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 A diagnostic model for Leptospirosis for use in resource limited settings(Sri Lanka Medical Association, 2015) Rajapakse, S.; Weeratunga, P.N.; Rodrigo, C.; Sriharan, S.; Niloofa, M.J.R.; Fernando, N.; de Silva, H.J.; Karunanayake, L.; Premawansa, S.INTRODUCTION AND OBJECTIVES: Leptospirosis is a zoonotic infection with significant morbidity and mortality. In this prospective study, we attempted to develop a model for diagnosis of leptospirosis. METHOD: Data was extracted from a prospective multicentre study. All patients with a suspected diagnosis of leptospirosis based on the WHO surveillance criteria were recruited. A derivation cohort and a validation cohort were selected. Positive MAT was used as the gold standard and significant associations in the derivation cohort were selected for construction of a multivariate regression model. Adjusted odds ratios were extracted for significant variables. ROC curves were generated. RESULTS: A total of 592 patients were included 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 possible source of leptospirosis (OR=2.878;95% Cl=1.527-5.425;p=0.001), serum creatinine>150u.mol/L (OR =2.742; 95% CN1.474-5.101; p=0.001), neutrophil differential percentage (on day 3 of illness) > 82.8% of total WBC count (OR 2.063; 95% Cl = 1.109 - 3.837; p =0.022), serum bilirubin > 27 U/L (OR = 1.767;95%CI 0.968 - 3.226; p=0.050) and platelet count (on day 3 of illness)< 85,000/mm3 (OR=2.350; 95%CI=1.281 -4.313;p=0.006). The Nagelkerke R2 was 0.654. ROC analysis demonstrated a diagnostic model score >14 to have a sensitivity of 80% and a specificity of 60% in the diagnosis of leptospirosis against MAT as the gold standard. CONCLUSION: This proposed diagnostic model for diagnosis of leptospirosis is of potential value to clinicians treating acute febrile illness in areas with limited diagnostic facilities.Item Clinical and laboratory associations of severity in a Sri Lankan cohort of patients with serologically confirmed Leptospirosis - a prospective study(Sri Lanka Medical Association, 2015) Rajapakse, S.; Weeratunga, P.N.; Rodrigo, C.; Sriharan, S.; Niloofa, M.J.R.; Fernando, N.; de Silva, H.J.; Karunanayake, L.; Premawansa, S.; Handunnetti, S.INTRODUCTION AND OBJECTIVES: Leptospirosis is a zoonotic infection of significant morbidity and mortality. This study elucidates the markers of severity in a cohort of Sri Lankan patients with serologically confirmed leptospirosis. METHOD: Prospectively recruited patients presenting to three healthcare institutions in the Western province of Sri Lanka with serological confirmation of leptospirosis with the microscopic agglutination test were included. Data regarding the socio-deruographic profile, clinical presentation, complications and biochemical parameters were recorded. Univariate associations and subsequent multivariate logistic regression models were constructed with severity as the dependent variable. RESULTS: A total of 232 patients were included. Majority were male (86.6%). Severe disease was noted in 68.5%. Significant clinical associations of severe disease included fever > 38.8°C on presentation (p=0.008), age>40 yrs; (p = 0.033), muscle tenderness (p=0.04) and tachycardia on admission (p=0.05). Laboratory associations of severe disease were highest white cell count > 12,350/mm3 (p<0.001) and < 7900/mm3 (p = 0.009), highest neutrophil percentage > 84% {p < 0.001). Hemoglobin > 11.2g/dL (p<0.001) and < 10.2 (p<0.001), packed cell volume > 33.8% (p <0.001) and <29.8% (p <0.001), lowest platelet count <63,500/mm3 (p = 0.01), highest ALT > 70 IU/L {p = 0.02) and hyponatremia with sodium <131mEq/L (p=0.004) On multivariate analysis, PCV < 29.8 (P = 0.011; adjusted OR =3.750; Cl = 1.394 - 10.423), ALT >70 P =0.044 adjusted OR =2.639; Cl =1.028-6.774 and hyponatremia< 131 (p=0.019 adjusted OR=6.413; Cl=1.353 -30.388) were found to be independent associations of severe disease. CONCLUSION: Severity associations were demonstrated with both clinical and laboratory parameters.Item Evidence of leptospira and Hanta virus co-infections amongst patients hospitalised for leptospirosis-like illness(Sri Lanka College of Microbiologists, 2003) Sunil-Chandra, N.P.; Premaratna, R.; Somasiri, D.A.D.H.; de Silva, H.J.INTRODUCTION: Hantavirus infection and leptospirosis are zoonoses with similar epidemiology and disease forms. Both infections spread to humans from infected rodents. OBJECTIVES: To assess the frequency and clinical manifestations of hantavirus infection in patients hospitalised with leptospirosis-like illness. METHODS: Two groups of patients admitted with leptospirosis-like illness to the University Medical Unit, Ragama, were investigated for evidence of both hantavirus infection and leptospirosis. Demographic data were obtained prospectively from 39 patients (Group 1) (M:F=34:5, mean age 35 yrs) (1996-1997), and retrospectively from 35 patients (Group 2) (M:F=34:1, mean age 30 yrs) who had been admitted to the unit during the previous year (1995-1996). Paired sera from 31/39 patients in Group 1 were tested for IgM antibodies and a single serum sample from 24/35 patients in Group 2 was tested for IgG antibodies to Hantaan and Puumala serotypes of hantavirus using m-capture ELISA separately. The same panels of sera were also tested for the presence of anti-leptospiral IgM (in Group 1) and IgG (in Group 2) antibodies. RESULTS: In Group 1, 9/31 and 25/31 sera were positive for hantavirus and leptospira IgM antibodies respectively. 5/31 were negative for both antibodies. 8/9 hantavirus IgM positive sera were also positive for leptospira IgM antibodies indicating co-infection. 1/9 showed seroconversion to hantavirus only, and 17/31 showed seroconversion to leptospira only. Based on the reactivity of hantavirus IgM antibody positive sera against recombinant hantavirus neucleocapsid proteins by m-capture ELISA, 5/9 had Puumala-like and 2/9 had Hantaan-like predominant antigenic specificities. The other 2/9 showed specificity to Puumala only. In Group 2, 10/24 and 23/24 sera were positive for hantavirus and leptospira IgG antibodies respectively. 1/24 was negative for both. All 10 hantavirus IgG antibody positive sera were also positive for leptospira IgG antibodies. 7 of 10 had specificity to Puumala, 2 of 10 had predominantly Puumala and 1 had predominantly Hantaan antigen specificity. Male predominance, occupations related to agriculture and farming, and exposure to rodents were risk factors associated with leptospirosis-like illness. Anorexia, nausea, and myalgia were features common to all patients More patients with hantavirus infection or with or without leptospirosis than those with leptospira infections only had hepatic (78% Vs. 17%) and renal (56% Vs. 17%) involvement during the course of their illness. Conclusions: In our study, hantavirus infection or co-infection with leptospirosis occurred in about one third of patients with leptospirosis-like illness admitted to hospital. The majority had hepatic and renal involvement. Three hantavirus serotypes, Puumala, Puumala-like and Hantaan-like, were detected.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.