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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Spatial epidemiology and hotspots of Rotavirus In children: an analysis and mapping using Geographic Information System
(Sri Lanka College of Paediatricians, 2010) Gunawardena, N.K.; Rajindrajith, S.; Chandrasena, T.G.A.N.; Nishizono, A.; Moji, K.; Ahmed, K.
INTRODUCTION: Rotavirus is a leading cause of acute gastroenteritis in Sri Lanka. Studies from the western world have assessed the seasonal variations of this infection and its association with environmental factors such as rainfall and temperature. However, little is known of its seasonal variation and geographical distribution in Sri Lanka. Areliable and updated distribution map of rotavirus infection is essential for target control strategies and policy making processes. Geographical Information. System (GIS) has previously been used to monitor spatial distribution of diseases and their transmission dynamics. For the first time we describe the spatial epidemiological patterns of rotavirus diarrhoea in Sri Lanka. OBJECTIVE: To study the spatial epidemiological distribution of rotaviral infection among children with diarrhoeal diseases admitted to the North Colombo Teaching Hospital, Ragama. DESIGN, SETTING AND METHOD: This study was carried out in two phases. Phase I, a prospective hospital-based study, was conducted in the North Colombo Teaching Hospital from January 2008 to October 2009 to detect the incidence of rotavirus infection in children with diarrhoea. Stool samples were analyzed for Group A rotavirus antigen by enzyme linked immunosorbent assay (EL1SA) (Rotaclone). During Phase II of the study, patients with rotavirus infection were mapped using geographic coordinates obtained from a hand-held GIS receiver (Trimble Juno SB). Rainfall and temperature data for the years 2008 and 2009 in the Gampaha District were obtained from the Department of Meteorology, Sri Lanka and correlated with the spatial distribution data. RESULTS: In 2008 and 2009, 71 (60.6% males) and 99 (63.6% males) had rotavirus infection respectively. Spatial distribution data showed that most rotavirus infections (78%) presenting to the Teaching Hospital, Ragama were coming from a 10 km radius of catchment area. The hot spots were clustered in and around the marshy land areas of the Gampaha District and 67% use water from their own well or from the well of a neighbour. The peak incidence in both years was between May and July which coincided with the highest rainfall to the area. There was no correlation between environmental temperature and rotavirus infection rates. CONCLUSION: Incidence of rotavirus infection is highest in children living around marshy lands and using water from private sources such as a well.
Rotavirus surveillance at the North Colombo Teaching Hospital, Sri Lanka, 2007-2008
(Sri Lanka College of Paediatricians, 2010) Chandrasena, T.G.A.N.; Rajindrajith, S.; Gunawardena, N.K.; Abayawardana, U.A.T.M.; Ranasinghe, S.L.; Nishizono, A.; Moji, K.; Ahmed, K.
INTRODUCTION: Rotavirus disease is a common paediatric problem and accounts for severe dehydrating diarrhoea, a large number of hospital admissions and an annually estimated 600,000 deaths across the world. Prospective Rotavirus surveillance was initiated at the North Colombo Teaching Hospital (NCTH), Sri Lanka from April 2005. The serorype distribution in our previous study was; G9P[S] 35.2%, G12P[8] 14.7%, G3P[4] 17.2%, G2P[8/4/6] 14%, GlP[8/4] 6.5% and G4P[8/4] 3.3%. OBJECTIVE: To describe the serotype distribution of rotavirus responsible for hospitalization at the NCTH. DESIGN, SETTING AND METHOD: A prospective hospital-based study was conducted in the paediatric units of the NCTH from November 2007-October 2008. Stool samples of children admitted with diarrhoea were analyzed for Group A rotavirus antigen by enzyme linked immunosorbent assay (ELISA) (Rotaclone). Stool samples positive for rotavirus were characterized by electropherotyping (PAGE) and serotyping (reverse transcription polymasase chain reaction - RT PCR). RESULTS: Group A rotavirus was detected in 78 (33%) of 231 children less than 5 years of age admitted with diarrhoea. G9, Gl, G2, G3 and G non-typable infections were seen in 33(42%), 31 (40%) 7 (9%), 1 (1.3%) and 4 (5%) respectively. A predominance of G9 serotype (84%) was seen during the initial seven months. Dramatic transition of genotypic predominance to Gl (70%) occurred in the latter half of the year. All Gl, G3 and G9 strains assayed for P genotype contained P8 except two mixed G9 infections which were associated with P4 and PS. In contrast to the previous report, all G2 strains identified were associated with P4 and serotypes G12P [8] and G4P [8/4] were not detected. Polyacrylamide-gel-electrophoresis revealed the presence of El, E2, E3, E4 and E5 electropherotypes with a co-dominance of Eland E5 (30.7%). CONCLUSIONS: During the study period a rising trend in prevalence with a fluctuating genotypic distribution was observed at CNTH, Sri Lanka. The diversity of rotavirus serotypes requires a vaccine that confers adequate homotypic and heterorypic protection against these strains.
Filarial dance sign (FDS) in patients with lymphatic illariasis
(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, epididyrno-orchitis, 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=20), lower limb cellulitis with lymphangitis (LCL, n=7), hydrocoele (H, n=7). acute epididymo-orchitis (AEO, 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.
High serum total IgE in children in geohelminthic endemic setting
(Sri Lanka Medical Association, 2008) Amarasekera, N.D.D.M.; Gunawardena, N.K.; de Silva, N.R.; Weerasinghe, A.
BACKGROUND: Elevated levels of total IgE (tlgE) in serum are characteristic of atopic diseases. However, the usefulness of tlgE in diagnosing atopic diseases in children living in areas endemic for helminth infections is not well established. OBJECTIVE: To assess the effect of geohelminth infections on serum tlgE levels in children with atopic diseases. DESIGN, SETTING AND METHODS: A total of 640 children in grade 5 were recruited from 17 schools in the Western Province. Data regarding atopic diseases were collected by a standard questionnaire. Screening for helminth infections was done by examining their stool samples by modified Kato-Katz technique. Serum tlgE was measured by fluoroenzymeimmunoassay. RESULTS: The mean age in the study population was 10 years (SD±0.3). The prevalence of geohelminth infection was 15.5%. Trichuris trichiura (14.3%) was the most common, followed by Ascaris lumbricoides (4.2%) and hookworm (0.2%). Mixed infection was detected in 20.3% of infected children. The cumulative prevalence of atopic diseases was 33.7%. Prevalence of asthma, rhinitis and eczema was 17%, 21.4% and 5% respectively. Geometric mean (GM) for tlgE for the geohelminth infected group (1039.9kU/L) was significantly higher than that of the non-infected group (575.4kU/L) (p=0.004). It was also higher in the allergic group (933.3kU/L) than in the non-allergic group (639.7kU/L) but the difference was not statistically significant (p=0.068). CONCLUSION: In the presence of geohelminth infections, raised IgE may be due to geohelminth infection or atopic diseases or both. Therefore, serum tlgE may not be a useful marker for allergic diseases in children living in areas endemic for geohelminth infections.
Integrated school-based surveillance for soil-transmitted helminth infections and for lymphatic filariasis in Gampaha district, Sri Lanka
(American Society of Tropical Medicine and Hygiene, 2013) Gunawardena, N.K.; Gunawardena, S.; Kahathuduwa, G.; Karunaweera, N.D.; de Silva, N.R.; Ranasinghe, U.S.; Rao, R. U.; Rebollo, M.; Weil, G. J.
The Sri Lankan Anti-Filariasis Campaign (AFC) conducted 5 rounds of annual mass drug administration (MDA) with albendazole and DEC in 2002-2006 in 8 districts that were endemic for lymphatic filariasis (LF) (target population approximately 10 million). AFC conducted transmission assessment surveys (TAS) in 2012, about 6 years after the last round of MDA. This study explored the practicality of integrating surveillance for soil transmitted helminth (STH) infections with TAS for LF in Gampaha district (population 2.3 million). The district was divided into two Evaluation Units (EUs), coastal and inland. Each TAS tested 1st and 2nd grade school children drawn from 30 randomly selected schools (N=1,462 inland, 1,642 coastal). Tests included the ICT card test for filarial antigenemia (performed by AFC personnel) and the Kato-Katz test for detection of STH ova (performed by university personnel). ICT rates were 0% and 0.1% (0.01-0.3% CI) in the inland and coastal EUs, respectively. These results suggest that LF transmission rates are very low in Gampaha District. The STH survey was conducted at the same time as the TAS in the inland EU (955 stools from 1,211 children) and several weeks after the TAS in the coastal EU (927 stools from 1,586 children). STH infection rates and stool sample participation rates were 0.8% and 79% in the inland EU and 2.8% and 58% in the coastal EU. Most of the STH infections detected were lowintensityTrichuris (present in 73% of positive stools). The low STH rates are probably due to the country’s national school deworming program (mebendazole in grades 1, 4, and 7) and relatively good sanitation in Gampaha district. The cost for STH testing was approximately $5,000 per EU. These results suggest that it is feasible for national NTD programs to integrate school based surveillance for STH and LF. Further work is needed to streamline procedures and to determine optimal sampling strategies for STH surveys, because these may not require as many samples or sampling sites as TAS.
Randomized placebo-controlled trial of the efficacy of mebendazole polymorphs in the treatment of hookworm infections
(American Society of Tropical Medicine and Hygiene, 2013) Gunawardena, N.K.; Kumarendran, B.; Manamperi, N.H.; Senarathna, B.P.; Silva, M.; Pathmeswaran, A.; de Silva, N.R.
Mebendazole has three polymorphic forms, identified as A, B and C. It has been suggested that unlike polymorph C, A is ineffective in the treatment of hookworm and whipworm infections. A randomized doubleblind, placebo-controlled trial was carried out to compare the efficacy of single dose 500 mg tablets of pure mebendazole Polymorph C with those containing a 1:1 mixture of Polymorphs A and C, for the treatment of hookworm infections. All eligible individuals living in 219 households were recruited after obtaining written, informed consent. A single fecal sample was obtained and examined the same day, using the Kato-Katz technique for intestinal nematode infections. Those who were found infected with hookworms were randomized to one of three treatment arms and requested to provide a second faecal sample 10 - 14 days after treatment. This was examined in the same manner as the first. A total of 892 individuals were recruited; 601 provided fecal samples; 214 were found positive for hookworm; 70, 74 and 70 individuals were randomized to treatment arms A (mixture of polymorphs A and C), B (pure polymorph C) and C (placebo) respectively. Follow-up samples were provided by 53, 48 and 49 persons respectively in each treatment arm. The cure rates in the three treatment arms were 28.3%, 18.8% and 16.3% respectively; they were not significantly different from one another. Comparison of fecal egg count reductions (FECR) in the 3 treatment arms (86.1%, 84.5% and -6.6% in Arms A, B and C respectively) showed that both mebendazole formulations performed significantly better than placebo, but there was no statistically significant difference between FECR with the two drug formulations. It is concluded that a single 500mg dose of mebendazole, either as Polymorph C alone, or as a mixture of Polymorphs A and C, has little efficacy in curing hookworm infections. However, both formulations were significantly better than placebo in reducing the intensity of infection, with no statistically significant difference between the two formulations.
Geographical Information System (GIS)-based maps for monitoring of entomological risk factors affecting transmission of Chikungunya in Sri Lanka
(Faculty of Tropical Medicine, Mahidol University, 2008) Hapugoda, M.D.; Gunawardena, N.K.; Kusumawathie, P.H.D.; Jayasooriya, G.A.J.S.K.; Hapuarachchi, H.A.C.; Abeyewickreme, W.
INTRODUCTION: Chikungunya is an important mosquito-born viral infection in Sri Lanka at present. OBJECTIVE: To prepare OUS-based maps Tor monitoring of entomological risk Factors affecting transmission of chikungunya. RESEARCH DESIGN: Entomological risk factors affecting transmission of chikungunya were examined in a chikungunya hot-spot in the District of Kandy, Sri Lanka from April to July in 2008. Hundred house-holds in 33 clusters were recruited. The distant between clusters was at least 200m which is beyond the maximum flight range of Aedes mosquitoes, the vectors of chikungunya. Monthly surveillance was conducted using standard entomological surveillance methods followed by obtaining information through a pre-tested questionnaire. G1S was used to map the selected house¬holds and display entomological data. RESULTS: GIS-based maps were developed to highlight the spatial and temporal distribution of vectors, their density and the presence of key breeding sites. Maps showed the presence of high density of Aedes albopictus mosquitoes in more than 90% of the key (artificial) breeding habitats in all clusters throughout the study period. DISCUSSION: Generalized high density of Ae. albopictus suggests that this species may play a major role in transmitting chikungunya in the study area. GIS-based 'maps may be used as an important tool to find out spatial and temporal distribution of vectors, their density and key breading sites in a selected hotspot, which would enable cost effective and efficient interventions for vector control in disease endemic areas.
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.
Comparison of five DNA extraction methods from human blood for the detection of Wuchereria bancrofti by polymerase chain reaction assays
(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.; Gunawardena, N.K.; Abeysundara, S.; Abeyewickreme, W.
Introduction: Lymphatic filariasis (Lf) is the second most common vector-borne disease globally. Approximately 90% of global burden of Lf is caused by Wuchereria bancrofti. W. bancrofti is routinely diagnosed by morphological identification of microfilariae (Mf) by microscopy which is a labour intense, low sensitive and time consuming method. Detection of W. bancrofti Deoxyribonucleic acid (DNA) using polymerase chain reaction (PCR) technique has become popular today, because of its high sensitivity and specificity. The overall success of the PCR strategy in detecting a filarial parasite in human blood varies between sample preparation methods. The objective of this study was to compare five DNA extraction methods (Lysis + centrifugation, Chelex method, Mf pellet method, Q1Aamp DNA Mini Kit commercial system, and Phenol-chloroform) with regard to duration of completion, labor involvement and PCR analytical sensitivity in-relation to DNA quality and quantity for the detection of W. bancrofti in human blood. Five blood samples positive for mf of W. bancrofti were tested for each DNA extraction method and were compared with respect to the sensitivity, time and quality/quantity of DNA and also by PCR analysis. Of the 5 methods tested, Mf pellet method was found to be the most simple and effective technique for the isolation of W. bancrofti Mf in human blood. This method was quick (15 min to complete), simple (5 min of manual labor), and very economical. It does not require any organic solvents, and the entire extraction procedure uses only two steps requiring supernatant transfer between tubes, hence minimizing the possibility of cross-contamination. Moreover, the PCR analytical sensitivity of the Mf pellet method was comparable to that of the commercial kit used. No PCR inhibitors were detected, independently of Mf count in the blood. Same method (optimal DNA extraction method) can be also used for the detection of parasite DNA from the field collected Mf positive mosquitoes using a PCR. Therefore, we recommend the Mf pellet method for processing large numbers of blood samples in community surveys aimed at determining the prevalence of W. bancrofti infection.
Factors affecting transmission of chikungunya using Geographical Information System (GIS)
(Sri Lanka Association for the Advancement of Science, 2009) Hapugoda, M.D.; Gunawardena, N.K.; Kusumawathie, P.H.D.; Jayasooriya, G.A.J.S.K.; Abeyewickreme, W.
Transmission of chikungunya has been observed in many parts of Sri Lanka during the past few years. The objective of this study was to identify possible factors affecting transmission of chikungunya in a high risk area and to intervene and monitor those using GIS. Entomological, environmental, socio-economic and other possible factors were examined with regard to a chikungunya hot-spot in Kandy municipality for 12 months starting from April 2008. Hundred house-holds from 33 clusters were recruited. The distant between each cluster was maintained at a minimum of 200 m. Micro level approaches for collection of position, population, environmental, socio-economic and other related information were performed at each house-hold through a pre-tested questionnaire. Monthly entomological and epidemiological surveillance were conducted for 12 months. Digital topographical maps and meteorological information were obtained. GIS was used to map the selected households and to highlight the spatial and temporal distribution of factors under study. Selected risk area was an urban area where homesteads were the major land use pattern. The weather pattern of the study area was typical that of the Wet Zone. Entomological surveillance conducted showed the presence of high density of Aedes albopictus mosquitoes in more than 90% of the key (artificial) breeding habitats. Socio-economic data revealed although all house-holds have a sound knowledge on transmission on dengue including preventive measures, they were less concerned about the key mosquito breeding sites. GIS maps generated during the study showed distribution of these identified factors in all clusters. House index and man hour density of Ae. albopictus showed a positive correlation with rainfall, with a lag period of 2 and 3 months. The generalized high density of Ae. Albopictus suggest that this species may play a major role in transmitting chikungunya in the study area. In conclusion, the presence of high density of Ae. albopictus and lack of concern about key mosquito breeding sites in all clusters may be important risk factors. GIS-based maps can be used as an important tool to find out spatial and temporal distribution of possible risk factors in a selected hotspot, which would enable health authorities to prioritize implementation of control activities in a cost effective manner

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