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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 Occurrence of major and potential malaria vector immature stages in different breeding habitats and associated biotic and abiotic characters in the district of Trincomalee Sri Lanka(New Delhi : National Institute of Malaria Research, 2020) Ranathunge, R.M.T.B.; Kannangara, D.N.; Gunathilaka, P.A.D.H.N.; Abeyewickreme, W.; Hapugoda, M.D.BACKGROUND & OBJECTIVES: Understanding the effect of biotic and abiotic factors on the biology and ecology of immature stages of anopheline larvae is very important in controlling malaria vector mosquitoes. Therefore, this study was focused on the monitoring of ecological factors affecting the distribution, dynamics, and density of malaria vector mosquitoes in the District of Trincomalee, Sri Lanka. METHODS: Permanent and temporary breeding habitats were identified and selected from five possible malaria sensitive sites in the district of Trincomalee. Anopheles larvae and macro-invertebrates were collected using standard methods for 16 months (from October 2013 to January 2015) and they were identified microscopically. Eight physico-chemical parameters of the breeding habitats were measured. RESULTS: Overall, a total of 4815 anopheline larvae belonging to 13 species were collected from 3,12,764 dips from 18 permanent and temporary breeding habitats. The abundance of anopheline larvae showed a significant positive correlation (p <0.05) with physico-chemical parameters in breeding habitats, such as temperature, dissolved oxygen, and turbidity. A total of 35 macro-invertebrate taxa were collected from the anopheline mosquito breeding habitats. INTERPRETATION & CONCLUSION: This study represents the first systematic update of water quality parameters, macro-invertebrate communities associated with Anopheles mosquito oviposition sites in the District of Trincomalee, Sri Lanka. Rainfall intensity and wind speed are critical meteorological factors for the distribution and abundance of malaria vectors. Knowledge generated on the ecology of Anopheles mosquitoes will help to eliminate malaria vectors in the country. KEYWORDS: Macro-invertebrates; Sri Lanka; malaria vectors; physico-chemical parameters.Item Multivariate spatio-temporal approach to identify vulnerable localities in dengue risk areas using Geographic Information System (GIS)(Nature Publishing Group, 2021) Withanage, G.P.; Gunawardana, M.; Viswakula, S.D.; Samaraweera, K.; Gunawardene, N.S.; Hapugoda, M.D.ABSTRACT: Dengue is one of the most important vector-borne infection in Sri Lanka currently leading to vast economic and social burden. Neither a vaccine nor drug is still not being practiced, vector controlling is the best approach to control disease transmission in the country. Therefore, early warning systems are imminent requirement. The aim of the study was to develop Geographic Information System (GIS)-based multivariate analysis model to detect risk hotspots of dengue in the Gampaha District, Sri Lanka to control diseases transmission. A risk model and spatial Poisson point process model were developed using separate layers for patient incidence locations, positive breeding containers, roads, total buildings, public places, land use maps and elevation in four high risk areas in the district. Spatial correlations of each study layer with patient incidences was identified using Kernel density and Euclidean distance functions with minimum allowed distance parameter. Output files of risk model indicate that high risk localities are in close proximity to roads and coincide with vegetation coverage while the Poisson model highlighted the proximity of high intensity localities to public places and possibility of artificial reservoirs of dengue. The latter model further indicate that clustering of dengue cases in a radius of approximately 150 m in high risk areas indicating areas need intensive attention in future vector surveillances.Item Use of novaluron-based autocidal gravid ovitraps to control Aedes dengue vector mosquitoes in the district of Gampaha, Sri Lanka(Hindawi Pub. Co., 2020) Withanage, G.P.; Viswakula, S.D.; Gunawardene, Y.I.N.S.; Hapugoda, M.D.ABSTRACT:Dengue is the most important mosquito-borne viral infection in Sri Lanka causing an enormous social and economic burden in the country. In the absence of therapeutic drugs and the developed vaccines are under investigation, vector control is the best strategy to reduce the disease transmission. Therefore, the development of novel tools to control dengue vector mosquitoes has become the need of the hour. Novaluron is a recently developed Insect Growth Regulator (IGR) which inhibits chitin synthesis in immature stages of insects. The aim of the study was to identify the efficacy of a simple and cost-effective Autocidal Gravid Ovitrap (AGO) developed using Novaluron to control dengue outbreaks in the District of Gampaha, Sri Lanka. Laboratory and semifield experiments were performed to identify the activity range, optimum field dosage, and residual effects of Novaluron following the World Health Organization guidelines, and field experiments were performed in the Ragama Medical Officer of Health (MOH) area. Two study areas 800 m apart were selected and assigned as treated and control areas randomly. In each study area, 30 households were selected randomly. Each household was given two ovitraps, one placed indoors and the other placed outdoors. Mortality and survival counts were recorded separately for one-year time period and data were analyzed using a two-way repeated measures analysis of variance model. During the laboratory experiments, the adult emerging inhibition was 100% in all tested concentrations. The optimum field dosage was 2 ppm and the residual effect was 28 days. In the field experiments, significantly higher mortality counts were recorded in treated areas both indoor- and outdoor-placed AGOs. Two-factor repeated measures ANOVA followed by Tukey's test confirmed that the mean mortality count is high for the developed AGOs both indoor and outdoor settings. The developed AGO can be deployed to control both indoor and outdoor dengue vector mosquito populations, and in dengue-risk areas, the ovitrap will be supportive to local health authorities to enhance the efficiency of future vector control programs.Item 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 LankaItem A forecasting model for dengue incidence in the District of Gampaha, Sri Lanka(BioMed Central, 2018) Withanage, G.P.; Viswakula, S.D.; Nilmini Silva Gunawardena, Y.I.; Hapugoda, M.D.BACKGROUND: Dengue is one of the major health problems in Sri Lanka causing an enormous social and economic burden to the country. An accurate early warning system can enhance the efficiency of preventive measures. The aim of the study was to develop and validate a simple accurate forecasting model for the District of Gampaha, Sri Lanka. Three time-series regression models were developed using monthly rainfall, rainy days, temperature, humidity, wind speed and retrospective dengue incidences over the period January 2012 to November 2015 for the District of Gampaha, Sri Lanka. Various lag times were analyzed to identify optimum forecasting periods including interactions of multiple lags. The models were validated using epidemiological data from December 2015 to November 2017. Prepared models were compared based on Akaike's information criterion, Bayesian information criterion and residual analysis. RESULTS: The selected model forecasted correctly with mean absolute errors of 0.07 and 0.22, and root mean squared errors of 0.09 and 0.28, for training and validation periods, respectively. There were no dengue epidemics observed in the district during the training period and nine outbreaks occurred during the forecasting period. The proposed model captured five outbreaks and correctly rejected 14 within the testing period of 24 months. The Pierce skill score of the model was 0.49, with a receiver operating characteristic of 86% and 92% sensitivity. CONCLUSIONS: The developed weather based forecasting model allows warnings of impending dengue outbreaks and epidemics in advance of one month with high accuracy. Depending upon climatic factors, the previous month's dengue cases had a significant effect on the dengue incidences of the current month. The simple, precise and understandable forecasting model developed could be used to manage limited public health resources effectively for patient management, vector surveillance and intervention programmes in the district.Item Identification of cattle, buffaloes and rodents as reservoir animals of Leptospira in the District of Gampaha, Sri Lanka(Biomed Central, 2017) Denipitiya, D.T.H.; Chandrasekharan, N.V.; Abeyewickreme, W.; Hartskeerl, R.A.; Hapugoda, M.D.BACKGROUND: Leptospirosis is an important emerging infectious disease in Sri Lanka. Rats are the most important reservoir of Leptospira but domestic and wild mammals may also act as important maintenance or accidental hosts. In Sri Lanka, knowledge of reservoir animals of leptospires is poor. The objective of this study was to identify potential reservoir animals of Leptospira in the District of Gampaha, Sri Lanka. FINDINGS: Blood and kidney samples were collected from 38 rodents and mid-stream urine samples were randomly collected from 45 cattle and five buffaloes in the District of Gampaha. Kidney and urine samples were tested by real-time polymerase chain reaction (PCR) and serum samples were tested by the microscopic agglutination test (MAT). Of the 38 rodent kidney samples, 11% (4/38) were positive by real-time PCR. The prevalence of leptospiral carriage was 11% (3/26) and 8% (1/12) in female and male rodents, respectively. Three rodent serum samples were positive by MAT. Of the 50 cattle/buffalo urine samples tested, 10% (5/50) were positive by real-time PCR. The prevalence of leptospiral carriage was 9% (4/45) and 20% (1/5) in cattle and buffaloes, respectively. CONCLUSION: Results of PCR and MAT showed that Leptospira were present in a significant proportion of the rodents and farm animals tested in this study and suggest that these (semi-) domestic animals form an infection reservoir for Leptospira. Therefore, there is a potential zoonotic risk to public health, most notably to farmers in this area.Item Composition of malaria vectors and diversity of anopheline breeding habitats in the district of Mannar, Sri Lanka(Central Environmental Authority (CEA), 2016) Gunathilaka, P.A.D.H.N.; Hapugoda, M.D.; Wickremasinghe, A.R.; Abeyewickreme, W.In the malaria elimination phase in Sri Lanka, investigation on biological and ecological factors of malaria vectors are important in planning appropriate vector controlling strategies. Lack of sufficient biological and ecological information on malaria vectors in the Northern Province of the country, a malaria endemic region, is a major constrain in successful implementation of malaria control programmes. Therefore, the objective of this study was to explore the diversity of breeding habitats and species composition of malaria vector mosquitoes in the District of Mannar, Sri Lanka. Potential habitats for Anopheles mosquito larvae were surveyed from June, 2010 to July 20 J2 on a monthly basis in selected sampling sites in the Mannar District: Mannar Town, Vankalai and Silawathiura, within a radius about 20 km. In each site, 4 sub sites were selected A total of 37,788 Anopheles representing ten species was recorded from 12 breeding habitat categories. Built wells and waste water collections were conducive for anopheline breeding. Anopheles subpictus (96.2%, n= 36,351) was the dominant species followed by An. peditaeniatus (1.47%, n= 557), An. barbirostris (1.23%, n= 463), An. nigerriums (0.75%,n = 285), An. varuna (0.19%, n= 74), An. barbumbrosus (0.1%, n= 38), An. vagus' (0.03%, n= 12), An. pallidus (0.01%, n= 4), An.jamesii (0.05%, n= 2) and An. pseudojamesi (0.05%, n= 2). Use of wells and waste water drains as breeding places by potential malaria vectors indicates that both of these habitats act as larval reservoirs during the dry season. Presence of theses habitats in close proximity to human habitats create a potential risk of malaria transmission among humans. Therefore, health authorities need to be vigilant on these new habitats in vector control programmes.Item Application of a real time Polymerase Chain Reaction (PCR) assay for the early diagnosis of human leptospirosis in Sri Lanka(Academic Press, Elsevier, 2016) Denipitiya, D.T.H.; Chandrasekharan, N.V.; Abeyewickreme, W.; Hartskeerl, C.M.; Hartskeerl, R.A.; Jiffrey, A.M.; Hapugoda, M.D.Leptospirosis has a major impact on health in Sri Lanka but is probably grossly under-recognized due to difficulties in clinical diagnosis and lack of diagnostic laboratory services. The objective of this study was to establish and evaluate a SYBR Green-based real-time Polymerase Chain Reaction (rt-PCR) assay for early, rapid and definitive laboratory diagnosis of leptospirosis in Sri Lanka. The rt-PCR assay was established and analytical specificity and sensitivity were determined using reference DNA samples. Evaluation of the assay for diagnosis of clinical samples was performed using two panels of serum samples obtained from 111 clinically suspected adult patients. Patients were confirmed as leptospirosis (n = 65) and non-leptospirosis (n = 30) by the Patoc - MAT. Other 16 samples gave ambiguous results. The analytical sensitivity of the rt-PCR was approximately 60 genome copies and no cross-reactivity was observed with saprophytic Leptospira spp. and other pathogenic microorganisms. Based on confirmation with Patoc-MAT on paired samples this corresponds to a diagnostic sensitivity and specificity of 67.7% (44/65) and 90.0% (27/30), respectively. This study showed that rt-PCR has the potential to facilitate rapid and definitive diagnosis of leptospirosis during early phase of infection in Sri Lanka.Item Molecular evidence of hantavirus infection among clinically suspected patients with hae-morrhagic fever with renal syndrome (HFRS)(Sri Lanka College of Microbiologists, 2013) Muthugala, M.A.R.V.; Manamperi, A.A.P.S.; Gunasena, S.; Hapugoda, M.D.; Butch, G.INTRODUCTION: Hantavirus disease is an emerging zoonotic viral infection with high fatality. Transmission is by inhalation of aerosols generated from virus contaminated rodent excreta. There are two major clinical forms, haemorraghic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). Clinical features of HFRS, often mimic leptospirosis. Large number of cases of leptospirosis like illness has been reported in Sri Lanka annually. Although there were serological evidence of different types of hantavirus infection in Sri Lanka, diagnosis of hantavirus is not routinely performed. Due to the genetic and antigenic diversity, an assay that could detect a wide range of hantaviruses need to be established. OBJECTIVES: To establish, evaluate and validate a genus specific hantavirus RT-PCR assay. To diagnose hantavirus infection among clinically suspected HFRS patients in three selected hospitals.To describe clinical manifestations of hantavirus infections in the study population. METHODOLOGY: Genus specific conventional RT-PCR assay was established using panhanta primers and evaluated, optimized and validated using synthetic genes of 12 known hantavirus species as reference samples. Assay was able to detect a wide range of hantaviruses at minimum detection limit of 70 copies/ reaction. Molecular diagnosis of hantavirus infection was carried out in three hospitals in Colombo and Gampaha districts. Study was conducted from 01st of January 2011 to 31st of April 2011 and 61 adult patients were recruited to this study. Hantavirus RT-PCR was performed on all collected samples after extraction of RNA by TRIzol® method. RESULTS: Of 61 tested samples, 05 were positive for hantavirus genome. These results were confirmed at reference laboratory as well and species identification result is pending. Of 58 tested samples, 06 samples were positive for hantavirus IgM by in-house ELISA. All PCR positive samples were positive for hanta virus IgM. All patients with hantavirus infection had clinical and biochemical features of liver involvement in addition to fever, thrombocytopenia and renal involvement. CONCLUSION: Established RT-PCR assay was able to detect a wide range of hantaviruses and by using it molecular evidence of hantavirus infection was demonstrated in humans in Sri Lanka. Further studies are required to describe the disease epidemiology and to identify natural hosts in the country.Item Clinical and virological features of dengue in 2010(Sri Lanka College of Microbiologists, 2011) Hapugoda, M.D.; Manamperi, H.; Gunasena, S.; Athapaththu, A.M.M.H.; Premawansa, G.; Wellawaththage, C.; Jayarathna, T.D.S.S.; Abeyewickreme, W.INTRODUCTION: Dengue is an important viral infection in Sri Lanka. All 4 serotypes co-circulate in Sri Lanka. OBJECTIVE: To study the clinical and virological features of dengue in 2010. DESIGN, SETTING AND METHODS: A hospital-based study was carried out at North Colombo Teaching Hospital, Ragama in 2010. Patients clinically suspected of having dengue, with fever less than 5 days were recruited. Acute and convalescent blood samples were collected within 7 days after obtaining informed written consent. Demographic, clinical information and laboratory results were obtained. Acute serum samples were tested using molecular (RT-PCR and Semi-Nested PCR) and serological (ELlSAs and HAI) assays. Convalescent samples were tested by serological assays. RESULTS: Of 209 patients enrolled, 93 % (195/209) were laboratory confirmed as recent positive cases of dengue viral infection; of these, 5% (9/195) were classified as dengue fever; 85%(1G5/195) dengue haemorrhagic fever (DHF) and 0.5% (1/195) dengue shock syndrome. Mean platelet value and packed cell volume (PCV) in laboratory confirmed dengue patients were 56,107/mm3 (range 10,000-306,000) and 42%(range 34-61 %) respectively. Patients infected with DHF showed both primary (n=45) and secondary (n=102) infections. Interestingly, secondary infection was not significantly correlated with DHF (x2-0.3:p=0.6). DEN-1 was responsible for the majority of cases, with a minority due to other three serotypes; all serotypes contributed to severe disease. CONCLUSION: DEN-1 was responsible for the majority of cases in 2010 but it circulated at a low level during previous epidemics. Majority of patients had severe clinical symptoms. In this epidemic, the clinical presentation of dengue differed according to the geographic region and viral serotype. ACKNOWLEDGMENTS: Financial assistance and technical co-operation by International Center for Genetic Engineering and Biotechnology (ICGEB CRP SRL 08/02), National Science Foundation (NSF/RG/2009/BT/01) and International Atomic Energy Authority (lAEA/SRL/5/042) is acknowledged.