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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 Risk factor analysis of cutaneous leishmaniasis in Sri Lanka through a nationwide survey(American Society of Tropical Medicine and Hygiene, 2024) Dewasurendra, R.; Samaranayake, N.; Silva, H.; Manamperi, N.; Senerath, U.; Senanayake, S.; De Silva, N.; Karunanayake, P.; Zhou, G.; Karunaweera, N.Leishmaniasis in Sri Lanka was first reported in the early 1990s. Cutaneous leishmaniasis (CL) cases have markedly increased in recent years, demanding due attention from health authorities. The spatial distribution of CL is not homogeneous. This case-control study investigated factors that may contribute to this heterogeneous distribution through a nationwide study. Information on sociodemographic, economic, and environmental characteristics was collected from study participants (cases, n = 303; controls, n = 2,762). All individuals were followed up for 3 years, and signs of CL or associated complications were recorded. Differences in possible risk factors between cases and controls were analyzed. Individuals <18 years old, electricity supply, spending >2 hours outdoors, visiting jungles/water bodies, and living near CL patients were identified as risk factors. Household members of 1.3% of cases, 2.3% of controls residing within a perimeter of 500 m from a patient, and 0.8% of controls living beyond 2 km from a case developed CL. Thus, CL in Sri Lanka appears intertwined with living environment and host behavior. Common environmental factors may be responsible for the higher risk of CL in individuals living in close proximity to CL patients. This may at least partly explain the clustering of CL cases in selected areas of the country.Item The use of recombinant K39, KMP11, and crude antigen-based indirect ELISA as a serological diagnostic tool and a measure of exposure for cutaneous leishmaniasis in Sri Lanka(Springer International, 2024) Karunathilake, C.; Alles, N.; Dewasurendra, R.; Weerasinghe, I.; Chandrasiri, N.; Piyasiri, S.B.; Samaranayake, N.; Silva, H.; Manamperi, N.; Karunaweera, N.Cutaneous leishmaniasis (CL) in Sri Lanka is caused by Leishmania donovani, a parasite widely known to cause visceral leishmaniasis. Despite the fact that CL is not generally believed to elicit serological immune responses, recent studies show the presence of antibody responses against this atypical form of CL. This study assesses the potential of using recombinant K39 (rK39), KMP11, and crude parasite antigen-based indirect ELISAs as serological diagnostic tools and measures of exposure for CL in Sri Lanka. The study used serum samples from confirmed CL patients (n = 266) and apparently healthy individuals from endemic settings (n = 411). Serum samples from individuals residing in non-endemic areas were used as negative controls. In-house indirect ELISAs were optimized and validated for recombinant antigens. Previously validated crude parasite extract-based indirect ELISA was performed for comparison. The statistical analyses were performed using SPSS v26.0. The rK39 (sensitivity = 71.2%, specificity = 64%) and KMP11 (sensitivity = 79.2%, specificity = 71.4%) based indirect ELISA were shown to be less suitable for the diagnosis of CL, while crude parasite extract-based indirect ELISA (sensitivity = 82.4%, specificity = 85.7%) might be a better method of diagnosis. All 03 ELISAs seemed to be good methods as measures of exposure since correlations were observed between the seropositivity of all 03 ELISAs (rK39: p = 0.037, KMP11: p = 0.007, CrudeAg: p = 0.000) with provincial case incidences. The findings will be important in identifying the disease hotspots in order to design the control measures for CL induced by L. donovani in Sri Lanka.Item Unfolded protein response pathway in leishmaniasis: A review(Wiley, 2023) Edirisinghe, N.M.; Manamperi, N.H.; Wanasinghe, V.S.; Karunaweera, N.Alteration in the physiological state of the endoplasmic reticulum (ER) leads to the specific response known as unfolded protein response (UPR) or ER stress response. The UPR is driven by three sensor proteins, namely: Inositol-Requiring Enzyme 1, Protein Kinase RNA-like ER kinase and Activating Transcription Factor 6 to restore ER homeostasis. Pathogenic infection can initiate UPR activation; some pathogens can subvert the UPR to promote their survival and replication. Many intracellular pathogens, including Leishmania, can interact and hijack ER for their survival and replication, triggering ER stress and subsequently ER stress response. This review aims to provide a comprehensive overview of the ER stress response in infections with the Leishmania species.Item Assessment of knowledge and perceptions on leishmaniasis: An island-wide study in Sri Lanka(Public Library of Science, 2022) Dewasurendra, R.; Silva, H.; Samaranayake, N.; Manamperi, N.; de Silva, N.; Karunanayake, P.; Senarath, U.; Senanayake, S.; Zhou, G.; Karunaweera, N.Cutaneous leishmaniasis (CL) is a notifiable disease in Sri Lanka with increasing case numbers reported from every part of the country. In addition to disease treatment and vector control measures, knowledge and perceptions in a community are key contributors to a successful intervention program. An island-wide survey was carried out to assess the knowledge and perceptions regarding CL across the island, with 252 confirmed CL cases and 2,608 controls. Data was collected by trained personnel, using a pre-tested Case Reporting Form (CRF). Although the percentage who referred to CL by its correct name was low (1.4%), majority stated that it is a fly induced skin disease (79.1%). Knowledge on the symptoms, curability and the name of the vector was high in these communities, but specific knowledge on vector breeding places, biting times and preventive methods were poor. The patients were more knowledgeable when compared to the controls. Differences in the level of knowledge could be identified according to the level of education of the participants as well as across the different areas of the country. The main source of information was through the healthcare system, but the involvement of media in educating the communities on the disease was minimal. While this study population was unaccustomed to the use of repellants or sprays, the use of bed nets was high (77.7% of the participants) in this study population. Although misconceptions and incorrect practices are rare in Sri Lankan communities, promoting health education programs which may improve disease awareness and knowledge on vector and its control will further strengthen the control and prevention strategies.Item Importance of private health sector in malaria surveillance: a case study in Nuwara-Eliya district, Sri Lanka(Sri Lanka College of Microbiologists, 2002) Kusumawathie, P.H.D.; Wickremasinghe, A.R.; Karunaweera, N.OBJECTIVE: To determine the Utilization of public and private health facilities by suspected malaria cases in Divisional Director of Health Services (DDHS) area Hanguranketha in Nuwara-eliya district (from July 2000 to June 2001). DESIGN, SETTING AND METHODS: Two state hospitals, DH Rikillagaskada and RH Gonagantenna were selected as public health facilities. Seven clinics at Rikillagaskada and Gonagantenna in which government medical officers engaged in private practice after duty hours were selected as private health facilities. The number of cases blood filmed for malaria at public facilities was obtained from hospital records. Data for the private sector was obtained using a pre designed form. Reporting from the private sector was done on a monthly basis. RESULTS: Among 572 cases blood filmed at government hospitals, 22 were positive for P.vfvax. In the private sector. 634 cases of suspected malaria were reported and treated on clinical grounds. During the study period, 40 P.vivax and 65 P.falciparum cases were detected by examining 1270 blood films collected by Active Case Detection and Special Malaria Clinics, conducted in the villages with risk of malaria transmission within the study area. Of the microscopically confirmed malaria cases, 15.4% of P.falciparum infections were resistant to chloroquine. Investigation of malaria cases revealed 66.7% of cases were indigenous while 33.3% were imported. If the Slide Positive Rate (SPR) of the government facilities is applied to the data of the private sector, 610 cases would have been given chloroquine without actually having malaria. CONCLUSIONS: According to this study, 52.57% of suspected malaria cases had sought treatment at private health facilities. Incorporating the private health sector in malaria surveillance would be helpful in correct treatment and control of malaria in malarious areas. Unnecessary anti malarial therapy should be reduced by provision of laboratory facilities at private health centers. ACKNOWLEDGEMENTS: Assistance provided by the Provincial Director Health Services, Central Province and Deputy Provincial Director Health Services, Kandy, and the Director Anti-Malaria Campaign is acknowledged.Item Malarial vectors in an irrigated rice cultivation area in southern Sri Lanka(Oxford University Press, 2005) Premasiri, D.A.; Wickremasinghe, A.R.; Premasiri, D.S.; Karunaweera, N.Entomological surveys were carried out from March 1998 to December 1999 to study the prevalence, distribution and abundance of malarial vectors in relation to selected environmental factors and potential mosquito breeding sites in irrigation channels in 15 villages in the Lunugamvehera Irrigation and Settlement Project, a malaria-endemic area of southern Sri Lanka. Mosquito collections were made at monthly intervals using four sampling methods. Thirteen anopheline species were collected. Following monsoonal rains, anopheline breeding took place primarily in rainwater accumulations. During the inter-monsoonal period, pools formed in the irrigation system, semi-permanent pools formed as a result of rainfall and permanent ground pools were the major breeding sites of anophelines. Very little anopheline breeding took place within the irrigation channels. Amongst the seven anopheline species collected from human dwellings, Anopheles subpictus was the most prevalent, followed by A. culicifacies; together these two species comprised more than 99% of the indoor resting population. The number of days of rain was an important macro-epidemiological factor influencing the density of malarial vectors. There was no consistent trend between the amount of water released or the number of days of water release from the reservoir and the outdoor or indoor resting densities of anophelines.