Browsing by Author "Gunathilaka, P.A.D.H.N."

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A Determination of air pollution in Colombo and Kurunegala, Sri Lanka, using energy dispersive X-ray fluorescence spectrometry on Heterodermia speciosa
(Scientific and Technological Research Council of Turkey (TÜBİTAK), 2011) Gunathilaka, P.A.D.H.N.; Ranundeniya, R.M.N.S.; Najim, M.M.M.; Seneviratne, S.
Sri Lanka is facing severe environmental problems such as air and water pollution due to rapid industrialisation and urbanisation. Because there have not been many studies on heavy metal pollution in Sri Lanka, the present study attempts to contribute to the literature a determination of metal pollution using indicators found in lichen specimens. Our study utilised energy dispersive X-ray l uorescence spectrometry to determine element concentrations resulting from air pollution in the lichen species Heterodermia speciosa Wulfen. h ese samples, collected from Colombo and Kurunegala, Sri Lanka, were analysed using the energy dispersive X-ray l uorescence (EDXRF) method in order to determine the concentrations of 13 dif erent elements. A radioisotope excited X-ray l uorescence analysis was applied to the elemental analysis of lichens using the method of multiple standard addition. Our qualitative analysis of spectral peaks showed that the samples contained potassium, calcium, titanium, iron, manganese, copper, zinc, lead, bromine, rubidium, strontium, yttrium, and gallium. Samples from the environment around Colombo, which is a highly congested urban area with much industrial development, were found to be more polluted when compared with Kurunegala, a city that is less congested and without industries. Concentrations of K, Ca, Ti, and Fe were always higher than other elemental concentrations in the lichens we analysed, a fact attributed to the proximity to the sea or exposed earth crustal sources. From the elements reported from the 2 cities, K, Ca, Ti, Fe, Mn, Zn, and Pb were reported at concentrations higher than background levels. Levels of Pb and Zn in samples from Colombo were higher than those from Kurunegala, relecting the increased vehicular trai c. h is study reveals that the common lichen species Heterodermia speciosa can be used as an indicator lichen to analyse the pollution level and other elements in the atmosphere.
Annotated checklist and review of the mosquito species (Diptera: Culicidae) in Sri Lanka
(Magnolia Press LTD, 2018) Gunathilaka, P.A.D.H.N.
Mosquito borne diseases remains as an importance source of morbidity and mortality in Sri Lanka. To better control vectors which transmit the diseases, updated list of the species present in the county is imperative. It is also vital in documenting the diversity of the family Culicidae. Original records were collected from a literature review to compile a list of the species recorded in Sri Lanka. This work illustrates the updated list of mosquito species in Sri Lanka and their current taxonomic status based on previous studies from 1901 to date. A total of 159 species belonging to 19 genera including sibling species, have been included in the revised mosquito checklist in Sri Lanka. The present work includes 13 species, two genera (Lutzia, Verrallina) and 9 subgenera in subfamily Culicinae, tribe Aedini of genus Aedes (Bruceharrisonius, Collessius, Danielsia, Dendroskusea, Downsiomyia, Fredwardsius, Hulecoeteomyia, Neomelaniconion, Phagomyia) in to the checklist which were not included in the previous mosquito checklist published nearly 26 years ago. However, further work is essential to refine this list and to explore the abundance of new species within the country. Improved morphological and molecular identification methods will sanction the refinement of the mosquito catalog in years to come
Annotated checklist of chigger mites (Trombidiformes: Leeuwenhoekiidae, Trombiculidae and Walchiidae) in Sri Lanka
(Elsevier, 2022) Ashani, M.L.S.; Gunathilaka, P.A.D.H.N.; Premaratna, B.A.H.R.; Chandrasena, T.G.A.N.; Jacinavicius, F.C.; Silva, R.B.
Chigger mites (Leeuwenhoekiidae, Trombiculidae, and Walchiidae) are parasites of any terrestrial vertebrate. The present study updates the list of chigger mite (Trombiculidae, Leeuwenhoekiidae, and Walchiidae) species recorded from Sri Lanka along with taxonomic classification based on previous investigations since 1946 to date and our observations in western and southern parts of the country. This checklist listed 15 species in 9 genera within the three chigger families. For now, murid species were the host most sampledparasitized by chiggers in Sri Lanka. However, further studies are required to increase the diversity of chigger mites in Sri Lanka and probably the description of new species, which will be possible with morphological and molecular characterization.
Anopheles subpictus s.l. breeding in polluted water bodies in Vankalai area in the Mannar District
(Sri Lanka Association for the Advancement of Science, 2014) Ranathunge, R.M.T.B.; Gunathilaka, P.A.D.H.N.; Kannangara, D.N.; Abeyewickreme, W.; Hapugoda, M.D.
Assessment of artificial blood feeding methods and efficacy of different blood meal sources in mass rearing of Aedes aegypti for innovative vector controlling strategies
(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2016) Gunathilaka, P.A.D.H.N.; Ranathunga, R.M.T.B.; Udayanga, N.W.B.A.L.; Abeyewickreme, W.
Background Mass rearing of vector mosquitoes of dengue is a crucial requirement for implementation of innovative vector controlling strategies such as Sterile Insect Technique (SIT), Incompatible Insect Technique (IIT) and transgenic mosquitoes. Selection of the artificial membrane-feeding technique and blood meal source have been recognized as key considerations in mass rearing of vectors. Methodology Three artificial membrane feeding techniques (Glass plate method, Metal plate and Hemotek membrane feeding method) and three blood sources (human, cattle and chicken) were evaluated based on feeding rates, fecundity and hatching rates of Ae. aegypti, under laboratory conditions. One-way ANOVA, cluster analysis, analysis of variance (ANOSIM) and principal coordinates (PCO) analysis, were used to investigate the significance in the variations among blood feeding. Results Feeding rates of Ae. aegypti significantly differed among the membrane feeding techniques as suggested by one-way ANOVA (p <0.05). The metal plate method was identified as the most efficient and cost effective feeding technique. Blood feeding rate of Ae. aegypti was higher with human blood followed by cattle and chicken blood, respectively. However, no significant difference was observed among mosquitoes fed with cattle blood and human blood, in terms of fecundity, oviposition rate and fertility. Conclusions Metal plate feeding technique could be recommended as the most effective membrane feeding technique for mass rearing of Ae. aegypti, due to its high feeding rate and cost effectiveness. Since, obtaining human blood for insectary colony maintenance is problematic due certain ethical issues, cattle blood could be recommended for mass rearing Ae. aegypti.
Awareness on dengue and solid waste management among selected school students in Gampaha District of Sri Lanka
(Moleclar Medicine Unit, Faculty of Medicine, University of Kelaniya, Sri Lanka, 2015) Radhika, N.M.L.; Gunathilaka, P.A.D.H.N.; Abeyewickreme, W.; Kasturiratne, K.T.A.A.
BACKGROUND: Community mobilization is often respected as a powerful tool in ensuring the effective controlling of dengue via promoting effective and sustainable dengue vector control strategies. The current study attempts to investigate the level of awareness on dengue and solid waste management, among selected school students in Gampaha District which is the second highest dengue reported district in Sri Lanka. METHODOLOGY: Awareness programmes on dengue (transmission, vector ecology and preventive measures) and solid waste management were conducted in 10 schools belong to Kelaniya Medical Officer of Health (MOH) area selecting a minimum group of 200 students from each school within the age of 13 - 15 years. Tools such audio-visual presentations, leaflets and videos were used for the awareness programmes. A questionnaire was given to each student prior to the awareness and after the awareness programs as pre and post evaluations respectively in order to assess the general awareness on dengue and solid waste management before and after the awareness programme. One-Way ANOVA, paired t-test and multiple regression techniques were utilized in evaluation of the degree of awareness and key factors affecting the level of awareness, prior and after the conducting the awareness programmes. RESULTS: The degree of initial awareness on dengue and solid waste management of the target school community was recognized to be significantly characterized by the grade of the students and the Education Zonal Category [EZU] (into which their school belongs to) in accordance with One-Way ANOVA (p < 0.05). A significant increment in post awareness of the target school community was recognized due to the conducting of awareness programmes in accordance with the statistics of paired t-test (p < 0.05). Furthermore, based on the multiple linear regression modelling, the post awareness was significantly influenced by the grade of the students and the initial awareness (p < 0.05), regardless of the EZU (p > 0.05). CONCLUSIONS: The awareness of school students on dengue and solid waste management is significantly affected by the grade of the students and EZCs. Awareness programmes are an effective media of raising the awareness of school communities on dengue and solid waste management, while motivating them to actively contribute for the controlling of dengue, via establishing a strong inter sectorial network among schools and other relevant institutions within the Gampaha District.
Bacterial Diversity in the Midgut of Field Caught Culex tritaeniorhynchus
(International Postgraduate Research Conference 2019, Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2019) Ranasinghe, H.A.K.; Gunathilaka, P.A.D.H.N.; Amarasinghe, L.D.; Rodrigo, W.W.P.
Ingestion of blood meal by female mosquitoes triggers a series of physiological processes in midgut where symbiotic microbes also exist. These symbiotic microbes can be engineered to produce molecules that inhibit pathogens; through paratransgenic approach. Little is known about the midgut microbes of Culex mosquitoes and no attempt has been made so far in Sri Lanka. Cx. tritaeniorhynchus mosquitoes were separated from the entomological surveys conducted at Kelaniya Medical officer of Health (MOH) area from June – August 2019. Unfed adult female mosquitoes were sacrificed using a cold shock and were surface sterilized using 70% ethanol followed by rinsing with phosphate buffer saline (PBS). Midgut of mosquitoes were dissected and midgut of ten mosquitoes were pooled in sterile PBS (250 μL) to make a homogenized lysate. A dilution series (100- 10-7) was made from lysate. 100 μL from each dilution was plated on Plate Count Agar (PCA) and were incubated for 48 hours at 37 0C. Pure cultures for each microbe were obtained from the primary plates using streak plate method, sub culturing in Nutrient Agar. The experiment set up was repeated 25 times with ten mosquito pools at each effort. Colony separation was done based on phenotypical differences and basic biochemical tests. Stab cultures of isolates were sequenced for 16S ribosomal RNA partial gene. To identify the closest related sequence, obtained sequences were analyzed by Bioedit software package and completely aligned sequences were compared with the BLAST database. The evolutionary history was inferred using the neighbor-Joining method and the evolutionary analyses were conducted in MEGA X. A total of eight bacterial strains namely; Staphylococcus pasteuri, Bacillus megaterium, Staphylococcus cohnii, Pantoea dispersa, Staphylococcus chromogenes, Bacillus aquimaris, Staphylococcus arlettae, Staphylococcus scuiri was isolated from Cx. tritaeniorhynchus (n=250). All of these species were belonged to two phyla; Firmicutes and Proteobacteria. Phylum Firmicutes was the dominant phyla which include seven species. The evolutionary distances which were computed using Tajima-Nei method were used to infer the phylogenetic tree. It represented a close relationship between the species of two genera; Staphylococcus and Bacillus while the relationship was distant for genus Pantoea. The present data strongly encourage further investigations to explore the potential usage of these microbes through the paratransgenic approach which is a novel eco-friendly vector control strategy
Blood-feeding patterns of Anopheles mosquitoes in malaria-endemic areas 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: Studies on host preference patterns in blood-feeding of anopheline mosquitoes are crucial for incriminating them as malaria vectors. However, little information is available on the host preferences of Anopheles mosquitoes in Sri Lanka. Therefore, the objective of the present study was to determine the hematophagic tendency of the anophelines. Methods: Adult Anopheles mosquitoes were collected using Cattle Baited Trap Collection (CBTC), Cattle Baited Net Collection (CBNC), Window Trap Collection (WTC), and Hand Collection (HC) from selected sentinel sites in Mannnar (3) and Trincomalee (5) Districts during June 2011- June 2012. Each blood fed mosquito was processed in to 9 cm whatman filter papers within 24 hours after blood meal has taken. DNA was extracted using the dried blood meal protocol of the QIAmp DNA mini kit. A multiplexed, Real Time Polymerase Reaction (RT- PCR) assay targeting 8 animals was developed for two panels (Panel 1: Bovine, cat, pig, monkey: Panel 2: Human, rat, dog, chicken) to identify the host meal of Anopheles. Human Blood Index (HBI), Forage Ratio (FR) and Host Feeding Index (HFI) were calculated. Results: A total of 216 field caught freshly engorged females mosquitoes belonging to 12 Anopheles species was analyzed. The host preference of anophelines observed in this study was bovine (86.17%), human (1.84%), cat (0.46%) and pig (0.46%). Only 6.91 % was positive for both human and bovine. In addition 5.0 % of the total samples tested were unknown. The overall HBI and HFI in the present study were low indicating the humans were not the preferred host for the tested anopheline species. Nevertheless, a small proportion engorged An. aconitus (0.37), An. culicifacies (0.27), An. barbirostris (0.2), An. annularis (0.125) and An. subpictus (0.12), An. peditaeniatus (0.08), An. pseudojamesi (0.04) and An. barbumbrosus (0.04) contained human blood, The FRs for human were <1.0 for most of the anophelines, except An. aconitus (1.04). Conclusion: The presence of human blood, in mosquito species indicates the possibility of them transmitting malaria. Hence, further studies on vector competence are needed to determine the role of each of the above anopheline species currently as efficient vectors of malaria.
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%).
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.
Characterization of a Dengue Positive Population in Colombo Municipal Council (CMC) Medical Officer of Health (MOH), Colombo
(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2016) Lakmal, M.G.K.; Udayanga, N.W.B.A.L.; Gunathilaka, P.A.D.H.N.; Fernando, S.D.; Karunathilaka, K.; Abeyewickreme, W.
Dengue that has caused 29,777 suspected infections in 2015 has emerged the most challenging health issue faced in Sri Lanka. Approximately 51% of dengue infections are reported from the Western Province. The susceptibility of a population to dengue is influenced by a combination of socio-economic, environmental and epidemiological factors. The current study was conducted to characterize a population of dengue patients residing in a high dengue risk area in terms of their socio-economic appearance. An interviewer administrated questionnaire was used to collect information on the socio-economic aspects of a group of 140 randomly selected dengue positive patients residing in Colombo Municipal Council (CMC) Medical Officer of Health (MOH) area. Out of 140, a majority (63.6%, n=89) were females, while the age groups of 31-40 and 21-30 years were recognized as the most susceptible age groups for dengue. High proportion of the patients (79.3%, n=111) were having an educational level below secondary school (O/L) with a total family income below 20,000 LKR (80.7%, n=113). All the homesteads were smaller (<5 perch) in size, with small roads for access (77.1%, n=108) and/or a footpath (22.9%, n=32) as the access route. Majority of the households (69.3%, n=97) were temporary with moderate conditions (51.4%, n=72), that were mainly utilized for both residential and commercial purposes (63.5%, n=89) at once. In a majority of households’ solid waste was disposed within 7 days (62.1%) via the Municipal Council or by keeping near the main roads (37.9%). Source separation of waste, home gardening and composting by the study population was minimal (n=137, 97.9%). Pipe water remained as the only water source while approximately 27.9% (n=39) households were lacking sanitary facilities. Use of mosquito coils and bed-nets were the most preferred mosquito biting prevention methods. Low educational level, income, poor living conditions and limitations in solid waste disposal methods were recognized as potential risk factors for high infection rates of dengue in this population. Special focus should be given to these key areas by the relevant vector controlling authorities in order to facilitate controlling of dengue outbreaks within the CMC area.
Characterization of Anopheline larval habitats and species composition of aquatic macro-invertebrates in Trincomalee District, Sri Lanka
(Faculty of Graduate Studies, University of Kelaniya, 2015) Ranathunga, R.M.T.B.; Gunathilaka, P.A.D.H.N.; Kannangara, D.N.; Abeyewickreme, W.; Hapugoda, M.D.
Malaria control methods that aim to reduce adult vector populations by targeting their aquatic immature stages. A better fundamental understanding of the biology and ecology of these essential stages could contribute to the implementation of current control methods and to the development of novel strategies. Objective of this study was to examine breeding habitat diversity and analysis of richness, diversity and geographical distribution of Anopheline larvae and the species composition of aquatic macro-invertebrates in their oviposition sites in Trincomalee District. Fifteen major permanent breeding places in five possible malaria sensitive sites (Gomarankadawala, Ichchallampaththu, Mollipothana, Padavisiripura and Thoppur) in Trincomalee District were selected. Anopheles larvae and macro-invertebrates were collected using standard methods for 16 months (April, 2013-July, 2014) and they were identified microscopically. The Shannon diversity index (H') was used to characterize species diversity at the five study sites by its abundance and evenness of the species present. ANOVA were used to analyze the correlation between macro-invertebrates and mosquito larval abundance. In total, 4478 including 11 species of Anopheles larvae were identified. An. subpictus, An. nigerrimus and An. peditaeniatus (71%) were the most abundant and widely-distributed species. Anopheline larval diversity was highest in Mollipothana (H‘=1.986). Whereas in Gomarankadawala, Ichchallampaththu and Thoppur where H‘=1.721, H‘= 0.857 and H‘=0.762 respectively. In total, 28 species of aquatic macro-invertibrates were identified and highest diversity was recorded in Mollipothana, Gomarankadawala and Ichchallampaththu (H‘=3.14-2.56). This deduces that the species richness and diversity of Anopheles mosquitoes and macro-invertebrates are higher in these areas. The presence of permanent breeding places may be the factors for this phenomenon. This study represents the first systematic update to the distribution of macro-invertebrates associated with Anopheles mosquito oviposition sites in Trincomalee District. Knowledge generated on the ecology of Anopheles mosquitoes will help to eliminate malaria vectors in the country.
Characterization of the sibling species status of Anopheles culicifacies breeding in polluted water bodies in Trincomalee District of Sri Lanka
(Sri Lanka Association for the Advancement of Science, 2015) Gunathilaka, P.A.D.H.N.; Prashath, K.; Abeyewickreme, W.
Anopheles culicifacies, the major vector of malaria in Sri Lanka, is known to breed in clean and clear water. However, recent findings have confirmed breeding in waste water containing drains. However, no study has been conducted to identify whether it is vector or non vector siblings. Therefore, the objective of the study was to identify the sibling species status of An. culicifacies breeding in waste water containing drains. An. culicifacies adult samples (Reared from larvae) were obtained from the Padavisiripura Entomological team attached to Tropical and Environmental Diseases and Health Associates (TEDHA) Malaria Elimination Program in the Trincomalee District. The collected mosquito specimens were processed for the extraction of genomic DNA individually. The PCR amplifications were carried out using different primer combinations for differentiating species A from D, species B from C, species B from E, and species B, C, and E from each other. The results obtained from the gel electrophoresis were compared with the marker, and band sizes of 359 bp, 248 bp, 95 + 248 bp, 166 + 359 bp and 178 + 248 bp were used to identify the sibling species A, B, C, D and E respectively. The molecular biological identification of the field caught An. culicifacies samples indicated that only 6.25% (1/16) represented sibling species B. About 93.75% (15/16) of the samples were An. culicifacies sibling species E. According to the results, the majority of the species belongs to sibling species E which is considered as the vector sibling species of An. culicifacies. This is the first time that An. culicifcicies E breeding in waste water was confirmed by a molecular method. However, malaria control programs focus on rural communities as a result of bio-ecology of Anopheles mosquitoes. Therefore, unusual breeding habitats such as waste water collections may mislead the current vector controlling programs. These results reconfirm that An. culicifacies has adapted to breed in water bodies including waste water collections. Since a majority of them belong to sibling E, which is considered as the vector, this may adversely affect the current malaria elimination program. Therefore, new strategies should be adopted to control malaria vector breeding in these unusual breeding habitats under the current malaria elimination program in Sri Lanka.
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.
Demographical characterization of dengue infected patients in Akurana medial officer of health area
(central Province of Sri Lanka, University of Sri Jayawardnapura, Sri Lanka., 2015) Udayanga, N.W.B.A.L.; Gunathilaka, P.A.D.H.N.; Iqbal, M.C.M.; Kusumawathie, P.H.D.; Najim, M.M.M.; Amarasingha, U.S.; Abeyewickreme, W.
Dengue has been recognized to be one of the major threats on the public health of many tropical countries including Sri Lanka. Controlling of the high rate of mortality caused by dengue, which remains without being altered regardless of the immense efforts and control strategies of the relevant authorities, has remained as a major challenge for the Sri Lankan health sector. Vulnerability assessment of communities to dengue infection is of higher importance in drafting and implementation of management plans to ensure effective management and controlling of dengue epidemics at the regional scale. Therefore, a statistic based analysis of the dengue patient characteristics was carried out to determine the susceptibility of population to dengue infection in Akurana Medical Officer of Health (MOH) area. Monthly records of reported dengue cases from 2010 to 2014 of the Akurana MOH division were collected. Normal Chi square test coupled with Paired-Chi square test was devised to investigate the impact of sex and age on the infection. MINITAB (version 14.12.0) software package was used for statistical analysis. In accordance with the results of the normal Chi square test, the Percentage Infected Male: Female Ratio (PIMFR) remains significantly altered throughout the period of study (p=0.001 61 (1.84%). However, according to the Paired-Chi square test, the vulnerability of age groups tend to shift significantly throughout the study period [>Χ2 (7, 0.95) = 14.067]. In conclusion males tend to indicate relatively high susceptibility to dengue. Age groups of 6 - 10, 11 - 20 and 21 - 30 could be recognized as highly vulnerable age groups in the community for dengue, while age group of >61 emerge as the least vulnerable age group for the infection of dengue in the Akurana MOH.
Dengue Encephalitis with Concurrent Infections by Multiple Dengue Virus Serotypes
(International Postgraduate Research Conference 2019, Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2019) Jayarathne, J.A.J.C.; Wijesinghe, W.A.T.A.; Mendis, S.; Waidyasekara, J.; Gunathilaka, P.A.D.H.N.; Gunasekara, D.
Dengue is a serious public health problem caused by an arbovirus. Abnormal-neurological presentations associated with dengue infection is rare. Herewith, we report a case of a patient with dengue encephalitis who was concurrently infected with multiple serotypes. A 36-year-old, male resident from Poogoda presented to North Colombo Teaching Hospital with a history of generalized tonic-clonic seizures (GTCS) and unconsciousness. On admission, he displayed only a persisting headache. He had no significant illnesses in the past. Detailed history revealed that he has had a fever and left the hospital against the medical advice on the same day. On clinical examination, he was afebrile and blood pressure was 110/80 mmHg. He was well oriented with a Glasgow Coma Scale (GCS) of 15/15 and there was no focal neurological deficit. The funduscopic examination was normal. His initial full blood count revealed a rise in white blood cells with a predominant elevation of neutrophils of 12.44 x 103/uL. His platelet count was reported to be 306 x103/uL and, he was treated for a bacterial infection. On the following day, the patient started developing a fever and GTCS. Aggressive behavior, confusion, and delirium were also demonstrated. Neck stiffness was not observed. Non-contrast computed tomography (NCCT) scan, contrast-enhanced computed tomography (CECT) scan, chest X-ray scan and magnetic resonance image (MRI) of the brain were normal. Electroencephalography (EEG) revealed encephalopathy with non-epileptic discharge. Lumbar puncture was performed on the third day of admission and analysis of cerebrospinal fluid (CSF) was unremarkable. IgM antibody for the dengue virus (DENV) was detected in CSF. All the other viral and parasitological studies were normal. The patient was treated with anti-epileptic, anti-psychotic, antibacterial and antiviral drugs. High fever spikes and seizures were continued. GCS started to deteriorate from 9/15 to 3/15. Urine out-put started to decline. Ultra-sound scanning revealed mild ascites. Blood picture analysis showed evidence of having a severe bacterial infection. On day 9, both CSF and serum specimens were referred to Molecular Diagnostic Laboratory, Faculty of Medicine, Ragama for dengue viral investigations. The presence of NS-1 antigen, IgM/IgG antibodies, and the occurrence of concurrent infections with serotype 2 and 3 in the serum sample confirmed that the patient was infected with DENV. The presence of IgM/IgG antibodies were observed in the CSF sample. On day 10, the patient was transferred to the medical intensive care unit and monitored thoroughly. As the condition was deteriorated, he was ventilated and incubated for 11 days in the intensive care unit. He started to recover gradually after the 31st day. On day 36, the patient was discharged without any residual neurological symptoms. The patient is currently being followed up at the neurological clinic. Dengue encephalitis is a rare and deleterious manifestation of dengue infection. It is believed that concurrent infections with multiple serotypes and serotype replacement may cause disease severity. Therefore, reporting uncommon cases will provide insights for the physicians in early diagnosis and effective management
Dengue risk based on sociocultural/socioeconomic geographic factors in Kelaniya MOH area
(Research Symposium 2009 - Faculty of Graduate Studies, University of Kelaniya, 2009) Nadeeka, P.V.J.; Amarasinghe, L.D.; Gunathilaka, P.A.D.H.N.; Madushani, I.L.D.
THIS STUDY INVOLVES GEOGRAPHIC, SOCIOCULTURAL AND SOCIOECONOMIC ANALYSIS CONDUCTED FOR THE YEAR 2008 DENGUE FEVER OUTBREAKS IN KELANIYA MEDICAL OFFICER OF HEALTH (MOH) AREA. LOCATIONS OF THE RESIDENCE OF THE 120 DENGUE CASES REPORTED AT KELANIYA MOH OFFICE WERE OBTAINED USING GPS. A STRUCTURED QUESTIONNAIRE THAT INCLUDED 16 OF PRIMARY DATA WAS GIVEN TO EACH PATIENT HOUSEHOLD AFTER VISITING INDIVIDUAL OF THEM AT RESIDENCE. GEOGRAPHIC ATTRIBUTES RELATED TO DENGUE INCIDENCE WERE RECORDED CONCURRENTLY. PRIMARY DATA INCLUDED FAMILY DETAILS, AGE AND GENDER OF THE FAMILY MEMBERS, LIVING CONDITIONS, AWARENESS AND KNOWLEDGE ABOUT DENGUE, HEALTH CARE, HUMAN DWELLINGS, OCCUPATIONAL STATUS, MOSQUITO PROTECTION PRACTICES, ACCESSIBILITY BY ROAD, SANITATION PRACTICES, WASTE DISPOSAL MANAGEMENT AND FREQUENCY, CULTURAL PRACTICES REGARDING STORAGE OF WATER CONTAINERS, VEGETATION COVER AROUND THE HOUSES, AND INDOOR /OUTDOOR AEDES MOSQUITO BREEDING PLACES. MOSQUITO LARVAE COLLECTED FROM BOTH INDOOR AND OUTDOOR POOLS WERE REARED UNTIL ADULTS ARE EMERGED IN THE LABORATORY. RESULTS REVEALED THAT 86% HOUSEHOLDS HAVE PERMANENT RESIDENCE. PERCENTAGE INFECTED MALE: FEMALE RATIO WAS 48%: 52% WHICH IS NOT SIGNIFICANTLY DIFFERENT. THE VULNERABILITY OF THE AGE GROUPS FOR DENGUE FEVER WERE FOUND AS 1-5 YRS (24%), 6-18 YRS (44%), 19-55 YRS (24%) AND MORE THAN 55 YRS (3%). THE ADULT MOSQUITO POPULATION CONTAINED 77.6% OF AEDES ALBOPICTUS ATTAINING INDOOR (20.7%) AND OUTDOOR (79.3%) BREEDING SITES WHILE 22.4% OF AE. AEGYPTI ATTAINING INDOOR (38.6 %) AND OUTDOOR (61.4%) BREEDING SITES. ONLY 32% OF HOUSE PREMISES WERE DENSELY COVERED WITH VEGETATION. RECORDED DENGUE CASES AND GEOGRAPHIC FACTORS WERE LINKED TO A GIS DATABASE AND PRESENTED IN DIGITIZED MAPS TO SHOW DENGUE RISK FACTORS IN KELANIYA MOH AREA.
Designing of immunogenic peptides from Dengue Virus NS1 region for production of monoclonal antibodies as diagnostic intermediates
(Molecular Medicine Unit, Faculty of Medicine, University of Kelaniya, Sri Lanka, 2015) Munasinghe, M.M.E.; Chandrasekharan, N.V.; Korbakis, D.; Soosaipillai, A.; Diamandis, E.P.; Athapaththu, A.M.M.H.; Gunathilaka, P.A.D.H.N.; Abeyewickreme, W.
BACKGROUND: Small peptide antigens have become an essential tool for antibody production in the recent life science research applications. The immunogenicity of peptide antigens is a critical factor to induce the immune response in order to produce desired antibodies. METHODS: In the current study, we have previously determined four Dengue (DEN) serotype specific peptides, containing 28 Amino Acid (AA) residues were re-designed. The peptides were re-designed considering many factors, for instance, sequence of the Sri Lankan isolates, abundance of Cysteine residues, solubility and the length of the peptide, carrier protein to be used and several other factors such as the N-terminal and C- terminal AAs and multiple AA residues. The peptide sequences were analysed using Antigen Profiler Peptide Tool (Thermo-scientific), Peptide Property Calculator (Genscript) and Swiss-Model (Biozentrum). RESULTS: The protein sequence of the peptides were changed according to the Sri Lankan isolates (AEB98757.1, ACS32038.1, AHG23239.1 and AHN50410.1). Oxidation of Cysteine residues results in significant conformational changes. Replacement of Cysteine with Serine prevents such oxidation reactions and it often retains full biological activity. Generally, peptides with a high number of hydrophobic AA (>50%) may result insoluble peptides. Similarly, to obtain a soluble peptide, it is important to contain at least one charged AA in every five AAs. Hence, the number of hydrophobic residues in the peptides were maintained below 50% and ensured that one out of every five amino acids is charged. The length of the peptide is an important factor as long peptide increases immunogenicity, but also increases the chance for cross-reactivity while a short peptide improves the specificity, but may not be immunogenic. In order to obtain both highly conserved and variable regions among four serotypes, the peptide length was determined as 29 residues. A terminal Cysteine was added to allow peptide conjugation with carrier protein. Keyhole Limpet Hemocyanin was selected as the carrier protein due to its higher immunogenicity. N-terminal Glutamine or Aspargine and C-terminal Proline or Glycine in the sequences were avoided. Finally, the peptides sequences were determined as: DEN1; CPESSDDQRA WNIWEVEDYGFGIFTTNIW,DEN2; CAESPN TNRA WNSLEVEDYGFGVFTTNIW, DEN3;CPESPSASRAWNVWEVEDYGFGVFTTNIW and .DEN4;CSESPNERRAWNSLEVEDYGFGMFTTNIW. CONCLUSION: These peptides have a high potential to be used as peptide antigens for Monoclonal Antibody production.
A determination of air pollution in Colombo and Kurunegala, Sri Lanka, using energy dispersive X-ray fluorescence spectrometry on Heterodermia speciosa
(The Scientific and Technological Research Council of Turkey, 2011) Gunathilaka, P.A.D.H.N.; Ranundeniya, R.M.N.S.; Najim, M.M.M.; Seneviratne, S.
ABSTRACT: Sri Lanka is facing severe environmental problems such as air and water pollution due to rapid industrialisation and urbanisation. Because there have not been many studies on heavy metal pollution in Sri Lanka, the present study attempts to contribute to the literature a determination of metal pollution using indicators found in lichen specimens. Our study utilised energy dispersive X-ray fluorescence spectrometry to determine element concentrations resulting from air pollution in the lichen species Heterodermia speciosa Wulfen. These samples, collected from Colombo and Kurunegala, Sri Lanka, were analysed using the energy dispersive X-ray fluorescence (EDXRF) method in order to determine the concentrations of 13 different elements. A radioisotope excited X-ray fluorescence analysis was applied to the elemental analysis of lichens using the method of multiple standard addition. Our qualitative analysis of spectral peaks showed that the samples contained potassium, calcium, titanium, iron, manganese, copper, zinc, lead, bromine, rubidium, strontium, yttrium, and gallium. Samples from the environment around Colombo, which is a highly congested urban area with much industrial development, were found to be more polluted when compared with Kurunegala, a city that is less congested and without industries. Concentrations of K, Ca, Ti, and Fe were always higher than other elemental concentrations in the lichens we analysed, a fact attributed to the proximity to the sea or exposed earth crustal sources. From the elements reported from the 2 cities, K, Ca, Ti, Fe, Mn, Zn, and Pb were reported at concentrations higher than background levels. Levels of Pb and Zn in samples from Colombo were higher than those from Kurunegala, reflecting the increased vehicular traffic. This study reveals that the common lichen species Heterodermia speciosa can be used as an indicator lichen to analyse the pollution level and other elements in the atmosphere. © TÜBITAK. AUTHOR KEYWORDS: Air; EDXRF; Heterodermia; Lichens; Metal pollution. INDEX KEYWORDS: atmospheric pollution; concentration (composition); fungus; heavy metal; lichen; radionuclide; spectrometry; urban area; X-ray fluorescence, Colombo; Sri Lanka; Western Province [Sri Lanka], Heterodermia; Heterodermia speciosa
Determination of appropriate positioning of the ovitraps for dengue mosquito surveillance
(Faculty of Graduate Studies, University of Kelaniya, 2015) Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S.; Chandrasena, T.G.A.N.; Dassanayake, R.S.; Gunathilaka, P.A.D.H.N.; Abeyewickreme, W.
Three months ovitrap survey was conducted to assess the suitable position in placing the ovitraps for dengue vector mosquito surveillance and this study was initiated due to loss of valuable data from our previous studies as a result of physical damage of the ground kept ovitarps. Thirty four households in the Ragama Medical Officer of Health area in Gampaha District were selected to conduct the ovitrap survey during the period of May to July, 2015 to select the most appropriate positioning of the ovitrap. The conventional black plastic ovitraps (3.2x 2.7 cm) were used in this purpose to collect aquatic stages of Aedes mosquitoes while placing plywood paddle (4 x 0.5 cm) over the upper rim of each coded ovitrap. A total of 136 ovitraps were used in the study site providing four ovitraps (2 each indoor & outdoor) for each house while one of the ovitraps of indoor and outdoor being hung and other being kept on the ground. In positioning ovitraps, the outdoor ones were kept 3m away from the house while leaving indoor ovitraps in the living room in close proximity to racks/hanging clothes or partially shaded places. Following collection of samples at each week, ovitraps were washed thoroughly, refilled with new water and a new paddle, and corresponding data were recorded and analyzed. These analyses revealed that number of larvae and the number of Aedes mosquito eggs present in the two different ovitrap positions (Ground kept vs Hung) were not significantly different; in spite of significant difference (P=0.001) between the outside and inside placements. Further, significantly higher values were observed for both number of mosquito eggs and larvae present in each ovitrap kept outside (60 and 13 respectively) than those placed inside (32 and 3 respectively). Furthermore, slightly higher values were observed for hung ovitraps (49 and 9 respectively) than ones kept on the ground (43 and 7 respectively). Finally, ovitrap placed above the ground level was selected in continuing the routine ovitrap survey, as there was considerable reduction of mechanical damage to the latter thus facilitating continuous data collection.