Journal/Magazine Articles

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This collection contains original research articles, review articles and case reports published in local and international peer reviewed journals by the staff members of the Faculty of Medicine

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Evaluating spatiotemporal dynamics of snakebite in Sri Lanka: Monthly incidence mapping from a national representative survey sample
(Public Library of Science, 2021) Ediriweera, D.S.; Kasturiratne, A.; Pathmeswaran, A.; Gunawardena, N.K.; Jayamanne, S.F.; Murray, K.; Iwamura, T.; Isbister, G.; Dawson, A.; Lalloo, D.G.; de Silva, H.J.; Diggle, P.J.
BACKGROUND: Snakebite incidence shows both spatial and temporal variation. However, no study has evaluated spatiotemporal patterns of snakebites across a country or region in detail. We used a nationally representative population sample to evaluate spatiotemporal patterns of snakebite in Sri Lanka. METHODOLOGY: We conducted a community-based cross-sectional survey representing all nine provinces of Sri Lanka. We interviewed 165 665 people (0.8% of the national population), and snakebite events reported by the respondents were recorded. Sri Lanka is an agricultural country; its central, southern and western parts receive rain mainly from Southwest monsoon (May to September) and northern and eastern parts receive rain mainly from Northeast monsoon (November to February). We developed spatiotemporal models using multivariate Poisson process modelling to explain monthly snakebite and envenoming incidences in the country. These models were developed at the provincial level to explain local spatiotemporal patterns. PRINCIPAL FINDINGS: Snakebites and envenomings showed clear spatiotemporal patterns. Snakebite hotspots were found in North-Central, North-West, South-West and Eastern Sri Lanka. They exhibited biannual seasonal patterns except in South-Western inlands, which showed triannual seasonality. Envenoming hotspots were confined to North-Central, East and South-West parts of the country. Hotspots in North-Central regions showed triannual seasonal patterns and South-West regions had annual patterns. Hotspots remained persistent throughout the year in Eastern regions. The overall monthly snakebite and envenoming incidences in Sri Lanka were 39 (95%CI: 38-40) and 19 (95%CI: 13-30) per 100 000, respectively, translating into 110 000 (95%CI: 107 500-112 500) snakebites and 45 000 (95%CI: 32 000-73 000) envenomings in a calendar year. CONCLUSIONS/SIGNIFICANCE: This study provides information on community-based monthly incidence of snakebites and envenomings over the whole country. Thus, it provides useful insights into healthcare decision-making, such as, prioritizing locations to establish specialized centres for snakebite management and allocating resources based on risk assessments which take into account both location and season.
Non-alcoholic fatty liver disease and its associations among adolescents in an urban, Sri Lankan community
(BioMed Central, 2017) Rajindrajith, S.; Pathmeswaran, A.; Jayasinghe, C.; Kottahachchi, D.; Kasturiratne, A.; de Silva, S.T.; Niriella, M.A.; Dassanayake, A.S.; de Silva, A.P.; de Silva, H.J.
BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is a common problem across the world. We aimed to determine the prevalence of NAFLD and its associations in Sri Lankan adolescents living in an urban Sri Lankan community. METHOD: The study population consisted of the birth cohort of the year 2000, residing in the Ragama Medical Officer of Health area. Socio-demographic and anthropometric data [anthropometric measurements, blood pressure and total body fat distribution] of these adolescents were collected by trained data collectors. Fasting blood sugar, serum insulin, fasting serum lipids and serum alanine aminotransferase (ALT) levels were measured and an abdominal ultrasound was performed. NAFLD was diagnosed on established ultrasound criteria for fatty liver and absent alcohol consumption. RESULTS: The study sample consisted of 499 adolescents [263 (51.8%) girls]. Forty two (8.4%) had NAFLD. NAFLD was significantly associated with being breast fed for less than 4 months (33.3% vs. 17.1 in controls, p = 0.02), higher waist circumference (prevalence risk ratio 83.3/20.3, 4.1, p < 0.0001), higher body mass index (prevalence risk ratio 40.5/4.8, 8.4, p < 0/0001),higher HOMA-IR (3.7 vs. 1.9, p < 0.0001) and high triglycerides (prevalence risk ratio 14.3/5.8, 2.5, p = 0.033). Adolescents with NAFLD also had a higher amount of total body fat (p < 0.001) and subcutaneous fat (p < 0.001) than those without NAFLD. The number of children with metabolic derangements was higher among adolescents with NAFLD than those without (85.8 vs 26.3 in controls, p < 0.0001), but a family history of hypertension, diabetes, myocardial infarction or dyslipidaemia were not. CONCLUSION: Prevalence of NAFLD was high in Sri Lankan adolescents, and was associated with metabolic derangements, especially obesity, insulin resistance and early cessation of breast feeding.
Genotypic characterization of Orientia tsutsugamushi from patients in two geographical locations in Sri Lanka
(BioMed Central, 2017) Premaratna, R.; Blanton, L.S.; Samaraweera, D.N.; de Silva, G.N.N.; Chandrasena, T.G.A.N.; Walker, D.H.; de Silva, H.J.
BACKGROUND: To date more than 20 antigenically distinct strains of Orientia tsutsugamushi (OT) reported within the tsutsugamushi triangle that cause an undifferentiated acute febrile illness in humans. Genotypic characterization of OT in different geographic regions or within the same country, is important in order to establish effective diagnostics, clinical management and to develop effective vaccines. Genetic and antigenic characterization of OT causing human disease in OT-endemic regions is not known for Sri Lanka. METHODS: Adult patients and children who were admitted with an acute febrile illness and presumed to having acute scrub typhus based on presence of an eschar and other supporting clinical features were recruited. Eschar biopsies and buffy coat samples collected from patients who were confirmed having OT by IFA were further studied by real time PCR (Orientia 47 kD) and nested PCR (Orientia 56 kD) amplification. DNA sequences were obtained for 56 kD gene amplicons and phylogenetic comparisons were analyzed using currently available data in GenBank [Neucleotide substitution per 100 residues, 1000 Bootstrap Trials]. RESULTS: Twenty eschar biopsies (Location1,19, Location 2,1) and eight buffy coat samples (Location1,6, Location2,2) examined by real time PCR revealed Orientia amplicons in 16 samples. DNA sequences were obtained for the 56 kD gene amplicons in 12 eschars and 4 buffy coat samples. The genotypes of the Location1 samples revealed that, 7 exhibiting close homology with JP1 [distantly related to UT177 Thai (Karp related)], five had close homology with Kato strain, two had close homology with JGv and JG AF [Distantly related to Kawasaki M63383] and one had close homology with Gilliam strain. The Location 2 strain was closely related to Kuroki-Boryong L04956, the genotype which is distributed in far eastern Asia. Similar to other patients in the cohort this patient also had never travelled out of Sri Lanka. CONCLUSIONS: We observed all three main OT genotypes in Sri Lanka, and the majority fell into Thai Karp related clade. These results demonstrate great antigenic diversity of OT in the studied areas of Sri Lanka.
A Diagnostic scoring model for Leptospirosis in resource limited settings
(Public Library of Science, 2016) Rajapakse, S.; Weeratunga, P.; Niloofa, R.; Fernando, N.; de Silva, N.L.; Rodrigo, C.; Maduranga, S.; Nandasiri, N.; Premawansa, S.; Karunanayake, L.; de Silva, H.J.; Handunnetti, S.
Leptospirosis is a zoonotic infection with significant morbidity and mortality. The clinical presentation of leptospirosis is known to mimic the clinical profile of other prevalent tropical fevers. Laboratory confirmation of leptospirosis is based on the reference standard microscopic agglutination test (MAT), direct demonstration of the organism, and isolation by culture and DNA detection by polymerase chain reaction (PCR) amplification. However these methods of confirmation are not widely available in resource limited settings where the infection is prevalent, and reliance is placed on clinical features for provisional diagnosis. In this prospective study, we attempted to develop a model for diagnosis of leptospirosis, based on clinical features and standard laboratory test results. METHODS: The diagnostic score was developed based on data from a prospective multicentre study in two hospitals in the Western Province of Sri Lanka. All patients presenting to these hospitals with a suspected diagnosis of leptospirosis, based on the WHO surveillance criteria, were recruited. Confirmed disease was defined as positive genus specific MAT (Leptospira biflexa). A derivation cohort and a validation cohort were randomly selected from available data. Clinical and laboratory manifestations associated with confirmed leptospirosis in the derivation cohort were selected for construction of a multivariate regression model with correlation matrices, and adjusted odds ratios were extracted for significant variables. The odds ratios thus derived were subsequently utilized in the criteria model, and sensitivity and specificity examined with ROC curves. RESULTS: A total of 592 patients were included in the final analysis with 450 (180 confirmed leptospirosis) in the derivation cohort and 142 (52 confirmed leptospirosis) in the validation cohort. The variables in the final model were: history of exposure to a possible source of leptospirosis(adjusted OR = 2.827; 95% CI = 1.517-5.435; p = 0.001) serum creatinine > 150 micromol/l (adjusted OR = 2.735; 95% CI = 1.374-4.901; p = 0.001), neutrophil differential percentage > 80.0% of total white blood cell count (adjusted OR 2.163; 95% CI = 1.309-3.847; p = 0.032), serum bilirubin > 30 micromol/l (adjusted OR = 1.717; 95% CI 0.938-3.456; p = 0.049) and platelet count < 85,000/mm3 (adjusted OR = 2.350; 95% CI = 1.481-4.513; p = 0.006). Hosmer-Lemeshow test for goodness of fit was 0.931. The Nagelkerke R2 was 0.622. The area under the curve (AUC) was noted as 0.762. A score value of 14 reflected a sensitivity of 0.803, specificity of 0.602, a PPV of 0.54, NPV of 0.84, a positive LR of 2.01 and a negative LR of 0.32. CONCLUSIONS: The above diagnostic model for diagnosis of leptospirosis is suggested for use in clinical settings. It should be further validated in clinical practice.
Concomitant leptospirosis-hantavirus co-infection in acute patients hospitalized in Sri Lanka: implications for a potentially worldwide underestimated problem
(Cambridge University Press, 2015) Sunil-Chandra, N.P.; Clement, J.; Maes, P.; de Silva, H.J.; Van Esbroeck, M.; Van Ranst, M.
Two global (re-)emerging zoonoses, leptospirosis and hantavirus infections, are clinically indistinguishable. Thirty-one patients, hospitalized in Sri Lanka for acute severe leptospirosis, were after exclusion of other potentially involved pathogens, prospectively screened with IgM ELISA for both pathogens. Of these, nine (29·0%) were positive for leptospirosis only, one (3·2%) for hantavirus only, seven (22·5%) for both pathogens concomitantly, whereas 13 (41·9%) remained negative for both. Moreover, in a retrospective study of 23 former patients, serologically confirmed for past leptospirosis, six (26·0%) were also positive in two different IgG ELISA hantavirus formats. Surprisingly, European Puumala hantavirus (PUUV) results were constantly higher, although statistically not significantly different, than Asian Hantaan virus (HTNV), suggesting an unexplained cross-reaction, since PUUV is considered absent throughout Asia. Moreover, RT-PCR on all hantavirus IgM ELISA positives was negative. Concomitant leptospirosis-hantavirus infections are probably heavily underestimated worldwide, compromising epidemiological data, therapeutical decisions, and clinical outcome.
Influence of non-alcoholic fatty liver disease on the development of diabetes mellitus
(Wiley-Blackwell, 2013) Kasturiratne, A.; Weerasinghe, S.; Dassanayake, A.S.; Rajindrajith, S.; de Silva, A.P.; Kato, N.; Wickremasinghe, A.R.; de Silva, H.J.
BACKGROUND AND AIM: Non-alcoholic fatty liver disease (NAFLD) is linked to metabolic syndrome, and is known to be associated with impaired fasting glycemia and diabetes mellitus. This prospective community-based study was conducted to determine the association between NAFLD and incidence of diabetes mellitus in an urban adult population in Sri Lanka. METHODS: Participants of the Ragama Health Study cohort were assessed for NAFLD using established ultrasound criteria in 2007. Those who were free of diabetes at baseline were followed up for 3 years. Incidence rates of diabetes mellitus were compared between subjects with and without NAFLD at baseline. RESULTS: Out of 2984 subjects, 926 had NAFLD and 676 had diabetes in 2007. Of the 2276 subjects who were free of diabetes in 2007, 1914 were re-assessed in 2010. After 3 years, 104 out of 528 subjects with NAFLD and 138 out of 1314 subjects without NAFLD had developed diabetes mellitus de novo. Incidence rates of diabetes were respectively 64.2 and 34 per 1000 person-years of follow up for those with and without NAFLD. NAFLD was an independent predictor of developing diabetes mellitus. Other independent predictors were impaired fasting glycemia and dyslipidemia. CONCLUSIONS: Subjects with ultrasonically diagnosed NAFLD have an increased risk of developing diabetes mellitus. Intervention for NAFLD through lifestyle modification may prevent progression of the current diabetes epidemic. © 2012 Journal of Gastroenterology and Hepatology Foundation and Wiley Publishing Asia Pty Ltd.
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.
Prevalence of inflammatory bowel disease in two districts of Sri Lanka: a hospital based survey
(BioMed Central, 2010) Niriella, M.A.; de Silva, A.P.; Dayaratne, A.H.G.K.; Ariyasinghe, M.H.A.D.P.; Navarathne, M.M.N.; Peiris, R.S.K.; Samarasekara, D.; Satarasinghe, R.L.; Rajindrajith, S.; Dassanayake, A.S.; Wickremasinghe, A.R.; de Silva, H.J.
BACKGROUND: Inflammatory bowel disease (IBD) is being increasingly diagnosed in Asia. However there are few epidemiological data from the region. METHODS: To determine prevalence and clinical characteristics of IBD, a hospital-based survey was performed in the Colombo and Gampaha districts (combined population 4.5 million) in Sri Lanka. Patients with established ulcerative colitis (UC) and Crohn's disease (CD), who were permanent residents of these adjoining districts, were recruited from hospital registries and out-patient clinics. Clinical information was obtained from medical records and patient interviews. RESULTS: There were 295 cases of IBD (UC = 240, CD = 55), of which 34 (UC = 30, CD = 4) were newly diagnosed during the study year. The prevalence rate for UC was 5.3/100,000 (95% CI 5.0-5.6/100,000), and CD was 1.2/100,000 (95% CI 1.0-1.4/100,000). The incidence rates were 0.69/100,000 (95% CI 0.44-0.94/100,000) for UC and 0.09/100,000 (95% CI 0.002-0.18/100,000) for CD. Female:male ratios were 1.5 for UC and 1.0 for CD. Mean age at diagnosis was (males and females) 36.6 and 38.1y for UC and 33.4 and 36.2y for CD. Among UC patients, 51.1% had proctitis and at presentation 58.4% had mild disease. 80% of CD patients had only large bowel involvement. Few patients had undergone surgery. CONCLUSIONS: The prevalence of IBD in this population was low compared to Western populations, but similar to some in Asia. There was a female preponderance for UC. UC was mainly mild, distal or left-sided, while CD mainly involved the large bowel.
Prevalence and risk factors for non-alcoholic fatty liver disease among adults in an urban Sri Lankan population
(Wiley-Blackwell, 2009) Dassanayake, A.S.; Kasturiratne, A.; Rajindrajith, S.; Kalubowila, U.; Chackrewarthy, S.; de Silva, A.P.; Makaya, M.; Mizoue, T.; Kato, N.; Wickremasinghe, A.R.; de Silva, H.J.
BACKGROUND AND AIMS: Non-alcoholic fatty liver disease (NAFLD) is an emerging problem in the Asia-Pacific region. However, its prevalence and risk factors in Asian (especially South Asian) communities is poorly studied. In this study, the aim was to determine the community prevalence and risk factors for NAFLD among adults in an urban Sri Lankan population. METHODS: The study population consisted of 35-64-year-old adults, selected by stratified random sampling. NAFLD was diagnosed on established ultrasound criteria for fatty liver, safe alcohol consumption (< 14 units/week for men, < 7 units/week for females) and absence of hepatitis B and C markers. Blood pressure (BP) and anthropometric measurements were made, and fasting glucose, glycosylated hemoglobin, serum lipids, fasting serum insulin and serum alanine aminotransferase (ALT) were determined. RESULTS: Of the 2985 study participants, 974 (32.6%) had NAFLD (605 [62.1%] women, mean age 52.8 years [standard deviation, 7.3]). On multivariate analysis, obesity, acanthosis nigricans, insulin resistance, elevated diastolic BP, fasting plasma glucose, plasma triglycerides, and ALT twice the upper limit of the reference range or more were independently associated with NAFLD. CONCLUSION: The prevalence of NAFLD among adults in this urban Sri Lankan community is high and is strongly associated with constituent features of the metabolic syndrome.
Identifying the biting species in snakebite by clinical features: an epidemiological tool for community surveys
(Oxford University Press, 2006) Pathmeswaran, A.; Kasturiratne, A.; Fonseka, M.; Nandasena, S.; Lalloo, D.G.; de Silva, H.J.
The outcome of snakebite is related to the biting species but it is often difficult to identify the biting snake, particularly in community settings. We have developed a clinical scoring system suitable for use in epidemiological surveys, with the main aim of identifying the presumed biting species in those with systemic envenoming who require treatment. The score took into account ten features relating to bites of the five medically important snakes in Sri Lanka, and an algorithm was developed applying different weightings for each feature for different species. A systematically developed artificial data set was used to fine tune the score and to develop criteria for definitive identification. The score was prospectively validated using 134 species-confirmed snakebites. It correctly differentiated the bites caused by the three snakes that commonly cause major clinical problems (Russell's viper (RV), kraits and cobra) from other snakes (hump-nosed viper (HNV) and saw-scaled viper (SSV)) with 80% sensitivity and 100% specificity. For individual species, sensitivity and specificity were, respectively: cobra 76%, 99%; kraits 85%, 99%; and RV 70%, 99%. As anticipated, the score was insensitive in the identification of bites due to HNV and SSV

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