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 Malaria in Sri Lanka: Investigating causes of the recent elimination and making plans to prevent reintroduction.(Malaria Research Centre/National Institute of Malaria Research., 2019) Perera, W.D.H.N.; Gunathilaka, P.A.D.H.N.; Taylor-Robinson, A.W.ABSTRACT: Sri Lanka is a country that has long suffered from epidemics of malaria. In this historical context, it is remarkable that in 2016 the Indian Ocean island nation was able to officially celebrate the elimination of this parasitic disease of major public health importance. The most devastating outbreak recorded in Sri Lanka was during 1934-35, when close to 80,000 human deaths were reported. Indoor residual spraying with the insecticides, DDT and malathion commenced in 1947 and was successful in causing a rapid decline in malaria incidence. However, poor vector control measures, resistance of mosquitoes to these insecticides and resistance of blood-stage Plasmodium parasites to the prevailing drugs used are considered the principal reasons for the occurrence of subsequent outbreaks. Despite this, Sri Lanka achieved the significant milestone of zero locally transmitted malaria cases in October 2012 and zero recorded deaths since 2007. Vector surveillance, parasitological examination, and clinical case management were collective effective activities that most likely led to elimination of malaria. Yet, there remains a high risk of reintroduction due to imported cases and an enduring vulnerability to vector transmission. In order to prevent re-establishment of malaria, continued financial support, sustained surveillance for vector species present in Sri Lanka and effective control of imported cases through rapid detection and early diagnosis are all required. In addition to these immediate practical priorities, further studies on vector biology and genetic variations that affect vectorial capacity would help to shed light on how to avoid reintroduction. This review affords an insight into the determinants of past malaria epidemics, strategies deployed to achieve and maintain the current status of elimination, lessons learnt from this success and plans to avoid resurgence of infection. KEYWORDS: Elimination; Plasmodium; Sri Lanka; importation; malaria; vector.Item Use of cyclopoid copepods for control of Anopheles (Diptera: Culicidae) mosquito larvae to prevent re-emergence of malaria in Sri Lanka(Malaria Research Centre, Indian Council of Medical Research, 2019) Ranathunge, T.; Abeyewickreme, W.; Iqbal, M. C. M.; Hapugoda, M.BACKGROUND & OBJECTIVES: Although malaria is eliminated from Sri Lanka, there is a possible risk of spread from infected persons coming from malaria endemic countries. The presence of major and potential vectors in several parts of the country along with drug resistance, necessitates the identification of effective and novel control methods. The present study focused on identifying effective biological control agents for anopheline larvae using carnivorous copepods under laboratory and field conditions to prevent re-introduction of malaria in the country. METHODS: Three copepod species, namely Mesocyclops scrassus, Cyclops varicans and C. languides collected from different areas in the country were cultured by adding supplementary food, and their predatory efficacy was evaluated under laboratory and field conditions. RESULTS: Significant variation (p <0.05) was observed in predation rates of studied copepod species. The species M. scrassus showed the highest predacious efficiency, and consumed the highest number of anopheline larvae under laboratory and field conditions. Further, M. scrassus had higher survival rate than C. varicans and C. languides. INTERPRETATION & CONCLUSION: The results of the study suggest that the predatory copepod M. scrassus can be used as a bio-control agent for the control of Anopheles mosquitoes to prevent re-emergence of malaria in the country. Additional research is suggested to identify naturally available copepod species and their predatory efficacy. KEYWORDS: Anopheles; Sri Lanka; biological control; copepods; malaria vectors; predatory efficacy.Item A Comprehensive analysis on abundance, distribution, and bionomics of potential malaria vectors in Mannar District of Sri Lanka(Hindawi Publishing Corporation, 2019) Gunathilaka, N.; Hapugoda, M.; Wickremasinghe, R.; Abeyewickreme, W.BACKGROUND:A detailed knowledge of the distribution of the malaria vectors in Mannar district of Sri Lanka has not been studied after 1927. Past records indicated the presence of only seven species of anophelines, namely, An. culicifacies, An. subpictus, An. barbirostris, An. peditaeniatus, An. nigerrimus, An. Jamesii, and An. maculatus. There have been many changes in terms of distribution of Anopheles in the district over time. METHODS: Entomological surveillance was conducted on a monthly basis, comprising indoor hand collection, window trap collection, cattle-baited net collection, cattle-baited hut collection, and larval survey from June 2010 to June 2012 in 12 study areas under three entomological sentinel sites. The relationship between seven abiotic variables of the breeding habitats was measured. Pearson's correlation coefficients were used to determine the associations between climatic variables and anopheline densities. RESULTS:A total of 74,181 mosquitoes belonging to 14 Anopheles species were recorded. An. subpictus was the most predominant species from all techniques representing 92% (n=68,268) of the total anopheline collection. However, Anopheles culicifacies was not recorded from any site during the study period. Larval surveys identified 12 breeding habitat categories including waste water collections, lagoon water collections, and drains which were not recorded as breeding habitats by previous studies. The mean dissolved oxygen level of waste water collections was 3.45±0.15 mg/l. The mean salinity and conductivity of lagoon water collections were 21105±1344 mg/l and 34734±1974 μs/cm, respectively.CONCLUSION: The present study provides the updated knowledge on anopheline distribution and vector bionomics. Therefore, documentation of the current knowledge would be useful for learners and health authorities to design appropriate vector control measures in the prevention of reintroduction of malaria.Item Role of a dedicated support group in retaining malaria-free status of Sri Lanka.(New Delhi : National Institute of Malaria Research, 2019) Datta, R.; Mendis, K.; Wickremasinghe, R.; Premaratne, R.; Fernando, D.; Parry, J.; Rolfe, B.No Abstract AvailableItem Effectiveness of passive case detection for imported malaria in a hospital setting in Sri Lanka during the prevention of re-introduction phase of malaria(Oxford University Press, 2019) Dharmawardena, P.; Premaratna, R.; Mendis, K.; Wickremasinghe, A.R.; Rodrigo, C.; Harintheran, A.; Fernando, D.INTRODUCTION: The effectiveness of the passive case detection (PCD) system for imported malaria was assessed in government hospitals in Sri Lanka post-elimination of malaria. METHODS: In 18 medical wards (test wards) in four government hospitals, the referral for malaria testing and the diagnosis of malaria by the ward physicians were monitored. Concurrently, in-ward febrile patients were assessed independently for their eligibility for referral for malaria diagnosis and were tested for malaria. The malaria incidence in 16 other wards (control wards), which the study did not screen, served as controls. RESULTS: Four imported malaria patients were diagnosed within the PCD system among 25 874 febrile patients admitted during the 14-month study period, two of whom were diagnosed in the test wards and two in the control wards. The study's screening programme did not detect any more malaria patients than detected by the routine PCD system of the wards. However, far fewer patients were screened for malaria (1.3%) than were eligible for screening (29.4%), and some infections were detected incidentally, rather than by a request for a malaria test. CONCLUSION: A continuous effort to maintain awareness of the disease among physicians would be required if the PCD system is to be effective for the detection of imported malaria, post-elimination.Item Use of a public-private partnership in malaria elimination efforts in Sri Lanka; a case study(BioMed Central, 2018) Fernando, D.; Wijeyaratne, P.; Wickremasinghe, R.; Abeyasinghe, R.R.; Galappaththy, G.N.L.; Wickremasinghe, R.; Hapugoda, M.; Abeyewickreme, W.; Rodrigo, C.BACKGROUND: In special circumstances, establishing public private partnerships for malaria elimination may achieve targets faster than the state sector acting by itself. Following the end of the separatist war in Sri Lanka in 2009, the Anti Malaria Campaign (AMC) of Sri Lanka intensified malaria surveillance jointly with a private sector partner, Tropical and Environmental Diseases and Health Associates Private Limited (TEDHA) with a view to achieving malaria elimination targets by 2014. METHODS: This is a case study on how public private partnerships can be effectively utilized to achieve malaria elimination goals. TEDHA established 50 Malaria Diagnostic Laboratories and 17 entomology surveillance sentinel sites in consultation with the AMC in areas difficult to access by government officials (five districts in two provinces affected by war). RESULTS: TEDHA screened 994,448 individuals for malaria, of which 243,867 were screened at mobile malaria clinics as compared to 1,102,054 screened by the AMC. Nine malaria positives were diagnosed by TEDHA, while the AMC diagnosed 103 malaria cases in the same districts in parallel. Over 13,000 entomological activity days were completed. Relevant information was shared with AMC and the data recorded in the health information system. CONCLUSIONS: A successful public-private partnership model for malaria elimination was initiated at a time when the health system was in disarray in war ravaged areas of Sri Lanka. This ensured a high annual blood examination rate and screening of vulnerable people in receptive areas. These were important for certification of malaria-free status which Sri Lanka eventually received in 2016.Item The need for preventive and curative services for malaria when the military is deployed in endemic overseas territories: a case study and lessons learned(BioMed Central, 2017) Fernando, S.D.; Booso, R.; Dharmawardena, P.; Harintheran, A.; Raviraj, K.; Rodrigo., C.; Danansuriya, M.; Wickremasinghe, A.R.BACKGROUND: Sri Lanka has been free from indigenous malaria since November 2012 and received the WHO certificate for malaria-free status in September 2016. Due to increased global travel, imported malaria cases continue to be reported in the country. Military personnel returning home from international peace-keeping missions in malaria endemic countries represent a key risk group in terms of imported malaria. The present study intended to characterize the potential causes of a malaria outbreak among the Sri Lankan security forces personnel deployed in the Central African Republic (CAR). METHODS: Data were collected from a cross-sectional survey distributed among Sri Lankan Air Force personnel who had returned from United Nations peace-keeping missions in the CAR region. A pre-tested questionnaire was used for the data collection, and focus group discussions were also conducted. RESULTS: One hundred twenty male Air Force personnel were interviewed (out of a group of 122 officers and airmen). All participants were deployed in the CAR for 14 months and were aware of the existence of chemoprophylaxis against malaria. The majority of the subjects (92.5%, 111/120) also knew that prophylaxis should be started prior to departure. However, the regular use of chemoprophylaxis was reported by only 61.7% (74/120) of the sample. Overall, 30.8% of the participants (37/120) had 44 symptomatic episodes of malaria during deployment, and one person succumbed to severe malaria. All cases were associated with noncompliance with chemoprophylaxis. CONCLUSION: Better coordination with overseas healthcare services and the establishment of directly observed chemoprophylaxis may help to avoid similar outbreaks in the future.Item Composition of malaria vectors and diversity of anopheline breeding habitats in the district of Mannar, Sri Lanka(Central Environmental Authority (CEA), 2016) Gunathilaka, P.A.D.H.N.; Hapugoda, M.D.; Wickremasinghe, A.R.; Abeyewickreme, W.In the malaria elimination phase in Sri Lanka, investigation on biological and ecological factors of malaria vectors are important in planning appropriate vector controlling strategies. Lack of sufficient biological and ecological information on malaria vectors in the Northern Province of the country, a malaria endemic region, is a major constrain in successful implementation of malaria control programmes. Therefore, the objective of this study was to explore the diversity of breeding habitats and species composition of malaria vector mosquitoes in the District of Mannar, Sri Lanka. Potential habitats for Anopheles mosquito larvae were surveyed from June, 2010 to July 20 J2 on a monthly basis in selected sampling sites in the Mannar District: Mannar Town, Vankalai and Silawathiura, within a radius about 20 km. In each site, 4 sub sites were selected A total of 37,788 Anopheles representing ten species was recorded from 12 breeding habitat categories. Built wells and waste water collections were conducive for anopheline breeding. Anopheles subpictus (96.2%, n= 36,351) was the dominant species followed by An. peditaeniatus (1.47%, n= 557), An. barbirostris (1.23%, n= 463), An. nigerriums (0.75%,n = 285), An. varuna (0.19%, n= 74), An. barbumbrosus (0.1%, n= 38), An. vagus' (0.03%, n= 12), An. pallidus (0.01%, n= 4), An.jamesii (0.05%, n= 2) and An. pseudojamesi (0.05%, n= 2). Use of wells and waste water drains as breeding places by potential malaria vectors indicates that both of these habitats act as larval reservoirs during the dry season. Presence of theses habitats in close proximity to human habitats create a potential risk of malaria transmission among humans. Therefore, health authorities need to be vigilant on these new habitats in vector control programmes.Item Contribution of the private sector healthcare service providers to malaria diagnosis in a prevention of re-introduction setting(BioMed Central, 2016) Fernando, S.D.; Dharmawardena, P.; Epasinghe, G.; Senanayake, N.; Rodrigo, C.; Premaratna, R.; Wickremasinghe, R.BACKGROUND: Sri Lanka is currently in the prevention of re-introduction phase of malaria. The engagement of the private sector health care institutions in malaria surveillance is important. The purpose of the study was to determine the number of diagnostic tests carried out, the number of positive cases identified and the referral system for diagnosis in the private sector and to estimate the costs involved. METHODS: This prospective study of private sector laboratories within the Colombo District of Sri Lanka was carried out over a 6-month period in 2015. The management of registered private sector laboratories was contacted individually and the purpose of the study was explained. A reporting format was developed and introduced for monthly reporting. RESULTS: Forty-one laboratories were eligible to be included in the study and 28 participated by reporting data on a monthly basis. Excluding blood bank samples and routine testing for foreign employment, malaria diagnostic tests were carried out on 973 individuals during the 6-month period and nine malaria cases were identified. In 2015, a total of 36 malaria cases were reported from Sri Lanka. Of these, 24 (67 %) were diagnosed in the Colombo District and 50 % of them were diagnosed in private hospitals. CONCLUSIONS: An equal number of cases were diagnosed from the private sector and government sector in the Colombo District in 2015. The private sector being a major contributor in the detection of imported malaria cases in the country should be actively engaged in the national malaria surveillance system.Item Breeding habitat diversity and species composition of Anopheles mosquitoes in Trincomalee district, Sri Lanaka(HABITATS Conservation Initiative, 2014) Gunathilaka, P.A.D.H.N.; Fernando, M.A.S.T.; Hapugoda, M.D.; Wijeyerathne, P.; Wickremasinghe, A.R.; Abeyewickreme, W.Entomological studies on the abundance of malaria vector Anopheles mosquitoes have not been studied in some malaria endemic areas of Sri Lanka over past 30 years in view of the security situation. The aim of this study was to explore the habitat diversity and distribution of anopheline species in Trincomalee District in order to prioritize vector breeding habitats for developing timely and cost effective larval controlling measures. Potential larval habitats for Anopheles mosquitoes were surveyed from June 2010 - December 2010, in selected sampling sites in the Trincomalee District; Gomarankadawala, Echchallampaththu, Mollipothana, Thoppur and Padavisiripura, within a radius about 20 km on weekly basis. The species distribution and density were calculated. A total of 3,701 larval specimens representing twelve Anopheles species were reported form 19 breeding habitats (Tank margin, main canal, paddy field, vegetative canal, lake, built well, burrow pit, distribution canal, pond, rock pool, canal, un-built well, common well, river margin, sand pool, animal foot print, rain water collection, quarry pit and marshy land). Ten habitats were categorized under structurally complex group based on the presence of biotic communities. Only An. subpictus can be regarded as constant according to Distribution (C) (C= 80.1-100%).An. nigerrimus, An. peditaeniatus, An. pallidus and An. vagus were frequent (C= 60.1 – 80%). An. varuna, An. barbirostris, An. annularis and An. barbumbrosus were shown as infrequent species (C= 20.1 – 40%) and other namely An. aconitus, An. culicifacies and An. jamesii can be categorized under sporadic appearance (C= 0 – 20%). According to Density (D) criterion, five species (An. subpictus, An. nigerrimus, An. varuna, An. pallidus, An. barbumbrosus) were within the dominant class (D > 5%). Four species (An. vagus, An. peditaeniatus, An. annularis, An. aconitus) were in the subdominant class (1< D <5%). Only An. jamesii and An. culicifacies were the satellite species (D < 1%).