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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 Lymphatic filariasis in the Southeast Asian region; status and control options.(CABI Publishing, 2020) Chandrasena, T.G.A.N.; Premaratna, R.; Mallawarachchi, C.H.; Gunaratna, D.G.A.M.; de Silva, N.R.ABSTRACT: The Global Program to Eliminate Lymphatic Filariasis (GPELF) was launched in year 2000 by the World Health Organization (WHO) with the goal set for elimination by 2020. Over half the global disease burden lies in the Southeast Asian region (SEAR). The preventive chemotherapy (PC) programme has been initiated in all the WHO SEAR member states with varying levels of progress. Maldives, Sri Lanka and Thailand have achieved the goal of elimination as a public health problem (EPHP) within the stipulated period with Bangladesh working towards validation in 2021. Both Sri Lanka and Thailand are continuing with post-validation surveillance combined with selective treatment, striving for zero transmission in-parallel with the morbidity management and disability prevention program (MMDP). Timor-Leste appears close to reaching critical transmission thresholds with 100% coverage and triple therapy in the last round of PC. Data on MMDP activities are insufficient to comment on reaching EPHP status. PC coverage and country reports indicate ongoing transmission in Nepal, Myanmar, Indonesia and India requiring further rounds of PC. The PELF has made considerable progress in the SEAR towards elimination but there still remain significant transmission and disease burden in the highly populated countries in SEAR.Item Morbidity management and disability prevention for lymphatic filariasis in Sri Lanka: Current status and future prospects(Public Library of Science, 2018) Chandrasena, N.; Premaratna, R.; Gunaratne, I.E.; de Silva, N.R.BACKGROUND: Sri Lanka was acknowledged to have eliminated lymphatic filariasis (LF) as a public health problem in 2016, largely due to its success in Mass Drug Administration (MDA) to interrupt disease transmission. Analysis of the Strengths, Weaknesses, Opportunities and Threats (SWOT) of the national Morbidity Management and Disability Prevention (MMDP) program, the other pillar of the LF control program, was carried out with the objective of evaluating it and providing recommendations to optimize the use of available resources. METHODOLOGY: A situation analysis of the MMDP activities provided by the state health sector was carried out using published records, in-depth interviews with key informants of the Anti Filariasis Campaign, site-visits to filariasis clinics with informal discussions with clinic workforce and personal communications to identify strengths and weaknesses; and opportunities to overcome weaknesses and perceived threats to the program were explored. The principal strength of the MMDP program was the filariasis clinics operational in most endemic districts of Sri Lanka, providing free health care and health education to clinic attendees. The weaknesses identified were the low accessibility of clinics, incomplete coverage of the endemic region and lack of facilities for rehabilitation. The perceived threats were diversion of staff and resources for control of other vector-borne infections, under-utilization of clinics and non-compliance with recommended treatment. Enhanced high level commitment for MMDP, wider publicity and referral systems, integration of MMDP with other disease management services and collaboration with welfare organizations and research groups were identified as opportunities to overcome weaknesses and challenges. CONCLUSIONS: The recommended basic package of MMDP was functional in most of the LF-endemic region. The highlighted weaknesses and challenges, unless addressed, may threaten program sustainability. The identified opportunities for improvement of the programme could ensure better attainment of the goal of the MMDP program, namely access to basic care for all affected by lymphatic filarial disease.Item Surveillance for transmission of lymphatic filariasis in Colombo and Gampaha districts of Sri Lanka following mass drug administration(Oxford University Press, 2016) Chandrasena, T.G.A.N.; Premaratna, R.; Samarasekera, D.S.; de Silva, N.R.BACKGROUND: Sri Lanka was recently declared by WHO to have eliminated lymphatic filariasis as a public health problem, after conclusion of annual mass drug administration. Our aim was to assess the lymphatic filariasis situation, following mass drug administration. METHODS: Surveillance was done in two districts of the Western Province in two consecutive phases (2009-2010 and 2013-2015), by examining 2461 thick night blood smears and performing 250 dipstick tests on children for antibodies to Brugia malayi. RESULTS AND CONCLUSIONS: Decline in bancroftian microfilaraemia (microfilaria rate 0.32% to zero) supports elimination, but re-emergence of brugian filariasisis (antibody rate, 1.6%; one microfilaria positive) is a cause for concern.Item Setaria digitata in advancing our knowledge of human lymphatic filariasis(London School of Hygiene and Tropical Medicine, 2016) Perumal, A.N.; Gunawardene, Y.I.N.S.; Dassanayake, R.S.Setaria digitata is a filarial parasite that causes fatal cerebrospinal nematodiasis in goats, sheep and horses, resulting in substantial economic losses in animal husbandry in the tropics. Due to its close resemblance to Wuchereria bancrofti, this nematode is also frequently used as a model organism to study human lymphatic filariasis. This review highlights numerous insights into the morphological, histological, biochemical, immunological and genetic aspects of S. digitata that have broadened our understanding towards the control and eradication of filarial diseases.Item Effects of antibiotics on filarial transmission(Sri Lanka College of Microbiologists, 2003) Chandrasena, T.G.A.N.; Taylor, M.J.INTRODUCTION: The symbiosis of filarial nematodes and intracellular Wolbachia bacteria has recently been exploited as a target for therapy of filariasis. OBJECTIVE: To study the effects of antibiotics on filarial transmission in-vitro. METHODS: Two groups of microfilariae (mf) of Brugia pahangi (cat filarial species) were maintained in culture and exposed to 10 µm) solutions of tetracycline and doxycycline respectively, for 48 hours. A control group of Mf was maintained for 48 hours with no added antibiotics except for those routinely included in the culture medium. Mf counts in cultures were determined at the onset of experiment (8000 mf/culture flask). Three groups of Aedes aegypti mosquitoes were artificially infected with the treated and untreated mf by membrane feeding technique (mf concentration; 2000 mf/ml of blood). Mosquito dissections were performed 2 hours and 15 days post-infection to assess mf intake and development in vector hosts. RESULTS: Mf intake was similar in the treated and the control groups {8,5 and 9 mf recovered in 4,3 and 3 mosquitoes from tetracycline(n=6), doxycycline(n=6) and control(n=6) groups respectively}. Mosquitoes fed on tetracycline treated B.pahangi (n=70) were completely free of L3 (infective larvae while in the doxycycline (n=71) and control groups (n=71) the percentage of infection was 1.4% (01 infective larva in 01 mosquito) and 24% (17 infective larvae in 13 mosquitoes) respectively. The infectivity of mosquitoes fed on antibiotic treated Mf was significantly reduced (P value < 0.001). CONCLUSIONS: Exposure of Mf of B.pahangi to physiological concentrations of anti-wolbachia antibiotics even for a brief duration significantly affects their transmission potential.Item Evaluation of the Mass Drug Administration(MDA) programme for filariasis control(Sri Lanka College of Microbiologists, 2003) Weerasinghe, C.R.; de Silva, N.R.Abstract availableItem Filarial dance sign (FDS) in patients with lymphatic filariasis(Sri Lanka Medical Association, 2008) Premaratna, R.; Chandrasena, T.G.A.N.; Gunawardena, N.K.; de Silva, N.R.; de Silva, H.J.BACKGROUND: Lymphatic filariasis causes acute lymphangitis, epididymo-orchi tis hydrocoele, lymphoedema and nocturnal cough. Diagnostic tests based on circulating filarial antigens (CFA) and filarial antibodies (FAT) have limitations in confirming symptomatic filariasis. Filaria dance sign (FDS) demonstrated using soft tissue ultrasonography permits identification of live adult filarial worms in-situ. OBJECTIVES: FDS, CFA and FAT status in patients with clinical features suggestive of lymphatic filariasis. DESIGN, SETTING AND METHODS: Adult males with symptoms suggestive of filarial infection were subjected to scrotal scans using a Toshiba 7.5MHz soft tissue transducer to elicit the FDS. All subjects were screened for CFA and FAT by NOW® Filariasis (Binax Inc. USA) and On-Site Filariasis IgG/IgM Rapid Test (Biotech. Inc. USA) respectively. RESULTS: Forty eight males, mean age 48.5 yrs (SD: 15.2), presenting with lymphoedema of lower limbs (LL, n=29), lower limb cellulitis with lymphangitis (LCL, n=7), hydrocoele (H, n=7), acute epididymo-orchitis (A.EO, n=3), hydrocoele with lower limb lymphoedema (HLL, n=2) and nocturnal-cough (NC, n=9) were studied. FDS was demonstrated in 38(79%); 7 patients with H, 16 with LL, 5 with LCL, AEO 1 and 9 with NC. Six of 41 (14.6%) patients tested for filarial antibodies were positive for filaria-specific IgG; 2 of them were also positive for filaria-specific IgM. Two of the six IgG positives were negative for FDS. The 4 IgG and FDS positives had LCL (n=2), H (n=l) and AEO (n=l). All were CFA negative CONCLUSIONS: Although time consuming, demonstration of FDS by soft tissue ultrasonography can be useful in confirming symptomatic filariasis compared to FAT and CFA.Item Effect of mass chemotherapy for filariasis control on soil-transmitted helminth infection in Western Province of Sri Lanka(The Royal Society of Tropical Medicine and Hygiene, 2007) Gunawardena, N.K.; Amarasekera, N.D.D.M.; Pathmeswaran, A.; de Silva, N.R.In July 2006, Sri Lanka completed five rounds of annual mass drug administration (MDA) with diethylcarbamazine citrate and albendazole as part of its national programme for elimination of lymphatic filariasis. Albendazole is also highly effective against soil-transmitted helminths (STH). This study was carried out to assess the impact of repeated annual MDA on STH infections in the Western Province of Sri Lanka, an area that is co-endemic for lymphatic filariasis and STH. A total of 17 schools in the Western Province were selected because they were included in a national survey of the health of school children in Grade 5 in 2003, when one round of MDA had been completed. Faecal samples were obtained again in 2006 (after five rounds of MDA), from one randomly selected class of Grade 5 students in the same schools. In both surveys, faecal samples were examined using the modified Kato-Katz technique. The prevalence and intensity of roundworm, whipworm and hookworm infections in 2003 and 2006 were compared using chi-square or Z-test for a difference between two percentages. Faecal samples from 255 children were examined in 2003; 448 were examined in 2006. Roundworm prevalence was marginally lower in 2006 (4.0%) than in 2003 (4.7%), as was hookworm (0.2% vs 0.4%) whereas whipworm prevalence was higher (13.8% vs 9.4%). Mean egg counts for all three infections were marginally higher in 2006. However, none of these differences were statistically significant. Compliance with MDA in 2006, as reported by the school children examined, was only 59%. These results indicate that four annual roundsof MDA with diethylcarbamazine and citrate and albendazole had virtually no impact on STH infections in the study area. It is likely that inclusion of of albendazole in MDA for lymphatic filariasis does not have much impact on STH infections in areas of low endemicity, unless very high coverage rates are achieved.Item 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.Item Entomological assesment of Wuchereria bancrofti transmission following mass treatment in Gampaha District, Sri Lanka.(Faculty of Tropical Medicine, Mahidol University, 2007) Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S.; Abeyewickreme, W.Global program to eliminate Lymphatic filariasis (Lf) relies mainly on Mass Drug Administration (MDA). Success of filariasis control programs depends on careful monitoring of infection levels in human populations as well as vectors following the introduction of the drug intervention. This study was conducted to assess the current level of Lf transmission following mass distribution of Diethylcarbamazine-Albendazole in the Gampaha district, Sri Lanka. Field study was conducted in 45 sites in all Medical Officer of Health (MOH) areas of the Gampaha district identified by the Anti Filariasis Campaign (AFC) as high risk for bancroftian filariasis. Investigation revealed 42.22% (19/45) of the sites were infested with mosquitoes positive for Wuchereria bancrofti. Only the sites in urban and semi urban areas were positively infested while rural areas were free of infection. An infection rate of 5.26% was observed among the mosquitoes caught from households and the larval density was 8.7 per positive mosquito. According to a study conducted by the AFC in a sample population (14 sites), the prevalence of Lf was 0.038%. Data recorded by the AFC in 1994 indicated that the infective rate, positivity of mosquitoes and microfilaria density were 90%, 3.05% and 23 respectively. The present study confirms that the level of transmission of W. bancrofti has not decreased in the Gampaha district, despite the MDA Programme been implemented since 2002. Therefore, a proper screening-programme combined with anti filarial treatment and. vector control programme is urgently required to minimize filarial morbidity and interrupt filarial transmission within the country.