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 Incidental diagnosis of strongyloidiasis in a patient with hepatic metastasis(Sri Lankan Society for Microbiology, 2023) Weerasekera, C.J.; Menike, C.W.; Anpahalan, J.P.; Senevirathne, S.A.A.; Perera, N.; de Silva, N.R.; Wickremasinghe, D.R.Strongyloides stercoralis is a soil-transmitted helminth infecting humans that can cause hyperinfection and disseminated disease in the immunocompromised host. This case report describes a 56-year-old patient, diagnosed with hepatic metastasis, who was screened for strongyloidiasis by faecal culture. The agar plate culture became positive on the third day of incubation, demonstrating characteristic tracks and yielding rhabditiform larvae. The charcoal and Harada-Mori cultures were negative. The patient was treated with albendazole for 7 days but declined further follow up.Item Lymphatic filariases and soil-transmitted helminthiases in Sri Lanka: the challenge of eliminating residual pockets of transmission(The Royal Society, 2023) Chandrasena, T.G.A.N.; Gunaratna, I.E.; Ediriweera, D.; de Silva, N.R.Sri Lanka has successfully met the challenge of controlling both lymphatic filariasis (LF) and soil-transmitted helminthiases (STH) as public health problems. The primary public health strategy for combatting both conditions has been preventive chemotherapy. The national programme for the elimination of LF implemented five annual rounds of mass chemotherapy in the endemic districts from 2002 to 2006 using a combination of diethylcarbamazine and albendazole. The overall microfilaria rate declined from 0.21% in 2001 before the mass chemotherapy, to 0.06% in 2016, at declaration of elimination of LF as a public health problem by the World Health Organization. Currently Sri Lanka is in the phase of post-validation surveillance. Achieving control of STH has been more difficult. Mass deworming programmes have been implemented for nearly a century, and national-level surveys reported prevalence rates declining from 6.9% in 2003 to 1% in 2017. However, neither of these infections has been completely eliminated. A situation analysis indicates continued transmission of both among high-risk communities. This paper explores the reasons for persistence of transmission of both LF and STH in residual pockets and the measures that are required to achieve long-term control, or perhaps even interrupt transmission in Sri Lanka. This article is part of the theme issue 'Challenges and opportunities in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs'.Item Ocular trematodiasis in children, Sri Lanka(National Center for Infectious Diseases, 2023) Mallawarachchi, C.H.; Dissanayake, M.M.; Hendavitharana, S.R.; Senanayake, S.; Gunathilaka, N.; Chandrasena, T.G.A.N.; Yahathugoda, T.C.; Wickramasinghe, S.; de Silva, N.R.Using histopathology and phylogenetic analysis of the internal transcribed spacer 2 gene, we found >2 distinct trematode species that caused ocular trematode infections in children in Sri Lanka. Collaborations between clinicians and parasitologists and community awareness of water-related contamination hazards will promote diagnosis, control, and prevention of ocular trematode infections.Item Molecular characterization of a reemergent Brugia malayi parasite in Sri Lanka, suggestive of a novel strain(Hindawi Pub. Co., 2021) Mallawarachchi, C.H.; Chandrasena, T.G.A.N.; Withanage, G.P.; Premaratna, R.; Mallawarachchi, S.M.N.S.M.; Gunawardene, Y.I.N.S.; Dasanayake, R.S.; Gunarathna, D.; de Silva, N.R.ABSTRACT: Sri Lanka achieved elimination status for lymphatic filariasis in 2016; still, the disease remains a potential public health issue. The present study is aimed at identifying a subperiodic Brugia sp. parasite which has reemerged in Sri Lanka after four decades via molecular-based analysis. Polymerase chain reaction performed with pan-filarial primers specific for the internal transcribed spacer region-2 (ITS-2) of the rDNA of Brugia filarial parasites isolated from human, canine, and feline blood samples yielded a 615 bp band establishing the species identity as Brugia malayi. Comparison of the ITS2 sequences of the reemerged B. malayi isolates with GenBank sequences revealed a higher sequence homology with B. pahangi than B. malayi with similar phylogenetic evidence. However, the mean interspecies Kimura-2-parameter pairwise divergence between the generated Brugia sequences with B. malayi and B. pahangi was less than 3%. During the analysis of parsimony sites of the new ITS2 sequences, substitutions at A36T, A296G, T373A, and G482A made the sequences different from both B. pahangi and B. malayi suggesting the possibility of a new genetic variant or a hybrid strain of B. malayi and B. pahangi. Mosquito dissections and xenomonitoring identified M. uniformis and M. annulifera as vectors of this novel strain of B. malayi circulating among cats, dogs, and humans in Sri Lanka.Item Lymphatic filariasis in the Southeast Asian region; status and control options.(CABI Publishing, 2020) Chandrasena, T.G.A.N.; Premaratna, R.; Mallawarachchi, C.H.; Gunaratna, D.G.A.M.; de Silva, N.R.ABSTRACT: The Global Program to Eliminate Lymphatic Filariasis (GPELF) was launched in year 2000 by the World Health Organization (WHO) with the goal set for elimination by 2020. Over half the global disease burden lies in the Southeast Asian region (SEAR). The preventive chemotherapy (PC) programme has been initiated in all the WHO SEAR member states with varying levels of progress. Maldives, Sri Lanka and Thailand have achieved the goal of elimination as a public health problem (EPHP) within the stipulated period with Bangladesh working towards validation in 2021. Both Sri Lanka and Thailand are continuing with post-validation surveillance combined with selective treatment, striving for zero transmission in-parallel with the morbidity management and disability prevention program (MMDP). Timor-Leste appears close to reaching critical transmission thresholds with 100% coverage and triple therapy in the last round of PC. Data on MMDP activities are insufficient to comment on reaching EPHP status. PC coverage and country reports indicate ongoing transmission in Nepal, Myanmar, Indonesia and India requiring further rounds of PC. The PELF has made considerable progress in the SEAR towards elimination but there still remain significant transmission and disease burden in the highly populated countries in SEAR.Item Progress in the prevention and control of schistosomiasis and soil-transmitted helminthiasis(Societa Italiana di Medicina Tropicale, 2002) Albonico, M.; Engels, D.; Montresor, A.; Cromptons, D.W.T.; de Silva, N.R.; Savioli, L.ABSTRACT: In the last two decades important progress have been made in the understanding the epidemiology and the disease burden of schistosomiasis and soil-transmitted nematodes infection. In addition, practical tools for disease control have been developed and a strategy for the prevention and control of morbidy of schistosomaisis and soil-transmitted nematodes infection has been endorsed by the World Health Organization. This paper presents the recent progress in the prevention and control of these infections: the estimates of chronic and subtle morbidity in high risk groups and the evidence that these chronic and severe sequelae of infections can be reversed by appropriate treatment; the use of anthelminthic drugs during pregnancy and lactation; the relevance to control morbidity due to these infections also in pre-school children; the efficacy of anthelminthic drugs and the possible threat of drug resistance; price, quality and accessibility of treatment by delivering drugs through the school system and ways of reaching also non enrolled school-age children. Finally, the strategy, targets and recommendations of the World Health Organization for the control of schistosomiasis and soil-transmitted nematodes infection are described.Item An epidemiological model to aid decision-making for COVID-19 control in Sri Lanka(Public Library of Science, 2020) Ediriweera, D.S.; de Silva, N.R.; Malavige, G.N.; de Silva, H.J.BACKGROUND: Sri Lanka diagnosed its first local case of COVID-19 on 11 March 2020. The government acted swiftly to contain transmission, with extensive public health measures. At the end of 30 days, Sri Lanka had 197 cases, 54 recovered and 7 deaths; a staged relaxing of the lockdown is now underway. This paper proposes a theoretical basis for estimating the limits within which transmission should be constrained in order to ensure that the case load remains within the capacity of Sri Lanka's health system. METHODS: We used the Susceptible, Infected, Recovered (SIR) model to explore the number of new infections and estimate ICU bed requirement at different levels of R0 values after lifting lockdown restrictions. We developed a web-based application that enables visualization of cases and ICU bed requirements with time, with adjustable parameters that include: population at risk; number of identified and recovered cases; percentage identified; infectious period; R0 or doubling time; percentage critically ill; available ICU beds; duration of ICU stay; and uncertainty of projection. RESULTS: The three-day moving average of the caseload suggested two waves of transmission from Day 0 to 17 (R0 = 3.32, 95% CI 1.85-5.41) and from Day 18-30 (R = 1.25, 95%CI: 0.93-1.63). We estimate that if there are 156 active cases with 91 recovered at the time of lifting lockdown restrictions, and R increases to 1.5 (doubling time 19 days), under the standard parameters for Sri Lanka, the ICU bed capacity of 300 is likely to be saturated by about 100 days, signaled by 18 new infections (95% CI 15-22) on Day 14 after lifting lockdown restrictions. CONCLUSION: Our model suggests that to ensure that the case load remains within the available capacity of the health system after lifting lockdown restrictions, transmission should not exceed R = 1.5. This model and the web-based application may be useful in other low and middle income countries which have similar constraints on health resources.Item Biochemical and histopathological changes in Wistar Rats after consumption of boiled and un-boiled water from high and low disease prevalent areas for Chronic Kidney Disease of Unknown Etiology (CKDu) in North Central Province (NCP) and Its comparison with Low disease prevalent Colombo, Sri Lanka(BioMed Central,, 2020) Thammitiyagodage, M.G.; de Silva, N.R.; Rathnayake, C.; Karunakaran, R.; Wgss, K.; Gunatillka, M.M.; Ekanayaka, N.; Galhena, B.P.; Thabrew, M.I.BACKGROUND: Chronic Kidney Disease of unknown etiology (CKDu) is prevalent in North Central Province (NCP) of Sri Lanka. Consumption of un-boiled dug well water has been identified as one of the causative factors. This in-vivo study was performed to investigate some of the suspected factors associated with the pathogenesis of CKDu mediated via ground water. METHOD: Rats were given water, collected from high and low disease prevalent areas from the NCP of Sri Lanka and the results compared with those obtained from previously identified low disease prevalent area; Colombo. Blood Urea Nitrogen, creatinine, urinary microalbumin:creatinine ratio together with ALT and AST levels were analyzed and results were compared using one-way ANOVA and paired t-Test. Histopathology was analyzed using non-parametric method. RESULTS: Rats that ingested water from New Town Medirigiriya (NTM) from high disease prevalent NCP reported significantly elevated microalbumin:creatinine ratios compared to other water sources after 8 months, whilst boiled water from NTM had been able to significantly reduce it. Histopathological findings after the 14 months experimental period revealed significantly high tubular lesion index in rats that ingested water from NCP compared to Colombo. Rats that ingested water from high disease prevalent Divuldamana (DD) from NCP showed the highest kidney lesion index though the fluoride content was relatively low in this area compared to other water sources from high disease prevalent NCP. Rats that ingested boiled and un-boiled water from NTM also developed severe lesions whilst the group from Colombo reported the lowest. Low disease prevalent area from NCP, Huruluwewa (HW) also reported elevated liver enzymes and altered renal histopathology. Association of Na+:Ca2+ ratio in the disease progression was not reflected by the current study. Compared to Colombo, high fluoride, calcium and sodium contents were observed in water from high disease prevalent areas. All the water samples were negative for heavy metals. CONCLUSIONS: Though Fluoride is a known kidney toxic agent it cannot be the sole reason for CKDu in NCP, Sri Lanka. Various toxic elements present in NCP water may contribute to different grade of kidney and liver lesions in Wistar rats. KEYWORDS: BUN; CKDu; Microalbumin:creatinine; NCP.Item The Diversity of Human Dirofilariasis in Western Sri Lanka(Hindawi Pub. Co, 2019) Chandrasena, T.G.A.N.; Premaratna, R.; Mallawaarachchi, C.H.; Gunawardena, N.K.; Gunathilaka, P.A.D.H.N.; Abeyewickrama, W.Y.; de Silva, N.R.BACKGROUND:Human dirofilariasis is an emerging zoonosis in many countries. Dirofilariasis caused by Dirofilaria repens may present with diverse clinical manifestations in humans due to aberrant localization of worm lesions causing diagnostic dilemmas. The aim of this retrospective study was to describe and update the demography and clinical spectrum of human dirofilariasis in western Sri Lanka. Nematode or nematode fragments isolated from excision biopsies that were confirmed as D. repens at the Department of Parasitology, Faculty of Medicine, University of Kelaniya, Sri Lanka, between 2012 and 2018 were included. Data on age, gender, and clinical details were obtained from case files. Identity of worms was established by morphometry and cuticle characteristics on wet-mount preparation. Specimens from unusual case presentations were further analyzed by PCR with specific primers for internal transcribed spacer region 2 (ITS2) of the ribosomal DNA. RESULTS:Sixteen nematode specimens isolated from subconjunctiva (n=2), subcutaneous (n=13) and intramuscular (n=1) locations were identified as D. repens by morphometry (average length 11.5 cm) and the characteristic longitudinal striations on cuticle visualized by microscopy. The age distribution of cases ranged from 1 to 65 years with a mean of 21.5. Females were more frequently affected (n=10, 62.5%) and worm locations were commonest in the orbital region (5/16) and scrotum (3/16). Imaging techniques were of use in detecting infections in deeper tissue levels. PCR analysis of DNA extracted from a worm in an intramuscular granuloma of the temporal region elicited the expected band at 484bp for D. repens. CONCLUSIONS: Human dirofilariasis is on an upward trend in incidence. Imaging techniques were of use in clinical diagnosis and molecular speciation in establishing the species identity in unusual case presentations. We suggest a more conservative approach in the management of human dirofilariasis and recommend a one health approach for control.Item The soil-transmitted helminths in Sri Lanka: a review of the recent literature(Sri Lankan Society for Microbiology, 2018) de Silva, N.R.The major soil-transmitted helminth (STH) infections caused by Ascaris lumbricoides, Trichuris trichiura and Necator americanus have been recognized as endemic in Sri Lanka for over a century. Although prevalence rates have declined drastically over this period because of mass deworming programmes and improved housing, these infections are still found in high risk communities with poor access to sanitation. The available scientific literature published on STH infections in Sri Lanka from around the year 2000 onwards is reviewed here in three broad areas: prevalence of STH infections and factors affecting transmission, impact of control activities on prevalence and drug resistance, and the impact of STH infections on the health of infected individuals. In conclusion, an overview of the current control strategy adopted by the Ministry of Health in Sri Lanka is presented.