Snakebites and climate change in California, 1997-2017

Predicting the drivers of Bothrops snakebite incidence across Brazil: A Spatial Analysis

Snakebite envenoming poses a significant public health challenge on a global basis, affecting millions of people annually and leading to complications that may result in fatalities. Brazil stands as one of the countries most impacted by snakebite envenoming, with snakes of the Bothrops genus being responsible for most bites. The current study aimed to identify the determinants of Bothrops snakebite incidence across different regions of Brazil. An ecological study was conducted using municipality-aggregated data, with snakebite incidence as the dependent variable. The study period comprised the years 2015-2021. We constructed Species Distribution Models (SDMs) for Bothrops species, and information was collected on precipitation, runoff, maximum and minimum temperatures, native forest, historical forest loss, agriculture, and pasture in each Brazilian municipality. These data were employed to assess the association between snakebite incidence and biotic, climatic, and landscape factors. The data were analyzed using Generalized Least Squares (GLS) regression. The SDMs demonstrated good performance. The average annual snakebite incidence during the study period ranged from zero to 428.89 per 100,000 inhabitants, depending on the municipality. Higher incidence rates were concentrated primarily in municipalities in the northern region of the country. In this study, we found that nationwide, areas with extensive native forests and those that have historically experienced significant loss of forest cover exhibited higher snakebite incidence rates. Additionally, areas with higher temperatures and precipitation levels, as well as greater climatic suitability for the species B. jararaca, showed significantly higher snakebite incidence rates in the South and Southeast of Brazil, respectively. These associations may be linked to increased snake abundance and active behavior, as well as to engagement in activities favoring human-snake contact in these areas. The findings of this study can contribute to the improvement of prevention and control strategies for this public health issue in Brazil.

Combining species distribution models and big datasets may provide finer assessments of snakebite impacts

BACKGROUND

Snakebite is a major poverty-related neglected tropical disease. An integrated scientific approach is needed to understand the dynamics of this important health issue. Our objective was to estimate snakebite occurrence in a tropical area by using a blend of ecological modelling and robust statistical analysis.

METHODS

The present study used climatic, environmental, and human population density data to determine the area with snakebite occurrence-probability for the first time in Bangladesh. We also analysed a large, 16-year dataset of hospitalized snakebite cases to reveal the epidemiology of snakebite in the south-eastern zone of the country.

FINDINGS

Our results show that cobra bite is the most commonly occurring venomous snakebite in humans (around ~12% of the total yearly snakebite records), and men are more frequently bitten than women (2/3 of human victims are men). Most bites occur during the rainy season for cobra and green pit viper, while krait bites are not restricted to any particular season. As snakebite incidents are closely related to climate conditions, we can model snakebite risk using temperature and precipitation variables. Whereas there is a lack of snakebite reports from several parts of the study area in official records, our models predict that the entire study area is favourable for snakebite incidents. Based on the combined evidence we estimate that about 200,000 snakebite events occur every year in the south-eastern part of Bangladesh alone. Considering future global climate change, our model projections show that snakebite incidence in Bangladesh might not significantly decrease in the future (- 2070-); however, the distribution of probabilities might change, with a predicted increase of snakebite incidence in the hilly areas of the country.

CONCLUSIONS

Using climatic data to predict snakebite incidence in Bangladesh allowed us to provide estimations of the total annual number of snakebite cases in the study area. As in most countries, the scarcity of accurate epidemiological data in official records might have masked the real magnitude of this problem. Our analysis suggests that the problem of snakebite envenoming in Bangladesh might be worse than currently perceived. A long-term sustainable snakebite program plan should be designed and institutionalized, considering climatic, geographical and human demographic variables, to obtain better data and facilitate the implementation of accurate snakebite management programs for this country.

The Association Between Ambient Temperature and Snakebite in Georgia, USA: A Case-Crossover Study

The World Health Organization has identified snakebite envenoming as a highest priority neglected tropical disease, yet there is a dearth of epidemiologic research on environmental risk factors, including outdoor temperature. Temperature may affect snakebites through human behavior or snake behavior; snakes are ectotherms, meaning outdoor temperatures influence their internal body temperature and thus their behavior. Here we investigate the relationship between short-term temperature and snakebites in Georgia, one of the most biodiverse US states in terms of herpetofauna. We acquired emergency department (ED) visit data for Georgia between 1 January 2014 and 31 December 2020. Visits for venomous and non-venomous snakebites were identified using diagnosis codes. For comparison, we also considered visits for non-snake (e.g., insects, spiders, scorpions) envenomation. Daily meteorology from the Daymet 1 km product was linked to patient residential ZIP codes. We applied a case-crossover design to estimate associations of daily maximum temperature and snakebite ED visits. During the 7-year study period, there were 3,908 visits for venomous snakebites, 1,124 visits for non-venomous bites and 65,187 visits for non-snake envenomation. Across the entire period, a 1°C increase in same-day maximum temperature was associated with a 5.6% (95%CI: 4.0-7.3) increase in the odds of venomous snakebite and a 5.8% (95%CI: 3.0-8.8) increase in non-venomous snakebite. Associations were strongest in the spring. We also observed a positive and significant (p < 0.05) association for non-snake envenomation, albeit slightly smaller and more consistent across seasons compared to those for snakebites.

Climate change maladaptation for health: Agricultural practice against shifting seasonal rainfall affects snakebite risk for farmers in the tropics

Snakebite affects more than 1.8 million people annually. Factors explaining snakebite variability include farmers' behaviors, snake ecology and climate. One unstudied issue is how farmers' adaptation to novel climates affect their health. Here we examined potential impacts of adaptation on snakebite using individual-based simulations, focusing on strategies meant to counteract major crop yield decline because of changing rainfall in Sri Lanka. For rubber cropping, adaptation led to a 33% increase in snakebite incidence per farmer work hour because of work during risky months, but a 17% decrease in total annual snakebites because of decreased labor in plantations overall. Rice farming adaptation decreased snakebites by 16%, because of shifting labor towards safer months, whereas tea adaptation led to a general increase. These results indicate that adaptation could have both a positive and negative effect, potentially intensified by ENSO. Our research highlights the need for assessing adaptation strategies for potential health maladaptations.

Seasonal variation, treatment outcome, and its associated factors among the snakebite patients in Somali region, Ethiopia

Background

Snakebite is a major cause of mortality and morbidity in many areas, particularly in the rural tropics, and is a major public health problem around the world. It also imposes significant economic burdens on snakebite victims due to treatment-related expenses and lost productivity.

Objective

The purpose of this study was to assess seasonal variation, treatment outcomes, and its associated factors among snakebite in Denan health center in the Somali region, Ethiopia.

Method

A facility-based cross-sectional study was conducted from 10 to 30 September 2020 in Denan health center, Somali region, Ethiopia. All snakebite cases in Denan health center from 1 September 2015 to 31 August 2020 were included. Data were collected using a pre-tested structured checklist from the patient cards. Data were entered into EpiData version 3.1 and analyzed using SPSS version 22 (IBM SPSS Statistics, 2013). The prevalence was reported by proportion with 95% confidence interval (CI) and summary measures. Predictors were assessed using a multivariable logistic regression analysis model and reported using an adjusted odds ratio with 95% CI. Statistical significance was declared at p-value < 0. 05.

Result

The overall prevalence of poor outcome of venomous snakebites was 31.4% (95% CI 26.3% 35.4%). Study participants with an age of less than 10 years old (AOR = 2.01; 95% CI 1.39, 4.05), age between 10 and 30 years old (AOR = 2.06; 95% CI 1.39, 9.30), arrival times greater than or equal to 6 hours (AOR = 2.37; 95% CI 1.39, 4.05), and timing of snakebite (AOR = 0.49; 95% CI 0.31-0.87) were factors found to be significantly associated with poor treatment outcome.

Conclusion

According to this study, about one in every three snakebite patients have a poor outcome. Patients with poor outcomes were those who did not improve as a result of treatment or died as a result of it. Designing appropriate engagement of public health education about snakebite prevention techniques, particularly during entry and exit of rainy seasons and establishment of appropriate case management protocol is strongly recommended, as well as increasing the accessibility or availability of antivenoms will undoubtedly have a significant impact on the reduction of mortality and disability related to that of the snakebites.

A Retrospective Evaluation of Snake Envenomation in Dogs in South Korea (2004-2021)

Snake envenomation is a medical emergency capable of causing local and systemic complications. However, information on venomous snakebite in dogs in South Korea is scarce. In this study, fifty-nine dogs treated at a private veterinary clinic from 2004 to 2021 were retrospectively studied. The aim was to characterize the demographics, elapsed time between snakebite and veterinary clinic presentation, laboratory findings, clinical signs, treatments, adverse reactions to antivenom, and prognosis of venomous snakebite. Snakebite was mostly observed between 12 p.m. and 5 p.m. from April to October. On the days of envenomation, the weather conditions were mostly cloudy, followed by rain/precipitation, and least frequently fair weather. Grassland was the most common incident location, and leashed dog walking was the most frequent activity when snakebite occurred. The main local symptoms were edema, hemorrhagic discharge, cutaneous erythema, ulceration, and necrosis. Major systemic clinical signs were tachypnea, tachycardia, altered mentation, ptyalism, and hypotension. Based on the time interval between snakebite and presentation at the veterinary clinic, two groups were defined: <4 h (Group 1, 49.2%) and ≥4 h (Group 2, 50.8%). Systemic inflammation was more frequently observed in Group 2. The level of C-reactive protein at presentation (p = 0.036) and the highest-level during hospitalization (p = 0.023) were significantly elevated in Group 2 (≥4 h). The dogs in Group 2 displayed more frequent muscle damage (increased creatine kinase) than the dogs in Group 1, and a higher level of creatine kinase was associated with delayed (≥4 h) presentation after snakebite (p = 0.003). All of the dogs were treated symptomatically, and 34 dogs (58%) received antivenom. Treatment with antivenom showed no adverse reactions in this study. All of the treated dogs recovered. One dog was euthanized without any treatment due to respiratory distress, hypotension, and cost constraints. In conclusion, this study provides baseline information on venomous snakebite in dogs in South Korea. The prognosis was excellent, especially when the dogs were treated within 4 h.

Association of daily high temperatures with increased snake envenomations: A case-crossover study

The prevention of snake envenomations in North America often focuses on avoiding interactions between humans and snakes. Previous strategies have focused on the influence of geography, type of habitat, and time of year, though a detailed analysis of weather patterns on snakebite envenomation behavior is lacking. We present a case-crossover study of non-pregnant adults (n = 489) who reported snake envenomations to a single state's poison control center from 2014 to 2018. Age and gender of the individual, as well as the date, time, zip code associated with the envenomation, and snake descriptions were collected. Information regarding barometric pressure, actual temperature, high and low daily temperature, and weather condition (fair, cloudy, or rain/precipitation) was collected and compared to the same zip code, date, and time exactly one week and one year prior to the envenomation using historical data from the Weather Underground database. Paired t-tests and Stuart-Maxwell tests were used to determine differences in weather conditions during the study period. This study was IRB-approved. At the time of envenomation, the weather was most often fair (52.2%), followed by cloudy (44%), and least frequently demonstrated rain/precipitation (3.9%). Snake envenomations increased significantly (p < 0.0001) on days with an elevated daily high temperature. There were statistical differences in the distribution of weather conditions (fair, cloudy, or rain/precipitation) on the day of envenomation compared to one week prior (p < 0.0001) and one year prior (p < 0.0008). Comparisons based on both control groups indicated that envenomations were significantly less likely to occur during rain/precipitation and cloudy weather than during fair weather. Limitations include its retrospective nature and low total number of envenomations. In our single-center study, snake envenomation behavior as it relates to readily reportable weather measurements, appears to be associated with the warmer days, the overall high temperature on the day of envenomation, and fair weather conditions. Actual temperature at the time of envenomation, low temperature, barometric pressure, and precipitation at the time of envenomation do not appear to be associated with an increased risk of envenomation. Additional studies to determine the cause of these associations would be beneficial in further delineating the findings of this study.

Rattlesnake envenomation in 2 Visayan warty pigs

Rattlesnake envenomation is an important cause of morbidity and mortality in humans and animals in the southwestern United States and elsewhere. Two Visayan warty pigs (Sus cebifrons) from a regional zoo were submitted for autopsy after being found dead close to a southern Pacific rattlesnake (Crotalus helleri) in their enclosure. Both pigs had severe regionally extensive cutaneous, subcutaneous, and muscle hemorrhage and edema with myonecrosis. Additionally, both pigs had lesions consistent with puncture wounds within the oral cavity, and one pig had a similar wound on a forelimb. The history, and gross and histologic findings, were consistent with envenomation by rattlesnake bite. There are few documented cases of snakebite envenomation in pigs, and it had been suggested that pigs may have some degree of resistance to envenomation. Our results indicate that warty pigs are susceptible to the action of rattlesnake venom.

The impact of climate change on neglected tropical diseases: a systematic review

Neglected tropical diseases (NTDs) are a diverse group of diseases that continue to affect >1 billion people, with these diseases disproportionately impacting vulnerable populations and territories. Climate change is having an increasing impact on public health in tropical and subtropical areas and across the world and can affect disease distribution and transmission in potentially diverse ways. Improving our understanding of how climate change influences NTDs can help identify populations at risk to include in future public health interventions. Articles were identified by searching electronic databases for reports of climate change and NTDs between 1 January 2010 and 1 March 2020. Climate change may influence the emergence and re-emergence of multiple NTDs, particularly those that involve a vector or intermediate host for transmission. Although specific predictions are conflicting depending on the geographic area, the type of NTD and associated vectors and hosts, it is anticipated that multiple NTDs will have changes in their transmission period and geographic range and will likely encroach on regions and populations that have been previously unaffected. There is a need for improved surveillance and monitoring to identify areas of NTD incursion and emergence and include these in future public health interventions.

Implications of global environmental change for the burden of snakebite

Snakebite envenoming is a set of intoxication diseases that disproportionately affect people of poor socioeconomic backgrounds in tropical countries. As it is highly dependent on the environment its burden is expected to shift spatially with global anthropogenic environmental (climate, land use) and demographic change. The mechanisms underlying the changes to snakebite epidemiology are related to factors of snakes and humans. The distribution and abundance of snakes are expected to change with global warming via their thermal tolerance, while rainfall may affect the timing of key activities like feeding and reproduction. Human population growth is the primary cause of land-use change, which may impact snakes at smaller spatial scales than climate via habitat and biodiversity loss (e.g. prey availability). Human populations, on the other hand, could experience novel patterns and morbidity of snakebite envenoming, both as a result of snake responses to environmental change and due to the development of agricultural adaptations to climate change, socioeconomic and cultural changes, development and availability of better antivenoms, personal protective equipment, and mechanization of agriculture that mediate risk of encounters with snakes and their outcomes. The likely global effects of environmental and demographic change are thus context-dependent and could encompass both increasing and or snakebite burden (incidence, number of cases or morbidity), exposing new populations to snakes in temperate areas due to “tropicalization”, or by land use change-induced snake biodiversity loss, respectively. Tackling global change requires drastic measures to ensure large-scale ecosystem functionality. However, as ecosystems represent the main source of venomous snakes their conservation should be accompanied by comprehensive public health campaigns. The challenges associated with the joint efforts of biodiversity conservation and public health professionals should be considered in the global sustainability agenda in a wider context that applies to neglected tropical and zoonotic and emerging diseases.

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Distribution and abundance of snakes are expected to be affected by climate change.

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Land-use change may also impact snakes but at smaller spatial scales than climate.

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Human populations could experience novel patterns and morbidity of snakebite.

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Reducing snakebite should be accompanied by actions that protect snake diversity.

Snakebites in Rio Branco and surrounding region, Acre, Western Brazilian Amazon

INTRODUCTION

Snakebites are considered a neglected tropical disease in many countries in Latin America, including Brazil. As few studies have assessed snakebites in the Amazon region and especially in the state of Acre, epidemiological studies are of great importance. The present study aimed to describe the epidemiological characteristics of snakebites in the Rio Branco region, observing their characteristics in rural and urban areas and their correlation with rainfall and river outflow.

METHODS

This retrospective, descriptive study analyzed epidemiological information obtained from snakebite notifications registered on the Information System for Notifiable Diseases that occurred from March, 2018 to February, 2019. The cases of snakebite were correlated with rainfall and flow.

RESULTS

A total of 165 cases of snakebite were registered in the period. Most cases were caused by Bothrops and affected mainly individuals of the male sex who were between 21 and 30 years old. Most of the snakebites occurred in Rio Branco (71.52%; 29 cases per 100,000 inhabitants). Of these, 60.2% occurred in the urban area and 39.8% in the rural area and the majority occurred during the rainy season.

CONCLUSIONS

Although studies have shown that a majority of cases occur in rural areas, in this study, urbanization of snakebites was observed. The Bothrops genus was responsible for the highest number of snakebites and, during the rainy season, bites occurred more frequently. Educational prevention campaigns, population advice, and first aid in case of snakebites for the population are thus suggested.

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.

Management and cost of snakebite injuries at a teaching and referral hospital in Western Kenya

Background: Data on the cost of snakebite injuries may inform key pillars of universal health coverage including proper planning, allocation, and utility of resources. This study evaluated the injuries, management, and costs resulting from snakebites at Jaramogi Oginga Odinga Teaching and Referral Hospital (JOOTRH) in Kenya.  Methods: In total, medical records of 127 snakebite victims attending JOOTRH between January 2011 and December 2016 were purposely selected and data on the age, gender, type of residence (urban or rural), part of the body bitten, time of bite, injuries, pre-hospital first aid, time to hospital, length of stay, treatment, and costs were collected. Regression analysis was used to predict the total indirect cost of snakebite injuries and p≤ 0.05 was considered significant. Mortality and loss of income of hospitalized victims were considered as direct costs. Results: It was found that 43 victims were 13-24 years of age, 64 were female, 94 were from rural areas, 92 were bitten on the lower limbs, 49 were bitten between 6.00 pm and midnight, 43 attempted pre-hospital first aid, and the median time to hospital was 4.5 hours. Antivenom, supportive therapy, antibiotics, antihistamines, corticosteroids, analgesics, and non-steroidal anti-inflammatory drugs were used. Cellulitis, compartment syndrome, gangrenous foot, psychiatric disorder, and death were the main complications. Most victims spent 1-5 days in hospital and the median cost of treating a snakebite was 2652 KES (~$26). Drugs, ward charges, and nursing procedures were the highest contributors to the total indirect cost. Victims hospitalized for 6-10 days and >10 days incurred 32% and 62% more costs, respectively, compared to those hospitalized for 1-5 days.  Conclusions: The longer snakebite victims are hospitalized, the higher the cost incurred. Continuous medical education on the correct management of snakebites should be encouraged to minimize complications that may increase hospital stays and costs incurred.