A simple mortality risk prediction score for viper envenoming in India (VENOMS): A model development and validation study

Handheld Point-of-Care Devices for Snakebite Coagulopathy: A Scoping Review

Venom-induced consumption coagulopathy (VICC) is a common complication of snakebite that is associated with hypofibrinogenemia, bleeding, disability, and death. In remote tropical settings, where most snakebites occur, the 20-minute whole blood clotting test is used to diagnose VICC. Point-of-care (POC) coagulation devices could provide an accessible means of detecting VICC that is better standardized, quantifiable, and more accurate. In this scoping review, the mechanistic reasons that previously studied POC devices have failed in VICC are considered, and evidence-based recommendations are made to prioritize certain devices for clinical validation studies. Four small studies have evaluated a POC international normalized ratio (INR) device in patients with Australian Elapid, Daboia russelii, and Echis carinatus envenoming. The devices assessed in these studies either relied on a thrombin substrate endpoint, which is known to underestimate INR in patients with hypofibrinogenemia, have been recalled due to poor accuracy, or have since been discontinued. Sixteen commercially available POC devices for measuring INR, activated clotting time, activated partial thromboplastin time, fibrinogen, D-dimer, and fibrin(ogen) degradation products have been reviewed. POC INR devices that detect fibrin clot formation, as well as a novel POC device that quantifies fibrinogen were identified, which show promise for use in patients with VICC. These devices could support more accurate allocation of antivenom, reduce the time to antivenom administration, and provide improved clinical trial outcome measurement instruments. There is an urgent need for these promising POC coagulation devices to be validated in prospective clinical snakebite studies.

Using a Machine Learning Approach to Predict Snakebite Envenoming Outcomes Among Patients Attending the Snakebite Treatment and Research Hospital in Kaltungo, Northeastern Nigeria

The Snakebite Treatment and Research Hospital (SBTRH) is a leading centre for snakebite envenoming care and research in sub-Saharan Africa, treating over 2500 snakebite patients annually. Despite routine data collection, routine analyses are seldom conducted to identify trends or guide clinical practices. This study retrospectively analyzes 1022 snakebite cases at SBTRH from January to June 2024. Most patients were adults (62%) and were predominantly male (72%). Key factors such as age, sex, and time between bite and hospital presentation were associated with outcomes, including recovery, amputation, debridement, and death. Adult males who took more than four hours to arrive to hospital were identified as a high-risk group for poor outcomes. Using patient characteristics, an XGBoost model was developed and was compared to Random Forest and logistic regression models. In general, all models had high positive predictive value and low sensitivity, meaning that if they predicted a patient to experience amputation, debridement, or death, that patient almost always actually experienced amputation, debridement, or death; however, most models rarely made this prediction. The XGBoost model with all features was optimal, given that it had both a high positive predictive value and relatively high sensitivity. This may be of significance to resource-limited settings like SBTRH, where antivenoms can be scarce; however, more research is needed to build better predictive models. These findings underscore the need for targeted interventions for high-risk groups, and further research and integration of machine-learning-driven decision support tools in low-resource-limited clinical settings.

Capillary leak syndrome due to snakebite in the Amazon: case report

Capillary leak syndrome is a unique complication characterized by extravasation of liquids in the interstitial space due to protein loss caused by snakebite envenoming. We describe the case of a 12-year-old boy from the district of Napo in the city of Iquitos in the Peruvian Amazon, who had edema and increased face volume due to the bite of a snake of the Bothrops genus in the lateral aspect of the right leg; he was the hospitalized and diagnosed with severe ophidism complicated with face edema. The patient received eight vials of antivenin, antibiotics and analgesics. Finally, the patient was discharged from the hospital after eight days of hospitalization, with favorable evolution and recovery.

Systemic capillary leak syndrome

The vascular endothelial barrier maintains intravascular volume and metabolic homeostasis. Although plasma fluids and proteins extravasate continuously from tissue microvasculature (capillaries, post-capillary venules), systemic vascular leakage increases in critical illness associated with sepsis, burns and trauma, among others, or in association with certain drugs or toxin exposures. Systemically dysregulated fluid homeostasis, which can lead to hypovolaemia, hypotensive shock and widespread tissue oedema, has been termed systemic capillary leak syndrome (SCLS) when overt secondary causes (for example, heart or liver failure) are excluded. In severe forms, SCLS is complicated by compartment syndrome in the extremities and multi-organ dysfunction syndrome due to shock and systemic hypoperfusion. The different forms of SCLS include idiopathic SCLS (ISCLS) and secondary SCLS (SSCLS), which can be triggered by several conditions, including certain infections and haematological malignancies. A subgroup of patients with ISCLS have monoclonal gammopathy-associated SCLS (also known as Clarkson disease), which is an ultra-rare and extreme form of ISCLS. ISCLS can be managed effectively with monthly prophylactic immunoglobulin therapy whereas SSCLS frequently does not recur once the underlying condition resolves or the offending agent is discontinued. Thus, differentiation between ISCLS, SSCLS and other causes of oedema is crucial for quick diagnosis and positive patient outcomes.

Oral varespladib for the treatment of snakebite envenoming in India and the USA (BRAVO): a phase II randomised clinical trial

INTRODUCTION

Snakebite envenoming (SBE) results in over 500 000 deaths or disabling injuries annually. Varespladib methyl, an oral inhibitor of secretory phospholipase A2, is a nearly ubiquitous component of snake venoms. We conducted a phase II clinical trial to assess efficacy and safety of oral varespladib methyl in patients bitten by venomous snakes.

METHODS

This double-blind, randomised, placebo-controlled trial enrolled patients in emergency departments in India and the USA. Patients with SBE were randomly assigned (1:1) to receive varespladib methyl or placebo two times per day for 1 week. All patients received standard of care, including antivenom. The primary outcome was change in the composite Snakebite Severity Score (SSS) measuring the severity of envenoming, from baseline to the average composite SSS at 6 and 9 hours.

RESULTS

Among 95 patients randomised August 2021 through November 2022, the most common snakebites were from Russell's vipers (n=29), copperheads (n=18) and rattlesnakes (n=14). The SSS improved from baseline to the average at 6 and 9 hours by 1.1 (95% CI, 0.7 to 1.6) in the varespladib group versus 1.5 (95% CI, 1.0 to 2.0) in the placebo group (difference -0.4, 95% CI, -0.8 to 0.1, p=0.13). While key secondary outcomes were not statistically different by treatment group, benefit was seen in the prespecified subgroup initiating study drug within 5 hours of bite (n=37). For this early treatment group, clinically important differences were observed for illness severity over the first week, patient-reported function on days 3 and 7 and complete recovery. No death or treatment emergent serious adverse event occurred.

CONCLUSION

For emergency department treatment of snakebites, the addition of varespladib to antivenom did not find evidence of difference for the primary outcome based on the SSS. A potentially promising signal of benefit was observed in patients initiating treatment within 5 hours of snakebite.

Hump-Nosed Pit Viper (Hypnale hypnale) Venom-Induced Irreversible Red Blood Cell Aggregation, Inhibition by Monovalent Anti-Venom and N-Acetylcysteine

Envenomation by the Hypnale hypnale in the Western Ghats of India (particularly in the Malabar region of Kerala) and the subcontinent island nation of Sri Lanka is known to inflict devastating mortality and morbidity. Currently, H. hypnale bites in India are devoid of anti-venom regimens. A detailed characterization of the venom is essential to stress the need for therapeutic anti-venom. Notably, the deleterious effects of this venom on human blood cells have largely remained less explored. Therefore, in continuation of our previous study, in the present study, we envisioned investigating the effect of venom on the morphological and physiological properties of red blood cells (RBCs). The venom readily induced deleterious morphological changes and, finally, the aggregation of washed RBCs. The aggregation process was independent of the ROS and the intracellular Ca2+ ion concentration. Confocal and scanning electron microscopy (SEM) images revealed the loss of biconcave morphology and massive cytoskeletal disarray. Crenation or serrated plasma membrane projections were evenly distributed on the surface of the RBCs. The venom did not cause the formation of methemoglobin in washed RBCs but was significantly induced in whole blood. Venom did not affect glucose uptake and Na+/K+ -ATPase activity but inhibited glucose 6 phosphate dehydrogenase activity and decreased the fluidity of the plasma membrane. Venom-induced RBC aggregates exhibited pro-coagulant activity but without affecting platelet aggregation. In pre-incubation or co-treatment studies, none of the bioactive compounds, such as melatonin, curcumin, fisetin, berberine, and quercetin, sugars such as mannose and galactose, and therapeutic polyvalent anti-venoms (Bharat and VINS) were inhibited, whereas only N-acetylcysteine and H. hypnale monovalent anti-venom could inhibit venom-induced deleterious morphological changes and aggregation of RBCs. In post-treatment studies, paradoxically, none of the bioactives and anti-venoms, including N-acetylcysteine and H. hypnale monovalent anti-venom, reversed the venom-induced RBC aggregates.

Pulmonary Thromboembolism following Russell's Viper Bites

Snakebite envenoming and its resulting complications are serious threats to the health of vulnerable people living in rural areas of developing countries. The knowledge of the heterogeneity of symptoms associated with snakebite envenoming and their management strategies is vital to treat such life-threatening complications to save lives. Russell's viper envenomation induces a diverse range of clinical manifestations from commonly recognised haemotoxic and local effects to several rare conditions that are often not reported. The lack of awareness about these unusual manifestations can affect prompt diagnosis, appropriate therapeutic approaches, and positive outcomes for patients. Here, we report pulmonary thromboembolism that developed in three patients following Russell's viper envenomation and demonstrate their common clinical features and diagnostic and therapeutic approaches used. All patients showed clinical signs of local (oedema) and systemic (blood coagulation disturbances) envenomation, which were treated using polyvalent antivenom. They exhibited elevated heart rates, breathlessness, and reduced oxygen saturation, which are non-specific but core parameters in the diagnosis of pulmonary embolism. The recognition of pulmonary embolism was also achieved by an electrocardiogram, which showed sinus tachycardia and computed tomography and echocardiogram scans further confirmed this condition. Anti-coagulant treatment using low-molecular-weight heparin offered clinical benefits in these patients. In summary, this report reinforces the broad spectrum of previously unreported consequences of Russell's viper envenomation. The constant updating of healthcare professionals and the dissemination of major lessons learned in the clinical management of snakebite envenoming through scientific documentation and educational programs are necessary to mitigate the adverse impacts of venomous snakebites in vulnerable communities.

Viper Venom Phospholipase A2 Database: The Structural and Functional Anatomy of a Primary Toxin in Envenomation

Viper venom phospholipase A2 enzymes (vvPLA2s) and phospholipase A2-like (PLA2-like) proteins are two of the principal toxins in viper venom that are responsible for the severe myotoxic and neurotoxic effects caused by snakebite envenoming, among other pathologies. As snakebite envenoming is the deadliest neglected tropical disease, a complete understanding of these proteins' properties and their mechanisms of action is urgently needed. Therefore, we created a database comprising information on the holo-form, cofactor-bound 3D structure of 217 vvPLA2 and PLA2-like proteins in their physiologic environment, as well as 79 membrane-bound viper species from 24 genera, which we have made available to the scientific community to accelerate the development of new anti-snakebite drugs. In addition, the analysis of the sequenced, 3D structure of the database proteins reveals essential aspects of the anatomy of the proteins, their toxicity mechanisms, and the conserved binding site areas that may anchor universal interspecific inhibitors. Moreover, it pinpoints hypotheses for the molecular origin of the myotoxicity of the PLA2-like proteins. Altogether, this study provides an understanding of the diversity of these toxins and how they are conserved, and it indicates how to develop broad, interspecies, efficient small-molecule inhibitors to target the toxin's many mechanisms of action.

Clinical Risk Factors Associated with Poor Outcomes in Snake Envenoming: A Narrative Review

Snakebite-related fatalities disproportionately affect populations in impoverished socio-economic regions, marked by limited access to adequate healthcare and constrained antivenom availability. Early medical intervention is pivotal in mitigating mortality and morbidity associated with snakebite envenoming (SBE). While clinical assessment remains fundamental in treating SBE, this review aims to spotlight objective parameters that could also affect outcomes. Selected studies that identify factors associated with poor outcomes are predominantly region-specific, single-site, and observational, yet collectively reveal similar findings. They consistently report factors such as treatment delays, susceptibility in vulnerable groups such as children and pregnant women, as well as various biochemical and haematological abnormalities. Acute kidney injury (AKI), low platelets, leucocytosis, abnormal coagulation, and elevated creatine kinase (CK) all show an association with poor outcomes. Furthermore, recognising rare and unusual SBE presentations such as adrenal insufficiency, severe hypertension, intracranial haemorrhage, acute angle closure glaucoma, and bowel ischaemia also has a bearing on outcomes. Despite the integration of these parameters into clinical decision tools and guidelines, the validation of this evidence is limited. This review underscores the imperative for high-quality, multi-centre studies aligned with consensus-driven Core Outcome Sets (COS) and Patient-Reported Outcome Measures (PROMS) to validate and strengthen the current evidence.

Severity of a Vipera palaestinae envenomation objective findings associated with a complicated hospitalization course following a Vipera palaestinae bite

The most common snake in Israel, responsible for most snakebites is Vipera palaestinae (VP). Envenomation signs and symptoms vary from local manifestations to systemic reactions that may end with death. Antivenom treatment, given to high-risk patients, reduces complications and mortality but carries risks. As of now, there is no standardized protocol for adults bitten by VP based on objective clinical and laboratory findings. We conducted A retrospective analysis of 159 patients admitted to two large tertiary care institutions in the center (Hadassah University Medical Center) and south (Soroka University Medical Center) of Israel with Vipera palaestinae bites during 1990-2017. Epidemiological and clinical data were extracted, and the patients were divided into two groups based on hospitalization time (over or under 48 h). 159 patients were included in this study. The average hospitalization time was 66.1 h, with 49.7% of patients admitted over 48 h. The main factors that statistically correlated with a longer hospitalization time were: Male gender, lower extremity bite, platelets lower than 150 K at presentation, leukocyte count of over 10 K at presentation and elevated D-Dimer levels. This study provides factors which are associated with a severe VP envenomation. These clinical or laboratory findings (along with accompanying clinical symptoms) are associated with a higher risk of a prolonged hospitalization with more complications and may require a more intensive treatment and monitoring.

Clinical aspects of snakebite envenoming and its treatment in low-resource settings

There is increasing recognition of the public health importance of snakebite envenoming. Worldwide annual incidence is likely to be 5 million bites, with mortality exceeding 150 000 deaths, and the resulting physical and psychological morbidity leads to substantial social and economic repercussions. Prevention through community education by trained health workers is the most effective and economically viable strategy for reducing risk of bites and envenoming. Clinical challenges to effective treatment are most substantial in rural areas of low-resource settings, where snakebites are most common. Classic skills of history taking, physical examination, and use of affordable point-of-care tests should be followed by monitoring of evolving local and systemic envenoming. Despite the profusion of new ideas for interventions, hyperimmune equine or ovine plasma-derived antivenoms remain the only specific treatment for snakebite envenoming. The enormous interspecies and intraspecies complexity and diversity of snake venoms, revealed by modern venomics, demands a radical redesign of many current antivenoms.