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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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 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.Item Polymerase Chain Reaction and mosquito dissection as tools to monitor filarial Infection levels following mass treatment in Gampaha District, Sri Lanka(Elsevier, 2008) Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S.; Manamperi, A.; Bandara, K.B.A.T.; Liyanage, T.; Abeyewickreme, W.BACKGROUND: Mass Drug Administration (MDA)-based Global Lymphatic filariasis (Lf) eradication programmes are aimed at stopping transmission of Wuchereria bancrofti by its mosquito vector. The study was designed to compare one year post treatment (mass distribution of Diethylcarbamazine-Albendazole) infection rates of Wuchereria bancrofti in Culex quenquifaciatus, the main vector of Lf in Sri Lanka using Conventional dissection techniques and a Polymerase Chain Reaction (PCR) assay based on parasite specific Ssp1 repeat which amplifies a fragment of 188 bp. METHODS: Field study was conducted in 45 sites in all Medical Officer of Health (MOH) areas in the Gampaha district, Sri Lanka; identified by the Anti Filariasis Campaign (AFC) as having high-risk for bancroftian filariasis transmission. Indoor-resting mosquitoes were collected by aspiration from 20 houses per each site. Part of the mosquitos were used for dissection and the remainder was used for PCR to detect the filarial parasites in mosquito. RESULTS: Mosquito dissection data revealed 42.22% (19/45) of the sites were infested with mosquitoes positive for Wuchereria bancrofti, indicating 8 transmission active MOH areas (53.33%; 8/15). An infection rate of 5.26% was observed among the mosquitoes caught from households and the larval density was 8.7 per positive mosquito. PCR investigation revealed that 46.67% (21/45) of the sites were positive for W. bancrofti DNA, indicating 11 transmission active areas (73.33%; 11/15). The PCR was found to be more sensitive compared to microscopy in detecting the filarial parasite in field collected mosquito samples with respect to the MOH areas. CONCLUSION: The PCR technique employed offers scope for detection of the filarial parasites with higher sensitivity and specificity; is efficient and rapid. This technique applied for the first time in Sri Lanka, can be adopted as a diagnostic tool for the detection of filarial parasites in the vector population in surveillance to enable effective control of filariasis in the country. Acknowledgements: Authors acknowledge the WHO/SEARO/TDR (grant no. SN 1152) and University of Kelaniya (Research grant no. RP/03/04/06/01/2006) and to Ms. H.M.Renuka and Mr. H.P.Anura U. Pathirana, Mr. M.I.M.Peris and Mr. Y.L.Rassapana for their support during field study activities. © 2008 Elsevier Inc.Item Night blood survey of a selected high-risk population for lymphatic filariasis(Sri Lanka Association for the Advancement of Science, 2007) Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S.; Abeyewickreme, W.; Gunawardena, N.K.; Hapuarachchi, H.A.C.; Abeysundara, S.Human infection with Wuchereria bancrofti causes a disabling parasitic disease known as lymphatic filariasis, which is a major public health and socio-economic problem in many parts of the world. Little is known about the prevalence of filariasis among high-risk populations for filariasis. Objective of this study was to determine such prevalence of lymphatic filariasis among Mahara prison inmates whom the Anti Filaria Campaign (AFC) has identified as a high-risk group. All inmates of Mahara Prison were screened for Microfilariae (Mf) except those in special cells, by night blood film microscopy to determine the prevalence of infection from February to May 2007. All inmates were males of greater than 15 years. Of the 423 inmates screened, 15 were positive for Mf, giving a Mf positive rate of 3.55% in the study population and a mean Mf density of 5 Mf/60 æl blood, ranging between 4 to 9.2 Mf /60 æl of blood with a standard deviation of 2.49. The highest number of infected inmates was residents of Colombo and Gampaha districts where transmission is currently taking place. This is one of the few studies undertaken to date to determine the prevalence of bancroftian filariasis among inmates of a prison, a neglected population in Sri Lanka. This study indicates that the Mf rate of bancroftian filariasis in this study population is far greater than the 0.18% currently reported in the country. Therefore, an intensive programme is recommended to contain the spread of infection within this study population. For this, a proper screening programme combined with antifilarial treatment and vector control programme is urgently required. Acknowledgements: Authors wish to acknowledge the financial assistance received from WHO/SEARO/TDR (grant no. SN 1152) and University of Kelaniya (Research grant no. RP/03/04/06/01/2006). Authors wish to thank Dr. Ravi Mudaliage, Senior Medical Officer, Prison's Hospital, Mahara, Ragama for his support and encouragement during field study activities. Authors also wish to thank Mr. M. Y. D. Dayanath, Ms. N.M. Ashoka Malanie, Mr. M.I.M.Peris, Mr. Y.L.Rassapana and other staff members of the Molecular Medicine Unit and Department of Parasitology, Faculty of Medicne, University of Kelaniya, Ragama for their assistance