Prognostic significance of clinical grading of patients envenomed by Bothrops lanceolatus in Martinique. Members of the Research Group on Snake Bite in Martinique

Long-term disability after cerebral ischemic stroke following a Bothrops atrox snakebite in the Brazilian Amazon

Bothrops atrox envenomations in the Brazilian Amazon are responsible for a number of local and systemic effects. Among these, stroke presents the worst prognosis for the patient since it may evolve into disabilities and/or premature death. This complication is caused by coagulation disorders and generates hemorrhagic and thrombotic conditions. This study presents a case report of a 54-year-old female patient who presented extensive cerebral ischemia after a B. atrox envenomation that occurred in the state of Amazonas, Brazil. The patient was hospitalized for 102 days, which included a stay in the intensive care unit. Clinical and laboratory findings indicated a thrombogenic coagulopathy. On discharge, the patient had no verbal response, partial motor response, and right hemiplegia. The assessment carried out four years after discharge evidenced incapacitation, global aphasia and bilateral lower and upper limbs showed hypotrophy with a global decrease in strength. Ischemic stroke is a possible complication of B. atrox snakebites even after antivenom treatment, with the potential to cause debilitating long-term consequences.

Capacity of community health centers to treat snakebite envenoming in indigenous territories of the Brazilian Amazon

INTRODUCTION

The deaths from and morbidities associated with snakebites - amputations, loss of function in the limb, visible scarring or tissue damage - have a vast economic, social, and psychological impact on indigenous communities in the Brazilian Amazon, especially children, and represent a real and pressing health crisis in this population. Snakebite clinical and research experts have therefore proposed expanding antivenom access from only hospitals to include the community health centers (CHC) located near and within indigenous communities. However, there are no studies examining the capacity of CHCs to store, administer, and manage antivenom treatment. In response to this gap, the research team calling for antivenom decentralization developed and validated an expert-based checklist outlining the minimum requirements for a CHC to provide antivenom.

METHODS

The objective of this study was thus to survey a sample of CHCs in indigenous territories and evaluate their capacity to provide antivenom treatment according to this accredited checklist. The checklist was administered to nurses and doctors from 16 CHCs, two per indigenous district in Amazonas/Roraima states.

RESULTS

Our results can be conceptualized into three central findings: 1) most CHCs have the capacity to provide antivenom treatment, 2) challenges to capacity are human resources and specialized items, and 3) antivenom decentralization is feasible and appropriate in indigenous communities.

CONCLUSION

Decentralization would provide culturally and contextually appropriate care accessibility to a historically marginalized and underserved population of the Brazilian Amazon. Future studies should examine optimal resource allocation in indigenous territories and develop an implementation strategy in partnership with indigenous leaders. Beyond the indigenous population, the checklist utilized could be applied to community health centers treating the general population and/or adapted to other low-resource settings.

Serpent strikes, sapien sways: A rare case of bilateral cerebellar infarct following viper bite

Ischemic stroke following snake bite is rare. We report a posterior circulation infarct involving bilateral cerebellum and occipital lobe following Russell's viper bite in a previously healthy individual. A 50 years old healthy individual, soon after being bitten by the Russel viper on the left foot he developed pain and swelling followed by drooping of eyelids, slurring of speech and giddiness with multiple episodes of vomiting. The patient was administered ASV as well as neostigmine and atropine injections. Following this, the neurological manifestations resolved except dysarthria. CT brain study done was normal. On day 2 of hospitalization, he developed left cerebellar signs (positive finger nose finger test, rebound phenomenon, dysdiadochokinesia, a positive heel shin test). Subsequently, an MRI with MR angiogram was done which showed acute infarcts in bilateral cerebellar hemispheres, with the left superior cerebellar peduncle showing restricted diffusion and low ADC values. Ischemic infarction following viper envenomation has been described by only few authors. In majority of the cases reported, ischemic infarction involved the anterior circulation. The possible mechanisms of infarction in this scenario are discussed. Patient was treated with anti-snake venom and showed a good recovery. Early imaging and early treatment with anti-snake venom is important for a favourable outcome.

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.

Bothrops venom-induced hemostasis disorders in the rat: Between Scylla and Charybdis

Hemostasis impairment represents the most threatening consequence of Viperidae envenoming, notably with Bothrops genus. In the French departments of America, B. atrox envenomation in French Guiana may lead to bleeding while B. lanceolatus envenomation in Martinique to thrombosis. Bleeding related to B. atrox envenomation is attributed to vascular damage mediated by venom metalloproteinases and blood uncoagulable state resulting from thrombocytopenia and consumptive coagulopathy. Thrombosis related to B. lanceolatus envenomation are poorly understood. We aimed to compare the effects of B. atrox and B. lanceolatus venoms in the rat to identify the determinants of the hemorrhagic versus thrombotic complications. Viscoelastometry (ROTEM), platelet count, plasma fibrinogen, thrombin generation assay, fibrinography, endothelial (von Willebrand factor, ADAMTS13 activity, ICAM-1, and soluble E-selectin), and inflammatory biomarkers (IL-1β, IL-6, TNF-α, MCP-1, and PAI-1) were determined in blood samples obtained at H3, H6, and H24 after the subcutaneous venom versus saline injection. In comparison to the control, initial fibrinogen consumption was observed with the two venoms while thrombocytopenia and reduction in the clot amplitude only with B. atrox venom. Moreover, we showed an increase in thrombin generation at H3 with the two venoms, an increase in fibrin generation accompanied with hyperfibrinogenemia at H24 and an increase in inflammatory biomarkers with B. lanceolatus venom. No endothelial damage was found with the two venoms. To conclude, our data support two-sided hemostasis complications in Bothrops envenoming with an initial risk of hemorrhage related to platelet consumption and hypocoagulability followed by an increased risk of thrombosis promoted by the activated inflammatory response and rapid-onset fibrinogen restoration.

Bothrops atrox and Bothrops lanceolatus Venoms In Vitro Investigation: Composition, Procoagulant Effects, Co-Factor Dependency, and Correction Using Antivenoms

Bothrops venoms are rich in enzymes acting on platelets and coagulation. This action is dependent on two major co-factors, i.e., calcium and phospholipids, while antivenoms variably neutralize venom-related coagulopathy effects. Our aims were (i) to describe the composition of B. atrox and B. lanceolatus venoms; (ii) to study their activity on the whole blood using rotational thromboelastometry (ROTEM); (iii) to evaluate the contribution of calcium and phospholipids in their activity; and (iv) to compare the effectiveness of four antivenoms (Bothrofav™, Inoserp™ South America, Antivipmyn™ TRI, and PoliVal-ICP™) on the procoagulant activity of these two venoms. Venom composition was comparable. Both venoms exhibited hypercoagulant effects. B. lanceolatus venom was completely dependent on calcium but less dependent on phospholipids than B. atrox venom to induce in vitro coagulation. The four antivenoms neutralized the procoagulant activity of the two venoms; however, with quantitative differences. Bothrofav™ was more effective against both venoms than the three other antivenoms. The relatively similar venom-induced effects in vitro were unexpected considering the opposite clinical manifestations resulting from envenomation (i.e., systemic bleeding with B. atrox and thrombosis with B. lanceolatus). In vivo studies are warranted to better understand the pathophysiology of systemic bleeding and thrombosis associated with Bothrops bites.

Effect of the time to antivenom administration on recovery from snakebite envenoming-related coagulopathy in French Guiana

BACKGROUND

Snakebite (SB) envenoming is an acute emergency requiring an early care delivery. We aimed to search for the time to reach healthcare facilities in various regions of French Guiana (FG) and to assess the impact of time to antivenom (AV) on the correction of coagulation parameters in these patients.

METHODOLOGY

This is a prospective observational study conducted in Cayenne General Hospital between January 1st, 2016, and July 31st, 2022. We included all patients hospitalized for SB envenoming less than 48h after the bite, and receiving antivenom (AV). We assessed the time lapse between SB and medical attention and the time needed to return of the coagulation parameters to normal.

PRINCIPAL FINDINGS

Overall, 119 patients were investigated, and 48.7% were from remote areas. The median time from SB to AV therapy was 09:15 h (05:32-17:47). The time was longer in patients from remote rural locations. AV was dispensed within the first six hours after the SB in 45 cases (37.8%). Time from SB to reaching normal plasma fibrinogen concentration was 23:27 h (20:00-27:10) in patients receiving AV≤6h vs. 31:23 h (24:00-45:05) in those receiving AV>6h (p<0.001). Whereas, the time from AV administration to reach normal fibrinogen dosage was similar in the two groups.

CONCLUSIONS

Patients from rural settings in FG suffer from a delay in AV administration after SB envenoming leading to an extended time in which patients are coagulopathic. Once AV is administered, clotting parameters recover at a similar rate. Supplying remote healthcare facilities with AV and with medical teams trained in its use should be planned.

Performance of the 20 minutes Whole Blood Clotting Test in detection, monitoring and antivenom therapy of West African Carpet viper (Echis romani) envenoming in resource constrained settings in Nigeria

The 20 minutes Whole Blood Clotting Test (20WBCT) was evaluated in 1541 snakebite patients at 3 hospitals in Nigeria. It was useful in detection, monitoring, guiding antivenom therapy and prognostication of coagulopathy, with initial sensitivity of 84.7% (95%CI:82.7-86.5%) and specificity of 64.3% (95%CI:50.4-76.7%) compared to clinical envenoming. It led to correct decisions regarding administration or withholding antivenom in 97.93% of patients. The proportion of carpet viper (Echis romani) envenomed patients who restored clotting rose steadily following effective antivenom therapy. Patients with positive 20WBCT had severer envenoming, required more blood transfusion, had longer hospital stay and derived higher antivenom protection against death from carpet viper. However, there was no association between positive 20WBCT and fatality or complications.

Bothrops (Fer-de-lance) snakebites in the French departments of the Americas (Martinique and Guyana): Clinical and experimental studies and treatment by immunotherapy

Snakebite envenomation is a relevant medical hazard in French Guiana and Martinique, two French territories in the Americas. All snakebite envenomations in Martinique are inflicted by the endemic viperid species Bothrops lanceolatus, whereas Bothrops atrox is responsible for the majority of snakebites in French Guiana, although other venomous snake species also occur in this South American territory. This review summarizes some of the key aspects of the natural history of these species, as well as of their venom composition, the main clinical manifestations of envenomations, and their treatment by antivenoms. B. atrox venom induces the typical set of clinical manifestations characteristic of Bothrops sp. venoms, i.e., local tissue damage and systemic alterations associated with coagulopathies, hemorrhage, hemodynamic alterations, and acute kidney injury. In the case of B. lanceolatus venom, in addition to some typical features of bothropic envenomation, a unique and severe thrombotic effect occurs in some patients. The pathogenesis of this effect remains unknown but may be related to the action of venom components and inflammatory mediators on endothelial cells in the vasculature. A monospecific antivenom has been successfully used in Martinique to treat envenomations by B. lanceolatus. In the case of French Guiana, a polyvalent antivenom has been used for some years, but it is necessary to assess the preclinical and clinical efficacy against viperid venoms in this country of other antivenoms manufactured in the Americas.

Bleeding and Thrombosis: Insights into Pathophysiology of Bothrops Venom-Related Hemostasis Disorders

Toxins from Bothrops venoms targeting hemostasis are responsible for a broad range of clinical and biological syndromes including local and systemic bleeding, incoagulability, thrombotic microangiopathy and macrothrombosis. Beyond hemostais disorders, toxins are also involved in the pathogenesis of edema and in most complications such as hypovolemia, cardiovascular collapse, acute kidney injury, myonecrosis, compartmental syndrome and superinfection. These toxins can be classified as enzymatic proteins (snake venom metalloproteinases, snake venom serine proteases, phospholipases A₂ and L-amino acid oxidases) and non-enzymatic proteins (desintegrins and C-type lectin proteins). Bleeding is due to a multifocal toxicity targeting vessels, platelets and coagulation factors. Vessel damage due to the degradation of basement membrane and the subsequent disruption of endothelial cell integrity under hydrostatic pressure and tangential shear stress is primarily responsible for bleeding. Hemorrhage is promoted by thrombocytopenia, platelet hypoaggregation, consumption coagulopathy and fibrin(ogen)olysis. Onset of thrombotic microangiopathy is probably due to the switch of endothelium to a prothrombotic phenotype with overexpression of tissue factor and other pro-aggregating biomarkers in association with activation of platelets and coagulation. Thrombosis involving large-caliber vessels in B. lanceolatus envenomation remains a unique entity, which exact pathophysiology remains poorly understood.

Association of a Network of Immunologic Response and Clinical Features With the Functional Recovery From Crotalinae Snakebite Envenoming

Background

The immunologic pathways activated during snakebite envenoming (SBE) are poorly described, and their association with recovery is unclear. The immunologic response in SBE could inform a prognostic model to predict recovery. The purpose of this study was to develop pre- and post-antivenom prognostic models comprised of clinical features and immunologic cytokine data that are associated with recovery from SBE.

Materials and Methods

We performed a prospective cohort study in an academic medical center emergency department. We enrolled consecutive patients with Crotalinae SBE and obtained serum samples based on previously described criteria for the Surgical Critical Care Initiative (SC2i)(ClinicalTrials.gov Identifier: NCT02182180). We assessed a standard set of clinical variables and measured 35 unique cytokines using Luminex Cytokine 35-Plex Human Panel pre- and post-antivenom administration. The Patient-Specific Functional Scale (PSFS), a well-validated patient-reported outcome of functional recovery, was assessed at 0, 7, 14, 21 and 28 days and the area under the patient curve (PSFS AUPC) determined. We performed Bayesian Belief Network (BBN) modeling to represent relationships with a diagram composed of nodes and arcs. Each node represents a cytokine or clinical feature and each arc represents a joint-probability distribution (JPD).

Results

Twenty-eight SBE patients were enrolled. Preliminary results from 24 patients with clinical data, 9 patients with pre-antivenom and 11 patients with post-antivenom cytokine data are presented. The group was mostly female (82%) with a mean age of 38.1 (SD ± 9.8) years. In the pre-antivenom model, the variables most closely associated with the PSFS AUPC are predominantly clinical features. In the post-antivenom model, cytokines are more fully incorporated into the model. The variables most closely associated with the PSFS AUPC are age, antihistamines, white blood cell count (WBC), HGF, CCL5 and VEGF. The most influential variables are age, antihistamines and EGF. Both the pre- and post-antivenom models perform well with AUCs of 0.87 and 0.90 respectively.

Discussion

Pre- and post-antivenom networks of cytokines and clinical features were associated with functional recovery measured by the PSFS AUPC over 28 days. With additional data, we can identify prognostic models using immunologic and clinical variables to predict recovery from SBE.

Infectious Complications Following Snakebite by Bothrops lanceolatus in Martinique: A Case Series

Infections secondary to snakebite occur in a number of patients and are potentially life-threatening. Bothrops lanceolatus bites in Martinique average 30 cases per year and may result in severe thrombotic and infectious complications. We aimed to investigate the infectious complications related to B. lanceolatus bite. A retrospective single-center observational study over 7 years (2011–2018) was carried out, including all patients admitted to the hospital because of B. lanceolatus bite. One hundred seventy snake-bitten patients (121 males and 49 females) were included. Thirty-nine patients (23%) presented grade 3 or 4 envenoming. Twenty patients (12%) developed wound infections. The isolated bacteria were Aeromonas hydrophila (3 cases), Morganella morganii (two cases), group A Streptococcus, and group B Streptococcus (one case each). Patients were treated empirically with third-generation cephalosporin (or amoxicillin–clavulanate), aminoglycoside, and metronidazole combinations. Outcome was favorable in all patients. The main factor significantly associated with the occurrence of infection following snakebite was the severity of envenoming (P < 0.05). Our findings clearly point toward the frequent onset of infectious complications in B. lanceolatus–bitten patients presenting with grade 3 and 4 envenoming. Thus, based on the bacteria identified in the wounds, we suggest that empiric antibiotic therapy including third-generation cephalosporin should be administered to those patients on hospital admission.

Does This Patient Have a Severe Snake Envenomation?: The Rational Clinical Examination Systematic Review

Importance

Venomous snakebite severity ranges from an asymptomatic dry bite to severe envenomation and death. The clinical evaluation aids in prognosis and is essential to determine the risks and potential benefits of antivenom treatment.

Objectives

To identify historical features, clinical examination findings, basic laboratory testing, and clinical grading scales that will risk-stratify patients with pit viper snake envenomation for severe systemic envenomation, severe tissue injury, and/or severe hematologic venom effects.

Data Sources

We conducted a structured search of PubMed (1966-October 3, 2017) and Embase database (1980-October 3, 2017) to identify English-language studies that evaluated clinical features predictive of severe envenomation.

Study Selection

We included studies that evaluated the test performance of at least 1 clinical finding with an acceptable reference standard of severe envenomation for venomous snakes of the Western Hemisphere. Only studies involving the most common subfamily, Crotalinae (pit vipers), were evaluated. Seventeen studies with data were available for abstraction.

Data Extraction and Synthesis

The clinical features assessed and severity outcome measures were extracted from each original study. We assessed severity in 3 categories: systemic toxicity, tissue injury, and hematologic effects. Differences were resolved by author consensus.

Results

The pooled prevalence of severe systemic envenomation was 14% (95% CI, 9%-21%). The pooled prevalence of severe tissue injury and severe hematologic venom effects were 14% (95% CI, 12%-16%) and 18% (95% CI, 8%-27%), respectively. Factors increasing the likelihood of severe systemic envenomation included the time from bite to care of 6 or more hours (likelihood ratio [LR], 3.4 [95% CI, 1.1-6.4]), a patient younger than 12 years (LRs, 3.2 [95% CI, 1.5-7.1] and 2.9 [95% CI, 1.3-6.2]), large snake size (LR, 3.1 [95% CI, 1.5-5.7]), and ptosis (LRs, 1.4 [95% CI, 1.0-2.1] and 3.8 [95% CI, 1.8-8.3]). Envenomation by the genus Agkistrodon (copperhead and cottonmouth), as opposed to rattlesnakes, decreased the likelihood of severe systemic envenomation (LR, 0.28 [95% CI, 0.10-0.78]). Initial hypofibrinogenemia (LR, 5.1 [95% CI, 1.7-15.0]) and thrombocytopenia (LR, 3.7 [95% CI, 1.9-7.3]) increased the likelihood of severe hematologic venom effects. Other clinical features from history, physical examination, or normal laboratory values were not discriminative.

Conclusions

Clinical features can identify patients at increased risk of severe systemic envenomation and severe hematologic venom effects, but there are few features that are associated with severe tissue injury or can confidently exclude severe envenomation. Physicians should monitor patients closely and be wary of progression from nonsevere to a severe envenomation and have a low threshold to escalate therapy as needed.

Multiple thromboembolic strokes in a toddler associated with Australian Eastern Brown snake envenomation

Venomous snakes are found in every state and territory in Australia and are amongst the most dangerous in the world. Of Australia's snakes the Eastern Brown snake (Pseudonaja textilis) is responsible for the majority of the cases of envenomation and death. We describe a case of thromboembolic stroke associated with Eastern Brown snake envenomation in a 2-year-old boy. Following the incident, the boy has made a good recovery.

Acute cerebral infarction following a Trimeresurus stejnegeri snakebite: A case report

RATIONALE

Acute cerebral infarction after snake bites is rare. The underlying mechanism causing the thrombotic process remains complex and unknown.

PATIENT CONCERNS

We herein describe a 49-year-old female who was bitten by a Trimeresurus stejnegeri. After 4 days of biting, she developed acute ischemic infarct.

DIAGNOSIS

The patient exhibited right side weakness and speech disturbances. Brain computed tomography (CT) scan showed no sign about cerebral hemorrhage symptoms, and brain magnetic resonance imaging (MRI) showed acute ischemic infarct in the left territory. The patient confirmed a diagnosis of acute cerebral infarction following a T. stejnegeri bite.

INTERVENTIONS

The patient received an injection of polyvalent anti-snake venom serum, neuroprotective therapy, and anti-platelet aggregate treatment.

OUTCOMES

At the 3-month follow-up visit, the patient's left lower extremity swelling disappeared, the right limb muscle strength recovered, and the modified Rankin scale (mRS) score was 4 points.

LESSONS

The patient was diagnosed with acute ischemic infarct interrelated to snake bite; further investigations were needed to ascertain mechanism. The clinicians should pay more attention to identify potential victims of neurologic complications, to reduce the mortality rate of snake bite.

Status epilepticus and bilateral middle cerebral artery infarction: A rare presentation after viper bite

Owing to the antihemostatic property of viper venom, hemorrhagic complications including intracerebral hemorrhage are the most commonly encountered after viper bite. Ischemic strokes have been rarely reported after viper envenomation, and its occurrence has been attributed to multiple mechanisms. Postsnakebite seizures are known to occur after neurotoxic bite. Here, we report the case of a viper bite victim who developed status epilepticus within 3 h after viper bite. He had only mild signs of local envenomation, and prolonged whole blood clotting time was the only manifestation of systemic envenomation. Subsequently, he was found to have developed right hemiparesis and global aphasia. Brain imaging revealed large infarcts in bilateral middle cerebral artery (MCA) territories. We report this as a unique case of viper bite which presented to the emergency room with status epilepticus. Moreover, bilateral MCA infarct, as was found in this case, is genuinely rare in scientific literature. Finally, the absence of overt features of envenomation makes this case stand out from other similar reported occurrences.

Cerebrovascular Accident and Snake Envenomation: A Scoping Study

BACKGROUND

Snake envenomation is associated with serious complications including infections, bleeding and, in rare occasions, thrombosis. Previous work by our group examined the association of snakebite and acute myocardial infarction. In this systematic review we aim to assess the clinical characteristics and outcomes of acute cerebrovascular accidents that are reported to be extremely rare complications of snake envenomation.

METHODS

We performed a literature search for reports on stroke associated with snake envenomation between Jan 1995 to Oct 2018, and summarized their characteristics.

RESULTS

Eighty-three published cases were reviewed. 66.3% of the cases were younger than 50 years of age. The mean time for the onset of the symptoms is 23.8±10.9 hours after exposure. 77.1% of the cases found to have ischemic stroke, 20.5% with intra-cranial hemorrhage and both infarction and hemorrhage in 2.4%. Mortality was reported in 16.9% with mean time between onset of the symptoms and death is 4.2 days.

CONCLUSION

Stroke secondary to snake envenomation is a rare but serious complication. Once stroke is suspected, initiating appropriate management is crucial in reducing morbidity and mortality associated with this potentially fatal complication of snake envenomation.

Oral Microbiota of the Snake Bothrops lanceolatus in Martinique

In Martinique, Bothrops lanceolatus snakebite, although relatively uncommon (~30 cases/year), may result in serious complications such as systemic thrombosis and local infections. Infections have been hypothesized to be related to bacteria present in the snake’s oral cavity. In this investigation, we isolated, identified, and studied the susceptibility to beta-lactams of bacteria sampled from the oral cavity of twenty-six B. lanceolatus specimens collected from various areas in Martinique. Microbiota from B. lanceolatus oral cavity was polymicrobial. Isolated bacteria belonged to fifteen different taxa; the most frequent being Aeromonas hydrophyla (present in 50% of the samples), Morganella morganii, Klebsiella pneumoniae, Bacillus spp., and Enterococcus spp. Analysis of antibiotic susceptibility revealed that 66.7% of the isolated bacteria were resistant to amoxicillin/clavulanate. In contrast, the majority of isolated bacteria were susceptible to the third-generation cephalosporins (i.e., 73.3% with cefotaxime and 80.0% with ceftazidime). Microbiota from B. lanceolatus oral cavity is polymicrobial with bacteria mostly susceptible to third-generation cephalosporins but rarely to amoxicillin/clavulanate. In conclusion, our findings clearly support that first-line antibiotic therapy in the B. lanceolatus-bitten patients, when there is evidence of infection, should include a third-generation cephalosporin rather than amoxicillin/clavulanate.

Early administration of Fab antivenom resulted in faster limb recovery in copperhead snake envenomation patients

BACKGROUND

No previous research has studied whether early snake antivenom administration leads to better clinical outcomes than late antivenom administration in North American pit viper envenomation.

METHODS

A secondary analysis of data from a clinical trial of Fab antivenom (FabAV) versus placebo for copperhead snake envenomation was conducted. Patients treated before the median time to FabAV administration were classified as receiving early treatment and those treated after the median time were defined as the late treatment group. A Cox proportional hazards model was used to compare time to full recovery on the Patient-Specific Functional Scale (PSFS) instrument between groups. Secondary analyses compared estimated mean PSFS scores using a generalized linear model and the estimated proportion of patients with full recovery at each time point using logistic regression. To evaluate for confounding, the main analysis was repeated using data from placebo-treated subjects.

RESULTS

Forty-five subjects were treated with FabAV at a median of 5.47 h after envenomation. Patients in the early treatment group had a significantly shorter time to full recovery than those treated late (median time: 17 versus 28 days, p = .025). Model-estimated PSFS scores were numerically higher at each time point in the early group. No difference was found between patients treated early versus late with placebo.

CONCLUSIONS

In this secondary analysis of trial data, recovery of limb function was faster when Fab antivenom was administered soon after envenomation, as opposed to late administration.

Three-dimensional computed tomography reconstructive diagnosis of snakebite-induced cerebral infarction

Despite common injury caused by snakebite, snakebite-induced ischemic stroke is rare. We reported on a patient who incurred a large cerebral infarction after being bitten by a Deinagkistrodon acutus, one of the most poisonous snakes in the southwestern of China. Applying 3D computed tomography (CT) of head combined with cerebral angiography examinations showed a large cerebral infarction, hernia in the right brain, developmental abnormalities of the right middle cerebral artery and cerebral artery of right brain. In conclusion, head CT imaging combined with cerebral angiography provides an efficient approach in diagnosis of stroke caused by snakebites.

Bites by the Monocled Cobra, Naja kaouthia, in Chittagong Division, Bangladesh: Epidemiology, Clinical Features of Envenoming and Management of 70 Identified Cases

AbstractWe describe 70 cases of monocled cobra (Naja kaouthia) bite admitted to Chittagong Medical College Hospital, Bangladesh. The biting snakes were identified by examining the dead snake and/or detecting N. kaouthia venom antigens in patients' serum. Bites were most common in the early morning and evening during the monsoon (May-July). Ligatures were routinely applied to the bitten limb before admission. Thirty-seven patients consulted traditional healers, most of whom made incisions around the bite site. Fifty-eight patients experienced severe neurotoxicity and most suffered swelling and pain of the bitten limb. The use of an Indian polyvalent antivenom in patients exhibiting severe neurotoxicity resulted in clinical improvement but most patients experienced moderate-to-severe adverse reactions. Antivenom did not influence local blistering and necrosis appearing in 19 patients; 12 required debridement. Edrophonium significantly improved the ability of patients to open the eyes, endurance of upward gaze, and peak expiratory flow rate suggesting that a longer-acting anticholinesterase drug (neostigmine) could be recommended for first aid. The study suggested that regionally appropriate antivenom should be raised against the venoms of the major envenoming species of Bangladesh and highlighted the need to improve the training of staff of local medical centers and to invest in the basic health infrastructure in rural communities.

Brainstem ischemic stroke after to Bothrops atrox snakebite

We report case of a 48 years old woman bitten on her right foot by a Bothrops atrox viper. As a result, she developed a severe coagulopathy which improved with application of polyvalent antivenom. Four days after bite she suffered a devastating brainstem ischemic stroke. Possible pathogenetic mechanisms are discussed.

Time to antivenom administration is not associated with total antivenom dose administered in a copperhead-predominant snakebite population

OBJECTIVES

To prevent unnecessary antivenom administration in crotaline snakebite, observation for progression is recommended for the patient with minor envenomation whose condition is stable and not progressing. The objective of this study was to determine the association between the time from bite to initial antivenom administration (Time(AV)) and the total amount of antivenom administered (Total(AV)) and to determine what proportion of patients did not have progression of the envenomation syndrome and did not receive antivenom.

METHODS

This was a retrospective chart review of patients presenting with crotaline snakebite within 24 hours from 2009 through 2012. Blinded dual-chart abstraction and strict data point definitions were used. Spearman correlation was used to determine the association between Time(AV) and Total(AV). A general linear model was used to examine this association using Time(AV) categorized to early and late administration, adjusted for likely confounders. Confounders included age, extremity involved, initial severity, and year of envenomation.

RESULTS

Ninety-five eligible patients were analyzed with 45 (47%) males and a mean (±SD) age of 36.5 (±21.1) years. Eighty-five (89%) received antivenom, with a median Time(AV) of 3.3 hours (interquartile range [IQR] = 2.5 to 5.2 hours). The median Total(AV) was 10 vials (IQR = 6 to 14 vials). The univariate analysis showed a small but statistically significant decrease in Total(AV) given to patients treated greater than 6 hours from bite (r = -0.26, p = 0.015). The multivariate analysis resulted in no significant relation between early or late Time(AV) and Total(AV) (p = 0.10) after adjustment for confounders. Most minimal envenomation syndromes (80%, or 41 of 51) progressed to moderate grade envenomations.

CONCLUSIONS

Time(AV) was not associated with Total(AV) when adjusted for likely confounders and supports current recommendations to observe for progression in minor envenomation. The majority of envenomations progressed, resulting in only a small proportion of patients not eventually receiving antivenom. The authors recommend observation in an environment where the patient can be adequately reassessed for progression of the envenomation.

Neurological effects of venomous bites and stings: snakes, spiders, and scorpions

Snake and spider bites, as well as scorpion sting envenoming, are neglected diseases affecting millions of people all over the world. Neurological complications vary according to the offending animal, and are often directly related to toxic effects of the venom, affecting the central nervous system, the neuromuscular transmission, the cardiovascular system, or the coagulation cascade. Snake bite envenoming may result in stroke or muscle paralysis. Metalloproteinases and other substances (common in vipers and colubrids) have anticoagulant or procoagulant activity, and may induce ischemic or hemorrhagic strokes. The venom of elapids is rich in neurotoxins affecting the neuromuscular transmission at either presynaptic or postsynaptic levels. The clinical picture of scorpion sting envenoming is dominated by muscle weakness associated with arterial hypertension, cardiac arrythmias, myocarditis, or pulmonary edema. These manifestations occur as the result of release of catecholamines into the bloodstream or due to direct cardiac toxicity of the venom. Cerebrovascular complications have been reported after the sting of the Indian red scorpion. Intracranial hemorrhages occur in the setting of acute increases in arterial blood pressure related to sympathetic overstimulation, and cerebral infarctions are related to either cerebral hypoperfusion, consumption coagulopathy, vasculitis, or cardiogenic brain embolism. Three main syndromes result from spider bite envenoming: latrodectism, loxoscelism, and funnel-web spider envenoming. Latrodectism is related to neurotoxins present in the venom of widow spiders. Most cases present with headache, lethargy, irritability, myalgia, tremor, fasciculation, or ataxia. Loxoscelism is caused by envenoming by spiders of the family Sicariidae. It may present with a stroke due to a severe coagulopathy. The venom of funnel-web spiders also has neurotoxins that stimulate neurotransmitter release, resulting in sensory disturbances and muscle paralysis. Proper management of the envenomed patient, including prompt transport to the hospital, correction of the hemostatic disorder, ventilatory support, and administration of antivenom, significantly reduce the risk of neurological complications which, in turn, reduce the mortality and improve the functional outcome of survivors.

Acute ischemic stroke following Hump-nosed viper envenoming; first authenticated case

Hump-nosed pit viper (Genus Hypnale) is a medically important venomous snake in Sri Lanka and Southwestern India which causes significant morbidity and mortality. Envenoming of this snake results in hemostastic dysfunction, thrombotic microangiopathy, acute kidney injury and death. This case describes an authenticated first case of ischemic stroke in a 65 year old male following envenoming by H.hypnale in Sri Lanka.

Severe envenomation by Cerastes cerastes viper: an unusual mechanism of acute ischemic stroke

Cerebral complications after snake bites--particularly ischemic complications--are rare. Very few cases of cerebral infarction resulting from a viper bite have been reported, and we call attention to this uncommon etiology. We discuss 3 authenticated reports of acute ischemic cerebrovascular accidents after 3 typical severe envenomations by Cerastes cerastes vipers. The 3 patients developed extensive local swelling and life-threatening systemic envenomation characterized by disseminated intravascular coagulopathy, increased fibrinolysis, thrombocytopenia, microangiopathic hemolytic anemia, and acute renal failure. This clinical picture involved atypical neurologic manifestations. These patients had either low Glasgow Coma Scale (GCS) or hemiparesis within hours to 4 days after being bitten, and they were found to have computed tomographic evidence of single or multiple ischemic (nonhemorrhagic) strokes of small- to large-vessel territories of the brain. One patient had good clinical recovery without neurologic deficits. Thrombotic complications occurred an average of 36 hours after being bitten, and their importance depends on the degree of envenomation. The possible mechanisms for cerebral infarction in these cases include generalized prothrombotic action of the venom (consumptive coagulopathy), toxin-induced vasculitis, and endothelial damage.

[Pulmonary embolism in the context of severe envenomation by a Moroccan viper]

Heparin, which was widely used thirty years ago for the treatment of viper envenomations, is now contra-indicated during the acute phase, which is at risk for hemorrhage and death. We report a case of pulmonary embolism, a rare situation in the context of viper envenomation. By means of this case report, we want to discuss the pathophysiological links between envenomation and thromboembolic disease, and on the other hand, the potential heparin usefulness, not during the acute, hemorrhagic phase, but as a prophylactic treatment when hemorrhagic risk has been replaced by an inflammatory syndrome, with increased fibrinogen and platelets which are then prothrombotic factors.

Neurological complications of venomous snake bites: a review

Snake bite envenoming is a neglected tropical disease affecting millions of people living in the developing world. According to the offending snake species, the clinical picture may be dominated by swelling and soft tissue necrosis in the bitten limb, or by systemic or neurological manifestations. Serious neurological complications, including stroke and muscle paralysis, are related to the toxic effects of the venom, which contains a complex mixture of toxins affecting the coagulation cascade, the neuromuscular transmission, or both. Metalloproteinases, serine proteases, and C-type lentins (common in viper and colubrid venoms) have anticoagulant or procoagulant activity and may be either agonists or antagonists of platelet aggregation; as a result, ischemic or hemorrhagic strokes may occur. In contrast, the venom of elapids is rich in phospholipase A(2) and three-finger proteins, which are potent neurotoxins affecting the neuromuscular transmission at either presynaptic or post-synaptic levels. Presynaptic-acting neurotoxins (called β-neurotoxins) inhibit the release of acetylcholine, while post-synaptic-acting neurotoxins (called α-neurotoxins) cause a reversible blockage of acetylcholine receptors. Proper management of the envenomed patient, including prompt transport to the hospital, correction of the hemostatic disorder, ventilatory support, and administration of antivenom, significantly reduces the risk of neurological complications which, in turn, reduce the mortality and improve the functional outcome of survivors.

Management of snakebites in France

Although not a major health problem in Europe, snakebite in the old continent was the focus of recent studies to evaluate their overall incidence and define management techniques. The purpose of this three-part report is to present the experience of the Marseille Poison Centre with snakebite in France. The first section deals with viper envenomation that now benefits from a validated therapeutic protocol using of purified antivenom of proven efficacy and tolerance in patients showing grade 2 and 3 symptoms. The second section describes the highly variable snakebite situation in French overseas territories that include areas where local species require specialized management, e.g. Martinique and French Guiana. The third section involves the emerging problems associated with the keeping of exotic snakes as pets with problems related to the use of antivenoms from foreign countries. The exotic-snake pets fashion was at the origin of the creation of a national antivenom bank by two French poison centers (Angers and Marseille) to ensure prompt delivery of antivenoms for exotic snake envenomation anywhere in mainland France.

[Creation and organization of an antivenomous serum bank in France]

For several years exotic snakes have been bred in France. In view of the increased risk of envenomation from some of these species, the Poison Centre in Angers has joined forces with several private licensed snake breeders to create an Anti-venom Serum Bank. The main objective of the new organization is to provide an effective means of dealing with bites and subsequent envenomation by exotic snakes by managing a stock of anti-venom serums in a hospital pharmacy, so that cases can be treated as quickly as possible. The hospital pharmacy has the authority to purchase and supply the anti-venom serums. The selection and purchase of the serums is done in conjunction with the French Ministry of Ecology, the French Drug Agency and specialist doctors. At the time of writing, the Antivenom Serum Bank has the capacity to treat about thirty different kinds of envenomation, compared to the 135 exotic venomous snake species officially registered. In the long term the Anti-venom Serum Bank will help eradicate the use of serums from unauthorized sources, evaluate the safety and efficacy of new serums and reduce transport times.

Bothrops lanceolatus bites: guidelines for severity assessment and emergent management

Approximately 20-30 declared snakebite cases occurin Martinique each year. Bothrops lanceolatus, a member of the Crotalidae family, is considered to be the only involved snake. B. lanceolatus, commonly named “Fer-de-Lance”, is endemic and only found on this Caribbean island. Envenomation local features include the presence of fang marks, swelling, pain, bleeding from punctures, and ecchymosis. Severe envenomation is associated with multiple systemic thromboses appearing within 48 h of the bite and resulting in cerebral, myocardial or pulmonary infarctions. Diagnosis requires first of all identification of the snake. Coagulation tests are helpful to identify thrombocytopenia or disseminated intravascular coagulation. A clinical score based on 4 grades is helpful to assess envonimation severity. A specific monovalent equine anti-venom (Bothrofav^®, Sanofi-Pasteur, France) to neutralize B. lanceolatus venom is available. Its early administration within 6h from the biting in case of progressive local injures, general signs or coagulation disturbances is effective to prevent severe thrombosis and coagulopathy. Its tolerance is considered to be good. Despite an increasing incidence of bites, no deaths have been recently attributed to B. lanceolatus in Martinique, probably due to the currently recommended strategy of early antivenom administration when required.

Thrombotic stroke following snake bites by the "Fer-de-Lance"Bothrops lanceolatus in Martinique despite antivenom treatment: a report of three recent cases

BACKGROUND

The severity of envenoming from Bothrops lanceolatus is determined by the development of cerebral, myocardial or pulmonary infarctions, and occasionnaly by serious local envenoming. Introduction of specific antivenom has resulted in a dramatic improvement in the prognosis of this envenoming. Against this background, we report 3 recent cases of patients bitten by B. lanceolatus who developed cerebral infarctions despite early administration of antivenom.

METHODS

In 1991 a protocol was designed to apply the same evaluation and treatment to all envenomed patients. The clinical results have been continuously monitored.

RESULTS

Between April 1993 and July 2003, 128 envenomed patients (age 6-83 (mean 45) years) were treated. No coagulopathy, thrombotic complication or death occurred in patients who were given early antivenom therapy--up to 6h following the bite--and 126 patients recovered. Between August 2003 and October 2004, 10 additional patients (18-66 (mean 46) years) were given antivenom at the time of admission at hospital. Of these, 3 developed cerebral infarctions within 24h. Effectiveness of antivenom was tested on mouse, and found to be lower than specified by the manufacturer.

DISCUSSION

Our data shows that recently the antivenom may have lost some of its efficacy. Possible mechanisms include variability in venom composition or loss of activity of the antibodies produced more than 15 years ago. The question is whether we should attempt to produce improved antivenom. This could include activity against the venom of Bothrops caribbaeus from the neighbouring island of St Lucia, which shares a monophyletic group with B. lanceolatus and whose venom produces a similar thrombotic syndrome.

CONCLUSION

Prevention of systemic vessels thrombosis remains the main therapeutic challenge of B. lanceolatus envenoming in Martinique.

Snake venoms and coagulopathy

Snakebite affects around 2.5 million humans annually, with greater than 100,000 deaths. Coagulopathy is a significant cause of both morbidity and mortality in these patients, either directly, or indirectly. This paper reviews clinical aspects of snakebite coagulopathy, including types of coagulopathy (procoagulant, fibrinogen clotting, fibrinolytic, platelet-active, anticoagulant, thrombotic, haemorrhagic), diagnosis and treatment. Examples of clinical laboratory findings in selected types of snakebite coagulopathy are presented. Where available, antivenom is the most effective treatment, while standard treatments for other forms of coagulopathy, such as factor replacement therapy and heparin, are either ineffective or dangerous in snakebite coagulopathy, except in specific situations.

Purification and characterization of a hemorrhagic metalloproteinase from Bothrops lanceolatus (Fer-de-lance) snake venom

Bothrops snake venoms contain metalloproteinases that contribute to the local effects seen after envenoming. In this work, a hemorrhagic metalloproteinase (BlaH1) was purified from the venom of the snake Bothrops lanceolatus by a combination of gel filtration, affinity (metal chelating) and hydrophobic interaction chromatographies. The hemorrhagin was homogeneous by SDS-PAGE and had a molecular mass of 28 kDa that was unaltered by treatment with beta-mercaptoethanol. BlaH1 gave a single band in immunoelectrophoresis and immunoblotting using commercial bothropic antivenom. BlaH1 had hemorrhagic, caseinolytic, fibrinogenolytic, collagenolytic and elastinolytic activities, but no phospholipase A(2) activity. The hemorrhagic and caseinolytic activities were inhibited by EDTA, indicating that they were metal ion-dependent. In contrast, aprotinin, benzamidine and PMSF did not affect these activities. The caseinolytic activity of BlaH1 had a pH optimum of 8.0 and was stable in solution at up to 40 degrees C; activity was completely lost at > or =70 degrees C. The hemorrhagic activity was neutralized by commercial bothropic antivenom. These properties suggest that this new hemorrhagin belongs to class P-I snake venom metalloproteinases.

Bothrops lanceolatus (Fer de lance) venom stimulates leukocyte migration into the peritoneal cavity of mice

The ability of Bothrops lanceolatus venom to induce neutrophil migration into the peritoneal cavity of mice was investigated. Intraperitoneal injection of venom caused dose- and time-dependent neutrophil migration, which peaked with 750 ng of venom/cavity 4h after venom injection. The neutrophil migration was significantly reduced by pretreatment with dexamethasone (0.5 mg/kg, s.c.), an indirect inhibitor of phospholipase A(2) (PLA(2)), and AA861 (0.01 mg/kg, s.c.), a 5-lipoxygenase inhibitor, but in contrast, was not modified by pretreatment with indomethacin (2 mg/kg, s.c.), an inhibitor of the cyclooxygenase pathway, meloxicam (5 mg/kg, s.c.), an inhibitor of the cyclooxygenase-2 pathway, or the PAF inhibitor WEB2086 (40 mg/kg, s.c.). Dexamethasone and AA861 also inhibited the neutrophil migration by 60% when administered immediately after venom injection, and the coadministration of these two drugs caused a 75% reduction in migration. BLV-induced neutrophil migration was not due to contamination by endotoxin since polymyxin B-treated venom retained its activity. Heating the venom (97 degrees C, 2 min) reduced the PLA(2) activity by 64% and this was accompanied by a corresponding reduction (68%) in neutrophil migration. These results suggest that arachidonate-derived lipoxygenase metabolites (possibly leukotriene B(4)) are involved in the chemotaxis observed. Macrophages may be an important source of these metabolites since the migratory response to venom was potentiated in mice pretreated with thioglycollate, but reduced when the peritoneal cavity was washed with sterile saline.

Medicinal and ethnoveterinary remedies of hunters in Trinidad

BACKGROUND

Ethnomedicines are used by hunters for themselves and their hunting dogs in Trinidad. Plants are used for snakebites, scorpion stings, for injuries and mange of dogs and to facilitate hunting success.

RESULTS

Plants used include Piper hispidum, Pithecelobium unguis-cati, Bauhinia excisa, Bauhinia cumanensis, Cecropia peltata, Aframomum melegueta, Aristolochia rugosa, Aristolochia trilobata, Jatropha curcas, Jatropha gossypifolia, Nicotiana tabacum, Vernonia scorpioides, Petiveria alliacea, Renealmia alpinia, Justicia secunda, Phyllanthus urinaria,Phyllanthus niruri,Momordica charantia, Xiphidium caeruleum, Ottonia ovata, Lepianthes peltata, Capsicum frutescens, Costus scaber, Dendropanax arboreus, Siparuma guianensis, Syngonium podophyllum, Monstera dubia, Solanum species, Eclipta prostrata, Spiranthes acaulis, Croton gossypifolius, Barleria lupulina, Cola nitida, Acrocomia ierensis (tentative ID).

CONCLUSION

Plant use is based on odour, and plant morphological characteristics and is embedded in a complex cultural context based on indigenous Amerindian beliefs. It is suggested that the medicinal plants exerted a physiological action on the hunter or his dog. Some of the plants mentioned contain chemicals that may explain the ethnomedicinal and ethnoveterinary use. For instance some of the plants influence the immune system or are effective against internal and external parasites. Plant baths may contribute to the health and well being of the hunting dogs.

Coagulant and anticoagulant activities of Bothrops lanceolatus (Fer de lance) venom

Bothrops lanceolatus venom contains caseinolytic, phospholipase, esterase and haemorrhagic activities. We have investigated the coagulant and anticoagulant actions of B. lanceolatus venom on human citrated plasma and on purified plasma components. Although B. lanceolatus venom up to 50 microg/ml was unable to clot citrated plasma, at concentrations > or = 5 microg/ml the venom dose-dependently clotted purified human fibrinogen, indicating the presence of a thrombin-like enzyme. Human plasma (final concentration > or = 12.5%) dose-dependently inhibited the venom-induced fibrinogen clotting. This finding suggested that endogenous plasma protease inhibitors can affect the venom's action on fibrinogen. To investigate this possibility, B. lanceolatus venom was incubated with different plasma protease inhibitors and the activity on fibrinogen tested. alpha(2)-Macroglobulin and alpha(1)-antitrypsin did not interfere with the coagulant activity of the venom whereas the antithrombin-III/heparin complex partially inhibited this activity. A non-toxic, acidic phospholipase A(2) purified from B. lanceolatus venom prolonged the activated partial thromboplastin time in human plasma from 39.7+/-0.5 s (control with saline) to 60.2+/-0.9 s with 50 microg of PLA(2) (p<0.001), suggesting an anticoagulant activity associated with this enzyme. This anticoagulant activity may account for some of the effects of the venom on blood coagulation.