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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 Initial response to SARS-CoV-2 (COVID-19) outbreak in Sri Lanka; views of public health specialists through an International Health Regulations lens(Public Library of Science, 2023) Caldera, A.; Wickremasinghe, R.; Newby, G.; Perera, R.; Mendis, K.; Fernando, D.The COVID-19 pandemic affected Sri Lanka despite having developed an International Health Regulations (IHR) steering committee in 2016 and a national action plan for health security following the Joint External Evaluation in 2018. Many steps were taken to improve the disaster management skills of healthcare workers even before the COVID-19 outbreak. We interviewed seven public health specialists to obtain their views on the country's response to the pandemic. A thematic analysis was conducted, leading to the emergence of three major themes and seven subthemes. The major themes included health security preparedness; COVID-19 management; and effects of COVID-19. The subthemes were; preparedness prior to pandemic and gaps in the preparedness (under health security preparedness); dual burden for the curative sector, strategies to reduce transmission and barriers to managing COVID-19 (under COVID-19 management) and negative and positive effects of COVID-19 (under effects of COVID-19). When COVID-19 reached Sri Lanka, healthcare workers, border control authorities and those involved with infectious disease control were overwhelmed by the magnitude of the pandemic. Healthcare workers' hesitation to work amidst the pandemic due to fear of infection and possible transmission of infection to their families was a major issue; the demand for personal protective equipment by health workers when stocks were low was also a contributory factor. Lockdowns with curfew and quarantine at government regulated centers were implemented as necessary. Perceptions of the public including permitting healthcare workers to perform field public health services, logistical barriers and lack of human resources were a few of the barriers that were expressed. Some persons did not declare their symptoms, fearing that they would have to be quarantined. The pandemic severely affected the economy and Sri Lanka relied on donations and loans to overcome the situation. Pandemic also brought about innovative methods to maintain and upgrade health service provision. Individuals with non-communicable diseases received their regular medications through the post which reduced their risk of being infected by visiting hospitals. Improvement of laboratory services and quarantine services, a reduction of acute respiratory infections and diarrhoeal diseases, improved intersectoral coordination and public philanthropic response were other positive effects.Item Effect of daily stressors and collective efficacy on post-traumatic stress symptoms among internally displaced persons in post-war northern Sri Lanka(Cambridge University Press, 2023) Somasundaram, D.; Jayasuriya, R.; Perera, R.; Thamotharampillai, U.; Wickremasinghe, R.; Tay, A.K.BACKGROUND: Daily stressors have been shown to mediate the relationship of war trauma and trauma-related distress among refugees and internally displaced persons exposed to war and conflict. AIMS: To examine the extent to which the relationship between war-related trauma and mental distress was mediated by daily stressors and collective efficacy among internally displaced communities a decade after exposure to war. METHOD: In a cross-sectional study, we recruited a random sample of residents in villages severely affected by conflict in five districts in the Northern Province of Sri Lanka. Measures of war trauma, daily stressors, collective efficacy and post-traumatic stress symptoms (PTSS) were examined. Statistical analyses of the mediating and moderating effects of daily stressors were conducted using regression based methods. RESULTS: Daily stressors mediated the association of war trauma and PTSS, as both paths of the indirect effect, war trauma to daily stressors and daily stressors to PTSS, were significant. The predictive effect of war trauma on PTSS was positive and significant at moderate and high levels of daily stressors but not at low levels. Higher levels of neighbourhood informal social control, a component of collective efficacy, function as a protective factor to reduce effects of war trauma and daily stressors on mental distress in this population. CONCLUSIONS: Daily stressors are an important mediator in the well-established relationship between war exposure and traumatic stress among internally displaced persons, even a decade after the conflict. Mental health and psychosocial support programmes that aim to address mental distress among war-affected communities could reduce daily stressors and enhance collective efficacy in this context.Item Laboratory scale evaluation of the feasibility of locally found bladderworts as biological agents to control dengue vector, Aedes aegypti in Sri Lanka(BioMed Central, 2023) Gunathilaka, N.; Perera, R.; Amerasinghe, D.; Udayanga, L.BACKGROUND: The carnivorous genus Utricularia also includes aquatic species that have the potential to trap a wide range of prey, leading its death due to anoxia. However, the effectiveness of such an approach with carnivorous plants for vector control has not been evaluated in Sri Lanka. METHODS: Early instar (i & ii) and late instar (iii & iv) larvae of Aedes aegypti were exposed to locally found bladderwort (U. aurea Lour and Utricularia sp.). The experimental design was set with 10 larvae (both early and late instars separately) in 250 mL of water with bladderworts containing approximately 100 bladders in plant segments of both species, separately. Each treatment and control were repeated 50 times. The survival status of larvae was recorded daily until death or adult emergence. The larvae found whole or partially inside the bladders were attributed to direct predation. The Cox-regression model and Mantel-Cox log rank test were carried out to assess the survival probabilities of larvae in the presence of two bladderworts separately. RESULTS: The highest predation was observed when using early instar larvae in both U. aurea (97.8%) and Utricularia sp. (83.8%). The mortality caused due to predation by U. aurea was observed to be significantly higher according to the Mantel-Cox log-rank test (HR = 60.71, CI; 5.69-999.25, P = 0.004). The mortality rates of late instar stages of Ae. aegypti were observed to be lower in both U. aurea (82.6%) and Utricularia sp. (74.8%). Overall, the highest predation efficacy was detected from U. aurea (HR = 45.02; CI: 5.96-850.51, P = 0.017) even in late instar stages. The results suggested the cumulative predation in both plants on Ae. aegypti larvae was > 72%. CONCLUSIONS: Utricularia aurea is a competent predator of Ae. aegypti larvae. Further, it is recommended to evaluate the feasibility of this plant to be used in the field as a control intervention in integrated vector management programmes.Item Malaria control, elimination, and prevention as components of health security: A review(American Society of Tropical Medicine and Hygiene, 2022) Perera, R.; Wickremasinghe, R.; Newby, G.; Caldera, A.; Fernando, D.; Mendis, K.International travel, a major risk factor for imported malaria, has emerged as an important challenge in sustaining malaria elimination and prevention of its reestablishment. To make travel and trade safe, the WHO adopted the International Health Regulations (IHR) which provides a legal framework for the prevention, detection, and containment of public health risks at source. We conducted a systematic review to assess the relevance and the extent of implementation of IHR practices that can play a role in reducing malaria transmission. Selected studies addressed control, elimination, and prevention of reestablishment of malaria. Study themes focused on appraisal of surveillance and response, updating national policies to facilitate malaria control and elimination, travel as a risk factor for malaria and risk mitigation methods, vector control, transfusion malaria, competing interests, malaria in border areas, and other challenges posed by emerging communicable diseases on malaria control and elimination efforts. Review results indicate that malaria has not been prioritized as part of the IHR nor has the IHR focused on vector-borne diseases such as malaria. The IHR framework in its current format can be applied to malaria and other vector-borne diseases to strengthen surveillance and response, overcome challenges at borders, and improve data sharing-especially among countries moving toward elimination-but additional guidelines are required. Application of the IHR in countries in the malaria control phase may not be effective until the disease burden is brought down to elimination levels. Considering existing global elimination goals, the application of IHR for malaria should be urgently reviewed and included as part of the IHR.Item Reactive Case Detection (RACD) and foci investigation strategies in malaria control and elimination: a review(BioMed Central, 2020) Perera, R.; Caldera, A.; Wickremasinghe, A.R.BACKGROUND: Reactive case detection (RACD) and foci investigation are key strategies in malaria elimination and prevention of its re-establishment. They are a key part of surveillance that has been recommended by the World Health Organization (WHO) to be considered as a core intervention and as one of the three pillars of the Global Technical Strategy for Malaria 2016-2030. METHODS: A search using the key words "Reactive Case Detection", "RACD", "RCD" and "Malaria" was carried out in PubMed, Scopus, Taylor and Francis online databases for studies published until 31st July 2019. The inclusion criteria for selection of articles for review included (1) how RACD is implemented in each country; (2) challenges faced in RACD implementation; (3) suggestions on how the effectiveness of RACD process can be improved. RESULTS: 411 titles were identified, 41 full text articles were screened and 29 were found eligible for inclusion in the review. Published literature on RACD, and case and foci investigations has mostly assessed the process of the activity. Most studies have documented that the yield of positives in RACD has been highest in the index case's household and the immediate neighbourhood of the index case. Microscopy and RDTs are the common tests used in RACD. The guidelines for case and foci investigation, and RACD and PACD, are not universally adopted and are country-specific. Some of the limitations and challenges identified include lack of proper guidelines, logistic issues and problems with public compliance. CONCLUSIONS: Although there is no documented evidence that RACD is useful in malaria elimination settings, most authors have opined that RACD is necessary for malaria elimination. Lack of knowledge in the target populations, a target radius and how to carry out the RACD process is a major challenge in the decision-making process. KEYWORDS: 1-3-7 strategy; Foci investigation; Malaria control; Malaria elimination; Reactive case detection.Item Mitochondrial metabolic genes provide phylogeographic relationships of global collections of Aedes aegypti (Diptera: Culicidae)(Public Library of Science, 2020) Fernando, H.S.D.; Hapugoda, M.; Perera, R.; Black Iv, W.C.; de Silva, B.G.D.N.K.ABSTRACT: Phylogeographic relationships among global collections of the mosquito Aedes aegypti were evaluated using the mitochondrial Cytochrome C Oxidase 1 (CO1) and NADH dehydrogenase subunit 4 (ND4) genes including new sequences from Sri Lanka. Phylogeographic analysis estimated that Ae. aegypti arose as a species ~614 thousand years ago (kya) in the late Pleistocene. At 545 kya an "early" East African clade arose that continued to differentiate in East Africa, and eventually gave rise to three lineages one of which is distributed throughout all tropical and subtropical regions, a second that contains Southeast Asian/Sri Lankan mosquitoes and a third that contains mostly New World mosquitoes. West African collections were not represented in this early clade. The late clade continued to differentiate throughout Africa and gave rise to a lineage that spread globally. The most recent branches of the late clade are represented by South-East Asia and India/Pakistan collections. Analysis of migration rates suggests abundant gene flow between India/Pakistan and the rest of the world with the exception of Africa.Item Gene flow patterns among Aedes aegypti (Diptera: Culicidae) populations in Sri Lanka(MDPI AG, 2020) Fernando, H.S.D.; Hapugoda, M.; Perera, R.; Black Iv, W.C.; de Silva, B.G.D.N.K.ABSTRACT:In Sri Lanka, dengue is the most serious arboviral disease. Recent increases in dengue cases suggest a higher infection rate and spread of the disease to new areas. The present study explores gene flow patterns of Ae. aegypti, the main vector of dengue disease, among 10 collection sites including major ports and inland cities using variations at 11 microsatellite loci. Discriminant analysis of principal components (DAPC) and k-means clustering estimated eight genetic clusters. Analysis of Molecular Variance (AMOVA) estimated equal variances among cities and among collections in Colombo, Sri Lanka. Significant evidence, although weak, was detected for isolation by distance. Analysis of gene flow rates and directions using MIGRATE-n indicated that populations throughout the island served as a source of immigrants for Colombo with abundant gene flow among major commercial cities in Sri Lanka, which appear to receive migrant mosquitoes from throughout Sri Lanka. The observed patterns probably arise through human movement of Ae. aegypti during commerce from throughout Sri Lanka into Colombo increasing the risk of spread. The patterns uncovered in this study are significant for global health as Sri Lanka is situated along a key international shipping route. KEYWORDS: Aedes aegypti; Sri Lanka; gene flow patterns; population structure.Item First report of V1016G and S989P knockdown resistant (kdr) mutations in pyrethroid-resistant Sri Lankan Aedes aegypti mosquitoes(BioMed Central, 2018) Fernando, S.D.; Hapugoda, M.; Perera, R.; Saavedra-Rodriguez, K.; Black WC 4th; de Silva, N.K.; ; ;BACKGROUND: Dengue is a serious arboviral disease in Sri Lanka with a large number of dengue fever (DF) cases every year. Control of the primary vector Aedes aegypti depends upon larval habitat source reduction and insecticide application. However, increases in the number of reported cases suggest the inefficiency of current control strategies and the possibility of resistance to currently used insecticides. Early detection of mutations in the voltage-gated sodium channel (vgsc) gene that confer knockdown resistance (kdr) to pyrethroid insecticides is important in resistance management in vector populations. RESULTS: Resistance to pyrethroid insecticides was detected in the three populations studied. Polymerase chain reaction was used to detect the presence of two kdr mutations F1534C and V1016G. During this process a S989P mutation was also detected in pyrethroid-resistant Ae. aegypti populations. These mutations were found to be widespread and frequent in the collections studied. CONCLUSIONS: To our knowledge, this study reveals for the first time the presence of V1016G and S989P mutant alleles in the vgsc of Sri Lankan Ae. aegypti populations. The spread of the mutant alleles throughout the country poses a threat of increased resistance to pyrethroids. Long-term insecticide applications and indiscriminate use of pyrethroids has led to the evolution of resistance. More strategic and diverse strategies, including novel insecticides with new modes of action and community participation, should be engaged for Ae. aegypti control.Item Incidence and risk factors for non-alcoholic fatty liver disease: A 7-year follow-up study among urban, adult Sri Lankans(Blackwell Munksgaard, 2017) Niriella, M.A.; Pathmeswaran, A.; de Silva, S.T.; Kasturiratne, A.; Perera, R.; Subasinghe, C.E.; Kodisinghe, K.; Piyaratna, C.; Rishikesawan, V.; Dassanayake, A.S.; de Silva, A.P.; Wickremasinghe, R.; Takeuchi, F.; Kato, N.; de Silva, H.J.BACKGROUND: This study investigated incidence and risk factors for NAFLD among an adult cohort with 7-year follow-up. METHODS: The study population (age-stratified random sampling, Ragama MOH area) was screened initially in 2007 (aged 35-64 years) and re-evaluated in 2014 (aged 42-71 years). On both occasions assessed by structured interview, anthropometric measurements, liver ultrasound, biochemical and serological tests. NAFLD was diagnosed on ultrasound criteria, safe alcohol consumption and absence of hepatitis B/C markers. Non-NAFLD controls did not have any ultrasound criteria for NAFLD. An updated case-control genetic association study for 10 selected genetic variants and NAFLD was also performed. RESULTS: Out of 2985 of the original cohort, 2148 (72.0%) attended follow-up (1238 [57.6%] women; mean-age 59.2 [SD-7.6] years) in 2014, when 1320 (61.5%) were deemed NAFLD subjects. Out of 778 who initially did not have NAFLD and were not heavy drinkers throughout follow-up, 338 (43.4%) (221 [65.4%] women, mean-age 57.8 [SD-8.0] years) had developed NAFLD after 7-years (annual incidence-6.2%). Central obesity (OR=3.82 [95%-CI 2.09-6.99]), waist increase >5% (OR=2.46 [95%-CI 1.20-5.05]) overweight (OR=3.26 [95%-CI 1.90-5.60]), weight gain 5%-10% (OR=5.70 [95%-CI 2.61-12.47]), weight gain >10% (OR=16.94 [95%-CI 6.88-41.73]), raised plasma triglycerides (OR=1.96 [95%-CI 1.16-3.29]) and diabetes (OR=2.14 [95%-CI 1.13-4.06]), independently predicted the development of incident NAFLD in multivariate analysis. The updated genetic association study (1362-cases, 392-controls) showed replicated association (P=.045, 1-tailed) with NAFLD at a candidate locus: PNPLA3 (rs738409). CONCLUSIONS: In this community cohort study, the annual incidence of NAFLD was 6.2%. Incident NAFLD was associated with general and central obesity, raised triglycerides and diabetes, and showed a tendency of association with PNPLA3 gene polymorphisms.Item A journey through history, religion, mythology and evolution(Sri Lanka College of Microbiologists, 2015) Perera, R.Abstract available