Conference Papers

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This collection contains abstracts of conference papers, presented at local and international conferences by the staff of the Faculty of Medicine

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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 Lanka
Establishment and maintenance of laboratory colonies of Aedes albopictus mosquitoes
(University of Peradeniya, 2015) Wijegunawardana, A.D.; Gunathilaka, H.N.; Dassanayake, R.; Gunawardene, Y.I.N.S.; Abeyewickreme, W.
With a mission of "providing authenticated, high-quality Aedes albopictus mosquito rearing information to the research community" maintenance of a Ae. albopictus mosquito colony was started. All environmental facilities inside the insectary were carefully maintained to better suit the Ae. albopictus mosquito colonization. The mean temperature of 27°C (± 0.5°C) was constantly maintained inside the insectary. Wet towels on adult mosquito cage racks were used for proper maintenance of humidity. Lighting was using fluorescent light and regulated with 16:8 hour continuous dark and light period. Pest insect was controlled to ensure essential absence of ants and cockroaches. This was achieved without any harm to the mosquito colonies either directly or by contamination with toxicants transported by pests. An adult mosquito trap placed inside the insectary was used to monitor released mosquitoes. Consistent effort was also made to improve the level of cleanliness inside the insectary. Written guidelines were given to each person responsible for a task. Insectary operations included egg counting, preparation of hatching bottles with boiled distilled water following cooling to room temperature, egg hatching, larvae rearing with International Atomic Energy Agency (IAEA) recommended diet of tuna meal, bovine liver powder, brewery yeast and vitamin complex in a ratio of 37.5:27:10.5:2 g in 1L up to one week, pupae counting and putting into adult emergency cages, adult male feeding with 10% sugar solution with Vitamin complex, adult female blood feeding from 4th day onwards with bovine blood, placing egg laying cups and collecting egg laying cups, drying egg papers and starting next generation from the dried eggs. Adult mosquito cages were blood fed every 4th day after emergence from pupa and for quality control reasons each adult cage was blood fed only 3 times and there after only 10% sugar solution with vitamin syrup was supplemented until all adult mosquitoes died. Documentation for maintenance and data record was maintained and updated daily. Records included larvae feeding records, larvae tray maintenance and cleaning charts, adult feeding records with both sugar solution and blood, insectary cleaning records with time and dates. Number of eggs and percentage of egg hatching, larvae death, pupation, adult emergence, egg laying and adult mosquito death with respect of the sex and time difference were recorded. For bio-safety reasons all discarded material from larvae trays, egg laying cups and adult cages were boiled thoroughly to facilitate total destruction of the contaminated mosquito eggs. All other infectious material were incinerated. Finally, all above conditions facilitated achievement of 100% egg hatching rate within maximum of 24 hours, 100% survival of larvae to pupa (~ 7 days), 100% survival of pupated larvae to adult emergence (~ 2 days) and 95.5% adult survival up to 12 days. No difference was observed on adult longevity between males and females within first 12 days of adult emergence. However, approximate life span for males (-17 days) was lower than the females (~ 25 days) and the mortality was regular through all generations (Fl to F21).
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.
Impact of repeated annual Diethylcarbamazine-Albendazole mass treatment on transmission of Wuchereria bancrofti in the Gampaha district.
(Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, 2007) Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S.; Abeyewickreme, W.
Entomological and parasitological surveys are critical for the baseline evaluation of impact of repeated annual. Diethylcarbamazine-Albendazole mass treatment on the reduction of microfilaria density and level transmission of Wuchereria bancrofti in Culex quinquefaciatus. The objective of this study was to assess the current situation, following the mass drug administration programme in the Gampaha district, with regard to lymphatic filariasis, using entomological and parasitological data. A pilot survey was carried out using parasitological, 'clinical and entomological indicators in 21 sites in 7 Medical Officer of Health areas of Gampaha district to assess the current filariasis situation. The localities were selected from. the Medical Officer of Health areas based on previous data obtained from the regional Anti Filariasis Campaign office. Results indicate that 76.19% (16/21) sites were infested with mosquitoes positive for Wuchereria bancroft and the positivity of 1.44% (31/2157) was observed among the mosquitoes caught from households in the selected sites. The microfilariae wasa determined to be 15.5 per positive mosquito. The parasitological result was indicated 0.017 % prevalence of lymphatic fllariasis in the selected population. Data recorded by the Anti Filariasis Campaign Gampaha in 1994, suggested that significant decrease of infective rate, positivity of mosquito and microfilaria density, which are respectively 90%, 3.05% and 23. Study confirms that active transmission of Wuchereria bancrofti is currently taking place in the Gampaha district, despite, the mass drug administration Programme been implemented since 2002. This study highlights the urgent requirement of a proper screening programme combined with anti filarial treatment and vector control programme to minimize filarial morbidity and interrupt filarial transmission within the country.
GIS mapping of Lymphatic Filariasis endemic areas in Gampaha district, Sri Lanka; based on the epidemiological and entomological screening
(Faculty of Tropical Medicine, Mahidol University, 2009) Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S.; Manamperi, A.; Abeyewickreme, W.
BACKGROUND: The health issues related to vector borne diseases appear always to be related to space and time. Therefore it is ideal to link Geographical Information Systems (GIS) with epidemiological and entomological data to monitor spread of infection and target control strategies. OBJECTIVE: The objective of this study was to develop a site directed GIS map for lymphatic filariasis (Lf) dispersed areas in Gampaha district, Sri Lanka as a guide to target control activities. METHODOLOGY: Epidemiological and entomological screening of Lf was done in nine pre-identified endemic areas in Gampaha district, using night blood screening and pool-screening PCR-ELISA protocols respectively. RESULTS: Overall, 1073 (286 children, 787 adults) from 9 sites were examined. Mf-positive cases were detected in 2 sites, with a prevalence rate of 10.5% (Hekiththa) and 3.4% (Peliyagoda) with over 30% Mf prevalence in adult mosquito populations. The overall prevalence of mosquitoes with L1-L2 larvae of W. bancrofti ranged from 0%-8.54% by dissection and point estimates of infection prevalence, as assayed by PCR-ELISA, ranged from 0% - 35.4%. According to geographical data, the highest number of cases was found at altitudes between 2.5-3.5 m and highly populated areas where transmission appears to be taken place. Questionnaires indicated limited community awareness can be a reason for the fairly static infection rate prevalent in Peliyagoda sentinel site. DISCUSSION: The maps derived indicate the substantial extent as well as the marked variability in the geographical distribution of Lf in Gampaha, demonstrating site related trends.
Population data for CSF1PO, TPOX, THO1, D16S539, D7S820, D13S317, FESFPS, vWA and F13B short tandem repeat (STR) polymorphisms in Sri Lanka
(Sri Lanka Association for the Advancement of Science, 2004) Manamperi, A.; Gunawardene, Y.I.N.S.; Bandara, K.B.A.T.; Dayanath, M.Y.D.; Hapuarachchi, H.A.C.; Abeyewickreme, W.
Molecular relatedness and diversity of insect antimicrobial defensin genes
(Sri Lanka Association for the Advancement of Science, 2004) Gunawardene, Y.I.N.S.; Dassanayake, R.S.
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.
Application of nucleic acid technology (NAT) in the diagnosis of active viral replication in HBV and HCV infections and evidence for HBV surface antigen mutants
(Sri Lanka Association for the Advancement of Science, 2008) Manamperi, A.; Gunawardene, Y.I.N.S.; Hapuarachchi, C.; Bandara, A.; Wellawaththage, C.; Abeyewickreme, W.; de Silva, J.
Introduction: The community prevalence of Hepatitis B (HBV) and hepatitis C (HCV) infections, although considered low (< 1%) in Sri Lanka based on serological markers, pose a significant health threat to patients in high risk groups. The early diagnosis of active viral infection is crucial in such situations to prevent further transmission and to enable the clinicians to initiate successful therapeutic interventions. Objective: This study was carried out to investigate the usefulness of polymerase chain reaction (PCR) in the diagnosis of active viral replication in HBV and HCV infections. Methodology: All specimens from patients with serological evidence of hepatitis B (HBV surface antigen and/or antibodies for HBV core protein) or hepatitis C (antibodies for hepatitis C core protein-Anti-HCV) and referred to the Molecular Medicine Unit from May 2005 to May 2008 were analyzed by PCR and reverse-transcription PCR (RT-PCR) for HBV DNA (n=130) and HCV RNA (n=95) respectively. Results: Of the 130 patients tested, 57 (44%) were positive for HBV DNA. The positive group of patients included 10 renal transplant patients, 4 multiply transfused patients, 4 paediatric patients with lymphoma, and 1 patient with cirrhosis. Six HBV DNA positive patients had negative HBsAg serology profiles indicating the possibility of surface antigen mutant strains. The HBV DNA negative patients with positive serology profiles indicate sero-converted/ patients with resolved infections or false positive serology results. Of the 95 patients tested, 14 (15%) were positive for HCV RNA and included 3 paediatric patients with thalassaemia. HCV RNA negative, anti-HCV positive profiles reflect either false positive serology results (due to less specific antibody assays) or donors who have been exposed to HCV previously and subsequently resolved their infections. Conclusions: A major proportion of patients with serological markers for HBV have active viral infection whereas only relatively a minor proportion of patients with serological markers for HCV have active viral replication. We have also found the first possible evidence of hepatitis B surface antigen mutant strains. This underlines the importance of the nucleic acid based technology in the diagnosis and assessment of infection with or suspected to have hepatitis B or C infections. We also emphasize the importance of introducing NAT for screening donors for HBV DNA and HCV RNA to substantially lower the risk of acquiring HBV/HCV infection from a transfusion.
Large-scale entomological assessment of Wuchereria bancrofti transmission by dissection and PCR-ELISA in Gampaha district, Sri Lanka
(Sri Lanka Association for the Advancement of Science, 2008) Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S.; Manamperi, A.; Hapuarachchi, H.A.C.; Bandara, K.B.A.T.; Abeyewickreme, W.
Entomological surveys are important tools for monitoring progress of lymphatic filariasis (Lf) eradication programs. In this study, dissection of Culex quinquefasciatus was compared with a Polymerase Chain Reaction - Enzyme Linked Immunosorbent Assay (PCR-ELISA) for pooled mosquitoes to assess filarial infection levels in the major vector of Wuchereria bancrofti in Gampaha district, following mass-treatment programme with diethylcarbamazine (DEC) and albendazole. Mosquitoes were collected in 30 sentinel and 15 non-sentinel sites in 15 Medical Officer of Health (MOH) areas of Gampaha district known for the presence of W. bancrofti transmission. Captured mosquitoes were dissected to determine the W. bancrofti larvae (L1, L2, L3). PCR was carried out using Deoxyribonucleic acid (DNA) extracted from mosquito pools (15 body parts/pool) utilizing primers specific for the Wb-SspI repeat. PCR products were analyzed by hybridization ELISA using fluorescein-labeled wild type specific probes. The prevalence of infected/infective mosquitoes in PCR pools (3pools/site) was estimated using the PoolScreenTM algorithm and a novel probability-based method. The prevalence of infected mosquitoes with L1-L2 larvae of W. bancrofti ranged from 0%-8.54% by dissection and point estimates of infection prevalence as assayed by PCR-ELISA, ranged from 0% - 25.4%. Mosquitoes collected from all MOH areas (80%, N = 12), except for Minuwangoda, Dompe and Ragama, were positive for W. bancrofti larvae, with a prevalence rate ranging from 0.78% to 16.97% in both methods. Of 30 sentinel sites, 43.3% (N = 13) were positive for W. bancrofti transmission whereas it was evident in 40% (N = 6) of non-sentinel sites. The proportion of positive pools detected by the PCR-ELISA assay was higher than that obtained by the dissection indicating that PCR-ELISA assay is more sensitive than the dissection method in detecting infected/infective mosquitoes. Also results of this study showed that autochthonous transmission of W. bancrofti continues in the Gampaha district despite completion of the 5 year mass drug administration (MDA) programme. Therefore, we emphasize the use of more sensitive tools such as PCR-ELISA to monitor the impact of the MDA programme on disease transmission. This study also emphasizes that control measures should be further continued until the microfilareamic population is reduced to a level which could interrupt transmission in the area. Financial assistance received from WHO/SEARO/TDR (grant no. SN 1152) and University of Kelaniya (Grant no. RP/03/04/06/01/2006) is acknowledged

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