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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Item ELISA based evaluation of antibody response to Leishmania in a region endemic for cutaneous leishmaniasis(Oxford, 2022) Piyasiri, S.B.; Samaranayake, T.N.; Silva, H.; Manamperi, N.H.; Karunaweera, N.D.Aims: Leishmaniasis includes several clinical forms. While routine diagnosis of cutaneous leishmaniasis (CL) is by microscopy, an antibody response to CL has been reported in several recent studies. This study evaluated anti-leishmanial IgG antibody responses as a biomarker of active leishmaniasis and a measure of exposure to Leishmania. Methods and results: Sera from 50 untreated CL patients, 140 patients under treatment and 280 healthy individuals residing in endemic regions collected as part of an epidemiological survey, was analysed with an ELISA established in-house using receiver-operator-characteristic (ROC) curve at optimised cut-off value. The assay showed high performance as a diagnostic tool in identifying exposure in endemic individuals (sensitivity: 98%, specificity: 90.3%). All patients showed lower antibody levels over time since onset of lesion/s. Antibody levels were higher (p ˂ 0.01) and persisted for a longer period in untreated patients. In patients under treatment, the level of anti-IgG antibodies was negatively correlated with the total duration the patient had been on treatment. Conclusion: The anti-leishmanial IgG response in L. donovani induced CL is transient and is unlikely to confer protective immunity. Optimised serological assays may be useful in endemic settings for diagnosis and monitoring the treatment response in CL.Item Spatiotemporal distribution of cutaneous leishmaniasis in Sri Lanka and future case burden estimates(Public Library of Science, 2021) Karunaweera, N.D.; Senanayake, S.; Ginige, S.; Silva, H.; Manamperi, N.; Samaranayake, N.; Dewasurendra, R.; Karunanayake, P.; Gamage, D.; de Silva, N.; Senarath, U.; Zhou, G.BACKGROUND: Leishmaniasis is a neglected tropical vector-borne disease, which is on the rise in Sri Lanka. Spatiotemporal and risk factor analyses are useful for understanding transmission dynamics, spatial clustering and predicting future disease distribution and trends to facilitate effective infection control. METHODS: The nationwide clinically confirmed cutaneous leishmaniasis and climatic data were collected from 2001 to 2019. Hierarchical clustering and spatiotemporal cross-correlation analysis were used to measure the region-wide and local (between neighboring districts) synchrony of transmission. A mixed spatiotemporal regression-autoregression model was built to study the effects of climatic, neighboring-district dispersal, and infection carryover variables on leishmaniasis dynamics and spatial distribution. Same model without climatic variables was used to predict the future distribution and trends of leishmaniasis cases in Sri Lanka. RESULTS: A total of 19,361 clinically confirmed leishmaniasis cases have been reported in Sri Lanka from 2001-2019. There were three phases identified: low-transmission phase (2001-2010), parasite population buildup phase (2011-2017), and outbreak phase (2018-2019). Spatially, the districts were divided into three groups based on similarity in temporal dynamics. The global mean correlation among district incidence dynamics was 0.30 (95% CI 0.25-0.35), and the localized mean correlation between neighboring districts was 0.58 (95% CI 0.42-0.73). Risk analysis for the seven districts with the highest incidence rates indicated that precipitation, neighboring-district effect, and infection carryover effect exhibited significant correlation with district-level incidence dynamics. Model-predicted incidence dynamics and case distribution matched well with observed results, except for the outbreak in 2018. The model-predicted 2020 case number is about 5,400 cases, with intensified transmission and expansion of high-transmission area. The predicted case number will be 9115 in 2022 and 19212 in 2025. CONCLUSIONS: The drastic upsurge in leishmaniasis cases in Sri Lanka in the last few year was unprecedented and it was strongly linked to precipitation, high burden of localized infections and inter-district dispersal. Targeted interventions are urgently needed to arrest an uncontrollable disease spread.Item Tissue impression smears as a supplementary diagnostic method for histopathology in cutaneous leishmaniasis in Sri Lanka(American Society of Tropical Medicine and Hygiene, 2018) Manamperi, N.H.; de Silva, M.V.C.; Pathirana, N.; Abeyewickreme, W.; Karunaweera, N.D.Cutaneous leishmaniasis (CL) is diagnosed mainly by light microscopy of smears made using lesion material. Histopathology is usually done in atypical presentations or when lesion smears are negative. Tissue impression smears (TIS) made from skin biopsy specimens were compared with histopathology for the diagnosis of CL. Out of the 111 patients included, 83 (74.8%) were positive by either methods. The TIS was positive in 70.3% whereas histopathology was positive in 56.8% of patients. Tissue impression smears can be used as a supplementary diagnostic test that gives sensitive and rapid results when tissue biopsies are used as the source of lesion material for diagnosis of CL.Item Impact of vitamin A supplementation on health status and absenteeism of school children in Sri Lanka(HEC Press, Australia, 2007) Mahawithanage, S.T.C.; Kannangara, K.K.; Wickremasinghe, R.; Chandrika, U.G.; Jansz, E.R.; Karunaweera, N.D.; Wickremasinghe, A.R.The objective of this study was to determine the impact of Vitamin A supplementation on health status and absenteeism of school children. A randomized double blind placebo controlled trial over a period of 13 months was conducted in a rural area of Sri Lanka involving 613 school children attending Grades 1-5 (aged 5 to 13 years). Children were assigned to either 200,000 IU of Vitamin A (n=297) or placebo (n=316) once every 4 months. Socio-demographic data were obtained at baseline, and anthropometry and haemoglobin concentrations were assessed at baseline and post intervention. Serum vitamin A concentrations were assayed by HPLC in a subgroup of children (n=193) before administration of each dose. School absenteeism was recorded. The two groups of children were similar at baseline in all variables. The subgroup of children was comparable to the main study population. The prevalence of vitamin A deficiency (< 20 microg/dL) in the subgroup of children was 8.2%. Changes in anthropometric indices and haemoglobin concentrations were similar in the two groups. The major causes for absenteeism were non-health causes and supplemented children lost a fewer number of school days due to illness than placebo children (p=0.053). Vitamin A concentrations improved with each dose and the improvement was greater with better compliance. Vitamin A supplementation with 200,000 IU every 4 months over 13 months improved vitamin A status and school attendance but not anthropometric status of these children.Item A cost analysis of the use of the rapid, whole-blood, immunochromatographic P.f/P.v assay for the diagnosis of Plasmodium vivax malaria in a rural area of Sri Lanka(Academic Press, 2004) Fernando, S.D.; Karunaweera, N.D.; Fernando, W.P.; Attanayake, N.; Wickremasinghe, A.R.Between May 2001 and March 2002, a prospective study was conducted in a malaria-endemic area of Sri Lanka, to determine the cost implications of using the immunochromatographic P.f/P.v test to detect Plasmodium vivax infection. All consecutive subjects aged >5 years who presented with a history of fever were recruited. Each was checked for P. vivax infection by the standard microscopical examination of bloodsmears and by theimmunochromatographic test (ICT). The costs of diagnosis using each method and the sensitivity, specificity and predictive values of the ICT (with blood smear examination used as the 'gold standard') were estimated, the costs/case detected being simulated for different slide positivity 'rates' and ICT sensitivities. In the detection of P. vivax, the ICT had a sensitivity of 70% and a specificity of 99%. The costs of the ICT per subject investigated and per case detected were, respectively, approximately 14 and 20 times more than those of bloodsmear examination. The costs of the ICT per case detected would fall as the sensitivity of the test increased. The ICT gave relatively few false-positive results. The current, relatively high cost of the ICT is the most important barrier to its routine operational use in the diagnosis of malaria. The test is already useful, however, in specific situations