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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 Evaluating spatiotemporal dynamics of snakebite in Sri Lanka: Monthly incidence mapping from a national representative survey sample(Public Library of Science, 2021) Ediriweera, D.S.; Kasturiratne, A.; Pathmeswaran, A.; Gunawardena, N.K.; Jayamanne, S.F.; Murray, K.; Iwamura, T.; Isbister, G.; Dawson, A.; Lalloo, D.G.; de Silva, H.J.; Diggle, P.J.BACKGROUND: Snakebite incidence shows both spatial and temporal variation. However, no study has evaluated spatiotemporal patterns of snakebites across a country or region in detail. We used a nationally representative population sample to evaluate spatiotemporal patterns of snakebite in Sri Lanka. METHODOLOGY: We conducted a community-based cross-sectional survey representing all nine provinces of Sri Lanka. We interviewed 165 665 people (0.8% of the national population), and snakebite events reported by the respondents were recorded. Sri Lanka is an agricultural country; its central, southern and western parts receive rain mainly from Southwest monsoon (May to September) and northern and eastern parts receive rain mainly from Northeast monsoon (November to February). We developed spatiotemporal models using multivariate Poisson process modelling to explain monthly snakebite and envenoming incidences in the country. These models were developed at the provincial level to explain local spatiotemporal patterns. PRINCIPAL FINDINGS: Snakebites and envenomings showed clear spatiotemporal patterns. Snakebite hotspots were found in North-Central, North-West, South-West and Eastern Sri Lanka. They exhibited biannual seasonal patterns except in South-Western inlands, which showed triannual seasonality. Envenoming hotspots were confined to North-Central, East and South-West parts of the country. Hotspots in North-Central regions showed triannual seasonal patterns and South-West regions had annual patterns. Hotspots remained persistent throughout the year in Eastern regions. The overall monthly snakebite and envenoming incidences in Sri Lanka were 39 (95%CI: 38-40) and 19 (95%CI: 13-30) per 100 000, respectively, translating into 110 000 (95%CI: 107 500-112 500) snakebites and 45 000 (95%CI: 32 000-73 000) envenomings in a calendar year. CONCLUSIONS/SIGNIFICANCE: This study provides information on community-based monthly incidence of snakebites and envenomings over the whole country. Thus, it provides useful insights into healthcare decision-making, such as, prioritizing locations to establish specialized centres for snakebite management and allocating resources based on risk assessments which take into account both location and season.Item Health seeking behavior following snakebites in Sri Lanka: Results of an island wide community based survey(Public Library of Science, 2017) Ediriweera, D.S.; Kasturiratne, A.; Pathmeswaran, A.; Gunawardena, N.K.; Jayamanne, S.F.; Lalloo, D.G.; de Silva, H.J.INTRODUCTION: Sri Lanka has a population of 21 million and about 80,000 snakebites occur annually. However, there are limited data on health seeking behavior following bites. We investigated the effects of snakebite and envenoming on health seeking behavior in Sri Lanka. METHODS: In a community-based island-wide survey conducted in Sri Lanka 44,136 households were sampled using a multistage cluster sampling method. An individual who reported experiencing a snakebite within the preceding 12 months was considered a case. An interviewer-administered questionnaire was used to obtain details of the bite and health seeking behavior among cases. RESULTS: Among 165,665 individuals surveyed, there were 695 snakebite victims. 682 (98.1%) had sought health care after the bite; 381 (54.8%) sought allopathic treatment and 301 (43.3%) sought traditional treatment. 323 (46.5%) had evidence of probable envenoming, among them 227 (70.3%) sought allopathic treatment, 94 (29.1%) sought traditional treatment and 2 did not seek treatment. There was wide geographic variation in the proportion of seeking allopathic treatment from <20% in the Western province to > 90% in the Northern province. Multiple logistic regression analysis showed that seeking allopathic treatment was independently associated with being systemically envenomed (Odds Ratio = 1.99, 95% CI: 1.36-2.90, P < 0.001), distance to the healthcare facility (OR = 1.13 per kilometer, 95% CI: 1.09 to 1.17, P < 0.001), time duration from the bite (OR = 0.49 per day, 95% CI: 0.29-0.74, P = 0.002), and the local incidence of envenoming (OR = 1.31 for each 50 per 100,000, 95% CI: 1.19-1.46, P < 0.001) and snakebite (OR = 0.90 for each 50 per 100,000, 95% CI: 0.85-0.94, P < 0.001) in the relevant geographic area. CONCLUSIONS: In Sri Lanka, both allopathic and traditional treatments are sought following snakebite. The presence of probable envenoming was a major contribution to seeking allopathic treatment.Item Development of a Snakebite risk map for Sri Lanka(Sri Lanka Medical Association, 2016) Ediriweera, D.S.; Kasturiratne, A.; Pathmeswaran, A.; Gunawardena, N.K.; Wijayawickrama, B.A.; Jayamanne, S.F.; Isbister, G.K.; Dawson, A.; Giorgi, E.; Diggle, P.J.; Lalloo, D.G.; de Silva, H.J.INTRODUCTION: Snakebite is a public health problem in Sri Lanka and about 37,000 patients are treated in government hospitals annually. At present, health care resources which are required to manage snakebite are distributed based on the administrative boundaries, rather than based on scientific risk assessment. OBJECTIVES: The aim of the study is to develop a snakebite risk map for Sri Lanka. METHOD: Epidemiological data was obtained from a community-based island-wide survey. The sample was distributed equally among the nine provinces. 165,665 participants (0.8%of the country’s population) living in 1118 Grama Niladhari divisions were surveyed. Generalized linear and generalized additive models were used for exploratory data analysis. Model-based geostatistics was used to determine the geographical distribution of snakebites. Monte Carlo maximum likelihood method was used to obtain parameter estimates and plug-in spatial predictions were obtained. Probability contour maps (PCM) were developed to demonstrate the spatial variation in the probability that local incidence does or does not exceed national snakebite incidence. RESULTS: Individual point estimate snakebite incidence map and PCM were developed to demonstrate the national incidence of snakebite in Sri Lanka. Snakebite hotspots and cold spots were identified in relation to the national snakebite incidence rate. Risk maps showed a within-country spatial variation in snakebites. CONCLUSIONS: The developed risk maps provide useful information for healthcare decision makers to allocate resources to manage snakebite in Sri Lanka.Item The Socio-economic burden of snakebite in Sri Lanka(Public Library of Science, 2017) Kasturiratne, A.; Pathmeswaran, A.; Wickremasinghe, A.R.; Jayamanne, S.F.; Dawson, A.; Isbister, G.K.; de Silva, H.J.; Lalloo, D.G.BACKGROUND: Snakebite is a major problem affecting the rural poor in many of the poorest countries in the tropics. However, the scale of the socio-economic burden has rarely been studied. We undertook a comprehensive assessment of the burden in Sri Lanka. METHODS: Data from a representative nation-wide community based household survey were used to estimate the number of bites and deaths nationally, and household and out of pocket costs were derived from household questionnaires. Health system costs were obtained from hospital cost accounting systems and estimates of antivenom usage. DALYs lost to snakebite were estimated using standard approaches using disability weights for poisoning. FINDINGS: 79% of victims suffered economic loss following a snakebite with a median out of pocket expenditure of $11.82 (IQR 2-28.57) and a median estimated loss of income of $28.57 and $33.21 for those in employment or self-employment, respectively. Family members also lost income to help care for patients. Estimated health system costs for Sri Lanka were $ 10,260,652 annually. The annual estimated total number of DALYS was 11,101 to 15,076 per year for envenoming following snakebite. INTERPRETATION: Snakebite places a considerable economic burden on the households of victims in Sri Lanka, despite a health system which is accessible and free at the point of care. The disability burden is also considerable, similar to that of meningitis or dengue, although the relatively low case fatality rate and limited physical sequelae following bites by Sri Lankan snakes means that this burden may be less than in countries on the African continent.Item Mapping the risk of snakebite in Sri Lanka - A national survey with geospatial analysis(Public Library of Science, 2016) Ediriweera, E.P.D.S.; Kasturiratne, A.; Pathmeswaran, A.; Gunawardena, N.K.; Wijayawickrama, B.A.; Jayamanne, S.F.; Isbister, G.K.; Dawson, A.; Giorgi, E.; Diggle, P.J.; Lalloo, D.G.; de Silva, H.J.BACKGROUND: There is a paucity of robust epidemiological data on snakebite, and data available from hospitals and localized or time-limited surveys have major limitations. No study has investigated the incidence of snakebite across a whole country. We undertook a community-based national survey and model based geostatistics to determine incidence, envenoming, mortality and geographical pattern of snakebite in Sri Lanka. METHODOLOGY/PRINCIPAL FINDINGS: The survey was designed to sample a population distributed equally among the nine provinces of the country. The number of data collection clusters was divided among districts in proportion to their population. Within districts clusters were randomly selected. Population based incidence of snakebite and significant envenoming were estimated. Model-based geostatistics was used to develop snakebite risk maps for Sri Lanka. 1118 of the total of 14022 GN divisions with a population of 165665 (0.8%of the country’s population) were surveyed. The crude overall community incidence of snakebite, envenoming and mortality were 398 (95% CI: 356–441), 151 (130–173) and 2.3 (0.2–4.4) per 100000 population, respectively. Risk maps showed wide variation in incidence within the country, and snakebite hotspots and cold spots were determined by considering the probability of exceeding the national incidence. CONCLUSIONS/SIGNIFICANCE: This study provides community based incidence rates of snakebite and envenoming for Sri Lanka. The within-country spatial variation of bites can inform healthcare decision making and highlights the limitations associated with estimates of incidence from hospital data or localized surveys. Our methods are replicable, and these models can be adapted to other geographic regions after re-estimating spatial covariance parameters for the particular region.Item Community incidence of snakebite in the Amiradhapura district(Sri Lanka Medical Association, 2013) Kasturiratne, A.; Gunawardena, N.K.; Wijayawickrama, B.A.; Jayamanne, S.F.; Pathmeswaran, A.; Isbister, G.; Dawson, A.; de Silva, H.J.INTRODUCTION AND OBJECTIVES: The community incidence of snakebite in Sri Lanka is unknown. To investigate incidence of snakebite, we undertook a community study in the Anuradhapura district as part of an ongoing countrywide survey on snakebite. METHODS: The survey was designed to sample at least 1% of the population in each district Within the district, a Grama Niladhari (GN) division, was defined as a cluster for data collection. The number of clusters required to sample at least 1 % of the population was first determined, and clusters were then selected using simple random sampling. In each selected cluster 40 households were sampled consecutively from a random starting point. Population estimates of snakebite were constructed for the district. RESULTS: The Anuradhapura district has a total of 694 GN divisions, and 84 were surveyed. This included 3357 households and a population of 13,428 (1.6% of the district's population). Eightysix snakebites were reported within the last 12 months. Extrapolating this to the district (mid-year population=855,373), the estimated snakebites in Anuradhapura district was 5478. The crude community incidence of snakebite in the Anuradhapura district was 640.5 per 100, 000 population. CONCLUSIONS: The incidence of snakebite in the community is high in the Anuradhapura district, with one in 156 persons bitten annually.Item Development and assessment of a psychological intervention for snakebite victims(Sri Lanka Medical Association, 2014) Wiiesinahe, C.A.; Williams, S.S.; Dolawatta, N.; Wimalaratne, A.K.G.P.; Kasturiratne, A.; Wijewickrema, B.; Jayamanne, S.F.; Lalloo, D.G.; Isbister, G.K.; Dawson, A.; de Silva, H.J.INTRODUCTION AND OBJECTIVES: There is significant delayed psychological morbidity and negative psycho-social impact following snakebite. However, no psychological support is provided to victims. We aimed to develop and assess the effectiveness of a brief intervention which can be provided by non-specialist medical officers aimed at reducing psychological morbidity. METHODS: In a single blind clinical trial at Polonnaruwa Hospital, 187 snakebite victims were randomised into three arms. One arm received no psychological intervention (Group A; n=59; control). Group B (n=60) received psychoeducation at discharge from hospital. Group C (n=68) received psychoeducation and a.second intervention one month later based on cognitive behavioural principles. All patients were assessed six months after discharge from hospital using standardised tools for presence of psychological symptoms and level of functioning. RESULTS: Compared with Group A, there was a significant reduction in anxiety symptoms measured by the Hopkins Psychiatric Symptom check list (16.9% vs. 5.9%, p=0.047, Chi-Squared test) and a non-significant trend towards improvement in the level of functioning measured by the Sheehan Disability inventory (6.47 vs. 4.69) in Group C, but not in Group B. There was no difference in rates of depression and post-traumatic stress disorder (PTSD) between the three groups. CONCLUSIONS: Our preliminary findings suggest that brief psychological interventions which include psychoeducation plus cognitive behavioural therapy given by non-specialist doctors, but not psychoeducation alone seem to reduce anxiety and facilitate a trend towards improved function in snakebite victims. However, these interventions had no effect on depression or PTSD.Item A Randomized Controlled Trial of a brief Intervention for delayed psychological effects in snakebite victims(Public Library of Science, 2015) Wijesinghe, C.A.; Williams, S.S.; Kasturiratne, A.; Dolawaththa, N.; Wimalaratne, P.; Wijewickrema, B.; Jayamanne, S.F.; Isbister, G.K.; Dawson, A.H.; Lalloo, D.G.; de Silva, H.J.BACKGROUND: Snakebite results in delayed psychological morbidity and negative psycho-social impact. However, psychological support is rarely provided to victims. AIM: To assess the effectiveness of a brief intervention which can be provided by non-specialist doctors aimed at reducing psychological morbidity following snakebite envenoming. METHOD: In a single blind, randomized controlled trial, snakebite victims with systemic envenoming [n = 225, 168 males, mean age 42.1 (SD 12.4) years] were randomized into three arms. One arm received no intervention (n = 68, Group A), the second received psychological first aid and psychoeducation (dispelling prevalent cultural beliefs related to snakebite which promote development of a sick role) at discharge from hospital (n = 65, Group B), while the third received psychological first aid and psychoeducation at discharge and a second intervention one month later based on cognitive behavioural principles (n = 69, Group C). All patients were assessed six months after hospital discharge for the presence of psychological symptoms and level of functioning using standardized tools. RESULTS: At six months, there was a decreasing trend in the proportion of patients who were positive for psychiatric symptoms of depression and anxiety from Group A through Group B to Group C (Chi square test for trend = 7.901, p = 0.005). This was mainly due to a decreasing trend for symptoms of anxiety (chi-square for trend = 11.256, p = 0.001). There was also decreasing trend in the overall prevalence of disability from Group A through Group B to Group C (chi square for trend = 7.551, p = 0.006), predominantly in relation to disability in family life (p = 0.006) and social life (p = 0.005). However, there was no difference in the proportion of patients diagnosed with depression between the three groups (chi square for trend = 0.391, p = 0.532), and the intervention also had no effect on post-traumatic stress disorder. CONCLUSIONS: A brief psychological intervention, which included psychological first aid and psychoeducation plus cognitive behavioural therapy that can be provided by non-specialist doctors appeared to reduce psychiatric symptoms and disability after snakebite envenoming, but not depression or post-traumatic stress disorder. TRIAL REGISTRATION: Sri Lanka Clinical Trials Registry: SLCTR/2011/003.Item Delayed psychological morbidity associated with snakebite envenoming(Public Library of Science, 2011) Williams, S.S.; Wijesinghe, C.A.; Jayamanne, S.F.; Buckley, N.A.; Dawson, A.H.; Lalloo, D.G.; de Silva, H.J.INTRODUCTION: The psychological impact of snakebite on its victims, especially possible late effects, has not been systematically studied. OBJECTIVES: To assess delayed somatic symptoms, depressive disorder, post-traumatic stress disorder (PTSD), and impairment in functioning, among snakebite victims. METHODS: The study had qualitative and quantitative arms. In the quantitative arm, 88 persons who had systemic envenoming following snakebite from the North Central Province of Sri Lanka were randomly identified from an established research database and interviewed 12 to 48 months (mean 30) after the incident. Persons with no history of snakebite, matched for age, sex, geograpical location and occupation, acted as controls. A modified version of the Beck Depression Inventory, Post-Traumatic Stress Symptom Scale, Hopkins Somatic Symptoms Checklist, Sheehan Disability Inventory and a structured questionnaire were administered. In the qualitative arm, focus group discussions among snakebite victims explored common somatic symptoms attributed to envenoming. RESULTS: Previous snakebite victims (cases) had more symptoms than controls as measured by the modified Beck Depression Scale (mean 19.1 Vs 14.4; p<0.001) and Hopkins Symptoms Checklist (38.9 vs. 28.2; p<0.001). 48 (54%) cases met criteria for depressive disorder compared to 13 (15%) controls. 19 (21.6%) cases also met criteria for PTSD. 24 (27%) claimed that the snakebite caused a negative change in their employment; nine (10.2%) had stopped working and 15 (17%) claimed residual physical disability. The themes identified in the qualitative arm included blindness, tooth decay, body aches, headaches, tiredness and weakness. CONCLUSIONS: Snakebite causes significant ongoing psychological morbidity, a complication not previously documented. The economic and social impacts of this problem need further investigation