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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 Detection of Dengue Viral Migration to Sri Lanka(19th Conference on Postgraduate Research, International Postgraduate Research Conference 2018, Faculty of Graduate Studies,University of Kelaniya, Sri Lanka, 2018) Withanage, G.P.; Hapuarachchi, H.C.; Gunawardene, Y.I.N.S.; Hapugoda, M.D.Dengue is one of the most important mosquito-borne viral infectionsin Sri Lanka.The causative agent is Dengue Viruses (DENV) and the primary vector of the virus is Aedesaegypti(Linnaeus) while Ae. albopictus (Skuse) is the subsidiary vector. The current research was focused on the detection of DENV serotypes and genotypes circulating in mosquitoes during the dengue epidemic in June and July, 2017 in the EriyawetiyaGramaNiladhari division, where one of the dengue high-risk area in Kelaniya Medical Officer of Health (MOH) area in the District of Gampaha, Sri Lanka. Aedesmosquitoes were collected following WHO guidelinesandthe field-caught mosquitoes were transported to the laboratory for species identification and subsequent analysis. Head and thorax of each mosquito was removed and mosquito samples were pooled separately. Total RNA was extracted from mosquito samples and semi-nested Polymerase Chain Reaction (PCR) was performed to identify DENV serotypes present in the mosquito samples. The results of the PCR indicated the presence of DENV2 in both Ae. aegypti (1/5) and Ae. albopictus (1/27) mosquitoes. Then complete Envelope (E) gene was amplified with DENV2 specific primers for genotyping of the virus which is required to identify the molecular evolution of the DENV2. Prior to sequencing the PCR products were purified and sequencing results were analyzed usingLaserGene software. The generated sequences were aligned with retrieved DENV2 sequences available at NCBI database and the phylogenetic trees were developed using MEGA7 software with General Time Reversible (GTR) substitution model with gamma distributed rates. The robustness of clades was determined by using bootstrap analysis of 500 replicates. The result of the phylogenetic analysis illustrates that the E gene sequences of DENV2 obtained from two DENVpositive mosquito poolsbelong to DENV2 Cosmopolitan Clade Ib, which has been the dominant strain in South-East Asia, specially Singapore, Indonesia, Malaysia, and China since August, 2015.The evidence suggests recent introduction of this DENV strain into Sri LankaItem Silent transmission as a risk factor affecting transmission of dengue fever.(Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, 2007) Hapangama, H.A.D.C.; Hapugoda, M.D.; Gunawardene, Y.I.N.S.; Premaratna, R.; Dayanath, M.Y.D.; Abeyewickreme, W.The global incidence of dengue fever has increased by more than four-folds over the last 30 years, making it the most threatening mosquito-borne viral disease at present. Objective of this study is to determine the role of silent transmission •on' incidence of dengue. A total of 40 households, living within a 300 m radius of seven selected ‘confirmed dengue cases at different dengue high risk localities in Gampaha District were recruited for this study. A minimum of three inhabitants were tested for anti-dengue antibodies using a commercial kit to determine the prevalence of silent transmission on dengue infection in each households. Entomological surveillance was carried out in all seven localities. Out of 40 households, 26 (65%) houses were positive for dengue viral infection. Total of 148 inhabitants (68 Males); mean age; 35.9 years were enrolled. Of the 148, 41 (27.7%) had evidence of exposure to dengue virus [positive for IgM: 28/41(68.4%), IgM'& IgG: 7/41(17%) and IgG: 6/41(14.6%)]. Out of 28 primary infections, 20(71.4%) were asymptomatic. Of the 7 secondary infections, 1(14.28%) was asymptomatic. Of the 6 previous exposures to dengue 4(66.67%) were asymptomatic. Of the 7 localities investigated, 1 had >50%, 4 had >25% and 2 had <25% clustering of cases. Ae. albopictus found in all seven localities and Ae. aegypti found only in two localities. This study suggests presence of silent transmission of dengue virus with a trend towards clustering around cases and also this shows that the presence of vectors increases the incidence of dengue.Item Serotype distribution of dengue in Gampaha District, Sri Lanka(Faculty of Tropical Medicine, Mahidol University, 2008) Jayasooriya, D.H.S.W.; Gunawardene, Y.I.N.S.; Manamperi, A.; Hapugoda, M.D.; Premaratna, R.Dengue Virus (DENV) affecting millions of people mainly in the tropical and subtropical regions is a positive sense RNA virus which exists in four different serotypes (DENV1-4) and several subtypes. All four serotypes have been found in Sri Lanka. The objective of the study was to determine the DENV serotype distribution in patients and mosquitoes of Gampaha district. Serum was isolated from acute phase blood samples collected from dengue suspected patients during the febrile period. Mosquitoes were collected from different locations where dengue confirmed cases were reported. Pooled and crushed mosquito heads and serum samples were separately subjected to RNA extraction, RT-PCR, semi nested PCR with Dengue serotype specific primers and solution hybridization with Phosphorous 32 labeled probes respectively. Out of 93 patients, 34 were positive for DENV out of which 19 corresponded to DENV2, 5 to DENV3 and 10 were co-infected with DENV2 and DENV3. Of the positive infections corresponding to serotypes 2, 3, 2-3 co-infected; 7/19 (36.8%), 3/5(60%), 0/10 (0%) had developed dengue haernorrhagic fever respectively Among 14 mosquito pools, 5 were positive of which 3 were infected with DENV2 and 2 with DENV3. It was observed that although both DENV2 and DENV3 circulate among patients and in mosquitoes in Garnpaha District, DENV2 was predominant in both. Only Aedes albopictus 'presence in all localities was significant. A greater percentage of severe form of the disease among DENV3 infected patients was observed while a less severe form of the disease was observed in DENV2 and DENV3 co-infected patientsItem Co-existence of double serotypes of dengue in patients of Gampaha District(Sri Lanka Association for the Advancement of Science, 2007) Jayasooriya, D.; Gunawardene, Y.I.N.S.; Hapugoda, M.D.; Premaratna, R.; Manamperi, A.; de Silva, H.J.; Abeyewickreme, W.Dengue virus (DENV) known to cause a productive cytolytic infection in humans exists in four different serotypes Dengue 1 (D1), Dengue 2 (D2), Dengue 3 (D3) and Dengue 4 (D4). Among 4 serotypes of DENV, D 3 thought to be associated with explosive DHF epidemics and severe disease in many countries. Our objective was to determine the prevalence of dengue serotypes in Gampaha District and to correlate them with disease severity. Serum samples were collected from patients who were within 4 days of onset of fever and clinically suspected of dengue according to WHO criteria. Total viral RNA extracted from each serum sample was subjected to RT-PCR followed by a semi-nested PCR using specific primers. Out of 91 samples collected between Nov 2005 and Dec 2006, 16 samples were confirmed positive for DENV RNA by RT-PCR. Our results of multiplex semi-nested PCR indicated that 9/16 (56.25 %) of the positive cases were co-infected with serotype 2 and 3 (D2 & D3), while 4/16 (25%) were infected with D 3 and 3/16 (18.75 %) with D 2. 3/4 of D 3 cases had DHF , 1/3 of D2 cases were DHF while there were no DHF cases among the D2 and D3 co-infected patients. The mean Packed cell Volume (PCV) values of D3, D2 and D2 & D3 co-infected were 53.8 %, 48 % and 39.6% respectively while the mean platelet values of those were 66,000 mm3, 123,000 mm3 and 174.000 mm3 , respectively. Dengue infection by a single serotype is common among patients. Although few cases of co-infection by more than one serotype had been previously reported in a few other countries, this is the first description of simultaneous co-infection by D2 and D3 in Gampaha district. In this limited study we have observed a reduction of disease severity in D2 and D3 simultaneously co-infected patients. Could simultaneous co-infection by more than one serotype or a combination of two particular serotypes have lead to a decrease in disease severity among dengue patients is a matter yet to be studied. Further studies are needed to support these conjectures and to establish the clinical implications of simultaneous co-infection on the prevalence of DHF and disease severity. Acknowledgement: NSF (grant SIDA/2006/BT/02) & IAEA (SRL TC 6/028)Item Effect of silent transmission and clustering of cases on transmission of dengue in Gampaha district(Sri Lanka Association for the Advancement of Science, 2007) Hapangama, H.A.D.C.; Gunawardene, Y.I.N.S.; Hapugoda, M.D.; Premaratna, R.; Dayanath, M.Y.D.; Abeyewickreme, W.Silent transmission of dengue virus and clustering of cases have been suggested as possible factors for the increasing incidence of dengue fever. Objective of this study was to determine the presence of silent transmission and clustering of cases of dengue fever in the Gampaha District. Study was carried out using cluster investigation method. A cluster consists of family members and immediate neighbours (minimum of 20) of a dengue index-case. Serum samples from volunteers were tested for anti-dengue antibodies using Dengue-Duo-IgM/IgG Rapid Cassette (Panbio diagnostics, Australia). Using 7 index cases, 148 volunteers (68 Males); mean age: 35.9 years were enrolled. Of the 148, 41 had evidence of exposure to dengue virus [positive for IgM: 68.4% (28/41), IgM & IgG: 17% (7/41) and IgG: 14.6% (6/41)]. Out of 28 primary infections, 71.4% (20/28) were asymptomatic. Of the 7 secondary infections, 14.28% (1/7) was asymptomatic. Of the 6 previous exposures to dengue, 4 (66.67%) were asymptomatic. There was no significant association between sex and exposure to infection [31% (21/68) males vs 25% (20/80) females, p>0.05] or between sex and occurrence of symptoms among exposed individuals [71% (15/21) males vs 50% (10/20) females, p>0.05]. Older individuals aged over 40 years, were most likely to be asymptomatic than younger persons (94% (14/15 exposed) vs 50% (13/26 exposed), P<0.01). Out of 7 clusters investigated, 1 had >50%, 4 had >25% and 2 had <25% clustering effects. A high proportion of asymptomatic infections were observed among adults over 40 years without gender difference. Study suggests persistence of silent transmission of dengue virus with a trend towards clustering around cases. Acknowledgement: World Health Organization (WHO/SEARO SN1144) and technical co-operation by International Atomic Energy Agency (TC/SRL 06/28)Item Knowledge, attitudes and practices (KAP) on dengue control in Gampaha district.(Sri Lanka Association for the Advancement of Science, 2008) Abeyewickreme, W.; Hapangama, H.A.D.C.; Gunawardene, Y.I.N.S.; Hapugoda, M.D.; Gunawardena, N.K.; Wickremasinghe, A.R.Dengue/Dengue Hemorrhagic Fever (DHF) has become a major public health problem in many parts of the tropics. In Sri Lanka, it is endemic in some parts of the country with outbreaks of dengue/ DHF. The present study was done to assess 1) knowledge regarding dengue among the general population in the district of Gampaha, 2) whether simple preventive measures are being practiced in the community. A cross-sectional survey was conducted in selected 2000 households in the Gampaha District from June - August, 2007 using a pre-tested structured questionnaire to assess the level of knowledge, attitudes and practices regarding dengue. The majority of the respondents interviewed were females (65.2%). More than 90% have had secondary education (90.2%). The main source of water supply were pipe borne (43.4%) and well water (40.6%). 64.3% households stored water for washing, drinking and cleaning purposes. More than 95% of the respondents had heard about dengue fever and its transmission. 91.3% cited that their main source of information on dengue was from television/radio. 34.3% had either received advice or participated in a training programme on dengue prevention and 7.8% had received support materials. The main preventive measure used to reduce the mosquito nuisance was personal protection with repellents (73.6%). Most of the respondents (56.8%) felt that no action was taken by the government to control mosquitoes. When respondents views were taken, the suggestions made by them to improve dengue control included, fogging (31.8%), educating people (30.5%), treating water (24.3%) and cleaning the environment (19.5%). When questions were directed at possible methods for community participation for dengue control, the majority were in favour of removing solid waste (84.15%), eliminating stagnant water collections (40.7%), removing larvae (8.75%) and covering all the water containers using lids (8.1%). The community had good understanding on dengue and the main source of information was from the electronic media. However it was found that good knowledge itself does not necessarily lead to good practices. The respondents' attitudes were found to be good and most of them were supportive of control measures. Mass media is an important means of conveying health messages to the public, thus research and development of educational strategies designed to improve behaviour and practices of effective control measures through mass media among the community are recommended. Financial support by World Health Organization TDR/WHO Multi Country Study on "Eco-Bio-Social Research on Dengue in Asia" is acknowledged.