Conference Papers
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This collection contains abstracts of conference papers, presented at local and international conferences by the staff of the Faculty of Medicine
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Item Awareness on Malaria among Public and Healthcare Providers during the Prevention of Re-Introduction Phase in Sri Lanka(Sri Lanka Medical Association, 2020) Hamsananthy, J.; Wickremasinghe, A.R.INTRODUCTION AND OBJECTIVES: Prevention of re-introduction/re-establishment of malaria is a challenge for Sri Lanka due to high receptivity and vulnerability. Imported cases are being reported and an introduced case was reported in 2018. The objective of this study was to assess the awareness on malaria among public and healthcare providers which is essential during the prevention of re-introduction/re-establishment phase. METHODOLOGY: Two national surveys were conducted among 3454 households and 766 healthcare providers in 2016. Household survey was conducted using a multistage cluster sampling method. Healthcare providers’ survey used stratified random sampling and a self-administered questionnaire. RESULTS: The mean awareness score of healthcare providers was 54.7% (SD=10.6). Although 99.1% of healthcare providers (n=759) identified fever as a symptom of malaria, the majority (n=634) had not seen, diagnosed or treated a malaria case during the last 5 years. The mean awareness score of heads of households was 28.6 % (SD = 9.03). 74.4% of heads of households (n=2570) had ever seen/heard messages about malaria; 7.2% (n=249) had seen/heard in the past 6 months. The common media of communication were television (n=2714, 78.6%) and mobile phones (n=2242, 64.9%). The majority knew that malaria is spread by a mosquito bite (92.7%, n=3202) and fever (71.8% n=2479) is a symptom of malaria. CONCLUSIONS: The majority of healthcare providers have not seen a case of malaria; updates on malaria should be regularly given to suspect malaria in the differential diagnosis of fever. Television and mobile phone technology can be used to increase awareness on malaria among the general public.Item Importance of private health sector in malaria surveillance: a case study in Nuwara-Eliya district, Sri Lanka(Sri Lanka College of Microbiologists, 2002) Kusumawathie, P.H.D.; Wickremasinghe, A.R.; Karunaweera, N.OBJECTIVE: To determine the Utilization of public and private health facilities by suspected malaria cases in Divisional Director of Health Services (DDHS) area Hanguranketha in Nuwara-eliya district (from July 2000 to June 2001). DESIGN, SETTING AND METHODS: Two state hospitals, DH Rikillagaskada and RH Gonagantenna were selected as public health facilities. Seven clinics at Rikillagaskada and Gonagantenna in which government medical officers engaged in private practice after duty hours were selected as private health facilities. The number of cases blood filmed for malaria at public facilities was obtained from hospital records. Data for the private sector was obtained using a pre designed form. Reporting from the private sector was done on a monthly basis. RESULTS: Among 572 cases blood filmed at government hospitals, 22 were positive for P.vfvax. In the private sector. 634 cases of suspected malaria were reported and treated on clinical grounds. During the study period, 40 P.vivax and 65 P.falciparum cases were detected by examining 1270 blood films collected by Active Case Detection and Special Malaria Clinics, conducted in the villages with risk of malaria transmission within the study area. Of the microscopically confirmed malaria cases, 15.4% of P.falciparum infections were resistant to chloroquine. Investigation of malaria cases revealed 66.7% of cases were indigenous while 33.3% were imported. If the Slide Positive Rate (SPR) of the government facilities is applied to the data of the private sector, 610 cases would have been given chloroquine without actually having malaria. CONCLUSIONS: According to this study, 52.57% of suspected malaria cases had sought treatment at private health facilities. Incorporating the private health sector in malaria surveillance would be helpful in correct treatment and control of malaria in malarious areas. Unnecessary anti malarial therapy should be reduced by provision of laboratory facilities at private health centers. ACKNOWLEDGEMENTS: Assistance provided by the Provincial Director Health Services, Central Province and Deputy Provincial Director Health Services, Kandy, and the Director Anti-Malaria Campaign is acknowledged.Item Entomological investigations on malaria vector studies in earlier conflict areas of Sri lanka after 30 years(University of Peradeniya, 2014) Gunathilaka, P.A.D.H.N.; Fernando, M.A.S.T.; Hapugoda, M.D.; Wijeyerathne, P.; Wickremasinghe, A.R.; Abeyewickreme, W.Entomological investigations on the abundance of malaria vector mosquitoes have not been studied in northern and eastern parts of the Sri Lanka over the past 30 years due to the separatist war. The main aim of this study was to explore diversity and abundance of Anopheles mosquitoes in earlier conflict areas in Sri Lanka. Monthly entomological monitoring was carried out at 60 possible malaria sensitive localities situated approximately 12 km apart in 15 selected sentinel sites in Ampara (4), Batticaloa (3), Mannar (3) and Trincomalee (5) districts for 32 months (June 2010 to August 2013). Adult mosquitoes were collected by WHO recommended techniques. Out of 701,356 anophelines collected, An. culicifacies was noted only in Ampara, Batticaloa and Trincomalee Districts. Although the main vector An. culicifacies (n= 1,876) was low in numbers, the presence of secondary vectors including An. subpictus (n= 205,594) were high in these areas. An. nigerrimus (n= 227,057), An. barbirostris (n= 35,150), An. vagus (n= 21,161), An. pallidus (n= 17,403), An. annularis (n= 4,882), An. varuna (n= 3151), An. tessellatus (n= 718) and An. aconitus (n= 591) were the other species reported. There was a change in breeding habitats of An. culicifacies and An. subpictus. They were found more conducive to breeding in built wells, brackish water habitats and waste water collections which were below 3 mg/l of dissolved oxygen (2.85 ± 0.03). These results indicate that particularly An. culicifacies has adapted to breed in wide range of water bodies including waste water collections although they were earlier considered to breed in clean and clear water with high dissolved oxygen. The adaptation of the major and subsidiary vector mosquitoes to widespread water bodies (along with increase in imported cases) could be a potential factor for the increase in the incidence of malaria in the future even though reported cases are low at present. Further, entomological surveillance detected the presence of An. jeyporiensis from the country after 106 years. Hence, more classical entomological studies are required to describe species currently found in the country; revision of morphological identification keys is a step in this direction. Financial assistance given by the Global Fund for Aids, Tuberculosis and Malaria (GFATM-Round 8-SRL809G11M.) through TEDHA malaria elimination program is acknowledged.Item Cost analysis of application of Poecilia reticulata (guppy) and temephos in anopheline mosquito control in river bed pools below the major dams in Sri Lanka(Sri Lanka Association for the Advancement of Science, 2004) Kusumawathie, P.H.D.; Wickremasinghe, A.R.; Karunaweera, N.D.; Wijeyaratne, M.J.S.Item Trends in densities of Anopheles culicifacies (Giles) and other potential malaria vector mosquitoes in the district of Trincomalee(Sri Lanka Association for the Advancement of Science, 2013) Gunathilaka, P.A.D.H.N.; Fernando, M.A.S.T.; Hapugoda, M.D.; Wijeyarathne, P.; Wickremasinghe, A.R.; Abeyewickreme, W.Item Some observations on abundance and breeding habitats of Anopheles sp. in Trincomalee, Sri Lanka(Sri Lanka Association for the Advancement of Science, 2010) Gunathilaka, P.A.D.H.N.; Fernando, M.A.S.T.; Hapugoda, M.D.; Wijeyerathne, P.; Wickremasinghe, A.R.; Abeyewickreme, W.Malaria is one of the most serious vector-borne diseases affecting millions of people in the world annually. More than 90% of the deaths, resulting from malaria occurred particularly in children aged 1-5 years. Despite the huge burden and the absence of an effective vaccine, few tools are available to control malaria. Malaria is transmitted by Anopheles mosquitoes. The abundance of Anopheles mosquitoes was not studied in some parts of the island, especially in North and East areas over 30 years because of the ethnic conflict. The main aim of this study was to explore the habitat range and distribution of Anopheline species in the Trincomalee district. Five hundred and seventy one Anopheles larvae were collected from different breeding sites in 5 areas (Sirajnagar, Hatharaela, Paraipanchankulam, Indiwewa and Uppuweli) in Trincomalee district in March 2010 using standard larval collection techniques. These areas were situated about 10 km apart from each other. Collected mosquito larvae weretransferred to the laboratory and reared. Emerged adult Anopheles mosquitoeswereidentified using taxonomic keys. Nine anopheline species wererecorded: Anophelesculicifacies 6% (32/571), An. subpictus 25% (145/571), An.vagus 23% (134/571), An. peditaeniatus 5% (28/571), An. nigerrimus 35% (200/571), An. barbirostris 2% (14/571), An.jemesi 1% (7/571), An. pallidus 0.3% (2/571) and An. varuna 0.3% (2/571). Overall, Anopheles nigerrimus, An. subpictus and An. Vagus were the most prevalent, and An. culicifacies, An. peditaeniatus, An. barbirostris, An. jemesi, An. varuna and An. pallidus were the least prevalent species. Paddy fields, burrow pits, field channels, ponds, irrigation channels, edges of tanks, mud pools and marshy lands were the main breeding sites of Anopheles mosquitoes in selected areas in Trincomalee district. The presence of some Anopheline mosquitoes which can act as potential malaria vectors may cause malaria epidemics in these areas. Acknowledgements: Financial assistance from the Global Fund for Aids, Tuberculosis and Malaria (GFATM) (Round 8)Item Species succession of malaria vector mosquitoes and physicochemical factors affecting their abundance in rice ecosystems in Trincomalee, Sri Lanka(University of Kelaniya, 2013) Gunathilaka, P.A.D.H.N.; Ranathunge, R.M.T.B.; Fernando, M.A.S.T.; Hapugoda, M.D.; Wijeyerathne, P.; Wickremasinghe, A.R.; Abeyewickreme, W.Background: Mosquito-borne diseases are a major public health threat in Asia. The present investigation was carried out to study the ecology of vector mosquitoes in Sri Lanka, in order to explore effective mosquito control strategies in rice ecosystems from the ecological point of view. Method: As part of investigations on potential linkages between irrigation and malaria transmission, all surface water bodies in and around 20 selected villages along an irrigation distributary in the District of Trincomalee, Sri Lanka, were surveyed for anopheline mosquito larvae (Diptera: Culicidae) from January 2012 - June 2013. Breeding sites were characterized according to exposure to sunlight, substratum, and presence of vegetation, fauna, inorganic matter and physical water condition (clear/turbid). Dissolved Oxygen (DO), conductivity, salinity, pH, temperature, Total Dissolved Solids (TDS) and turbidity were recorded. Results: A total of 3914 Anopheles larvae of twelve morphological types were collected from 685 breeding habitats. Anopheles peditaeniatus (n= 1041), was the most abundant, followed by An. subpictus (n= 893), An. nigerrimus (n= 808), An. barbirostris (n= 581), An. pallidus (n= 184), An. annularis (n=124), An. jamesii (n= 80), An. varuna (n= 76), An. vagus (n= 56), An. barbumbrosus (n= 48). An. culicifacies (n= 22) and An. aconitus (n= 1). The four most abundant species were significantly associated with waterlogged paddy fields. Anopheles culicifacies was noted only from irrigational canals with vegetation. Conductivity, salinity, and TDS were positively correlated with larval densities of An. peditaeniatus (Pearson correlations= 0.04, 0.17, 0.33: P= 0.94, 0.77, 0.58), An. subpictus (Pearson correlations= 0.6, 0.68, 0.56: P= 0.19, 0.20, 0.31), and An. vagus (Pearson correlations= 0.6, 0.42, 0.17: P= 0.28, 0.47, 0.77). However all physicochemical variables were negatively correlated with An. culicifacies densities. Conclusion: Major malaria vector of An. culicifacies complex occurred at relatively low densities, mainly in irrigated and waterlogged fields. These findings support understanding of mosquito ecology and will support future mosquito control strategies in rice ecosystems in Sri Lanka.Item Resting behavior of malaria vectors in Mannar District of Sri Lanka with reference to zooprophylaxis(University of Kelaniya, 2013) Gunathilaka, P.A.D.H.N.; Fernando, M.A.S.T.; Hapugoda, M.D.; Wijeyerathne, P.; Wickremasinghe, A.R.; Abeyewickreme, W.Background: The most important factors for effective zooprophylaxis in reducing malaria transmission are the presence of predominate populations of a strongly zoophilic mosquitoes and domestic animals for their blood-meal. Methods: Resting behavior of anopheline mosquitoes was evaluated using indoor and outdoor mosquito collection techniques. Mosquitoes were captured using 389 outdoor cattle-baited traps and indoor hand catches in 5672 houses at 12 possible malaria sensitive areas situated 12 km apart; Pesali, Keeri, Erukkallampeddi, Moor, Vankalai, Narawallikulam, Vanchiyankulam, Arvanum, Arrippu, Kokkupadayan, Koolankulam and Pandaraveilli for 12 months (June 2012 to June 2013) on a weekly basis. These areas had mostly homogenous characteristics in vegetations and house type. All collected mosquitoes were identified using standard taxonomic keys. A hypothesis test was conducted to determine whether there is a difference between indoor and outdoor collections. Results: A total of 3986 anopheline mosquitoes were collected from both indoor (n= 3122) and outdoor (n= 864) collection techniques. Anopheles subpictus was found to account for over 97.5% (n= 3887) of Anopheles species collected in the study areas. Other species were; 1.4% An. peditaeniatus (n= 57), 0.6% An. varuna (n= 22), 0.3% An. pallidus (n= 10), 0.2% An. nigerrimus (n= 7), 0.05% An. tessellatus (n= 2), and 0.03% An. aconitus (n= 1). Only 3 species namely, An. subpictus (n= 485), An. tessellatus (n= 2) and An. aconitus (n= 1) were recorded from indoor hand catches. In experimental cattle-baited hut trials, An. subpictus (n= 3026) was found to have the highest exophilic tendency (96.9%) compared to other anophelines encountered. The hypothesis test suggests that there was a significant difference of An. subpictus attracted to cattle-baited traps and human dwellings (P = 0.008). Although the main vector An. culicifacies was absent, the presence of the secondary vector An. subpictus was observed in high numbers in the District. Conclusion: Exophilic and zoophilic tendencies of An. subpictus are conducive for zooprophylaxis. The study further indicates that zooprophylaxis may be a potential strategy for malaria control. It is recommended that in areas with a predominant An. subpictus population, cattle could be kept close to human dwellings to maximize the effects of zooprophylaxis.Item Breeding of Anopheles culicifacies in different waterbodies in the district of Trincomalee(University of Kelaniya, 2012) Gunathilaka, P.A.D.H.N.; Fernando, M.A.S.T.; Hapugoda, M.D.; Wijeyerathne, P.; Wickremasinghe, A.R.; Abeyewickreme, W.Introduction: Anopheles culicifacies (Diptera: Culicidae), the major vector of malaria in Sri Lanka is known to breed in clean and clear water. This study was focused to understand the larval habitats of the major malaria vector with the eco system changes in the Trincomalee district of the Eastern Province. Method: Potential larval habitats for Anopheles mosquitoes were surveyed on a monthly basis for 17 months (January 2011 –June 2012) in 4 different selected sampling sites (Murthankulam, Kommnaimottai, Paranamadawachchiya and Kokmotawewa). Collected larvae were identified using standard taxonomic keys. The species Distribution (C) and Density (D) were calculated. Results: A total of 2996 larval specimens representing 13 Anopheles species were reported from 16 different breeding habitats namely, waste water (n= 635), built well (n= 1229), earth well (n=149), agricultural well (n=9), rain water collection (n=89), animal hoof print (n=17), burrow pit (n=256), rock pool (n=10), canal (n=15), irrigation canal (n=27), lake margin (n=27), tank margin (n=448), pond margin (n=15), marshy land (n=13), paddy field (n=15) and slow moving water (n=42). An. culicifacies was observed as the most predominant species throughout the survey. According to Density criterion, An. culicifacies (44.0%), An. subpictus (19.2%), An. barbirostris (13.2%), An. peditaeniatus (10.28%) and An. nigerrimus (8.7%) were within the dominant class; (D > 5%). Two species (An. vagus, An. pallidus) were in the subdominant class (1< D <5%). Only An. annularis, An. varuna, An. barbumbrosus, An. pseudojamesi, An. jamesii and An. tessellatus were the satellite species (D < 1%). An. nigerrimus, An. subpictus and An. peditaeniatus can be regarded as constant according to distribution (C= 80.1-100%). Only An. vagus was the most frequently reported (C= 60.1 – 80%) species. All other Anopheles including An. culicifacies were observed as infrequent species (C= 20.1 – 40%) and no species was identified as sporadic appearance (C= 0 – 20%). Most productive breeding site for An. culicifacies were drains covered with waste water (Density= 81.57%) in remote areas. Interpretation & conclusion: These results indicate that An. culicifacies has adapted to breed in a wide range of water bodies including waste water collections although they are considered to breed in clean and clear water. The survival of the major vector mosquito in widespread water bodies could be responsible for the increase in the incidence of malaria in the future.Item Susceptibility of malaria vectors to insecticides in Ampara, Batticaloa, Trincomalee & Mannar districts of Sri Lanka(University of Kelaniya, 2012) Gunathilaka, P.A.D.H.N.; Fernando, M.A.S.T.; Hapugoda, M.D.; Wijeyerathne, P.; Wickremasinghe, A.R.; Abeyewickreme, W.Background: The current status of insecticide resistance was studied for potential malaria vectors in four districts namely Ampara, Batticaloa, Mannar and Trincomalee of Sri Lanka. Methods: Insecticide-susceptibility tests were carried out using WHO standard kits against various chemical compounds at ambient room temperature of 27+1oC and relative humidity of 75-80% for adult and larvae separately. A total of 3629 adult female Anopheles mosquitoes belong to nine species (An. subpictus, An. vagus, An. nigerrimus, An. peditaeniatus, An. pallidus, An. annularis, An. jamesii, An. pseudojamesi and An. barbirostris) were exposed to cyfluthrin- 0.15%, etofenofrox- 0.5%, bendiocarb- 0.01%, malathion – 5%, deltamethrin – 0.05%, permethrin – 0.75%, λ- cyhalothrin– 0.05%, fenitrothion – 1.0% and propoxur – 0.1%. A total of 610 larvae belong to five Anopheles species (An. subpictus, An. vagus, An. barbirostris and An. peditaeniatus) were exposed to 0.0025, 0.005, 0.125 and 0.625 mg/l of viz. temephos (Abate). Results: All of the mosquito larvae or adult species used for the study were susceptible for selected insecticides (Mortality 98-100%). Adult Anopheles species showed a possibility of developing resistance to some chemicals (Mortality 97- 80%): An. nigerrimus (lambdacyhalothrin and permethrin), An. peditaeniatus (malathion, deltamethrin and cyfluthrin) An. subpictus (deltamethrin, permethrin, propoxur, cyfluthrin, and etofenprox), An. vagus (deltamethrin, permethrin and etofenprox) and An. pallidus (deltamethrin). Anopheles larvae of An. subpictus, An. barbirostris and An. peditaeniatus showed the potential of developing resistance (Mortality 97-80%). Interpretation & conclusion: As a result of resettlements and expanding commercial agriculture there can be a potentiality of developing insecticide resistance in mosquito individuals. Therefore, proper use of chemicals as pesticides should be adopted in these areas.