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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 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 A preliminary survey for filarial parasites among dogs and cats in mahawewa, puttalam and their vector identification(Elsevier, 2022) Nimalrathna, S.; Mallwarachchi, C.; Chandrasena, T.G.A.N.; de Silva, N.; Kimber, M.; de Silva, N.R.; Harischandra, H.PURPOSE This study investigated the prevalence of zoonotic filarial parasites within the canine and feline population in Mahawewa, Puttalam, and their vectors based on a brugian filariasis positive human case reported to the Anti-filariasis Campaign in January 2021.METHODS & MATERIALS All reachable dogs and cats, both stray and domestic, within a 500m radius of the index human case of brugian filariasis were screened for microfilaria using Giemsa stained thick blood smears prepared from capillary blood, obtained from an ear-lobe prick. Mosquito collection was done using a dog-baited trap, two window traps and a B.G. Sentinel trap from the same study site and identified using morphological keys. The head and the thorax regions of randomly selected mosquito specimens were dissected for morphological identification of larval filaria parasites via microscopy. RESULTS A total of nine dogs and three cats were surveyed, of which seven dogs and one cat had filarial infections. All the infected animals harbored B.malayi microfilariae, while four dogs and one cat were co-infected with Dirofilaria repens and two dogs with an unidentified species. A total of 119 mosquitoes were caught and identified by taxonomic keys using a dog-baited trap, two window traps and a B.G. Sentinel trap from the study site. Dissection of heads and thoraces of randomly selected 12 Mansonia annulifera, 18 Mansonia indiana 20 Mansonia uniformis and 8 Culex spp. revealed filarial larvae in M.annulifera (n=4, 33.33%), M. indiana (n=14, 77.78%), M. uniformis (n=10, 50.00%) and Culex spp.(n=5, 62.5%) via microscopy. CONCLUSION M.indiana was incriminated as a potential vector of filarial parasites for the first time in Sri Lanka. Preliminary evidence generated indicate a high prevalence of B.malayi and D.repens among dogs and cats in Mahawewa, Puttalam with an abundance of mosquito vectors mostly of Mansonia and Culex spp. This warrants further studies with a larger sample size and molecular identification of the filarial larvae within mosquito and animal samples, especially as re-emergence of brugian filariasis in humans is being reported after four decades of quiescence, and a zoonotic brugian parasite has been detected over the recent past, raising a concern from a one health perspective.Item Regulation of the medical profession in Sri Lanka: reform is urgently needed(Sri Lanka Medical Association, 2019) de Silva, N.; de Silva, H.No abstract availableItem Acute Dermato-Lymphangio-Adenitis Following Administration of Infliximab for Crohn's Disease.(American College of Gastroenterology, 2019) Liyanage, I.K.; Niriella, M.A.; de Silva, A.P.; de Silva, N.; de Silva, H.J.Tumor necrosis factor-α inhibitor (TNF-α) is frequently used for Crohn's disease and other autoimmune conditions. Increased risk of infection is an accepted adverse effect of TNF-α, and routine screening for potential infections are carried out before initiation of therapy. We report the case of a patient who developed a localized painful swelling near the injection site, which was diagnosed as acute dermato-lymphangio-adenitis due to filarial infection. This adds to the limited number of case reports on parasitic complications following TNF-α therapyItem Reassessment of the prevalence of soil-transmitted helminth infections in Sri Lanka to enable a more focused control programme: a cross-sectional national school survey with spatial modelling(Elsevier, 2019) Ediriweera, D.S.; Gunawardena, S.; Gunawardena, N.K.; Iddawela, D.; Kannathasan, S.; Murugananthan, A.; Yahathugoda, C.; Pathmeswaran, A.; Diggle, P. J.; de Silva, N.BACKGROUND:In Sri Lanka, deworming programmes for soil-transmitted helminth infections became an integral part of school health in the 1960s, whereas routine antenatal deworming with mebendazole started in the 1980s. A 2003 national soil-transmitted helminth survey done among schoolchildren found an overall prevalence of 6·9%. In our study, we aimed to reassess the national prevalence of soil-transmitted helminth infections to enable implementation of a more focused control programme that targets smaller administrative areas at risk of continued transmission.METHODS:We did a cross-sectional, school-based, national survey using multistage stratified cluster sampling, covering all nine provinces as well as populations at high risk of soil-transmitted helminth infections living in urban slums and in plantation-sector communities. Our study population was children aged 5-7 years attending state schools. Faecal samples were collected and analysed with duplicate modified Kato-Katz smears. We modelled the risk of soil-transmitted helminth infection using generalised linear mixed-effects models, and we developed prevalence maps to enable informed decision making at the smallest health administrative level in the country.FINDINGS:Between Jan 23 and May 9, 2017, we recruited 5946 children from 130 schools; 4276 (71·9%) children provided a faecal sample for examination. National prevalence of soil-transmitted helminth infection was 0·97% (95% CI 0·63-1·48) among primary schoolchildren. Prevalence in the high-risk communities surveyed was higher than national prevalence: 2·73% (0·75-6·87) in urban slum communities and 9·02% (4·29-18·0) in plantation sector communities. Our prevalence maps showed that the lowest-level health administrative regions could be categorised into low risk (prevalence <1%), high risk (prevalence >10%), or intermediate risk (1-10%) areas.INTERPRETATION:Our survey findings indicate that the national prevalence of soil-transmitted helminth infection has continued to decline in Sri Lanka. On the basis of WHO guidelines, we recommend discontinuation of routine deworming in low-risk areas, continuation of annual deworming in high-risk areas, and deworming once every 2 years in intermediate-risk areas, for at least 4 years.FUNDING:Task Force for Global Health and WHO.Item Helminth infections: soil-transmitted helminth infections and schistosomiasis(Oxford University Press and World Bank, 2006) Hotez, P. J.; Bundy, D.A.P.; Beegle, K.; Brooker, S.; Drake, L.; de Silva, N.; Montresor, A.; Engels, D.; Jukes, M.; Chitsulo, L.; Chow, J.; Laxminarayan, R.; Michaud, C. M.; Bethony, J.; Correa-Oliviera, R.; Xiao Shu-Hua; Fenwick, A.; Savioli, L.Item Evaluation of rapid extraction and isothermal amplification techniques for the detection of Leishmania donovani DNA from skin lesions of suspected cases at the point of need in Sri Lanka(BioMed Central, 2018) Gunaratna, G.; Manamperi, A.; Bohiken-Fascher, S.; Wickremasinghe, R.; Gunawardena, K.; Yapa, B.; Pathiana, N.; Pathirana, H.; de Silva, N.; Sooriyaarachchi, M.; Deerasinghe, T.; Mondal, D.; Ranasinghe, S.; Abd EI Wahed, A.BACKGROUND: Leishmaniasis is a disease caused by vector-borne protozoans. In Sri Lanka, the cutaneous form of the disease is predominant, which is usually diagnosed using Giemsa-stained slit skin smear examination and by histology. However, the sensitivity of slit skin smears and histology are reportedly low. Moreover, facilities for the highly sensitive polymerase chain reaction (PCR) are available only in a few highly-equipped parasitology laboratories. Therefore, there is a need for low cost, sensitive and specific screening tests for diagnosis of leishmaniasis at the point of need. RESULTS: In this study, a mobile suitcase laboratory applying novel extraction (SpeedXtract) and isothermal amplification and detection (recombinase polymerase amplification assay, RPA) methods were evaluated for the diagnosis of cutaneous leishmaniasis in Sri Lanka. First, the developed assay was applied to three different sample types (punch biopsy, slit skin smears and fine needle aspirates) at a local hospital. The results showed that the 2 mm punch biopsy sample produced the best exponential amplification curve and early fluorescence signal in the RPA assay. Secondly, punch biopsies were collected from 150 suspected cutaneous leishmaniasis cases and screened with SpeedXtract/RPA, RNAlater/PCR and ATL buffer/PCR, in addition to Giemsa-stained slit skin smears. Fifty-seven samples were negative in all detection methods. In total 93 samples were positive with assay sensitivities of 65.5% (SpeedXtract/RPA), 63.4% (RNAlater/PCR) and 92.4% (ATL buffer/PCR). The Giemsa-stained slit skin smear delivered the worst clinical sensitivity (32.2%). CONCLUSIONS: The SpeedXtract/RPA method under field conditions took 35 min, while almost 8 h were needed to finalize the extraction and detection by PCR in the laboratory. The SpeedXtract/RPA method produced similar sensitivity to samples preserved in RNAlater and subjected to PCR amplification, but both were less sensitive than ATL-preserved samples subjected to PCR amplification. There is a need for a standardization of sample collection and nucleic acid extraction methods.Item Isothermal Diagnostic Assays for monitoring single nucleotide polymorphisms in Necator americanus associated with Benzimidazole drug resistance(Public Library of Science, 2016) Rashwan, N.; Bourguinat, C.; Keller, K.; Gunawardena, N.K.; de Silva, N.; Prichard, R.BACKGROUND: Soil-transmitted helminths (STHs) are the most prevalent intestinal helminths of humans, and a major cause of morbidity in tropical and subtropical countries. The benzimidazole (BZ) drugs albendazole (ABZ) and mebendazole (MBZ) are used for treatment of human STH infections and this use is increasing dramatically with massive drug donations. Frequent and prolonged use of these drugs could lead to the emergence of anthelmintic resistance as has occurred in nematodes of livestock. Previous molecular assays for putative resistance mutations have been based mainly on PCR amplification and sequencing. However, these techniques are complicated and time consuming and not suitable for resource-constrained situations. A simple, rapid and sensitive genotyping method is required to monitor for possible developing resistance to BZ drugs. METHODS: To address this problem, single nucleotide polymorphism (SNP) detection assays were developed based on the Smart amplification method (SmartAmp2) to target codons 167, 198, and 200 in the β-tubulin isotype 1 gene for the hookworm Necator americanus. FINDINGS: Diagnostic assays were developed and applied to analyze hookworm samples by both SmartAmp2 and conventional sequencing methods and the results showed high concordance. Additionally, fecal samples spiked with N. americanus larvae were assessed and the results showed that the Aac polymerase used has high tolerance to inhibitors in fecal samples. CONCLUSION: The N. americanus SmartAmp2 SNP detection assay is a new genotyping tool that is rapid, sensitive, highly specific and efficient with the potential to be used as a field tool for monitoring SNPs associated with BZ resistance. However, further validation on large numbers of field samples is required.Item World Health Organization Estimates of the Global and Regional Disease Burden of 11 Foodborne Parasitic Diseases, 2010: A Data Synthesis(Public Library of Science, 2015) Torgerson, P.R.; Devleesschauwer, B.; Praet, N.; Speybroeck, N.; Willingham, A.L.; Kasuga, F.; Rokni, M.B.; Zhou, X.N.; Fèvre, E.M.; Sripa, B.; Gargouri, N.; Fürst, T.; Budke, C.M.; Carabin, H.; Kirk, M.D.; Angulo, F.J.; Havelaar, A.; de Silva, N.BACKGROUND: Foodborne diseases are globally important, resulting in considerable morbidity and mortality. Parasitic diseases often result in high burdens of disease in low and middle income countries and are frequently transmitted to humans via contaminated food. This study presents the first estimates of the global and regional human disease burden of 10 helminth diseases and toxoplasmosis that may be attributed to contaminated food. METHODS AND FINDINGS: Data were abstracted from 16 systematic reviews or similar studies published between 2010 and 2015; from 5 disease data bases accessed in 2015; and from 79 reports, 73 of which have been published since 2000, 4 published between 1995 and 2000 and 2 published in 1986 and 1981. These included reports from national surveillance systems, journal articles, and national estimates of foodborne diseases. These data were used to estimate the number of infections, sequelae, deaths, and Disability Adjusted Life Years (DALYs), by age and region for 2010. These parasitic diseases, resulted in 48.4 million cases (95% Uncertainty intervals [UI] of 43.4-79.0 million) and 59,724 (95% UI 48,017-83,616) deaths annually resulting in 8.78 million (95% UI 7.62-12.51 million) DALYs. We estimated that 48% (95% UI 38%-56%) of cases of these parasitic diseases were foodborne, resulting in 76% (95% UI 65%-81%) of the DALYs attributable to these diseases. Overall, foodborne parasitic disease, excluding enteric protozoa, caused an estimated 23.2 million (95% UI 18.2-38.1 million) cases and 45,927 (95% UI 34,763-59,933) deaths annually resulting in an estimated 6.64 million (95% UI 5.61-8.41 million) DALYs. Foodborne Ascaris infection (12.3 million cases, 95% UI 8.29-22.0 million) and foodborne toxoplasmosis (10.3 million cases, 95% UI 7.40-14.9 million) were the most common foodborne parasitic diseases. Human cysticercosis with 2.78 million DALYs (95% UI 2.14-3.61 million), foodborne trematodosis with 2.02 million DALYs (95% UI 1.65-2.48 million) and foodborne toxoplasmosis with 825,000 DALYs (95% UI 561,000-1.26 million) resulted in the highest burdens in terms of DALYs, mainly due to years lived with disability. Foodborne enteric protozoa, reported elsewhere, resulted in an additional 67.2 million illnesses or 492,000 DALYs. Major limitations of our study include often substantial data gaps that had to be filled by imputation and suffer from the uncertainties that surround such models. Due to resource limitations it was also not possible to consider all potentially foodborne parasites (for example Trypanosoma cruzi). CONCLUSIONS: Parasites are frequently transmitted to humans through contaminated food. These estimates represent an important step forward in understanding the impact of foodborne diseases globally and regionally. The disease burden due to most foodborne parasites is highly focal and results in significant morbidity and mortality among vulnerable populations.Item Cochrane Reviews on deworming and the right to a healthy, worm-free life(Public Library of Science, 2015) de Silva, N.; Ahmed, B.N.; Casapia, M.; de Silva, H.J.; Gyapong, J.; Malecela, M.; Pathmeswaran, A.