Medicine

Permanent URI for this communityhttp://repository.kln.ac.lk/handle/123456789/12

This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty

Browse

Search Results

Now showing 1 - 10 of 26

Occurrence of major and potential malaria vector immature stages in different breeding habitats and associated biotic and abiotic characters in the district of Trincomalee Sri Lanka
(New Delhi : National Institute of Malaria Research, 2020) Ranathunge, R.M.T.B.; Kannangara, D.N.; Gunathilaka, P.A.D.H.N.; Abeyewickreme, W.; Hapugoda, M.D.
BACKGROUND & OBJECTIVES: Understanding the effect of biotic and abiotic factors on the biology and ecology of immature stages of anopheline larvae is very important in controlling malaria vector mosquitoes. Therefore, this study was focused on the monitoring of ecological factors affecting the distribution, dynamics, and density of malaria vector mosquitoes in the District of Trincomalee, Sri Lanka. METHODS: Permanent and temporary breeding habitats were identified and selected from five possible malaria sensitive sites in the district of Trincomalee. Anopheles larvae and macro-invertebrates were collected using standard methods for 16 months (from October 2013 to January 2015) and they were identified microscopically. Eight physico-chemical parameters of the breeding habitats were measured. RESULTS: Overall, a total of 4815 anopheline larvae belonging to 13 species were collected from 3,12,764 dips from 18 permanent and temporary breeding habitats. The abundance of anopheline larvae showed a significant positive correlation (p <0.05) with physico-chemical parameters in breeding habitats, such as temperature, dissolved oxygen, and turbidity. A total of 35 macro-invertebrate taxa were collected from the anopheline mosquito breeding habitats. INTERPRETATION & CONCLUSION: This study represents the first systematic update of water quality parameters, macro-invertebrate communities associated with Anopheles mosquito oviposition sites in the District of Trincomalee, Sri Lanka. Rainfall intensity and wind speed are critical meteorological factors for the distribution and abundance of malaria vectors. Knowledge generated on the ecology of Anopheles mosquitoes will help to eliminate malaria vectors in the country. KEYWORDS: Macro-invertebrates; Sri Lanka; malaria vectors; physico-chemical parameters.
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.
The Diversity of Human Dirofilariasis in Western Sri Lanka
(Hindawi Pub. Co, 2019) Chandrasena, T.G.A.N.; Premaratna, R.; Mallawaarachchi, C.H.; Gunawardena, N.K.; Gunathilaka, P.A.D.H.N.; Abeyewickrama, W.Y.; de Silva, N.R.
BACKGROUND:Human dirofilariasis is an emerging zoonosis in many countries. Dirofilariasis caused by Dirofilaria repens may present with diverse clinical manifestations in humans due to aberrant localization of worm lesions causing diagnostic dilemmas. The aim of this retrospective study was to describe and update the demography and clinical spectrum of human dirofilariasis in western Sri Lanka. Nematode or nematode fragments isolated from excision biopsies that were confirmed as D. repens at the Department of Parasitology, Faculty of Medicine, University of Kelaniya, Sri Lanka, between 2012 and 2018 were included. Data on age, gender, and clinical details were obtained from case files. Identity of worms was established by morphometry and cuticle characteristics on wet-mount preparation. Specimens from unusual case presentations were further analyzed by PCR with specific primers for internal transcribed spacer region 2 (ITS2) of the ribosomal DNA. RESULTS:Sixteen nematode specimens isolated from subconjunctiva (n=2), subcutaneous (n=13) and intramuscular (n=1) locations were identified as D. repens by morphometry (average length 11.5 cm) and the characteristic longitudinal striations on cuticle visualized by microscopy. The age distribution of cases ranged from 1 to 65 years with a mean of 21.5. Females were more frequently affected (n=10, 62.5%) and worm locations were commonest in the orbital region (5/16) and scrotum (3/16). Imaging techniques were of use in detecting infections in deeper tissue levels. PCR analysis of DNA extracted from a worm in an intramuscular granuloma of the temporal region elicited the expected band at 484bp for D. repens. CONCLUSIONS: Human dirofilariasis is on an upward trend in incidence. Imaging techniques were of use in clinical diagnosis and molecular speciation in establishing the species identity in unusual case presentations. We suggest a more conservative approach in the management of human dirofilariasis and recommend a one health approach for control.
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
A Statistical Approach to Define Thresholds for Dengue Epidemic Management in Akurana Medical Officer of Health Area, Kandy District of Sri Lanka
(19th Conference on Postgraduate Research, International Postgraduate Research Conference 2018, Faculty of Graduate Studies,University of Kelaniya, Sri Lanka, 2018) Udayanga, N.W.B.A.L.; Gunathilaka, P.A.D.H.N.; Iqbal, M.C.M.; Fernando, M.A.S.T.; Abeyewickreme, W.
Stegomyia indices, namely; Premise Index (PI), Breteau Index (BI) and Container Index (CI) are used forvector management approaches in Sri Lanka. Properly defined threshold values for larval indices are of higher importance to provide forecasts on dengue epidemics and also for effective larval management of dengue vectors. However, such critical thresholds are poorly defined for Sri Lanka. The present study aimed to define threshold values forabove larval indices for dengue epidemic management in the Akurana Medical Officer of Health (MOH) in the Kandy District. Larval surveys were conducted on a monthly basis from January, 2016 to June, 2018. Four larval indices, namely BI for Aedesaegypti (BIA) and Aedesalbopictus (BIB), PI and CI were calculated. Further, monthly larval indices of AkuranaMOH area from January, 2012 to December, 2015, were obtained from the MOH office, along with monthly reported dengue cases for the entire study period. Receiver Operating Characteristic (ROC) curves in SPSS (version 23) were used to assess the discriminative power of the larval indices in determiningdengue epidemics and thresholds based on larval indices. As indicated by the area of ROC curve (AUC), the BIA (0.661) and PI (0.637) were having a notable discriminative power to forecast dengue epidemics at a two-month lag period. Both BIB (0.397) and CI (0.526) were non-informative influencers at one and two-month lag periods. The BIA and PI were better predictors of dengue incidence than BIB and CI. Based on the ROC curve, three risk thresholds were defined for BIA as Low Risk (BIA≤2.1), Moderate Risk (3.9≤BIA<4.85), and High Risk (BIA≥4.85), with respect to Ae. aegypti. According to the PI, thresholds were defined as Low Risk (PI≤6.2), Moderate Risk (7.7≤ PI<9.9), and High Risk (PI≥ 9.9). Threshold values defined for BI of Ae. aegypti and PI, could be recommended to be considered in implementing vector control efforts in the above study area for effective dengue epidemic management, through pre planned entomological management of dengue vectors.
Intestinal and Ectoparasites of Human Health Importance among Stray Dogs in Galle District, Sri Lanka.
(19th Conference on Postgraduate Research, International Postgraduate Research Conference 2018, Faculty of Graduate Studies,University of Kelaniya, Sri Lanka, 2018) Rathnayake, S.P.; Sudusinghe, H.P.; Nilaweera, T.H.W.T.; Marasinghe, M.A.P.; Sriyalatha, W.A.; Gunathilaka, P.A.D.H.N.
Human-animal bond is a reciprocally favorable dynamic relationship which is beneficial to the health and well-being of both. Dogs have close contact with humans and play a pivotal role as definitive hosts or reservoirs for different zoonotic parasites, especially in developing countries. There are only few studies have focused on the zoonotic potential of animals in Sri Lanka. Therefore, the objective of the present study was the determine the intestinal and ectoparasites among dog population that may be important for human health. A total of 40 stray dogs captured for an animal welfare clinic conducted in Galle District of Sri Lanka was recruited for the study. Faecal samples were collected per rectal in to separate vials containing 10% formaldehyde. Ectoparasites of selected dogs were collected using a lose comb and stored in alcohol solution. The stool samples were processed by Kato-Katz techniques and intestinal parasitic stages were morphologically identified. For quantitative analysis, the modified McMaster technique was used to estimate eggs per gram of feces. The ectoparasites were characterized referring to morphological features. The results revealed eight intestinal parasites namely; Ancylostomacaninum (Prevalence: 66.75%; Eggs per gram: 362.82), Toxocaracanis (13.51%; 73.41), Enterobiusvermicularis (9.1%; 49.41), Trichurisvulpis (7.0%; 38.12), Physalopterarara (1.56%; 8.47), Paragonimuskellicotti (1.0% 5.65), Uncineriastenocephala (0.78%; 4.24) and Eucoleusaerophilus (0.26%; 1.41). The high prevalence rates of T. canis may cause visceral and ocular larva migrans to humans, which lead to blindness and A. caninum associated with hookworm related cutaneous larva migrans. Humans can be infected with T. vulpis when they accidentally ingest embryonated eggs, through contamination of infected soil, food or fomites even though it has been recorded as a rare infection. P. rara infection can be caused to humans by the accidental ingestion of arthropod hosts such as German cockroaches. In addition, the P. kellicotti, U. stenocephala, E. aerophilus and E. vermicularis may cause some health issues to humans. Even though present study did not indicate the presence of Echinococcusgranulosus which resides in the small bowel of dogs and other canids may lead to cause echinococcosis in humans. Argaspersicus (Prevalence; 34.18%) was the predominant among ectoparasites followed by Ctenocephalidescanis (32.91%) and Ixodesscapularis (32.91%). A. persicus can cause serious allergies on humans. The bites of I. scapularis may lead to cause human babesiosis (Babesiamicroti), human granulocytic ehrlichiosis (HGE); and tick-borne encephalitis (TBE). The presence of C. canis may indicate the transmission potential of Dipylidiumcaninum to humans as an occasional host. Overall, the investigation indicated that stay dogs in Galle District contain a multitude of ectoand endoparasites, thus posing a risk for the human population.
Efficacy of blood sources and artificial blood feeding methods in rearing of aedes aegypti (Diptera: Culicidae) for sterile insect technique and incompatible insect technique approaches in Sri Lanka
(Hindawi, 2017) Gunathilaka, P.A.D.H.N.; Ranathunge, T.; Udayanga, L.; Abeyewickreme, W.
INTRODUCTION: Selection of the artificial membrane feeding technique and blood meal source has been recognized as key considerations in mass rearing of vectors. METHODOLOGY: Artificial membrane feeding techniques, namely, glass plate, 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 Aedes aegypti. Significance in the variations among blood feeding was investigated by one-way ANOVA, cluster analysis of variance (ANOSIM), and principal coordinates (PCO) analysis. Results. Feeding rates of Ae. aegyptisignificantly 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 from the mosquitoes fed with cattle and human blood, in terms of fecundity, oviposition rate, and fertility as suggested by one-way ANOVA (p>0.05). CONCLUSIONS: Metal plate method 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. Cattle blood could be recommended for mass rearingAe. aegypti.
Evaluation of the spatial and temporal trends of dengue outbreaks in Akurana, Central Province, Sri Lanka
(Sri Lanka Association for the Advancement of Science, 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.; Amerasinghe, U.S.; Abeyewickreme, W.
Renowned as the world's fastest growing vector borne disease, dengue has become one of the major health issues in Sri Lanka leading to an alarming concern due to recent outbreaks throughout the country. Despite the immense efforts taken by the relevant authorities to reduce the rate of mortality, the average number of dengue cases recorded in each year remains around 30,000-35,000 without being changed significantly over time in Sri Lanka. Investigation of the trends in spatial and temporal distribution patterns of dengue is often treasured in the drafting and implementation of management/action plans to ensure effective management of dengue epidemics at regional scale. Thus, a statistical and geo informatics based analysis of the recent trends in dengue distribution was carried out to identify spatial and temporal trends in distribution patterns of Dengue in the Akurana Medical Officer of Health (MOH) area. Monthly records of reported dengue cases from 2010 to 2014 of the Akurana MOH area were obtained and were subjected to a scatter plot analysis in MINITAB (version 14.12.0) to identify the temporal patterns in the recorded dengue cases. Spatial maps of the recorded dengue case distribution in each GND for each month and for the whole study period were prepared by using Arc GIS 10.1. The spatial and temporal variations of dengue outbreak distribution within the Akurana MOH (at GND level) were analyzed to identify the recent trends in dengue incidence. Akurana, Bulugahathenna, Dippitiya, Dunuwila, Konakalagala and Neeralla localities could be identified as areas with relatively high risk to dengue outbreaks throughout the study period, while localities such as Balakanduwa, Delgasgoda, Delgasthenna, Malgamandeniya, Marahela, Palleweliketiya and Udawelikatiya emerged as areas with low risk. As suggested by the results of the paired-Chi square test [>Χ2 (30, 0.95) = 43.773], the emergence of dengue outbreaks indicated a significantly declining trend of recorded dengue cases in most of the GNDs (Aswadduma, Delgasgoda, Kurugoda, Malgamandeniya, Palleweliketiya and Walahena etc.) during the recent years. The evaluation of the trends in temporal and spatial distribution of dengue outbreaks at the localized level, could be recommended as a useful tool in the planning and implementation of action plans to control the rise of dengue, while evaluating the efficacy of already implemented control measures at regional scale.
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.
Emerging spatio-temporal trends of dengue incidence in Colombo and Kandy Districts, Sri Lanka
(Moleclar Medicine Unit, Faculty of Medicine, University of Kelaniya, Sri Lanka, 2015) Udayanga, N.W.B.A.L.; Gunathilaka, P.A.D.H.N.; Iqbal, M.C.M.; Kusumawathie, P.H.D.; Abeyewickreme, W.
BACKGROUND: Dengue has become a prominent challenge to the health sector in Sri Lanka. Prior identification/prediction of possible risk areas with high susceptibility to dengue, could be of major importance in ensuring the effective regulation of dengue epidemics. Therefore, the current study attempts to investigate the spatio-temporal trends in dengue incidence and priority risk factors that characterize dengue epidemics, aiming to stratify the Colombo and Kandy Districts into high, moderate and low risk areas via development of dengue risk maps by devising a statistical and geo-informatics based approach. METHODOLOGY: Socio-economic data of dengue patients and healthy volunteers in selected high risk MOH areas of Colombo (5) and Kandy (5) Districts were obtained through an interviewer administrated questionnaire. Previously reported dengue cases from 2009 to 2014 in each MOH were acquired. The spatio-temporal trends in dengue incidence of studied MOHs, were investigated at the Grama Niladhari Division (GND) level by using Arc GIS (version 10.2). The impacts of gender and age of the community on the disease prevalence were investigated by using normal Chi square test and Paired-Chi square test in SPSS (version 23). RESULTS: At present, 95% and 81% of the overall socio-economic surveillance has been completed in Kandy and Colombo Districts, respectively. Spatial maps on disease outbreaks have been developed for Akurana, Doluwa, Gampola, Gangawatakorale, Kandy Municipal Council (KMC), Kundasale and Poojapitiya MOH areas. According to results of the Paired-Chi square test, the emergence of dengue outbreaks indicated a significantly declining trend in recorded dengue cases in most of the GNDs within the studied MOHs, during the recent years. The Percentage Infected Male:Female Ratio (PIMFR) remained significantly altered throughout the period of study (p=0.001<0.05 at 95% of significance). Within the studied MOHs, males tend to indicate relatively high susceptibility for dengue infection than females (with 58.6: 41.5 of average PIMFR). The age group of 11 – 20 and 21 – 30 years were identified as with highest vulnerability to dengue, while the age > 61 years indicated the least vulnerability in all the MOHs. According to the Paired-Chi square test, the vulnerability of age groups was found to shift significantly throughout the study period [>Χ2 (7, 0.95) = 14.067]. CONCLUSIONS: The KMC and Gampola MOHs indicate relatively high susceptibility to dengue within the district of Kandy. Within all the studied MOHs, males tend to indicate relatively high susceptibility to dengue. Age groups of 11 - 20 and 21 – 30 denote relatively higher vulnerability to dengue, while age group of > 61 emerge as the least vulnerable group for the infection of dengue in the studied MOHs.

Medicine

Browse

Filters

Settings

Sort By

Results per page

Search Results