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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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
16 results
Search Results
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 Evaluating temporal patterns of snakebite in Sri Lanka: the potential for higher snakebite burdens with climate change(Oxford University Press, 2018) Ediriweera, D.S.; Diggle, P.J.; Kasturiratne, A.; Pathmeswaran, A.; Gunawardena, N.K.; Jayamanne, S.K.; Isbister, G.K.; Dawson, A.; Lalloo, D.G.; de Silva, H.J.BACKGROUND: Snakebite is a neglected tropical disease that has been overlooked by healthcare decision makers in many countries. Previous studies have reported seasonal variation in hospital admission rates due to snakebites in endemic countries including Sri Lanka, but seasonal patterns have not been investigated in detail. METHODS: A national community-based survey was conducted during the period of August 2012 to June 2013. The survey used a multistage cluster design, sampled 165 665 individuals living in 44 136 households and recorded all recalled snakebite events that had occurred during the preceding year. Log-linear models were fitted to describe the expected number of snakebites occurring in each month, taking into account seasonal trends and weather conditions, and addressing the effects of variation in survey effort during the study and of recall bias amongst survey respondents. ResulTS: Snakebite events showed a clear seasonal variation. Typically, snakebite incidence is highest during November–December followed by March–May and August, but this can vary between years due to variations in relative humidity, which is also a risk factor. Low relative-humidity levels are associated with high snakebite incidence. If current climate-change projections are correct, this could lead to an increase in the annual snakebite burden of 31.3% (95% confidence interval: 10.7–55.7) during the next 25–50 years. CONCLUSIONS: Snakebite in Sri Lanka shows seasonal variation. Additionally, more snakebites can be expected during periods of lower-than-expected humidity. Global climate change is likely to increase the incidence of snakebite in Sri Lanka.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 snake bite in Sri Lanka(Faculty of Medicine, University of Kelaniya, Sri Lanka, 2016) Pathmeswaran, A.There are few studies on community incidence of snake bite. There are no national level data. We undertook a community-based country-wide survey on snake bite in Sri Lanka. The survey was designed to sample 1% of the population of Sri Lanka. A Grama Niladhari (GN) division was defined as a cluster for data collection. 125 clusters were allocated to each province. The clusters were selected using simple random sampling and in each cluster, 40 households were sampled consecutively from a random starting point. Population based incidence rates of snake bite were then constructed. 1,125 GN divisions with 43,827 households and a population of 164,746 (0.81% of country’s population) were surveyed. 694 snakebites and 317 significant envenoming (local tissue necrosis and systemic envenoming) were reported within the past 12 months. The crude overall community incidence of snake bites and significant envenoming were 421 and 192 per 100,000 population, respectively. There was wide variation within districts, the worst affected being Mullaitivu, Anuradhapura, Batticaloa and Polonnaruwa, all mainly agricultural areas in the Dry Zone of the country. It is concluded that Sri Lanka has a high community incidence of snake bite and envenoming, with marked geographical variation within the country.Item Estimates of disease burden due to snakebite in Sri Lankan hospitals(Sri Lanka Medical Association, 2003) Kasturiratne, A.; Pathmeswaran, A.; Fonseka, M.M.D.; Lalloo, D.G.; Brooker, S.; de Silva, H.J.INTRODUCTION: There have been no country-wide studies or estimates of disease burden due to snakebite in Sri Lankan hospitals. OBJECTIVES: To assess disease burden due to snakebite and estimate relative frequency of the biting species in hospitals situated in different parts of the country. METHODS: Hospital morbidity and mortality data on snakebite was obtained for each administrative district. Sri Lanka was divided into 5 zones based on climate and available data on snake habitat (Zone 1-wet zone altitude <900m; Z2-intermediate zone; Z3-dry zone, Z4-wet zone altitude >900m; Z5-northern and north-western dry zone). Administrative districts were allocated to zones based on their geographical location and population using geographical information systems technology. Hospital morbidity and mortality data were collated for the 5 zones. A survey among physicians (37 physicians in 42 hospitals covering the 5 zones) was used (Delphi technique) to estimate the proportion of snakebites by different species and requirement of hospital resources, in each zone. Results: There was a clear difference in incidence of hospital admissions due to snakebite in the different zones (Z3-3.5 and Z4-0.4 per 1000 population). The distribution of bites by individual species also varied between zones (deadly venomous species Z3-85%, Z2-45%), moderately venomous and mildly-venomous species Z4-100%, Zl-70%). These trends corresponded to estimates of requirements for AVS and other hospital facilities (in 2000, Z3-86100 vials of AVS, 7380 Intensive care unit patient-days; Zl-26400 vials of AVS, 2640ICU patient-days). CONCLUSIONS: Incidence of hospital admissions due to snakebite and estimates of relative medical importance of different snake species show geographic variation within the country. This is reflected in estimates of requirements for facilities. Zoning based on environmental information rather than on political boundaries could lead to better distribution of health care resources for management of snakebite in hospitals situated in different parts of the country.Item Beliefs and knowledge regarding snakebite in rural Sri Lanka: a qualitative survey(Sri Lanka Medical Association, 2003) Makita, L.S.; Nandasena, S.; Costa, M.R.A.; Kasturiratne, A.; Pathmeswaran, A.; Lalloo, D.G.; de Silva, H.J.OBJECTIVES: To identify common beliefs and assess knowledge regarding snakebite in rural Sri Lanka, and their influence on health-seeking behaviour. METHODS: Qualitative methods (focus group discussions and key informant interviews) were used to obtain data in five rural locations in wet, intermediate and dry zones. Data was subjected to "framework analysis" involving familiarisation, identification of thematic frame, indexing and coding, charting, mapping, and interpretation. RESULTS: People are aware of risk-behaviour associated with snakebite, and have reasonable knowledge regarding venomous and non-venomous snakes. However, differences in nomenclature sometimes lead to confusion in identifying species. Beliefs and legends, which are linked to religion, have lead people to respect the cobra. Traditional healers claim they can determine the snake species, clinical manifestations that may occur, and prognosis, based on phenomena, such as, day of the week and phase of the moon when the bite took place. They still employ treatment methods, such as wound incision with broken glass and scalp incision for applying potions. Although there is respect for traditional healing, there is acceptance of the efficacy of western medicine. Beliefs, such as, anti-venom though effective is toxic, long-term effects of snake venom can be completely neutralised only by traditional medicine, and producing the dead snake is essential for treatment in hospitals, lead people to seek treatment by traditional healers rather than in hospitals. CONCLUSIONS: Beliefs and misconceptions influence health-seeking behaviour following snakebite. There seems to be a growing acceptance of western medicine. However, traditional healing methods are still popular, but include harmful^rjractices. This information could form a basis for. educational intervention.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.