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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 Distribution and seasonal variation of malaria vectors in the Mannar and Jaffna Districts; an entomological investigation during the phase of prevention of re-establishment of malaria in Sri Lanka(Springer Link, 2024) Jude, J.; Gunathilaka, N.; Wijerathna, T.; Fernando, D.; Wickremasinghe, R.; Abeyewickreme, W.Sri Lanka has been declared “malaria-free” since 2016. The presence vectors and the cent establishment of new vectors are key challenges. This study documents the distribution of malaria vectors in previously high malaria endemic areas in Sri Lanka. Three locations were selected in Mannar and Jaffna districts. Entomological surveillance was carried out during January 2019 to January 2020 in both districts using cattle baited net (CBNT), hand collection (HC), and larval collection. The variation of mosquito abundance with selected climatic variables were evaluated using Pearson’s correlation. A total of 44,526 anophelines belonging to 12 species was encountered from both districts. The CBNT was the most productive technique that represented 78.65% (n = 35,022) of the total collection. Anopheles subpictus was the predominant species among adult collections in both districts, while in larval surveys, An. stephensi (60.1%; n = 2963) and An. varuna (40.9%; n = 1026) were observed in Jaffna and Mannar districts, respectively. The adult density indicated significantly strong positive correlations to the rainfall (r = 0.619, P < 0.05) and humidity (r = 0.524, P < 0.05) in both Jaffna and Mannar (rainfall: r = 0.553, P < 0.05; humidity: r = 0.553, P < 0.05). The number of larvae was not directly correlated with climatic variables. The present study reports the presence of An. culicifacies, An. subpictus and An. stephensi. Considering the fact that imported malaria cases are reported across the country the fact that there is an entomological risk to transmit malaria locally is a challenge. This warrants the continuous monitoring of vector population and seasonal variation, especially in previous malaria endemic regions.Item Approach to study the efficacy and safety of new complementary and alternative medicine formulations: Lesson during COVID-19 from Sri Lanka(Wolters Kluwer - Medknow, 2023) Pilapitiya, S.; Jayasinghe, S.; Silva, A.; Wickremasinghe, R.; Paranagama, P.; de Silva, J.; Lekamwasam, S.; Kularatne, S.A.M.; Wanigasuriya, K.; Kaluthota, S.; Sumathipala, S.; Rathnnasooriya, C.; Siribaddana, S.COVID-19 affected Sri Lanka from early 2020, a time of considerable ignorance accompanied by wide media coverage of a devastating epidemic in Italy and Europe. Many were attracted to complementary and alternative medicine (CAM) or traditional medicine (TM) in this desperate situation. Several preparations were claimed to be effective against COVID-19 globally. Dammika Bandara Syrup© was one such preparation promoted for preventing and treating SARS-CoV-2 infection. It was based on bees' honey, pericarp and mace of Myristica fragrans (nutmeg), the seed of Foeniculum vulgare and fresh rhizome of Zingiber officinale, all believed to have anti-viral properties. Following an unpublished clinical study claiming efficacy, Dammika Bandara Syrup© gained wide media publicity and political patronage. The producer claimed of Goddess Kali revealing the formula added an anthropological, cultural, and religious complexity to the issue. The demand for the product increased rapidly as a debate raged both in public and in the parliament on utilizing such products in combating COVID-19. The Department of Ayurveda, which is statutorily responsible for regulating CAM/TM had to respond to the situation. The legislation to regulate such indigenous medicinal products was weak, and the crisis deepened as thousands converged to the production facility, defying mobility restrictions introduced to control COVID-19. This led to the Ministry of Health requesting academics to form a team and conduct a clinical trial to prove its efficacy. This paper outlines the process and issues faced during the regulatory approval for the trial in a polarized political environment. Some health professionals accused the researchers of bowing to political pressure and questioned the scientific justification for the trial. However, the team considered this as an opportunity to streamline a path for research into CAM/TM therapies in situations such as COVID-19. Several processes were identified and addressed, such as the provisional registration of CAM preparations, assessing the potential efficacy of a CAM product, confirmation of authenticity and safety, standardization and supervision of production respecting cultural identities, obtaining approval for human use, choice of comparators, and ethical issues. We believe the study has helped set standards and a benchmark for CAM and TM research in Sri Lanka.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 Comparative analysis of the larvicidal activity of temephos (EC50) and novaluaron (EC10) to control Anopheles stephensi in Sri Lanka(Elsevier, 2023) Jude, J.; Gunathilaka, N.; Udayanga, L.; Fernando, D.; Premarathne, P.; Wickremasinghe, R.; Abeyewickreme, W.Background: Anopheles stephensi was first recorded in the coastal area of Mannar District, Sri Lanka, in December 2016. Since then, this vector has been isolated from other districts in the Northern and Eastern Provinces of Sri Lanka. Chemical control is the main arm of vector control that can be used to reduce the vector densities within a short period. Thus, the present study aimed at evaluating the efficacy of using selected insecticides for the control of An. stephensi larvae. Method: The third and fourth instar larval stages of An. stephensi (F2 generation) of field mosquitoes that were caught using cattle baited net trap collections from Columbuthurai, Kurunagar, and Navanthurai areas in Jaffna District, Sri Lanka, were obtained from the laboratory colony established at Jaffna. Batches of 100 larvae were taken for experiments and introduced separately to a concentration series of temephos and novaluron (0.04-400 ppm). A control test was also performed at each setup without introducing insecticides. The mortality rates of An. stephensi larvae exposed to different concentrations of larvicides were recorded at 1, 24 and 48-h intervals. The experiment was replicated five times at individual concentrations for each selected chemical. Data were analyzed using the General Linear Model (GLM) and Probit analysis. Results: The highest mortality rate (100%) at a 1-h exposure period was observed from temephos at >100 ppm. The mortality rates varied significantly for different concentrations and larvicides (p < 0.05). At 24-h of the exposure period, the 100% mortality of An. stephensi larvae were observed from both temephos and novaluron even at 0.04 ppm. Conclusion: Both temephos and novaluron reported 100% mortality rates in An. stephensi larvae at 1-h and 24-h exposure periods. Based on the findings, temephos and novaluron can be recommended as effective larvicides for chemical-based control of An. stephensi in Jaffna, Sri Lanka. Further, it is recommended to conduct a field-based study, where habitat types and water quality are highly heterogeneous and may affect the residual activity.Item Biology, bionomics and life-table studies of Anopheles stephensi (Diptera: Culicidae) in Sri Lanka and estimating the vectorial potential using mathematical approximations(Elsevier, 2023) Jude, J.; Gunathilaka, N.; Udayanaga, L.; Fernando, D.; Premarathne, P.; Wickremasinghe, R.; Abeyewickreme, W.Background: Anopheles stephensi is an invasive mosquito in Sri Lanka that can potentially transmit malaria. The transmission intensity is linked with biology, bionomic and behavioral aspects of a vector that are associated with the Vectorial Capacity (VC). However, the influence of larval conditions eventually affects the vectorial potential of An. stephensi are not well understood. Methods: A colony of An. stephensi was established at the Regional Centre of the Open University of Sri Lanka, Jaffna District. The colony was maintained under confined conditions according to standard protocols. Biotypes of An. stephensi were characterized by referring to the number of egg ridges. Information on (a) biological aspects of eggs (duration for egg hatching, egg development and hatchability), (b) larval development time, larval survivorship pupation success, resting depth of larvae), (c) pupae (adult emergence rate, average time for adult emergence) and (d) adults (biting frequency, mating success gonotrophic cycle, fecundity, duration for egg-laying, percentage of sexes, adult survival/longevity) were evaluated under life-table analysis. Further, selected morphometric characters of each life cycle stage were recorded from the eggs (length and breadth), larvae (head length, width of head, length of thorax, width of thorax, length of abdomen, width of abdomen, and the total length of larvae), pupae (cephalothoracic length and width) and adults (length & width of wing, thorax and abdomen). The VC was calculated using a mathematical-based approach. Descriptive statistics, General Linear Model (GLM) and independent-sample t-test were used for the statistical analysis. Results: All three biotypes were identified based on egg morphology. Mysorensis biotype (47%; n = 470) was predominant followed by type (38.1%; n = 381) and intermediate (14.9%; n = 149). The mean egg length (F(2,997) = 3.56; P = 0.029) and breadth (F(2,997) = 4.57; P = 0.011) denoted significant differences among the three biotypes. The mating success of females observed was 80.7 ± 4.45%. The mean hatching period was 1.9 ± 0.03 days, with a hatching rate of 86.2 ± 0.77%. Overall, 8.0 ± 0.14 days were required for larval development and 30.3 ± 0.14 h were spent in the pupal stage. The pupation success was 94.5 ± 0.37%, and the majority were males (53.1 ± 0.73%). The mean fecundity was 106.5 ± 6.38 eggs and a gonotrophic cycle of 3.4 ± 0.06 days. The female survival rate was 43.2 ± 2.4%, with a mean biting frequency of 66.6 ± 3.5%. The average VC of adult An. stephensi was estimated to be 18.7. Conclusions: The type biotype, which is an effective vector in the Indian subcontinent is present in Sri Lanka. According to the mathematical approximation, An. stephensi found locally has a vectorial capacity of over 18. Therefore, this study warrants the health authorities and vector control programmes to continue the entomological surveys, monitoring of vector densities and implementing appropriate vector control interventions based on biology and bionomic information of vectors.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 Developmental responses and survival of Anopheles stephensi larval stages at different salinity levels(Royal Society of Tropical Medicine and Hygiene, 2022) Jude, J.; Gunathilaka, N.; Udayanaga, L.; Fernando, D.; Premarathne, P.; Wickremasinghe, R.; Abeyewickreme, W.BACKGROUND: Anopheles stephensi is a newly invaded vector in Sri Lanka. It has been identified in coastal areas in the northern and eastern parts of the country and evidences the ability to breed in brackish water environments. METHODS: Laboratory investigations were conducted with batches of 100 first and third instar larvae exposed to a salinity gradient (0-40 ppt). Survival rates at 1 h, 24 h and until pupation were recorded for first and third instar larvae at different salinity levels. The experiment was repeated four times for both instars. Data were analysed using the general linear model and probit analysis. RESULTS: Significant variations in adult emergence were observed from both larval stages at different salinity levels (p<0.05). The highest pupation rates were observed at 2.5 ppt salinity. The survival rate of first instar larvae after 24 h of salinity exposure was >80% up to 12.5 ppt, while 100% mortality was observed for from the ≥25 ppt level of salinity. More than 90% of the third instar larvae pupated from salinity levels <15 ppt. The lowest survival rate was reported as 15.8±2.47% at 25 ppt. CONCLUSIONS: This indicates a high potential of increasing density of A. stephensi in coastal ecosystems in lagoons and other saline water bodies. Hence it is high time to redesign vector control interventions for vector breeding in coastal ecosystems.Item Chemoprophylaxis for malaria: A costly approach to prevent re-establishment of malaria in Sri Lanka(Sri Lanka Medical Association, 2021) Muzrif, M.M.; Mendis, K.N.; Weerasekera, C.J.; Karunaratna, S.; Wickremasinghe, R.; Ranaweera, K.D.N.P.; Fernando, S.D.Introduction and Objectives As a measure to prevent the re-establishment of malaria in the country, the Anti Malaria Campaign (AMC) provides antimalarial chemoprophylactic medicines for up to six months free-of-charge to anyone travelling to malaria endemic countries. The objective of this study was to identify the trends of chemoprophylaxis prescription by the AMC and the costs involved. Methods Data were extracted from the national malaria database regarding the number of travellers issued with antimalarial chemoprophylactic medicines during the years 2017-2019. The amount spent for purchase of antimalarial chemoprophylactic medicines was determined. Results Over the three year period the overall number of individuals issued with antimalarial chemoprophylaxis increased (1714 in 2017, 2600 in 2018 and 3053 in 2019). The number of travellers obtaining chemoprophylaxis for malaria when travelling to African countries reduced, while the number travelling to India increased. The cost incurred to the Government of Sri Lanka to purchase mefloquine and doxycycline for prophylaxis was USD 45,755, while the cost to purchase CQ over the three year period for prophylaxis alone was USD 310,714. The total cost incurred to purchase the prophylactic antimalarials have also increased significantly over the three year period, the cost being eleven times higher in 2019 than in 2017. Conclusion Chemoprophylaxis against malaria remains an important strategy to sustain the malaria elimination status in Sri Lanka, and the cost of this intervention is considerable and increasing over time. The local production of anti malarials might be warranted if it will reduce the cost of chemoprophylaxis.Item The Alcohol marketing policy environment and adolescent drinking in Sri Lanka: A qualitative exploration of stakeholder perspectives(Wiley-Blackwell, 2022) Athauda, L.; Peiris-John, R.; McCool, J.; Wickremasinghe, R.; Ameratunga, S.ABSTRACT: Adolescents continue to be exposed to alcohol marketing, despite the existence of alcohol control policies in Sri Lanka. National-level policies restrict all forms of alcohol advertising, promotions, and sponsorship and sale to minors. The act calls for the need to protect children and adolescents from exposure to the harm of alcohol. This article investigates stakeholders' perceptions of the alcohol marketing policy environment in Sri Lanka, with a specific focus on policies designed to prevent or curtail adolescent drinking. Between May and July 2019, in-depth interviews were conducted with policy stakeholders in Colombo, Sri Lanka. Thematic analysis was conducted on the audio-recorded interviews that were transcribed and translated and imported to NVivo12. Fifteen policy stakeholders from government and nongovernment organizations participated in this study. The overarching theme identified a lukewarm alcohol marketing policy environment. This situation was facilitated by the alcohol industry acting as the vector, an amber light approach towards public health programs, and other factors contributing to the perceived ineffectiveness of the alcohol marketing policy environment. A unified public health approach supported by policy and political commitment may pave the way for better alcohol control in Sri Lanka.Item Diagnosing human cutaneous leishmaniasis using fluorescence in situ hybridization(Taylor & Francis Publishing, 2021) Kaluarachchi, T.J.; Wickremasinghe, R.; Weerasekera, M.; Yasawardene, S.; McBain, A.J.; Yapa, B.; de Silva, H.; Menike, C.; Jayathilake, S.; Munasinghe, A.; Wickremasinghe, R.; Ranasinghe, S.ABSTRACT: Cutaneous leishmaniasis (CL) is endemic in Sri Lanka. Giemsa-stained slit-skin-smears (SSS-Giemsa) and histology are routinely used in diagnosis with a sensitivity of 40-70%. PCR currently has limited accessibility. Therefore, we assessed the sensitivity and specificity of a previously described fluorescence in situ hybridization assay, on skin smears and biopsy samples to overcome the limitations encountered with routine diagnostic methods.Samples from a total of 123 suspected CL patients were collected and subjected to SSS-Giemsa, fluorescence in situ hybridization (FISH) on slit skin smears (SSS-FISH), formalin-fixed-paraffin-embedded-tissues stained with Hematoxylin & Eosin staining (FFPE-H&E) and FISH on formalin-fixed-paraffin-embedded-tissues (FFPE-FISH). Negative controls of 61 patient samples were collected from a CL non-endemic area and subjected to the same procedures. The gold standard PCR was used as a comparator. For FISH, two previously described cyanine 3 tagged Leihsmania genus-specific probes were used.Compared to PCR, SSS-Giemsa, SSS-FISH, FFPE-H&E, and FFPE-FISH had sensitivities of 76.5%, 79.1%, 50.4% and 80.9%, respectively. Routine diagnostic tests (SSS-Giemsa and FFPE-H&E) had a specificity of 100%. SSS-FISH and FFPE-FISH had specificities of 96.7% and 93.4%, respectively. FFPE-FISH had a statistically significant higher diagnostic performance than FFPE-H&E (p < 0.001). The relative performance of SSS-Giemsa, SSS-FISH and FFPE-FISH was similar (p > 0.05 for all comparisons).We conclude that FFPE-FISH is a more accurate diagnostic tool than FFPE-H&E. SSS-FISH did not have an additional advantage over SSS-Giemsa in diagnosis. However, SSS-FISH could be recommended as a minimally invasive method in studies assessing wound healing where immunological probes are used. KEYWORDS: Cutaneous leishmaniasis; Sri Lanka; fluorescence in situ hybridization.