Browsing by Author "Viswakula, S."

Now showing 1 - 4 of 4

Assessment of Possible Risk Factors Affecting Transmission of Dengue in the District of Gampaha Based on Reported Dengue Cases
(International Postgraduate Research Conference 2019, Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2019) Perera, E.H.L.; Viswakula, S.; Gunawardene, Y.I.N.S.; Subasinghe, U.; Hapugoda, M.D.
Dengue is a fast spreading arboviral infection transmitted by the bite of infected females of Aedes aegypti (Linnaeus) and Ae. albopictus (Skuse). According to the Epidemiology Unit, the second highest number of dengue cases is reported in the District of Gampaha, Sri Lanka over past ten years. Objective of this study was to investigate the entomological and socio-economic risk factors affecting transmission of dengue in laboratory-confirmed dengue case reported stations in the District of Gampaha. Laboratory confirmed positive dengue patients (n=100) by dengue NS1 antigen test during the period of June, 2018-August, 2019 were selected. Entomological surveillance was conducted by visiting to each patient within one week of notification of a positive case. For the collection of socio-economic data, an interviewer-administrated questionnaire was used. Adult Aedes mosquito samples collected using a back-pack aspirator showed, 98.64% (73/74) of Ae. albopictus and 1.35% (1/74) of Ae. aegypti mosquitoes. Larval collection using standard larval surveillance techniques showed 92.96% (185/199) and 7.04% (14/199) of Ae. albopictus and Ae.aegypti larvae respectively. The highest House Index (55.17%-16/29), Container Index (28.89%-13/45) and Breteau Index (44.83%-13/29) were reported in the month of June, 2019. The major Aedes breeding place was identified as plastic buckets/barrels (48.6%-84/173) that being used to discard waste. Piped borne water (88%-88/100) was the major water source of the house-holds. Water source of tube well (9%-9/100) was the next popular water source and 66.67%(6/9) of tube wells were positive breeding places for Aedes larvae. Average homestead of the premises of dengue patients was 16.14 perches. From the 100 dengue cases, 67 cases were from middle of town areas, while 2 were from rural areas. Vegetation coverage of the 78% (78/100) house-holds were grass, bushes and small trees and 3% (3/100) house-holds didn’t have any vegetation coverage. The major mosquito prevention method was usage of mosquito nets (54%-54/100) and among dengue patients 7% (7/100) of dengue patients weren’t using any mosquito prevention method. High density of Ae. albopictus mosquitoes, was reported although Ae. aegypti is the major vector of dengue. Therefore, it is required to draw more attention about the Ae. albopictus breeding sites in dengue control programmes. Participants from the study sites were well aware about the disease but still there is a lack of knowledge on breeding sites and vector control methods. Drawbacks in the waste disposal methods, lack of cleanliness in gardens, unplanned water sources and neglecting preventive actions could be considered as the possible risk factors.
Assessment of the distribution of Aedes breeding sites at the households of district of Gampaha
(Faculty of Graduate Studies, University of Kelaniya Sri Lanka, 2022) Perera, E. H. L.; Hapugoda, M. D.; Viswakula, S.; Gunawardene, Y. I. N. S.; Subasinghe, U.; Fernando, L.; Manamperi, A.
Dengue is the most important mosquito-borne viral infection in Sri Lanka at present. Integrated Vector Management (IVM) targeting dengue vector mosquitoes has become the main disease control measure. The objective of this study was to assess the distribution of the Aedes breeding habitats in dengue high and low risk areas in the District of Gampaha where the second highest incidence of dengue reported during last 10 years. Negombo Medical Officer of Health (MOH) area was selected based high incidence of dengue cases reported in the District of Gampaha during last 10 years. A dengue high risk (Kurana East) and low risk (Udayarthoppuwa) Grama Niladhari (GN) divisions with similar geographical situation in the same MOH area were selected as study and control areas respectively. Standard larval surveillance was conducted randomly selected 150 houses in each site for 18 months (April, 2018-October, 2019). In the dengue high risk and low risk areas, the proportions of the larvae of Aedes species to the total larval collection were 34.19% (185/541) and 21.68% (147/678) respectively. High densities of Ae. albopictus larvae were reported in both high [171/185=92.4%)] and low [141/147=95.92%) risk areas. Ae. aegypti was present in low abundance in both areas [High risk-7.56% (14/185) and Low risk- 2.72% (4/147)]. In the high-risk site, breeding sites of the Ae. albopictus larvae were reported as plastic buckets/barrels (55.19 %-154/279), waste plastics (35.15%-98/279), metal tins (3.94%-11/279) and tube wells (2.86%-8/279). In low-risk area, the majority of breeding sites for Ae. albopictus larvae was found in coconut shells (76.14%- 201/264) and plastic waste (21.96%-51/264). In both areas, Ae. aegypti larvae was found in plastic buckets/barrels only. There is a significance difference between the Ae. albopictus breeding places in the dengue high and low risk areas (P=0.024). Although Ae. aegypti is considered as the major vector of dengue, Ae. albopictus was reported as the prominent dengue vector species in the high dengue risk area in the District of Gampaha. Even though, municipal council removes solid waste weekly, a large number of breeding sites are available at both areas. As there is a significant difference between Ae. albopictus breeding sites at the dengue high and low risk areas, it is essential to specifically focus on removal of breeding sites for successful vector control measure.
Spatial and seasonal analysis of human leptospirosis in the District of Gampaha, Sri Lanka
(Sri Lankan Society for Microbiology, 2016) Denipitiya, D.T.H.; Chandrasekharan, V.; Abeyewickreme, W.; Viswakula, S.; Hapugoda, M.
Leptospirosis is a zoonostic infectious disease, caused by a pathogenic species of the Genus Leptospira. In recent years, a markedly increased number of leptospirosis cases have been reported in the District of Gampaha, in the Western Province of Sri Lanka. Typically, the risk of the disease in the district is seasonal with a small spike occurs in March to May and a large spike occurs during October to December. Objectives of this study were to analyze spatial and seasonal patterns of human leptospirosis and to predict the leptospirosis epidemic trend in the District of Gampaha, Sri Lanka. All Divisional Secretariats (DS) of the district of Gampaha were selected for the study. Epidemiological data were obtained from the Regional Epidemiological Unit, Gampaha. The leptospirosis cases were georeferenced according to DS in where these cases were reported. The cumulative incidence and the fatality were calculated for each DS. Of the georeferenced data, highest mean (±S.E.) of number of leptospirosis cases (72.60 ±15.54) were observed from DS of Mirigama. The highest mean cumulative incidence (4.97±1.10) and case fatality rate (3.88±2.42) were observed from DS of Divulapitiya and Katana respectively. According to past 10 years data on leptospirosis, highest mean numbers of leptospirosis cases were reported in March (51.00±12.99) and November (56.80±8.27). A predictive model for clinically confirmed human leptospirosis was designed for the district by using TSA package of the statistical software R. This study provides an evidence base for reducing disease burden by improving the understanding of the dynamic patterns of the disease in the District of Gampaha, Sri Lanka.
Validation of fluorescence in situ hybridization (FISH) assay using an analyte-specific reagent in detecting aneuploidies of chromosomes 13, 18, 21, X, and Y in prenatal diagnosis
(LIDSEN Publishers, 2023) Ralalage, B.M.S.K.P.; Kaluarachchi, N.; Randunu, M.; Jainulabdeen, M.; Nanthakumar, R.; Viswakula, S.; Galhena, B.P.
Fluorescence In-Situ hybridization (FISH) is a sensitive and highly efficient technique commonly used in routine diagnostics. Most of these tests that use analyte-specific reagents are not approved by US Food and Drug Administration (FDA) but are developed by individual test laboratories. There is an emerging demand for prenatal diagnosis of aneuploidies by FISH. Since most of these assays are laboratory-developed tests, it is essential to validate them prior to their use in diagnosis. However, validation procedures of these assays are oversight despite the presence of several validation guidelines. To validate FISH assay using analyte-specific reagents in detecting aneuploidies of chromosomes 13, 18, 21, X, and Y as per American College of Medical Genetics (ACMG) guidelines in 2016. Analyte-specific reagents supplied by Oxford Gene Technologies were used in the validation process using blood and amniotic fluid samples obtained from healthy male and female adults and fetuses respectively. The validation process includes probe localization, evaluation of assay specificity, and establishment of lower cut-off and reportable reference ranges. Probe localization indicated a 100% specificity for all probes tested. Interphase FISH on uncultured amniotic fluid demonstrated significantly high (≥95%) overall disomic signal patterns for all autosomes and sex chromosomes tested. The reportable 95% confidence interval was 94.84, 94.84, 95.24, 94.54, and 94.54 for chromosomes 13, 18, 21, X, and Y respectively. The present study illustrates an experimental design in validating laboratory-developed FISH assay using analytespecific reagents in detecting aneuploidies of chromosomes 13, 18, 21, X, and Y as per ACMG guidelines. Test probes used in the present study are consistent with probe localization characteristics, assay specificity, and reportable reference ranges recommended by ACMG. Therefore, the FISH assay used in the present study could be recommended as a supplementary prenatal diagnostic test that can be carried out along with standard chromosomal analysis.