Browsing by Author "Somaratne, P."

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Evaluation of two immunodiagnostic tests for early rapid diagnosis of leptospirosis in Sri Lanka: a preliminary study
(BioMed Central, 2015) Eugene, E.J.; Handunnetti, S.M.; Wickramasinghe, S.A.; Kalugalage, T.L.; Rodrigo, C.; Wickremesinghe, H.; Dikmadugoda, N.; Somaratne, P.; de Silva, H.J.; Rajapakse, S.
BACKGROUND: Leptospirosis is often treated based on clinical diagnosis. There is a need for rapid laboratory diagnosis for this condition. The aim of this study was to compare the diagnostic accuracy of two rapid IgM based immunodiagnostic assays with the microscopic agglutination test (MAT), in acute leptospirosis infection. METHODS: MAT, IgM based immunochromatographic test (Leptocheck-WB) and IgM ELISA were performed using acute sera of patients clinically suspected to have leptospirosis (n = 83). Bayesian latent class modeling was used to compare the accuracy of these tests. RESULTS: Percentage positivity for MAT, Leptocheck-WB, and IgM ELISA were 48.1, 55.3, and 45.7 % respectively. Bayesian latent class modeling showed a combined positivity rate of leptospirosis of 44.7 %. The sensitivity of MAT, Leptocheck-WB and IgM ELISA were 91.4, 95 and 81.1 %, and specificity were 86.7, 76.4 and 83.1 %, respectively. CONCLUSIONS: Leptocheck-WB has high sensitivity, and, because it is quick and easy to perform, would be a good screening test for acute leptospirosis infection. IgM ELISA has good specificity, and is comparable with MAT; given that it is easier to perform and more widely available than MAT, it would be a more appropriate confirmatory test for use in hospitals with limited access to a specialized laboratory.
Low serum total nitrite and nitrate levels in severe leptospirosis
(BioMed Central, 2013) Kalugalage, T.; Rodrigo, C.; Vithanage, T.; Somaratne, P.; de Silva, H.J.; Handunnetti, S.; Rajapakse, S.
BACKGROUND: The relationship between inducible nitric oxide synthatase activity and disease severity in leptospirosis is unclear. Nitric oxide is converted to nitrites and nitrates, thus nitrite and nitrate levels (NOx) in serum are considered surrogate markers for nitric oxide. NOx are excreted through the kidneys, and elimination is diminished in renal impairment. We assessed the correlation of NOx with disease severity in patients with leptospirosis, compared with healthy controls and non-leptospirosis fever patients. METHODS: All patients admitted over a two-month period to the National Hospital, Colombo, Sri Lanka with a clinical picture suggestive ofleptospirosis were included. Leptospirosis was confirmed by the microscopic agglutination test (titre ≥ 400). Severe leptospirosis was defined by the presence of two or more of the following criteria: jaundice (bilirubin> 51.3 μmol/l), oliguria (urine output < 400 ml/day), serum creatinine> 133 μmol/l or blood urea > 25.5 mmol/l, or the presence of organ dysfunction. Non-leptospirosis fever patients and healthy volunteers were used as control groups. NOx levels were measured using a modified Griess reaction. RESULTS: Forty patients were confirmed as having leptospirosis and 26 of them had severe disease. NOx levels were significantly higher in confirmed leptospirosis patients compared to healthy controls, MAT equivocal patients and non-leptospirosis fever patients (p<0.001). NOx concentrations were also significantly higher in patients with severe compared to mild leptospirosis (p<0.001). Once NOx levels were corrected for renal function, by using the ratio NOx/creatinine, NOx levels were actually significantly lower in patients with severe disease compared to other patients, and values were similar to those of healthy controls. CONCLUSIONS: We postulate that high NOx levels may be protective against severe leptospirosis, and that finding low NOx levels (when corrected for renal function) in patients with leptospirosis may predict the development of severe disease and organ dysfunction. © 2013 Kalugalage et al.; licensee BioMed Central Ltd.
A pilot study on comparison of rapid immunodiagnostics for confirmation of leptospirosis
(Sri Lanka Medical Association, 2012) Eugene, E.J.; Wickramasinghe, S.A.; Kalugalage, T.L.; Rodrigo, C.; Wickremesinghe, H.; Dikmadugoda, N.; Somaratne, P.; de Silva, H.J.; Rajapakse, S.; Handunnetti, S.M.
INTRODUCTION: In Sri Lanka, leptospirosis is mostly diagnosed on clinical grounds. Serological confirmation is not obtainable during the acute stage of the illness. There is a need for rapid immunodiagnostics for confirmation of leptospirosis. Two immunodiagnostic assays, ie: enzyme linkedimmnnosorbent assay (ELISA) and immunochromatographic technique Leptocheck-WB test (LCT) areused to detect leptospira specific IgM antibodies which are prevalent in early stages of acute infections. AIMS: To compare the efficacy of these two rapid immunodiagnostic assays with the microscopic agglutination assay (MAT) to determine their applicability. Methods: A set of sera (n=83) collected in 2010 for which MAT titres were available was used to perform IgMELISAandLCT. RESULTS: Positivity for LCT and IgM ELISA were 55.4% and 48.2% respectively, and both assays detected acute infection by day 3 of the illness. MAT> 400 was used as the reference standard. For LCT, the overall sensitivity, specificity, accuracy, PPV and NPV (86.5%, 75.0%, 79.6%, 69.6% and 89.4% respectively) were higher compared to the respective values for IgM ELISA (50.0%, 62.3%, 57.1%, 50.0%, 62.3%). The highest of these values were observed during the first week for LCT and during the second week for IgM ELISA. The highest agreement was observed between LCT and MAT>400 (p=0.568) and there was a good agreement between LCT and IgM ELISA (p=0.520). CONCLUSIONS: The high sensitivity and specificity, ease of use, and non-requirement of specialized skills and equipment makes LCT a good choice for screening, while IgM ELISA is an appropriate test for confirming acute leptopsirosis.
Serum nitrite levels in Sri Lankan patients with leptospirosis
(Elsevier, Singapore, 2012) Gunaratna, R.I.; Handunnetti, S.M.; Bulathsinghalage, M.R.C.; Somaratne, P.; Jayanaga, A.; de Silva, H.J.; Rajapakse, S.
OBJECTIVE: To determine whether blood nitrite levels are elevated in patients with leptospirosis.METHODS: Male patients fulfilling clinical and epidemiological criteria for a diagnosis of leptospirosis were recruited. Those with MAT titre of ≤400 together with those seroconverting to a titer of ≤200 were included in the analysis. Serum nitrite levels were measured in these patients and age, sex matched healthy controls. RESULTS: Patients from 3 hospitals (n=75) were screened during a 3 month period from 28th June to 3rd September 2009, of whom 20 were eligible for the study. Serum nitrite levels were found to be significantly higher in patients with acute leptospirosis [n=20, (0.359±0.229)μ M] compared to controls [(n=13,(0.216±0.051)μ M](P=0.014). A significant correlation was also observed between the MAT titre and the day of illness (r = 0.547; P<0.0001). CONCLUSIONS: Serum nitrite levels are higher in patients with acute leptospirosis compared to age and sex matched controls. No correlation could be assessed with severity of illness, as sample size was inadequate to determine this