapitiya MOH area were acquired and spatial maps of the recorded dengue case distribution in each Grama Niladhari Division (GND) were developed by using Arc GIS (version 10.2). Normal Chi square test coupled with Paired-Chi square test in MINITAB (version 14.12.0) were used to investigate the impact of gender and age on the infection. Galhinna GND indicated the highest susceptibility to dengue throughout the study period, while the rest of the GNDs indicate less (37 GNDs) or null (29 GNDs) susceptibilities. As suggested by the results of the Paired-Chi square test [>Χ 2 (66, 0.95) = 85.951], the emergence of dengue outbreaks indicated a significantly declining trend in recorded dengue cases in all of the GNDs (regardless of the outbreak in 2012) during recent years. The Percentage Infected Male : Female Ratio (PIMFR) suggested that the, males had a relatively high susceptibility for dengue infection than females with 63.9 : 36.1 of average PIMFER (p=0.00<0.05 at 95% of significance). According to the Paired-Chi square test, the vulnerability of the age groups shifts significantly throughout the study period [>Χ 2 (7, 0.95) = 14.067], where the age groups of 11 - 20 and 21 – 30 indicated high vulnerability to dengue, while >61 age group remained as the least vulnerable group for dengue infection. The identification of the potential high risk GNDs with high susceptibility to the infection of dengue along with the vulnerable age groups in the community would assist the relevant vector controlling agencies to concentrate their efforts, ensuring the effective controlling of dengue outbreak occurrence within the of Poojapitiya MOH.Item Determination of appropriate positioning of the ovitraps for dengue mosquito surveillance(Faculty of Graduate Studies, University of Kelaniya, 2015) Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S.; Chandrasena, T.G.A.N.; Dassanayake, R.S.; Gunathilaka, P.A.D.H.N.; Abeyewickreme, W.Three months ovitrap survey was conducted to assess the suitable position in placing the ovitraps for dengue vector mosquito surveillance and this study was initiated due to loss of valuable data from our previous studies as a result of physical damage of the ground kept ovitarps. Thirty four households in the Ragama Medical Officer of Health area in Gampaha District were selected to conduct the ovitrap survey during the period of May to July, 2015 to select the most appropriate positioning of the ovitrap. The conventional black plastic ovitraps (3.2x 2.7 cm) were used in this purpose to collect aquatic stages of Aedes mosquitoes while placing plywood paddle (4 x 0.5 cm) over the upper rim of each coded ovitrap. A total of 136 ovitraps were used in the study site providing four ovitraps (2 each indoor & outdoor) for each house while one of the ovitraps of indoor and outdoor being hung and other being kept on the ground. In positioning ovitraps, the outdoor ones were kept 3m away from the house while leaving indoor ovitraps in the living room in close proximity to racks/hanging clothes or partially shaded places. Following collection of samples at each week, ovitraps were washed thoroughly, refilled with new water and a new paddle, and corresponding data were recorded and analyzed. These analyses revealed that number of larvae and the number of Aedes mosquito eggs present in the two different ovitrap positions (Ground kept vs Hung) were not significantly different; in spite of significant difference (P=0.001) between the outside and inside placements. Further, significantly higher values were observed for both number of mosquito eggs and larvae present in each ovitrap kept outside (60 and 13 respectively) than those placed inside (32 and 3 respectively). Furthermore, slightly higher values were observed for hung ovitraps (49 and 9 respectively) than ones kept on the ground (43 and 7 respectively). Finally, ovitrap placed above the ground level was selected in continuing the routine ovitrap survey, as there was considerable reduction of mechanical damage to the latter thus facilitating continuous data collection.Item Characterization of Anopheline larval habitats and species composition of aquatic macro-invertebrates in Trincomalee District, Sri Lanka(Faculty of Graduate Studies, University of Kelaniya, 2015) Ranathunga, R.M.T.B.; Gunathilaka, P.A.D.H.N.; Kannangara, D.N.; Abeyewickreme, W.; Hapugoda, M.D.Malaria control methods that aim to reduce adult vector populations by targeting their aquatic immature stages. A better fundamental understanding of the biology and ecology of these essential stages could contribute to the implementation of current control methods and to the development of novel strategies. Objective of this study was to examine breeding habitat diversity and analysis of richness, diversity and geographical distribution of Anopheline larvae and the species composition of aquatic macro-invertebrates in their oviposition sites in Trincomalee District. Fifteen major permanent breeding places in five possible malaria sensitive sites (Gomarankadawala, Ichchallampaththu, Mollipothana, Padavisiripura and Thoppur) in Trincomalee District were selected. Anopheles larvae and macro-invertebrates were collected using standard methods for 16 months (April, 2013-July, 2014) and they were identified microscopically. The Shannon diversity index (H') was used to characterize species diversity at the five study sites by its abundance and evenness of the species present. ANOVA were used to analyze the correlation between macro-invertebrates and mosquito larval abundance. In total, 4478 including 11 species of Anopheles larvae were identified. An. subpictus, An. nigerrimus and An. peditaeniatus (71%) were the most abundant and widely-distributed species. Anopheline larval diversity was highest in Mollipothana (H‘=1.986). Whereas in Gomarankadawala, Ichchallampaththu and Thoppur where H‘=1.721, H‘= 0.857 and H‘=0.762 respectively. In total, 28 species of aquatic macro-invertibrates were identified and highest diversity was recorded in Mollipothana, Gomarankadawala and Ichchallampaththu (H‘=3.14-2.56). This deduces that the species richness and diversity of Anopheles mosquitoes and macro-invertebrates are higher in these areas. The presence of permanent breeding places may be the factors for this phenomenon. This study represents the first systematic update to the distribution of macro-invertebrates associated with Anopheles mosquito oviposition sites in Trincomalee District. Knowledge generated on the ecology of Anopheles mosquitoes will help to eliminate malaria vectors in the country.