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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 Low prevalence of Hepatitis B and C molecular markers in a cohort of Sri Lankan patients with hepatocellular carcinoma(Sri Lanka Medical Association, 2007) Dassanayake, A.S.; Manamperi, A.; Gunawardena, N.K.; Abeyewickreme, W.; de Silva, A.P.; de Silva, H.J.INTRODUCTION: Hepatitis B (HBV) and C (HCV) infections are leading causes of hepatocellular carcinoma (HCC). Although HCV is the predominant aetiological factor in many parts of the world, HBV remains more important in South Asia. Detection of molecular markers is the most reliable means of diagnosing infection. Molecular studies on HBV and HCV infection in HCC have not been performed in Sri Lanka. OBJECTIVES: To investigate the prevalence of HBV and HCV using molecular markers of infection in a cohort of Sri Lankan patients with HCC. DESIGN, SETTING AND METHODS: 34 consecutive patients with HCC were investigated for evidence of HBV and HCV infection. In addition to serology, serum was tested for HBV DNA and HCV RNA by PCR (sensitivity 500 copies/ml serum) and RT-PCR (sensitivity 200 copies/ml serum ) respectively. A detailed clinical work-up, screening for diabetes mellitus and iron studies were also performed. RESULTS: Of the 34 patients, 32 (94%) -were males; median age was 68 years. All had evidence of background cirrhosis. Five had evidence of past or present HBV infection, four were HBV DNA positive, one was anti-HBc positive but HBV DNA negative, and one was HCV RNA positive. In addition, 23 (67%) had a history of alcohol abuse and 18 (52%) had long standing diabetes. None had evidence of haemochromatosis. CONCLUSIONS: Prevalence of HBV and HCV infection was low in this cohort of Sri Lankan patients with HCC. This is in keeping with the low prevalence of these infections in the community.Item Patterns of monthly Culex mosquito density variation in Gampaha district, Sri Lanka.(Faculty of Tropical Medicine, Mahidol University, 2009) Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S.; Manamperi, A.; Abeyewickreme, W.BACKGROUND: The ecology, development, behavior, and survival of mosquitoes and the transmission dynamics of the diseases they transmit are strongly influenced by climatic factors. OBJECTIVE: The objective of this study was to identify the population density variation of Culex mosquitoes within a period of one year in Gampaha district, Sri Lanka together with potential climatic factors that influenced the Culex population density variation. METHODOLOGY: Culex mosquitoes were routinely collected on monthly basis from 9 sites in Gampaha district. Climate data was obtained from the Department of Meteorology. RESULTS: An exponential growth of Culex population densities was observed in all sites starting in December to February during the study period. The maximum density occurred in January and decreased from March until July. It again increased during August and thereafter decreased until December. Among the study sites the maximum Culex density (mosquitoes/man-hour) was observed in Hekiththa ranging between 89 to 22 and the minimum was from Kurukulawa ranging from 6 to 1. Climatic data suggest that temperature is a limiting factor for the Culex population growth while it was strongly influenced by the rain fall pattern. DISCUSSION: Similar Culex population density variation pattern was observed in all sites but exhibited enormous variation between sites, probably due to different local conditions. Also it was suggested that estimation of W, bancrofti transmission levels in Culex mosquitoes should be practiced in field settings where high mosquito density was observed. Since mosquito density appears difficult to be analyzed by individual dissection use of pool-screen PCR-ELISA would be a better method.Item 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.Item 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.Item Hepatitis B virus (HBV) genotypes in a group of Sri Lankan patients with chronic infection(Malaysian Society of Parasitology and Tropical Medicine, 2011) Manamperi, A.; Gunawardene, N.S.; Wellawatta, C.; Abeyewickreme, W.; de Silva, H.J.Hepatitis B infection causes a wide spectrum of liver diseases. Previous analyses of hepatitis B virus (HBV) genome have revealed eight HBV genotypes (A-H), with distinct geographical distribution worldwide. The epidemiology of HBV genotypes and their implications for natural history of disease progression and response to anti viral therapy have been increasingly recognized. This study was undertaken to determine the HBV genotypes in a group of Sri Lankan patients with chronic infection who presented for investigation prior to treatment. Genotypes were determined (2007-2009) in 25 patients with evidence of chronic HBV infection. A genotyping system based on multiplex-nested PCR using type-specific primers was employed in assigning genotypes A through F. Genotypes G and H were not determined. Among the 25 patients tested, genotypes B [9 (36%)], C [4 (16%)], D [3 (12%)], A [2 (8%)] and E [1 (4%)] were detected. There was a relatively high prevalence of mixed infections with genotypes B+C (3), A+D (1), and B+D (2), which overall constituted 24% of patients. Although this is a non-representative sample, HBV infections among this group of Sri Lankan patients were predominantly genotypes B, C and D.