Snakebite Risk Research Articles

The Burden of Snakebite in Rural Communities in Kenya: A Household Survey.

Annually, about 2.7 million snakebite envenomings occur worldwide, primarily affecting those living in rural regions. Effective treatment exists but is scarce, and traditional treatments are commonly used. To inform context-specific policies in Kenya, this study aimed to determine the health-seeking behavior and the health, social, and economic burden of snakebites in rural communities. Nonprobability sampling was used to survey 382 respondents from four snakebite-endemic counties, from February to August 2020, using a structured questionnaire. Descriptive statistics, Fisher's exact tests, binary logistic regressions, and Mantel-Haenszel tests were used for analysis. Life-time experience with snakebites included 13.1% of respondents who reported being personally bitten and 37.4% who reported knowing of a community member being bitten. Respondents reported death after a snakebite in 9.1% of bitten community members and in 14.6% of bitten family members. Risk of snakebite was not significantly associated with sex, educational level, or occupation. Snakebite victims were most often walking (38%) or farming (24%) when bitten. Of those bitten, 58% went to a health facility, 30% sought traditional treatment, and 12% first went to a traditional healer before visiting a facility. Significant differences existed in perceptions on the financial consequences of snakebites among those who had been personally bitten and those who had observed a snakebite. Most commonly mentioned preventive measures were wearing shoes and carrying a light in the dark. Community engagement, including engagement with traditional healers, is needed to reduce snakebites. This should be done through education and sensitization to improve used preventive measures and effective health-seeking behavior.

Addressing the global snakebite crisis with geo-spatial analyses – Recent advances and future direction

Venomous snakebite is a neglected tropical disease that annually leads to hundreds of thousands of deaths or long-term physical and mental ailments across the developing world. Insufficient data on spatial variation in snakebite risk, incidence, human vulnerability, and accessibility of medical treatment contribute substantially to ineffective on-ground management. There is an urgent need to collect data, fill knowledge gaps and address on-ground management problems. The use of novel, and transdisciplinary approaches that take advantage of recent advances in spatio-temporal models, ‘big data’, high performance computing, and fine-scale spatial information can add value to snakebite management by strategically improving our understanding and mitigation capacity of snakebite. We review the background and recent advances on the topic of snakebite related geospatial analyses and suggest avenues for priority research that will have practical on-ground applications for snakebite management and mitigation. These include streamlined, targeted data collection on snake distributions, snakebites, envenomings, venom composition, health infrastructure, and antivenom accessibility along with fine-scale models of spatio-temporal variation in snakebite risk and incidence, intraspecific venom variation, and environmental change modifying human exposure. These measures could improve and ‘future-proof’ antivenom production methods, antivenom distribution and stockpiling systems, and human-wildlife conflict management practices, while simultaneously feeding into research on venom evolution, snake taxonomy, ecology, biogeography, and conservation.

Retrospective hospital-based study on snakebite envenomation in Sudan.

BackgroundSnakebite statistics are lacking in Sudan despite the high estimated burden. In this study we aimed to describe the incidence of snakebite envenomation and death in Sudan and to show the state-wise distribution of snakebite episode.MethodsWe retrospectively analyzed hospital-based data on snakebite for 2014–2018. Data were obtained from the annual health statistical reports of the Ministry of Health. Descriptive statistics were used to illustrate the results.ResultsA total of 63 160 people were envenomed during 2014–2018 with an average of 12 632 cases/year. The death rate between inpatient cases was 2.5%. The annual incidence was 18– 47 cases/100 000 population. Gadarif state recorded the highest incidence (132/100 000 population) of snakebite envenomation in Sudan whereas Northern state had the least incidence (5/100 000 population). The 15–24 y age group experienced the highest risk of snakebite and males were more exposed to snakebites than females.ConclusionsAlthough hospital-based records underestimate the burden of snakebite, they can still provide an insight regarding the actual numbers. Here, we highlight the at-risk states in Sudan to be targeted for further questionnaire-based epidemiological studies and to guide health authorities to reduce the burden of snakebite envenomation by insuring proper antivenom distribution to the highly affected areas.

Applying species distribution models in public health research by predicting snakebite risk using venomous snakes\u2019 habitat suitability as an indicating factor

Snakebite envenoming is an important public health problem in Iran, despite its risk not being quantified. This study aims to use venomous snakes’ habitat suitability as an indicator of snakebite risk, to identify high-priority areas for snakebite management across the country. Thus, an ensemble approach using five distribution modelling methods: Generalized Boosted Models, Generalized Additive Models, Maximum Entropy Modelling, Generalized Linear Models, and Random Forest was applied to produce a spatial snakebite risk model for Iran. To achieve this, four venomous snakes’ habitat suitability (Macrovipera lebetinus, Echis carinatus, Pseudocerastes persicus and Naja oxiana) were modelled and then multiplied. These medically important snakes are responsible for the most snakebite incidents in Iran. Multiplying habitat suitability models of the four snakes showed that the northeast of Iran (west of Khorasan-e-Razavi province) has the highest snakebite risk in the country. In addition, villages that were at risk of envenoming from the four snakes were identified. Results revealed that 51,112 villages are at risk of envenoming from M. lebetinus, 30,339 from E. carinatus, 51,657 from P. persicus and 12,124 from N. oxiana. Precipitation seasonality was identified as the most important variable influencing distribution of the P. persicus, E. carinatus and M. lebetinus in Iran. Precipitation of the driest quarter was the most important predictor of suitable habitats of the N. oxiana. Since climatic variables play an important role in shaping the distribution of the four venomous snakes in Iran, thus their distribution may alter with changing climate. This paper demonstrates application of species distribution modelling in public health research and identified potential snakebite risk areas in Iran by using venomous snakes’ habitat suitability models as an indicating factor. Results of this study can be used in snakebite and human–snake conflict management in Iran. We recommend increasing public awareness of snakebite envenoming and education of local people in areas which identified with the highest snakebite risk.

Forty-four years of global trade in CITES-listed snakes: Trends and implications for conservation and public health

Trade in venomous and non-venomous snakes can negatively impact wild snake populations and may drive snakebite risk for people. However, we often lack sufficient trade data to identify where the potential risks for snake population decline and snakebite are highest. Currently, the legal, international trade of 164 snake species is regulated by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). We analyzed CITES-listed snake trade from 1975 to 2018 using the recently released shipment-level CITES Trade Database to identify spatiotemporal trends of snake trade and generate insights regarding snake conservation and potential public health risks from snakebite. Commercially purposed pythons dominated the global snake trade, comprising 38.8% of all traded snakes. Live snakes were mainly exported by Ghana, Indonesia, Togo, and Benin, and imported by China and the USA. Venomous snake trade comprised 10.8% of all traded snakes, and over 75% of wild-sourced venomous snakes came from Indonesia. Although traded snakes in recent years are increasingly comprised of captive-bred animals, the majority of snakes are still wild-sourced (> 60% between 2015 and 2017), including IUCN-listed species, with potentially detrimental impacts on conservation status. Further, the CITES Trade Database reveals geographic regions where venomous snakes are sourced from the wild, posing potential risks to snake catchers, traders, and pet owners. The database also documents the movement of non-native snake species through trade, with implications for conservation of native species. This study represents the first global analysis focused specifically on CITES-listed snake trade using the CITES Trade Database.

Increase in the risk of snakebites incidence due to changes in humidity levels: A time series study in four municipalities of the state of Rondônia.

INTRODUCTION: Snakebites represent a serious global public health problem, especially in tropical countries. In Brazil, the incidence of snakebites ranges from 19 to 22 thousand cases per 100000 persons annually. The state of Rondônia, in particular, has had an increasing incidence of snakebites. METHODS: A retrospective cross-sectional study on snakebites was conducted from January 2007 to December 2018. Brazil’s Information System for Notifiable Diseases was queried for all snakebites reported in Porto Velho, Ariquemes, Cacoal, and Vilhena. Data on land surface temperatures during the day and night, precipitation, and humidity were obtained using the Google Earth Engine. A Bayesian time series model was constructed to describe the pattern of snakebites and their relationship with climate data. RESULTS: In total, 6326 snakebites were reported in Rondônia. Accidents were commonly caused by Bothrops sp. (n=2171, 81.80%). Snakebites most frequently occurred in rural areas (n=2271, 85.5%). Men, with a median age of 34 years (n=2101, 79.1%), were the most frequent bitten. Moderate clinical manifestation was the most common outcome of an accident (n=1101, 41.50%). There were clear seasonal patterns with respect to rainfall, humidity, and temperature. Rainfall and land surface temperature during the day or night did not increase the risk of snakebites in any city; however, changes in humidity increased the risk of snakebites in all cities. CONCLUSION: This study identified the population exposed to snakes and the influence of anthropic and climatic factors on the incidence of snakebites. According to climate data, changes in humidity increased the risk of snakebites.

Adjusting for spatial variation when assessing individual-level risk: A case-study in the epidemiology of snake-bite in Sri Lanka.

BackgroundHealth outcomes and causality are usually assessed with individual level sociodemographic variables. Studies that consider only individual-level variables can suffer from residual confounding. This can result in individual variables that are unrelated to risk behaving as proxies for uncaptured information. There is a scarcity of literature on risk factors for snakebite. In this study, we evaluate the individual-level risk factors of snakebite in Sri Lanka and highlight the impact of spatial confounding on determining the individual-level risk effects.MethodsData was obtained from the National Snakebite Survey of Sri Lanka. This was an Island-wide community-based survey. The survey sampled 165,665 individuals from all 25 districts of the country. We used generalized linear models to identify individual-level factors that contribute to an individual’s risk of experiencing a snakebite event. We fitted separate models to assess risk factors with and without considering spatial variation in snakebite incidence in the country.ResultsBoth spatially adjusted and non-adjusted models revealed that middle-aged people, males, field workers and individuals with low level of education have high risk of snakebites. The model without spatial adjustment showed an interaction between ethnicity and income levels. When the model included a spatial adjustment for the overall snakebite incidence, this interaction disappeared and income level appeared as an independent risk factor. Both models showed similar effect sizes for gender and age. HEmployment and education showed lower effect sizes in the spatially adjusted model.ConclusionsBoth individual-level characteristics and local snakebite incidence are important to determine snakebite risk at a given location. Individual level variables could act as proxies for underling residual spatial variation when environmental information is not considered. This can lead to misinterpretation of risk factors and biased estimates of effect sizes. Both individual-level and environmental variables are important in assessing causality in epidemiological studies.

The “T’s” of snakebite injury in the USA: fact or fiction?

BackgroundVenomous snakebites can result in serious morbidity and mortality. In the USA, the “T’s of snakebites” (testosterone, teasing, touching, trucks, tattoos & toothless (poverTy), Texas, tequila, teenagers, and tanks) originate...

Climate change impacts on the distribution of venomous snakes and snakebite risk in Mozambique

This paper aims to understand the impacts of global climate change (GCC) on the distribution of dangerous venomous snakes and snakebite risk in Mozambique, as a contribution to the enhancement of public health policies and snake conservation. We modelled current and future distribution of all 13 dangerous snakes occurring in Mozambique using ecological niche models to assess the likely impacts of climate change estimated as the difference between lost and gained climatic suitable area per species. In addition, we developed a normalized index of snakebite risk based on species diversity and species-specific traits for each time slice. We then superimposed our index to data on human population density to identify areas most prone to this burden. Our findings suggest considerable future reduction in climatically suitable area for nine out of 13 species, with species experiencing a north-south range shift and high rates of species turnover in northern Mozambique. We also found that GCC might alter the spatial patterns of snakebite risk in the country, with considerable increase in the future, affecting most areas in central and southern regions. This finding suggests that GCC will be harmful to venomous snakes in Mozambique with potentially adverse effects on public health. As GCC might induce the approximation of snake climatic suitable areas to highly populated areas, efforts are needed to increase human knowledge of snakebite prevention measures and increase awareness of the relative safety and attacking behaviour associated with some of the snakes studied here ensuring reduction in snakebites and improving species conservation.

357 Climate Change and Snakebites in California, 1997 to 2017

The global climate change effect on flora and fauna has been scientifically documented, but the effect of drought and precipitation changes on North American snakebites is unknown. This study's objective was to correlate snakebite incidence with weather and climate changes in California over 20 years. A retrospective analysis of all snakebite exposures reported to the Californian Poison Control System from 1997 to 2017. Demographics, morbidity, and envenomation variables were cohorted by caller zip code as a proxy for county-based incidence, and then correlated 6 separate databases containing: climate and weather data, air temperature, precipitation, population data, eco-regions, and land characteristics. These data were temporally and spatially aligned to provide aggregate incidence within land type, and adjusted for population to calculate incidence per million individuals. Time series modeling was performed using seasonal decomposition by Loess curve fitting. Dynamic linear lagged time series regression was used to develop predictive models between snakebite incidence and weather covariates. Multiple linear regression was used to explore how environmental and demographic variables in each county-year combination may have contributed to the incidence of envenomations. There were 5,365 reported snakebites during the study period, with a median age of 37 years (22 - 51) with 76% male (p < 0.001, 95% CI 76% to 78%). For patients between 20 - 30 years old, the male to female ratio was 5:1; 2:1 in all ages. Most envenomation outcomes were coded as minor (1363, 25%) or moderate (2607, 49%), with 3 deaths. Among the 3580 (67%) of reports with detailed treatment data, the most common intervention was FAB antibody (59%). Adjusted for population, the annualized incidence of snakebites did not significantly change during the study period (rho = -0.11, p = 0.65). The snakebite incidence per million people appeared to rise after a period of no drought and declined during periods of drought (r = -0.41, p-value < 0.01). Snakebite incidence decreased by 6 month prior drought (- 3.8% for each 10% increase in drought), and increased by 18 month prior precipitation (+ 3.9% for each 10% increase in precipitation). Weather patterns appear to have a significant and predictive effect on snakebites in California. Snakebite incidence decreased following drought, and increased after precipitation. Awareness of these trends may assist the public with seasonal snakebite risk assessment, and medical providers with preparation and appropriate resource allocations.

Estimating geographic patterns of ophidism risk in Ecuador

The species richness of venomous snakes in Ecuador (~39 species) is among the highest in the world. However, until now no information exists regarding geographic patterns of ophidism. In this study, we present a detailed spatial snakebite risk map which was built by stacking weighted ecological niche models of the 19 snake species responsible for the majority of Ecuador’s envenomation cases. Our weights were based on the proportion of cases reported for each species on local epidemiological studies. Based on our analyses, we identify 184 densely populated rural communities with high snakebite risk that should be monitored by health organizations. We also identified three densely populated rural locations (Palora Metzera, Sangay and Shell) that may require special attention because they had much higher snakebite risk values than the rest.

The Association Between Heat Waves and Other Meteorological Parameters and Snakebites: Israel National Study

BackgroundPublished annual estimates report a global burden of 2.5 million snakebite cases and >100,000 deaths. In Israel, envenomations are the third most frequent cause of poisonings that are of moderate to major clinical severity. Most studies focus on the clinical descriptions of snakebites in tropical climates, and we sought to investigate the association between snakebite frequency and meteorological parameters. ObjectiveWe sought to investigate the seasonality of snakebites and evaluate the association between increasingly common heat waves and other meteorological parameters and snakebite frequency in a semiarid nontropical climate. MethodsWe obtained data for all medical evacuations (2008–2015) because of snakebites in Israel. Climate data included daily 24-hour average temperature (°C) and relative humidity (%). We used a time-stratified case crossover method, in which a conditional logistic regression was applied to estimate the association, and we also stratified our analysis by season and by region. ResultsWe identified 1234 snakebite cases over 8 years, of which most (74.2%) occurred in hot seasons and between 6 pm and 9 pm. The risk of snakebite was positively associated with temperature >23°C (odds ratio [OR] 1.24, 95% confidence interval [CI] 1.01–1.53) and inversely with humidity >40% (OR 0.74, 95% CI 0.57–0.97). We also found an association with heat waves both in cold (OR 1.62, 95% CI 1.01–2.60) and hot seasons (OR 1.50, 95% CI 1.18–1.92). ConclusionsIn a semiarid nontropical climate, we observed an association between an increase in the number of snakebite cases and higher temperatures and lower humidity. Moreover, heat waves increased the frequency of snakebites in both cold and hot seasons.

A Survey of Snakebite Knowledge among Field Forces in China.

Background: A snakebite is a neglected extrinsic injury associated with high morbidity and global mortality. Members of Chinese field forces are at high risk of snakebites, and their perception and knowledge of snakebites are unknown. The aim of this study is to assess perception and knowledge of snakebites in field forces in southeast China; Methods: A cross-sectional questionnaire-based survey was conducted in July 2016. A total of 216 field force members participated in this study; Results: A total of 10.3% had experienced snakebites and 86.4% rated their demands for knowledge about snakebite as “high”. No significant correlation between the actual and perceived snakebite knowledge status was detected (κ = 0.0237, p = 0.3852). Ineffective and harmful traditional first-aid methods, such as the application of tourniquets, sucking the venom out of the wound, and making local incisions, were used by more than three quarters of the respondents. However, pressure immobilization bandages were applied by only 17.3% of members. The proportion of responses for each question was not significantly different among the respondents when considering separate demographic groups; Conclusions: Snakebite knowledge among Chinese field force members is inadequate and in some cases misleading, when focusing on manifestation, prevention, and first-aid. A pragmatic, intensive educational scheme should be undertaken in at-risk populations.

Mapping the Risk of Snakebite in Sri Lanka - A National Survey with Geospatial Analysis.

BackgroundThere 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 FindingsThe 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/SignificanceThis 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.

Public perceptions of snakes and snakebite management: implications for conservation and human health in southern Nepal

BackgroundVenomous snakebite and its effects are a source of fear for people living in southern Nepal. As a result, people have developed a negative attitude towards snakes, which can lead to human-snake conflicts that result in killing of snakes. Attempting to kill snakes increases the risk of snakebite, and actual killing of snakes contributes to loss of biodiversity. Currently, snake populations in southern Nepal are thought to be declining, but more research is needed to evaluate the conservation status of snakes. Therefore, we assessed attitudes, knowledge, and awareness of snakes and snakebite by Chitwan National Park’s (CNP) buffer zone (BZ) inhabitants in an effort to better understand challenges to snake conservation and snakebite management. The results of this study have the potential to promote biodiversity conservation and increase human health in southern Nepal and beyond.MethodsWe carried out face-to-face interviews of 150 randomly selected CNP BZ inhabitants, adopting a cross-sectional mixed research design and structured and semi-structured questionnaires from January–February 2013.ResultsResults indicated that 43 % of respondents disliked snakes, 49 % would exterminate all venomous snakes, and 86 % feared snakes. Farmers were the most negative and teachers were the most ambivalent towards snakes. Respondents were generally unable to identify different snake species, and were almost completely unaware of the need of conserve snakes and how to prevent snakebites. Belief in a snake god, and the ability of snakes to absorb poisonous gases from the atmosphere were among many superstitions that appeared to predispose negativity towards snakes of BZ residents.ConclusionPeople with predisposed negativity towards snakes were not proponents of snake conservation. Fear, negativity, ambivalence towards, and ignorance about, snakes and the need for snake conservation were strong indicators of the propensity to harm or kill snakes. It seems that if wanton killing of snakes continues, local snake populations will decline, and rare and endangered snake species may even become locally extirpated. Moreover, inappropriate perception and knowledge about snakes and snakebites may put BZ people at increased risk of venomous snakebite. Therefore, intensive, pragmatic educational efforts focused on natural history and ecology of snakes and prevention of snakebite should be undertaken in communities and at schools and universities.

Human, snake, and environmental factors in human-snake conflict in North Bihar — a one-year descriptive study

Background: The state of Bihar has the third largest number of snakebite deaths in India. The purpose of this study is to explore the factors related to human-snake conflicts in northwest Bihar and southern Nepal. Using these findings, various strategies were proposed to reduce the incidence of snakebites. Method: Data were collected from 609 patients at Duncan Hospital in Raxaul, Bihar, India between 1 July 2012 and 30 June 2013. Patients were included if they had a history of snakebite or unknown bites. Patients with symptoms of envenomation but no known bites were also included, as were patients who were dead on arrival due to a snakebite. Results: The 10-19 year old age group is the peak age group (28.4%) for snakebite. There is a slight preponderance of males (52.7%). 51.4% of bites occurred on the foot/ankle. The envenomation rate was 12.6%. The mortality rate of those envenomed that arrived at the hospital alive was 6.3%. Fourteen people were dead on arrival at the hospital. 75% of people were unable to identify what, or what type of snake, bit them. Common Wolf Snakes (Lycodon aulicus) were the most common snakes brought to the hospital, followed by Spectacled Cobra (Naja naja). Patients who brought snakes to the hospital and attempted identification were all successful at identifying cobras, but all those who brought in Common Wolf Snakes incorrectly identified them as Kraits. The highest monthly frequency of snakebites occurred between June and September; while on a daily basis, the highest frequency occurred between 1700hrs-2200hrs, the time in which 39.1% of all bites occurred. 59.2% of the bites occurred in and around the house. Farming, housework, sleeping, playing, and toileting in fields were the activities most commonly occurring when bitten. Sleeping on the floor increased the risk of envenomation [OR= 5.8, 95%CI 1.8-18.6], while sleeping under a mosquito net decreased the risk of envenomation [OR= 0.17, 95%CI 0.04-0.6]. Conclusion: Snakebite is a rural hazard in Northern Bihar, not just an occupational hazard. Use of toilets and sleeping on beds with well tucked in mosquito nets may help prevent snakebites. Education to reduce the risk of snakebites should begin in childhood and be regularly reinforced prior to the rainy season. Prevention measures should include environmental management such as keeping eating areas clean and keeping food storage and sleeping areas a distance apart.

A possible association between the resumption of agricultural activities and a venomous snakebite after Fukushima nuclear crisis.

A 42-year-old male was brought to our hospital in Fukushima, Japan, due to a snakebite by a Mamushi (Gloydius blomhoffii) on his right index finger (Fig. 1). The bite occurred while he was cutting bushes in Iitate village, a mountainous area originally famous for agriculture but contaminated by radioactive agents following Fukushima nuclear crisis in 2011. Evacuation orders led to mass evacuation and abandonment of the village. However, in the past year, there has been a slow resumption of agricultural activities. Figure 1: Ecchymosis exists around the bite site at the distal interphalangeal joint of his right index finger, with swelling around his right hand and forearm. There may be an increased risk of venomous snakebites after natural disasters, due to infrastructural damage, as well as poor knowledge regarding possibly dangerous native fauna among local residents and emergency personnel [1]. Moreover, rapid environmental changes may contribute to the destruction and invasion of snake habitats, possibly increasing their encounters with humans [2]. On the other hand, after nuclear disasters, damage to infrastructure in surrounding areas is usually less than would occur after natural disasters [3]. Additionally, nuclear disasters can lead to evacuation of local residents [3, 4], lessening the chance of human–snake interactions. Therefore, immediate risk of snakebites after nuclear disasters may be lower than that after natural disasters. However, little is known about long-term risk of snakebites after nuclear disasters. The present venomous snakebite may be associated with the resumption of agriculture, 3 years after the disaster. Post-evacuation, Mamushi habitats may have expanded due to increased amounts of fallen debris on farming fields, where they prefer to live [5]. While a range of physiological, developmental, genetic, morphological and behavioral consequences of radiation exposure have been investigated in flora and fauna in Fukushima [6], there is little information on potential effects on reptiles, calling for further research. We should be aware of an increased risk of snakebites in previously abandoned areas of Fukushima, and other long-deserted post-disaster areas.

Mapping current and future potential snakebite risk in the new world

Snakebite envenoming is an important public health concern worldwide. In the Americas, ~300,000 bites occur annually, leaving 84,110–140,981 envenomings and 652–3466 deaths. Here, we modeled current and future snakebite risk using ecological niche models (ENMs) of 90 venomous snake taxa. Current snakebite risk predictions were corroborated by incidence data from eight regions/periods with different characteristics. Detailed projections of potential future range shifts on distributions of the medically most relevant species indicated that North American species’ ranges are likely to increase in the future, but mixed results were obtained for Latin American snakes. A likely expansion of overall risk area and an increase of rural population at risk were observed from a consensus model among future scenarios. Our study highlights the capacity of ENMs to provide detailed information on current and future potential distributions of venomous snakes, as well as useful perspectives on snakebite risk, at least broad scales.

The Use of Ecological Niche Modeling to Infer Potential Risk Areas of Snakebite in the Mexican State of Veracruz

BackgroundMany authors have claimed that snakebite risk is associated with human population density, human activities, and snake behavior. Here we analyzed whether environmental suitability of vipers can be used as an indicator of snakebite risk. We tested several hypotheses to explain snakebite incidence, through the construction of models incorporating both environmental suitability and socioeconomic variables in Veracruz, Mexico.Methodology/Principal FindingsEcological niche modeling (ENM) was used to estimate potential geographic and ecological distributions of nine viper species' in Veracruz. We calculated the distance to the species' niche centroid (DNC); this distance may be associated with a prediction of abundance. We found significant inverse relationships between snakebites and DNCs of common vipers (Crotalus simus and Bothrops asper), explaining respectively 15% and almost 35% of variation in snakebite incidence. Additionally, DNCs for these two vipers, in combination with marginalization of human populations, accounted for 76% of variation in incidence.Conclusions/SignificanceOur results suggest that niche modeling and niche-centroid distance approaches can be used to mapping distributions of environmental suitability for venomous snakes; combining this ecological information with socioeconomic factors may help with inferring potential risk areas for snakebites, since hospital data are often biased (especially when incidences are low).

Using Geographical Information Systems to Identify Populations in Need of Improved Accessibility to Antivenom Treatment for Snakebite Envenoming in Costa Rica

IntroductionSnakebite accidents are an important health problem in rural areas of tropical countries worldwide, including Costa Rica, where most bites are caused by the pit-viper Bothrops asper. The treatment of these potentially fatal accidents is based on the timely administration of specific antivenom. In many regions of the world, insufficient health care systems and lack of antivenom in remote and poor areas where snakebites are common, means that efficient treatment is unavailable for many snakebite victims, leading to unnecessary mortality and morbidity. In this study, geographical information systems (GIS) were used to identify populations in Costa Rica with a need of improved access to antivenom treatment: those living in areas with a high risk of snakebites and long time to reach antivenom treatment.Method/Principal FindingsPopulations living in areas with high risk of snakebites were identified using two approaches: one based on the district-level reported incidence, and another based on mapping environmental factors favoring B. asper presence. Time to reach treatment using ambulance was estimated using cost surface analysis, thereby enabling adjustment of transportation speed by road availability and quality, topography and land use. By mapping populations in high risk of snakebites and the estimated time to treatment, populations with need of improved treatment access were identified.Conclusion/SignificanceThis study demonstrates the usefulness of GIS for improving treatment of snakebites. By mapping reported incidence, risk factors, location of existing treatment resources, and the time estimated to reach these for at-risk populations, rational allocation of treatment resources is facilitated.