Journal/Magazine Articles
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This collection contains original research articles, review articles and case reports published in local and international peer reviewed journals by the staff members of the Faculty of Medicine
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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 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 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 Low-dose adrenaline, promethazine, and hydrocortisone in the prevention of acute adverse reactions to antivenom following snakebite: a randomised, double-blind, placebo-controlled trial(Public Library of Science, 2011) de Silva, H.A.; Pathmeswaran, A.; Ranasinha, C.D.; Jayamanne, S.; Samarakoon, S.B.; Hittarage, A.; Kalupahana, R.; Ratnatilaka, G.A.; Uluwatthage, W.; Aronson, J.K.; Armitage, J.M.; Lalloo, D.G.; de Silva, H.J.BACKGROUND: Envenoming from snakebites is most effectively treated by antivenom. However, the antivenom available in South Asian countries commonly causes acute allergic reactions, anaphylactic reactions being particularly serious. We investigated whether adrenaline, promethazine, and hydrocortisone prevent such reactions in secondary referral hospitals in Sri Lanka by conducting a randomised, double-blind placebo-controlled trial. METHODS AND FINDINGS: In total, 1,007 patients were randomized, using a 2 × 2 × 2 factorial design, in a double-blind, placebo-controlled trial of adrenaline (0.25 ml of a 1∶1,000 solution subcutaneously), promethazine (25 mg intravenously), and hydrocortisone (200 mg intravenously), each alone and in all possible combinations. The interventions, or matching placebo, were given immediately before infusion of antivenom. Patients were monitored for mild, moderate, or severe adverse reactions for at least 96 h. The prespecified primary end point was the effect of the interventions on the incidence of severe reactions up to and including 48 h after antivenom administration. In total, 752 (75%) patients had acute reactions to antivenom: 9% mild, 48% moderate, and 43% severe; 89% of the reactions occurred within 1 h; and 40% of all patients were given rescue medication (adrenaline, promethazine, and hydrocortisone) during the first hour. Compared with placebo, adrenaline significantly reduced severe reactions to antivenom by 43% (95% CI 25-67) at 1 h and by 38% (95% CI 26-49) up to and including 48 h after antivenom administration; hydrocortisone and promethazine did not. Adding hydrocortisone negated the benefit of adrenaline. CONCLUSIONS: Pretreatment with low-dose adrenaline was safe and reduced the risk of acute severe reactions to snake antivenom. This may be of particular importance in countries where adverse reactions to antivenom are common, although the need to improve the quality of available antivenom cannot be overemphasized.Item The Global burden of snakebite: a literature analysis and modelling based on regional estimates of envenoming and deaths(Public Library of Science, 2008) Kasturiratne, A.; Wickremasinghe, A.R.; de Silva, N.; Gunawardena, N.K.; Pathmeswaran, A.; Premaratna, R.; Savioli, L.; Lalloo, D.G.; de Silva, H.J.BACKGROUND: Envenoming resulting from snakebites is an important public health problem in many tropical and subtropical countries. Few attempts have been made to quantify the burden, and recent estimates all suffer from the lack of an objective and reproducible methodology. In an attempt to provide an accurate, up-to-date estimate of the scale of the global problem, we developed a new method to estimate the disease burdendue to snakebites. METHODS AND FINDINGS: The global estimates were based on regional estimates that were, in turn, derived from data available for countries within a defined region. Three main strategies were used to obtain primary data: electronic searching for publications on snakebite, extraction of relevant country-specific mortality data from databases maintained by United Nations organizations, and identification of grey literature by discussion with key informants. Countries were grouped into 21 distinct geographic regions that are as epidemiologically homogenous as possible, in line with the GlobalBurden of Disease 2005 study (Global Burden Project of the World Bank). Incidence rates for envenoming were extracted from publications and used to estimate the number of envenomings for individual countries; if no data were available for a particular country, the lowest incidence rate within a neighbouring country was used. Where death registration data were reliable, reported deaths from snakebite were used; in other countries, deathswere estimated on the basis of observed mortality rates and the at-risk population. We estimate that, globally, at least 421,000 envenomings and 20,000 deaths occur each year due to snakebite. These figures may be as high as 1,841,000 envenomings and 94,000 deaths. Based on the fact thatenvenoming occurs in about one in every four snakebites, between 1.2 million and 5.5 million snakebites could occur annually. CONCLUSIONS: Snakebites cause considerable morbidity and mortality worldwide. The highest burden exists in South Asia, Southeast Asia, and sub-Saharan Africa. Comment in Estimating the global burden of snakebite can help to improve management. [PLoS Med. 2008]Item Identifying the biting species in snakebite by clinical features: an epidemiological tool for community surveys(Oxford University Press, 2006) Pathmeswaran, A.; Kasturiratne, A.; Fonseka, M.; Nandasena, S.; Lalloo, D.G.; de Silva, H.J.The outcome of snakebite is related to the biting species but it is often difficult to identify the biting snake, particularly in community settings. We have developed a clinical scoring system suitable for use in epidemiological surveys, with the main aim of identifying the presumed biting species in those with systemic envenoming who require treatment. The score took into account ten features relating to bites of the five medically important snakes in Sri Lanka, and an algorithm was developed applying different weightings for each feature for different species. A systematically developed artificial data set was used to fine tune the score and to develop criteria for definitive identification. The score was prospectively validated using 134 species-confirmed snakebites. It correctly differentiated the bites caused by the three snakes that commonly cause major clinical problems (Russell's viper (RV), kraits and cobra) from other snakes (hump-nosed viper (HNV) and saw-scaled viper (SSV)) with 80% sensitivity and 100% specificity. For individual species, sensitivity and specificity were, respectively: cobra 76%, 99%; kraits 85%, 99%; and RV 70%, 99%. As anticipated, the score was insensitive in the identification of bites due to HNV and SSVItem Estimates of disease burden due to land-snake bite in Sri Lankan hospitals(SEAMEO Regional Tropical Medicine and Public Health Project, 2005) Kasturiratne, A.; Pathmeswaran, A.; Fonseka, M.M.D.; Lalloo, D.G.; Brooker, S.; de Silva, H.J.Snake bite is a common cause of hospital admission in Sri Lanka. Despite this, there have been no countrywide studies or national estimates of disease burden due to snake bites in Sri Lankan hospitals. We assessed the disease burden due to snake bite in our hospitals and estimated the frequency of admissions due to bites by different snake species. Sri Lanka was divided into four zones based on climate and topography. Hospital morbidity and mortality data, which are available on an administrative district basis, were collated for the four zones. A survey of opinion among specialist physicians (the Delphi technique) was used to estimate the proportion of bites by different species, and requirements for anti-venom (AV) and intensive care facilities for management of snake bites in hospitals in each of the four zones. A study of hospital admissions due to snake bites in seven selected hospitals was also performed to validate the opinion survey. There was a clear difference in the incidence of hospital admissions due to snake bites in the different zones. Estimates of hospital admissions due to bites by different species also varied considerably between zones. These trends corresponded to estimates of requirements of AV and other supportive health care. Health care planning using data based on environmental information, rather than merely on political boundaries, could lead to targeted distribution of AV and intensive care requirements to manage snake bites.Item Envenoming due to snake bite during pregnancy(Oxford University Press, 2002) Seneviratne, S.L.; de Silva, C.E.; Fonseka, M.M.D.; Pathmeswaran, A.; Gunatilake, S.B.; de Silva, H.J.No Abstract Available