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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 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 The presence of strongyloidiasis and associated risk factors in patients undergoing treatment at the National Cancer Institute, Maharagama, Sri Lanka(Sri Lanka Medical Association, 2023) Weerasekera, C.J.; Menike, C.W.; Wimalasiri, U.; Wijerathna, T.; Jayathilake, D.C.C.; Somawardane, U.A.B.P.; Saravanamuttu, U.; Yoganathan, N.; Perera, N.; Gunathilaka, N.; de Silva, N.R.; Wickremasinghe, D.R.INTRODUCTION: Strongyloides stercoralis can cause severe disease in the immunocompromised. Without a proper gold-standard diagnostic technique, strongyloidiasis is scarcely studied both globally and locally. OBJECTIVES: We aimed to estimate the prevalence of strongyloidiasis among immunocompromised adult patients and to identify risk factors. METHODS: This study was carried out between February to October 2022. A faecal sample and 2 ml of venous blood were collected from consented patients. Direct faecal smear, agar plate, Harada-Mori and Charcoal cultures were performed on the faecal samples. Qualitative Polymerase Chain Reaction (PCR) was performed on selected faecal samples using S. stercoralis targeting ITS1 region. Strongyloides IgG ELISA was carried out on the serum samples using DRG Strongyloides IgG ELISA kit. RESULTS: Collectively, 144 patients (males = 68, females = 76) provided blood/faecal sample or both. Relevant to strongyloidiasis-associated symptoms, some patients had diarrhoea (n=12) and eosinophilia (n=11). Some of them (n=74) had occupational or recreational exposure to soil as potential risk factors. Overall, 24 patients were positive for strongyloidiasis from one or more diagnostic method (5 PCR and 19 ELISA). There were zero culture or direct smear positives. There was no significant association between disease positivity with either of the clinical features or risk factors. CONCLUSION: The prevalence of strongyloidiasis in patients with malignancies was 16.66%. Strongyloidiasis is existent in the immunocompromised in Sri Lanka even in the absence of suggestive clinical features or regular exposure to risk factors. Screening immunocompromised patients with sensitive techniques such as PCR for timely diagnosis and treatment is recommended.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 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 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 Lapses of professionalism occurring among Sri Lankan medical students: How should they be remediated?(Sri Lanka Medical Association., 2019) Ellawala, A.T.; Chandratilake, M.N.; de Silva, N.R.INTRODUCTION & OBJECTIVES: Early recognition and correction of lapses of professionalism occurring during 'the undergraduate period is vital. This study aimed to explore the lapses of professionalism occurring among local medical students and identify appropriate remedial measures. METHODS: The study was conducted in two phases. In Phase I, in-depth interviews and focus group discussions were conducted with medical teachers, clinicians, deans, students, nurses and patients (n= 129) to explore lapses they had witnessed. Conversations were audio-recorded, transcribed and analysed inductively. Description by multiple groups was considered an indicator of prevalence of a behaviour. In Phase II, a consensus conference with medical teachers, clinicians, deans and students (n=3 I), was conducted to achieve consensus on remediation strategies for identified lapses occurring as a first-time offence or a repeated behaviour pattern. Degree of consensus was based on modal distribution of responses. RESULTS: In Phase I, over 100 types of misconduct were described. The most common behaviours included, 'not doing allocated ward work', 'not contributing to group work' and 'several students examining a patient at the same time'. In Phase II, it was possible to achieve an acceptable level of agreement (50% or higher consensus) regarding remediation strategies for over 70% of the items, including almost all lapses identified as most common. Strategies ranged from 'ignore' to 'expulsion' and included measures such as discussion with peers, remedial work and counselling. CONCLUSION: Sri Lankan medical students exhibit a wide range of professionalism lapses of varying severity. The value of correcting such behaviour in a standardized manner is recognised.