Medicine
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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty
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Item Symptoms of dengue at the acute and post-infection stage in the Western Province, Sri Lanka: A cross-sectional study(Wolters Kluwer Medknow Publications, 2019) Abeysena, C.; Peiris, S.; Welgama, I.; Gunasekara, U.; Wickramage, K.OBJECTIVE: To describe the symptoms of dengue at acute and post-infection stage and to identify preventive strategies adopted by the patients in the Western Province, Sri Lanka. METHODS: This was a descriptive cross-sectional study conducted in the Western Province of Sri Lanka in November 2017. The study population consisted of 473 confirmed dengue patients aged from 18 to 64 years who were hospitalized between June and August 2017. A stratified random sampling technique was applied to select the participants. Data collection was done by trained interviewers, using a structured, pre-tested interviewer-administered questionnaire. RESULTS: The most common symptoms of dengue fever at the acute stage was body ache (81.81%, n=387), followed by headache (71.67%, n=339), loss of appetite (66.80%, n=316), tiredness (53.06 %, n=251) and vomiting (41.86%, n=198). The most common symptom during the post-infection stage was body ache (48.62%, n=230), followed by fatigue (39.74%, n=188), and loss of appetite (28.75%, n=136). Adding sand to the water in places where water accumulates (41.64%, n=197) was the most common method used to prevent transmission of dengue followed by removing/draining stagnant water regularly (36.15%, n=177). Use of mosquito nets (83.08%, n=393) was the most common method in preventing mosquito bites followed by the use of fans among dengue patients (56.02%, n=265). CONCLUSIONS: The study shows a prolonged persistence of clinical symptoms during the postinfection period. KEYWORDS: Control, Dengue, Outbreak, Symptoms, Vector, VirusItem Effect of larval nutritional regimes on morphometry and vectorial capacity of Aedes aegypti for Dengue transmission(BioMed Research International, 2019) Gunathilaka, N.; Upulika, H.; Udayanga, L.; Amarasinghe, D.BACKGROUND: Nutritional level in larval diet of mosquito vectors influence on life history traits and vectorial capacity (VC). Therefore, the present study was carried out to assess the effect of larval diet concentration on vector bionomic and VC of Aedes aegypti in Sri Lanka. Method. Three batches of 400 Ae. aegypti larvae (first instar) were reared under different concentrations of larval diet (6%, 8%, and 10%; Volume/Volume), which was prepared by mixing 12.5 g of tuna meal, 9.0 g of bovine liver powder, and 3.5 g of Brewer’s yeast, in 100 ml of distilled water. The effect of larval diet concentration on different morphometric and functional parameters of larvae (length and width of head, abdomen, survival rate, and pupation success), pupae (length and width of cephalothorax, survival rate, and adult emersion), adult (length and width of thorax, abdomen, survival rate, longevity, biting frequency and fecundity of adults) were examined. In addition, VC of Ae. aegypti was evaluated. The General Linear Model (GLM) was used for the statistical analysis. Results. Larval head length, head width, thoracic width, abdominal length, abdominal width, total length, and survival rate significantly increased with higher doses of larval diet (P<0.05). In case of pupae, length, and width of cephalothorax, survival rate and adult emergence rate denoted an increasing trend with the elevated larval diets. However, the variations of survival rate and adult emergence rate were statistically significant (P<0.05). In adults, all morphometric parameters (thoracic length, abdominal length, abdominal width, and wing length) significantly increased with elevating larval diets levels (except for thoracic width) along with the biting frequency, fecundity, and survival rate (P<0.05) of adult females. The VC also denoted significant variations (F4,14 = 24.048; ) with the larval diet concentration, whereby the highest VC of 196.37 was observed at 10% treatment. Conclusion. Larval food availability has a significant influence on the adult fitness and thus may affect the incidence of dengue due to variations in the VC of Ae. aegypti. Hence, this investigation highlights the requirement in accounting the environmental variation at the larval stages in order to understand transmission dynamics and control of dengue in Sri Lanka.Item Level of Awareness of Dengue Disease among School Children in Gampaha District, Sri Lanka, and Effect of School-Based Health Education Programmes on Improving Knowledge and Practices.(Hindawi Pub. Co., 2019) Radhika, N. M. L.; Gunathilaka, N.; Udayanga, L.; Kasturiratne, A.; Abeyewickreme, W.INTRODUCTION:Limited awareness and nonsystematized health education programmes have contributed adversely to the increase in dengue incidence at schools due to limited attention which has positively contributed to the increase in vector receptivity. The current study was conducted to evaluate the existing level of awareness of dengue infection among a selected group of school children and to assess the effectiveness of dengue awareness programmes to improve the existing knowledge and preventive practices on dengue.METHODS:A cohort of 2,194 students (13-15 years old) from 10 schools at Kelaniya educational zone, Gampaha District, Western Province of Sri Lanka, was enrolled for the current study, which was conducted during 2015-2016. A self-administered questionnaire, comprising 20 questions, was used to evaluate the present knowledge of the students on various aspects of dengue. A structured awareness programme (2 hours) was conducted for students, followed by a reassessment. General Linear Model (GLM) and chi-square test of independence were used to investigate the variations in knowledge levels.RESULTS:The majority of students were characterized by "Good" (46.31%, n= 1016) and "Moderate" (42.62%, n= 935) awareness, while only 2.92% (n= 64) of students fell into the "Excellent" (>80%) category prior to the awareness programme. Even though, existing knowledge of students about dengue ranged between "Moderate" and "Good" categories, awareness of "symptoms & patient care" and "control & prevention practices" were limited. After the programme, the awareness level reached the "Excellent" (41.84%, n=918) level indicating a significant increase by 38.92%, according to the chi-square test (p<0.05 at 95% level of confidence).CONCLUSION:We recommend implementing school-based educational programmes in order to raise the awareness and to translate knowledge into sound practice to control dengue disease epidemics in these areas.Item Predatory efficacy of five locally available copepods on Aedes larvae under laboratory settings: An approach towards bio-control of dengue in Sri Lanka.(San Francisco, CA : Public Library of Science, 2019) Udayanga, L.; Ranathunge, T.; Iqbal, M. C. M.; Abeyewickreme, W.; Hapugoda, M.Many countries are in search of more effective and sustainable methods for controlling dengue vectors, due to undeniable inefficiencies in chemical and mechanical vector control methods. Bio-control of vectors by copepods is an ideal method of using interactions in the natural ecosystem for vector management, with minimum consequences on the environment. Current study determined the predatory efficacy of five locally abundant copepod species on, Aedes larvae under laboratory conditions. Copepods were collected from the pre-identified locations within the districts of Gampaha and Kandy, and identified morphologically. Individual species of copepods were maintained as separate colonies with Paramecium culture and wheat grain as supplementary food. Five adult copepods of each species was introduced into separate containers with 200 larvae (1st instar) of Aedes aegypti. Number of larvae survived in containers were enumerated at 3 hour intervals within a duration of 24 hours. Each experiment was repeated five times. The same procedure was followed for Ae. albopictus. Significance in the variations among predation rates was evaluated with General Linear Modelling (GLM) followed by Tukey's pair-wise comparison in SPSS (version 23). Significant variations in predation rates of studied copepod species were reported (p<0.05), whereby M. leuckarti indicated the highest followed by M. scrassus, while C. languides indicated the lowest predatory efficacy. The effect of different Aedes larval species on the predation rates of copepods remained significant (p<0.05), even though the effect on predatory efficiency was not significant. Based on the findings, both M. leuckarti and M. scrassus, with the highest predatory efficiencies, could be recommended as potential candidates for biological controlling of Aedes vectors in Sri Lanka.Item Evaluation of the effects of Aedes vector indices and climatic factors on dengueincidence in Gampaha District, Sri Lanka(Hindawi Publishing Corporation, 2019) Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S.; Chandrasena, T.G.A.N.; Dassanayake, R.S.; Udayanga, N.W.B.A.L.; Abeyewickreme, W.Constant monitoring of Aedes vector indices such as Aedes mosquito abundance and ovitrap data is important for the control of dengue epidemics. Therefore, the current study attempted to evaluate the effect of larval and climatic factors on the incidence of dengue outbreaks in the Gampaha district. Based on the distribution of previously reported dengue cases, 34 households in Narangodapaluwa PHI area, Ragama, Sri Lanka, were selected randomly, and entomological surveillance was done fortnightly using adult mosquito catches and larval surveillance techniques for a period of two years. Further, weekly ovitrap surveillance was conducted for one year, by maintaining four ovitraps in a single house, two indoors and two outdoors at ground and at a height of 1.5-2 m. Based on the findings, larval indices, namely, Breteau index (BI), House index (HI), and Container index (CI), were calculated, along with the Ovitrap index (OI). The study area was positive for Ae. albopictus with an adult capturing range of 1~15/34 households. BI initially remained < 3%, which subsequently decreased up to 0. No significant difference in OI was found between the ovitraps placed at ground level and at a height of 1.5-2m (p>0.05), 95% level of confidence. The OI varied from 56.9% to 94.7% during the study period of 12 months, indicating two peaks at the monsoons. Statistics of one-way ANOVA revealed a significant difference in the monthly OI during the study period (p≤0.001) with two peaks representing the monsoonal rainfall patterns. Pearson's correlation analysis revealed that the association between dengue cases and larval indices (BI, CI, HI, and OI) and meteorological parameters was not significant (p<0.05). Migration of mosquitoes and patients could be considered as possible factors affecting the absence of a significant relationship.Item Early hepatitis is the strongest risk factor for the development of severe dengue infection: A points-based risk-score to predict critical disease in dengue fever(Sri Lanka Medical Association, 2018) Niriella, M.A.; Udeshika, A.K.M.A.; Liyanage, I.K.; de Silva, A.P.; de Silva, H.J.INTRODUCTION AND OBJECTIVES: Some dengue fever (DF) patients develop plasma leakage [critical-phase (CP)], which may progress to multi-organ failure. We attempted to identify early predictors ofCP in DF. METHODS: This was a retrospective, case-record-based study. Clinical, laboratory features in the first three-days (Dl-3) of illness was used to formulate a risk prediction model (RPM). Patients with serologically confirmed DF, admitted to the University Medical Unit, Teaching Hospital, Ragama, from 01.01.2017-30.06.2017 were included. Patients were randomly assigned to training (TD) and validation datasets (VD) of equal size. Stepwise multivariate logistic regression (p<0.05) was used to identify risk factors in TD. Versions of RPM were compared using Akaike criteria and McFadden's adjusted R2. Coefficients from the best RPM were used to derive weighted risk scores. Best RPM was validated in VD using C-statistic. RESULTS: 697 patients were included (mean-age:34.7±16.1 years, females-48.8%, TD=350, VD=346). CP developed inJ27 (32.6%). Mortality was I%. Risk predictors (p<0.05) were: female gender (OR=2.l), diabetes (OR=l.8), vomiting (OR=l.9), platelets60 IU/L (OR=3.3). In multivariate analysis, female gender (score=2), vomiting (score=3), platelets<120,000/mm-3 (score=3) and AST>60 IU/L 3 (score=4) were significant while diabetes was non-significant. Calculated RPM score ranged from 0-12. C-statistic for the TD was 0.78 and VD 0.77 (Hosmer-Lemeshow test: p=0.19 and 0.34 respectively). A cut-off of 5 was selected to maximise sensitivity (0.96), negative predictive value (0.95) with specificity of 0.44. CONCLUSION: This simple risk score seems useful in identifying those at risk ofCP within Dl-3 of the onset ofDF. The early presence of dengue hepatitis was the strongest predictor of CP.Item Comprehensive evaluation of demographic, socio-economic and other associated risk factors affecting the occurrence of dengue incidence among Colombo and Kandy Districts of Sri Lanka: a cross-sectional study(BioMed Central, 2018) Udayanga, L.; Gunathilaka, N.; Iqbal, M.C.M.; Lakmal, K.; Amarasinghe, U.S.; Abeyewickreme, W.BACKGROUND: Comprehensive understanding of risk factors related to socio-economic and demographic status and knowledge, attitudes and practices (KAP) of local communities play a key role in the design and implementation of community-based vector management programmes, along with the identification of gaps in existing control activities. METHODS: A total of 10 Medical Officers of Health (MOH) areas recording high dengue incidence over the last five years were selected from Colombo (n = 5) and Kandy (n = 5) Districts, Sri Lanka. From each MOH area, 200 houses reporting past dengue incidence were selected randomly as test group (n = 1000 for each district) based on the dengue case records available at relevant MOH offices. Information on socio-economic and demographic status and knowledge, attitudes and practices were gathered using an interviewer administered questionnaire. The control group contained 200 households from each MOH area that had not reported any dengue case and the same questionnaire was used for the assessment (n = 1000 for each district). Statistical comparisons between the test and control groups were carried out using the Chi-square test of independence, cluster analysis, analysis of similarities (ANOSIM) and multi-dimensional scaling (MDS) analysis. RESULTS: Significant differences among the test and control groups in terms of basic demographic and socio-economic factors, living standards, knowledge, attitude and practices, were recognized (P < 0.05 at 95% level of confidence). The test group indicated similar risk factors, while the control group also shared more or less similar characteristics as depicted by the findings of cluster analysis and ANOSIM. Findings of the present study highlight the importance of further improvement in community education, motivation and communication gaps, proper coordination and integration of control programmes with relevant entities. Key infrastructural risk factors such as urbanization and waste collection, should be further improved, while vector controlling entities should focus more on the actual conditions represented by the public on knowledge, attitudes and personal protective practices. CONCLUSIONS: The design of flexible and community friendly intervention programmes to ensure the efficacy and sustainability of controlling dengue vectors through community based integrated vector management strategies, is recommended.Item 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.Item Is Total Serum Nitrite and Nitrate (NOx) Level in Dengue Patients a Potential Prognostic Marker of Dengue Hemorrhagic Fever?(Hindawi Pub. Corp., 2018) Mapalagamage, M.; Handunnetti, S.; Premawansa, G.; Thillainathan, S.; Fernando, T.; Kanapathippillai, K.; Wickremasinghe, R.; de Silva, A.D.; Premawansa, S.Potential use of total nitrite plus nitrate (NOx) and nitrite (NO2-) separately as surrogate markers for serum nitric oxide in severe dengue and their longitudinal changes along with the progression of infection was studied. Deproteinized sera from confirmed dengue fever (DF, n = 145) and dengue hemorrhagic fever (DHF, n = 74) patients on admission-A, critical-C, discharge-D, and convalescence-CON stages and from age-gender matched healthy individuals (HC, n = 77) were taken to assess NO2- and NOx levels using Griess and modified Griess assays. Serum NOx in DHFA was significantly lower compared to DFA (p < 0.001). HC had the lowest NOx and NO2- compared to all patient categories (p < 0.001) except NO2- in DF-CON and DHF-CON and NOx in DHF-CON. Serum NOx and NO2- in DHF patients admitted on fever day 3 (DHFA-3) was significantly lower compared to DFA-3 (p < 0.05). Cut-off values of 4.46 μM for NOx (91.3% sensitivity and 80.1% specificity) and 1.25 μM for NO2-(75.0% sensitivity and 73.3% specificity) were obtained for day 3 of fever. Serum NOx may be used as potential prognostic marker of DHF in patients presenting with DF in the early stage (on day 3 of fever) of the disease.Item Empirical optimization of risk thresholds for dengue: an approach towards entomological management of Aedes mosquitoes based on larval indices in the Kandy District of Sri Lanka(BioMed Central, 2018) Udayanga, L.; Gunathilaka, N.; Iqbal, M.C.M.; Najim, M.M.M.; Pahalagedara, K.; Abeyewickreme, W.BACKGROUND: Larval indices such as Premise Index (PI), Breteau Index (BI) and Container Index (CI) are widely used to interpret the density of dengue vectors in surveillance programmes. These indices may be useful for forecasting disease outbreaks in an area. However, use of the values of these indices as alarm signals is rarely considered in control programmes. Therefore, the current study aims to propose threshold values for vector indices based on an empirical modeling approach for the Kandy District of Sri Lanka. METHODS: Monthly vector indices, viz PI, BI and CI, for Aedes aegypti and Aedes albopictus, of four selected dengue high risk Medical Officer of Health (MOH) areas in the Kandy District from January 2010 to August 2017, were used in the study. Gumbel frequency analysis was used to calculate the exceedance probability of quantitative values for each individual larval index within the relevant MOH area, individually and to set up the threshold values for the entomological management of dengue vectors. RESULTS: Among the study MOH areas, Akurana indicated a relatively high density of both Ae. aegypti and Ae. albopictus, while Gangawata Korale MOH area had the lowest. Based on Ae. aegypti, threshold values were defined for Kandy as low risk (BIagp > 1.77), risk (BIagp > 3.23), moderate risk (BIagp > 4.47) and high risk (BIagp > 6.23). In addition, PI > 6.75 was defined as low risk, while PI > 9.43 and PI>12.82 were defined as moderate and high risk, respectively as an average. CONCLUSIONS: Threshold values recommended for Ae. aegypti (primary vector for dengue) along with cut-off values for PI (for Ae. aegypti and Ae. albopictus), could be suggested as indicators for decision making in vector control efforts. This may also facilitate the rational use of financial allocations, technical and human resources for vector control approaches in Sri Lanka in a fruitful manner.