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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 Spatial and seasonal analysis of human leptospirosis in the District of Gampaha, Sri Lanka(Sri Lankan Society for Microbiology, 2016) Denipitiya, D.T.H.; Chandrasekharan, V.; Abeyewickreme, W.; Viswakula, S.; Hapugoda, M.Leptospirosis is a zoonostic infectious disease, caused by a pathogenic species of the Genus Leptospira. In recent years, a markedly increased number of leptospirosis cases have been reported in the District of Gampaha, in the Western Province of Sri Lanka. Typically, the risk of the disease in the district is seasonal with a small spike occurs in March to May and a large spike occurs during October to December. Objectives of this study were to analyze spatial and seasonal patterns of human leptospirosis and to predict the leptospirosis epidemic trend in the District of Gampaha, Sri Lanka. All Divisional Secretariats (DS) of the district of Gampaha were selected for the study. Epidemiological data were obtained from the Regional Epidemiological Unit, Gampaha. The leptospirosis cases were georeferenced according to DS in where these cases were reported. The cumulative incidence and the fatality were calculated for each DS. Of the georeferenced data, highest mean (±S.E.) of number of leptospirosis cases (72.60 ±15.54) were observed from DS of Mirigama. The highest mean cumulative incidence (4.97±1.10) and case fatality rate (3.88±2.42) were observed from DS of Divulapitiya and Katana respectively. According to past 10 years data on leptospirosis, highest mean numbers of leptospirosis cases were reported in March (51.00±12.99) and November (56.80±8.27). A predictive model for clinically confirmed human leptospirosis was designed for the district by using TSA package of the statistical software R. This study provides an evidence base for reducing disease burden by improving the understanding of the dynamic patterns of the disease in the District of Gampaha, Sri Lanka.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 Evaluation of a case definition for leptospirosis diagnosis using serological assays(Sri Lanka Association for the Advancement of Science, 2013) Denipitiya, D.T.H.; Jiffriy, A.M.; Chandrasekharan, N.V.; Abeyewickreme, W.; Hapugoda, M.D.Item A Comparative study of molecular-based diagnostic assays for early definitive diagnosis of human leptospirosis(Sri Lanka Association for the Advancement of Science, 2013) Jiffriy, A.M.; Abeyewickreme, W.; Denipitiya, D.T.H.; Hapugoda, M.D.Item Detection of pathogenic Leptospira species in rat blood samples by molecular-based assays(University of Kelaniya, 2013) Denipitiya, D.T.H.; Chandrasekharan, N.V.; Abeyewickreme, W.; Hapugoda, M.D.Background: Leptospirosis is a worldwide zoonotic infection, caused by pathogenic species of the genus Leptospira. It was traditionally known as ‘rat fever’ in Sri Lanka, because rodents, especially rats, are considered to be the most important reservoirs or maintenance hosts of Leptospira. In 2012, the highest numbers of cases were reported in the District of Gampaha. The objective of this study is to detect pathogenic Leptospira species in rat blood samples by molecular based assays. Method: Rats (n=38) were trapped in a high risk area (Mirigama) in the District of Gampaha, from May 2012 to February 2013 by using live traps. Each rat was anesthetized by using diethyl ether and 2-3 ml sample of blood was collected from each rat. Blood samples collected from all rats were tested by molecular- based assays and a serological assay. Qualitative Polymerase Chain Reaction (PCR), real time PCR and Loop Mediated Isothermal Amplification (LAMP) were used as molecular-based assays which targetted conserved gene regions among pathogenic serovars of Leptospira species. Microscopic Agglutination Test (MAT), the Gold Standard assay for detection of anti Leptospira antibody was used as a serological assay. Results and Discussion: Of the 38 rat blood samples, molecular-based assays confirmed Leptospira infection in 5% (2/38), 16% (6/38) and 11% (4/38) by qualitative PCR, real time PCR and LAMP assay respectively. None of the samples was positive by MAT. After first infection, some Leptospira species live in the host animal as commensal bacteria. Therefore, host does not stimulate antibody production further and that may be below the detection level of the antibody by MAT. Conclusions: Results of molecular based assays showed that Leptospira are circulating among the rats tested in this study, although at the time of collection, their antibody levels were too low to detect by MAT, which had the lowest detection limit of 1:800.Item Risk factors associated with human leptospirosis in the District of Gampaha, Sri Lanka(University of Kelaniya, 2013) Denipitiya, D.T.H.; Athapaththu, M.; Chandrasekharan, N.V.; Abeyewickreme, W.; Hapugoda, M.D.Background & Objective: A large number of leptospirosis cases are recorded in Sri Lanka every year. Increased numbers of cases have been reported in the District of Gampaha in the recent past. The incidence of leptospirosis is often influenced by various socio-economic, occupational, environmental and other factors. To date, a study on potential risk factors has not been conducted in the District of Gampaha. The objective of this study is to identify risk factors involved in transmission of leptospirosis to humans in the District of Gampaha. Methods: Data were collected at the household level, using an interviewer-administered questionnaire and by inspecting the surrounding of laboratory confirmed leptospirosis patients (n=81) and non leptospirosis persons (n=117) during the period of June 2011 to June 2013. The risk factors in the questionnaire were divided into three broad categories: environmental, contact with animals and behavioral/occupational factors. Chi-square test (The SAS System for Windows 9.0) was used for comparison of data from different categories. Results and discussion: 95% of the leptospirosis patients were adult males (77/81) and they had a monthly income of Rs. 10,001-20,000 and 50% of them were agricultural and rental work labourers (40/81). In contrast, 56% of persons not infected with leptospirosis were adult females (66/117) and most of them (48%) were housewives or homemakers (56/117). Data on the type of premises were collected under three categories as poor, moderate and well constructed along with the land use type of the surrounding areas. There were significant statistical associations between the leptospirosis patient with the type of premises (, χ2=23.38, p=0.00), surrounding cleanliness of premises (χ2=45.05, p=0.00), sanitary facilities (χ2=11.66, p=0.00), waste disposal method (χ2=32.23, p=0.00) and age level of patients (χ2=21.07, p=0.00). No significant statistical associations were observed between recorded leptospirosis cases and vegetation coverage in surrounding area of premises (χ2=1.25, p>0.05), source of drinking water (χ2= 0.55, p>0.05) and numbers of persons in family (χ2=0.17, p>0.05). Conclusion: Identification of the potential risk factors would help understand the transmission dynamics of the disease and formulate public health interventions.Item Application of a Real Time Polymerase Chain Reaction (PCR) for Detection of Pathogenic Leptospira in Clinical Samples(University of Kelaniya, 2012) Denipitiya, D.T.H.; Jiffrey, A.M.; Abeyewickreme, W.; Wellawaththge, C.; Hapugoda, M.D.Leptospirosis, is a zoonotic disease with worldwide distribution, caused by pathogenic species of the genus Leptospira. It has the greatest impact on health in developing countries where it is often grossly under-recognized. Clinical features are similar to a range of other infectious diseases that occur in the same environmental and climatologic conditions. Therefore, laboratory confirmation is essential for proper management of leptospirosis patients. Molecular assays offer definitive laboratory confirmation of leptospirosis at the early phase of infection (1-5 days of fever) within a few hours. The objective of this study was to establish and evaluate potential use of a real time- PCR assay for early, definitive laboratory confirmation of leptospirosis patients. A SYBR green-based real time PCR assay targeting a 203 bp fragment on the secY gene which is conserved among pathogenic serovars of Leptospira was established using a reference DNA sample (Leptospira interrogans strain RGA). Analytical specificity of the assay was tested with the DNA from pathogenic and non-pathogenic Leptospira spp. and five other micro organisms. Analytical sensitivity of the assay was tested using serial dilutions of the reference sample. A panel of acute blood samples (n=150) collected during early phase of infection (1-5 days of fever) from leptospirosis suspected patients was used for evaluation of real time PCR vs qualitative PCR. The results show, real time PCR assay with high analytical specificity (100%) was established and the assay shows 100 times higher sensitivity over qualitative PCR assay (1.3 pg/ml). Real time PCR and qualitative PCR could diagnose current leptospirosis infection in 37.3% (56/150) and 19.3% (29/150) suspected patients respectively. These results indicate high sensitivity of real time PCR over qualitative PCR for diagnosis of leptospirosis patients. In conclusion, this study shows that real time PCR has the potential to facilitate rapid and sensitive diagnosis of acute leptospirosis during early phase of infection.Item Identification of cattle/buffalo and rats as reservoir animals of pathogenic Leptospires in the Gampaha district(Sri Lanka Association for the Advancement of Science, 2014) Denipitiya, D.T.H.; Chandrasekharan, N.V.; Abeyewickreme, W.; Hapugoda, M.D.Item Spatial and seasonal analysis of human leptospirosis in the District of Gampaha, Sri Lanka(University of Kelaniya, 2014) Denipitiya, D.T.H.; Abeyewickreme, W.; Hapugoda, M.D.; Chandrasekharan, N.V.Leptospirosis is a zoonostic infectious disease, caused by a pathogenic species of the genus Leptospira. In Sri Lanka, around 1500 human leptospirosis cases are reported annually. Typically, the risk of the disease is seasonal with a small spike occurs in March to May and a large spike occurs during October to December. Objective of this study was to analyze spatial and seasonal pattern of human leptospirosis in the District of Gampaha, Sri Lanka.