Comparative study of the in vivo toxicity and pathophysiology of envenomation by three medically important Egyptian snake venoms.

Snakebite envenomation is a serious medical problem in many developing tropical and subtropical countries. Envenomation is registered by the World Health Organization as a neglected tropical disease due to critical shortages in the production of antivenom. Envenomation causes more than 100,000 deaths annually. Snakebites result in several effects to include edema, blistering, hemorrhage, necrosis and respiratory paralysis. Antivenom is the preferred treatment for the systemic effects of snakebite envenomation, though these are often ineffective in neutralizing venom toxin-induced local tissue damage. To effectively treat snakebites, it is important to determine the lethal potency and pathophysiological effects induced by specific snake venoms. In the current study, we compared the lethality, and the hemorrhagic and dermonecrotic activities of venoms from three snakes in Egypt that are the primary causes of local tissue necrosis. Our data show that the intraperitoneal median lethal doses (LD50) for Cerastes cerastes, Echis carinatus and Naja nigricollis venoms are 0.946, 1.744 and 0.341 mg/kg mouse body weight, respectively. These results indicated that N. nigricollis venom is the most toxic and significantly accelerated the time of death compared to the other two venoms. However, no hematoma or associated edema appeared upon sub-plantar injection of N. nigricollis venom into the mice hind paw. Two hours following intradermal injection of C. cerastes and E. carinatus venoms, macroscopic analysis of the inner surface of mouse skin showed severe hemorrhagic lesions, whereas only insignificant hemorrhagic lesion appeared in mice injected with the highest dose of N. nigricollis venom. Furthermore, the minimum necrotic doses (MND) for the same venoms were 43.15, and 70.87 µg/mouse, or not observed in the case of N. nigricollis venom, respectively. These LD50 values and pathophysiological results can be used to guide development of antivenom against bites by these dangerous Egyptian snakes.

One Bite, Two Patients: Disparate Clinical Courses Following Simultaneous Crotalus oreganus abyssus Envenomation.

A number of crotaline species have been associated with neurotoxic envenomation in North America. One clinical sign that can occur is myokymia: fine, involuntary, wave-like muscle movements occurring at regular intervals. We report an unusual scenario in which a single snakebite resulted in simultaneous envenomation of 2 patients. Both developed myokymia, with 1 having respiratory compromise. One patient also developed a hypersensitivity reaction to antivenom. Envenomation by the Grand Canyon rattlesnake, Crotalus oreganus abyssus, can produce significant neurotoxicity and resultant respiratory compromise. Antivenom may be helpful but can produce hypersensitivity reactions.

Angioedema and Dual Nurse Flight Crew Cricothyrotomy After Envenomation by a Severed Rattlesnake Head.

Crotalid envenomation may result in airway compromise from angioedema, anaphylaxis, or an anaphylactoid reaction. A 57-year-old man was transported by helicopter to the emergency department (ED) after a bite to his hand from a severed rattlesnake head. He rapidly developed facial and oropharyngeal edema that did not respond to standard treatment. After 2 unsuccessful attempts at intubation, the dual flight nurse team performed a cricothyrotomy. They notified the ED team en route, and antivenom was prepared before arrival. Angioedema was suspected because there was no concomitant urticaria, bronchoconstriction, or persistent hypotension. Edema and ecchymosis of the affected extremity were mild. Severe coagulopathy ensued, which was treated with bolus doses of antivenom and continuous infusion. This case report is significant for several reasons. It is the first detailing a prehospital cricothyrotomy performed by flight crew nurses for life-threatening airway edema caused by snakebite envenomation. In-flight notification enabled the ED staff to prepare and administer antivenom immediately after arrival. Despite the use of antivenom in bolus dosing, crotalid envenomation may be complicated by persistent or recurring coagulopathy, and continuous antivenom infusion may be useful. Finally, it highlights the danger of snakebite envenomation even after the death and decapitation of a snake.

Defining the role of post-synaptic α-neurotoxins in paralysis due to snake envenoming in humans.

Snake venom α-neurotoxins potently inhibit rodent nicotinic acetylcholine receptors (nAChRs), but their activity on human receptors and their role in human paralysis from snakebite remain unclear. We demonstrate that two short-chain α-neurotoxins (SαNTx) functionally inhibit human muscle-type nAChR, but are markedly more reversible than against rat receptors. In contrast, two long-chain α-neurotoxins (LαNTx) show no species differences in potency or reversibility. Mutant studies identified two key residues accounting for this. Proteomic and clinical data suggest that paralysis in human snakebites is not associated with SαNTx, but with LαNTx, such as in cobras. Neuromuscular blockade produced by both subclasses of α-neurotoxins was reversed by antivenom in rat nerve-muscle preparations, supporting its effectiveness in human post-synaptic paralysis.

Proteomics analysis to compare the venom composition between Naja naja and Naja kaouthia from the same geographical location of eastern India: Correlation with pathophysiology of envenomation and immunological cross-reactivity towards commercial polyantivenom.

BACKGROUND: Cobra bite is frequently reported across the Indian subcontinent and is associated with a high rate of death and morbidity. In eastern India (EI) Naja naja and Naja kaouthia are reported to be the two most abundant species of cobra. RESEARCH DESIGN AND METHODS: The venom proteome composition of N. naja (NnV) and N. kaouthia (NkV) from Burdwan districts of EI were compared by separation of venom proteins by 1D-SDS-PAGE followed by LC-MS/MS analysis of protein bands. The potency of commercial polyantivenom (PAV) was assessed by neutralization, ELISA, immuno-blot and venom-PAV immunoaffinity chromatography studies. RESULTS: Proteomic analysis identified 52 and 55 proteins for NnV and NkV, respectively, when searched against the Elapidae database. A small quantitative difference in venom composition between these two species of cobra was observed. PAVs exhibited poor cross-reactivity against low molecular mass toxins (<20 kDa) of both cobra venoms, which was substantiated by a meager neutralization of their phospholipase A2 activity. Phospholipase A2 and 3FTx, the two major classes of nonenzymatic and enzymatic proteins, respectively, were partially recognized by PAVs. CONCLUSIONS: Efforts must be made to improve immunization protocols and supplement existing antivenoms with antibodies raised against the major toxins of these venoms.

Exploration of the Inhibitory Potential of Varespladib for Snakebite Envenomation.

Phospholipase A2s (PLA2) is a major component of snake venom with diverse pathologic toxicities and, therefore, a potential target for antivenom therapy. Varespladib was initially designed as an inhibitor of mammal PLA2s, and was recently repurposed to a broad-spectrum inhibitor of PLA2 in snake venom. To evaluate the protective abilities of varespladib to hemorrhage, myonecrosis, and systemic toxicities that are inflicted by different crude snake venoms, subcutaneous ecchymosis, muscle damage, and biochemical variation in serum enzymes derived from the envenomed mice were determined, respectively. Varespladib treatment showed a significant inhibitory effect to snake venom PLA2, which was estimated by IC50 in vitro and ED50 in vivo. In animal models, the severely hemorrhagic toxicity of D. acutus and A. halys venom was almost fully inhibited after administration of varespladib. Moreover, signs of edema in gastrocnemius muscle were remarkably attenuated by administration of varespladib, with a reduced loss of myonecrosis and desmin. Serum levels of creatine kinase, lactate dehydrogenase isoenzyme 1, aspartate transaminase, and alanine transaminase were down-regulated after treatment with varespladib, which indicated the protection to viscera injury. In conclusion, varespladib may be a potential first-line drug candidate in snakebite envenomation first aid or clinical therapy.

Russell's Viper Envenomation-Associated Addisonian Crisis.

Snakebite envenomation is an important public health problem in tropical countries. We report a case of bilateral adrenal hemorrhage in a 28-y-old man with Russell's viper bite that occurred in the Sathyamangalam forest range in the Indian state of Tamil Nadu. In this case, a combination of early bite recognition, hospital-based supportive care, corticosteroid therapy, and timely administration of polyvalent antivenom resulted in a favorable clinical outcome.

Pituitary dysfunction in survivors of Russell's viper snake bite envenomation: A prospective study.

PURPOSE: Endocrinal insufficiency caused by vasculotoxic snake envenomation is under-recognized and is mostly confined to a specific geographic area. We conducted a prospective study to determine the prevalence and pattern of pituitary-target gland insufficiencies caused by snake envenomation. MATERIALS AND METHODS: The hormonal evaluation of patients who had suffered from vasculotoxic snake envenomation was done at baseline and at 6 months of follow-up. Those patients with a documented hormonal insufficiency underwent magnetic resonance imaging (MRI) of the hypothalamo-pituitary area. The severity of envenomation was assessed by the acute physiology and chronic health evaluation II (APACHE-II) score, the sepsis-related organ failure assessment (SOFA) score, and the snake bite severity score (SBSS) for all patients. RESULTS: Seventy-six patients were seen during the study period, of which 60 were available for a repeat hormonal evaluation at 6 months, with the majority of patients belonging to the middle age group (mean age, 37.6 ± 14.9 years). The mean lag period at presentation was 32 ± 20 h. Thirty-five patients (46.1%) had coagulopathy, 20 patients (26.3%) had acute kidney injury (AKI), and 8 of 76 patients (10.5%) needed renal replacement therapy (RRT) in the form of hemodialysis. Six patients (out of 41 with vasculotoxic bites) developed chronic hypopituitarism, which was in continuation with the acute hypopituitarism that they developed. Growth hormone and glucocorticoid deficiencies were the most common endocrinopathies observed. The occurrence of hypopituitarism was observed only in patients with a vasculotoxic snake bite (due to Russell's viper); coagulopathy, renal insufficiency, or any of the scoring tools did not predict the occurrence of hypopituitarism. CONCLUSION: Acute asymptomatic and chronic symptomatic or asymptomatic hypopituitarism are important sequelae of viper bite in a small proportion of patients and can occur in the presence of normal pituitary imaging. Routine prospective pituitary hormone screening should be done in all patients within the first 6 months of envenomation by the vasculotoxic snakebite as chronic pituitary dysfunction can often occur in these patients.

THE FIRST REPORT OF A CROTALID ENVENOMATION IN A DOMESTICATED FERRET ( MUSTELA FURO) AND SUCCESSFUL TREATMENT WITH A NOVEL F(AB')2 ANTIVENOM.

A case report of a domesticated ferret ( Mustela furo) envenomated by a presumptive rattlesnake ( Crotalus sp.) treated successfully and safely with the novel Fab (2') North American Snake Antivenom (Veteria Labs). The ferret presented with clinical signs of depressed mentation and facial edema following a rattlesnake ( Crotalus sp.) bite. It developed hypotension, thrombocytopenia, and ecchymosis following the envenomation. It was treated with Fab (2') antivenom and given supportive care including crystalloid fluids and analgesia to resolution of clinical signs. This is the first documented case of rattlesnake envenomation in this species. This case supports the efficacy and short-term safety of this Fab (2') antivenom in this species without the use of antihistamines or glucocorticoids. This report also addresses the current standards of care with thorough review of the literature involving rattlesnake envenomation in zoological species.

The Efficacy of Crotalidae Polyvalent Immune Fab (Ovine) Antivenom Versus Placebo Plus Optional Rescue Therapy on Recovery From Copperhead Snake Envenomation: A Randomized, Double-Blind, Placebo-Controlled, Clinical Trial.

STUDY OBJECTIVE: Copperhead snake (Agkistrodon contortrix) envenomation causes limb injury resulting in pain and disability. It is not known whether antivenom administration improves limb function. We determine whether administration of antivenom improves recovery from limb injury in patients envenomated by copperhead snakes. METHODS: From August 2013 through November 2015, we performed a multicenter, randomized, double-blind, placebo-controlled, clinical trial to evaluate the effect of ovine Crotalidae polyvalent immune Fab (ovine) (CroFab; FabAV) antivenom therapy on recovery of limb function in patients with copperhead snake envenomation at 14 days postenvenomation. The study setting was 18 emergency departments in regions of the United States where copperhead snakes are endemic. Consecutive patients aged 12 years or older with mild- to moderate-severity envenomation received either FabAV or placebo. The primary outcome was limb function 14 days after envenomation, measured by the Patient-Specific Functional Scale. Additional outcomes included the Patient-Specific Functional Scale at other points; the Disorders of the Arm, Shoulder, and Hand, Lower Extremity Functional Scale, and Patient's Global Impression of Change instruments; grip strength; walking speed; quality of life (Patient-Reported Outcomes Measurement Information System Physical Fucntion-10); pain; and analgesic use. RESULTS: Seventy-four patients received study drug (45 FabAV, 29 placebo). Mean age was 43 years (range 12 to 86 years). Fifty-three percent were men, 62% had lower extremity envenomation, and 88% had mild initial severity. The primary outcome, the least square mean Patient-Specific Functional Scale score at 14 days postenvenomation, was 8.6 for FabAV-treated subjects and 7.4 for placebo recipients (difference 1.2; 95% confidence interval 0.1 to 2.3; P=.04). Additional outcome assessments generally favored FabAV. More FabAV-treated subjects experienced treatment-emergent adverse events (56% versus 28%), but few were serious (1 in each group). CONCLUSION: Treatment with FabAV reduces limb disability measured by the Patient-Specific Functional Scale 14 days after copperhead envenomation.

Clinical profile & complications of neurotoxic snake bite & comparison of two regimens of polyvalent anti-snake venom in its treatment.

BACKGROUND & OBJECTIVES: The optimal anti-snake venom (ASV) dose required to treat neurotoxic snake envenomation is not known. Low-dose ASV (national protocol: maximum dose 200 ml) may be as efficacious as the conventional regimen (100 ml six hourly till all symptoms disappear), but a direct comparison of the regimens is not available. The aim of this study was to test the efficacy of low-dose ASV regimen against the conventional high-dose regimen. METHODS: The clinical profile of 51 patients with neurotoxic snake envenomation was studied. Patients were treated with either the national protocol or the conventional protocol for ASV administration. The time to complete recovery of symptoms, duration of mechanical ventilation and total dose of ASV were compared. RESULTS: More patients were females (28 vs. 23) bitten in the early morning hours (2400-0600 h). Thirty nine of 51 (76.4%) patients required mechanical ventilation. In terms of progression of neuroparalysis, time to complete resolution of ptosis and occurrence of VAP and ASV reactions, there was no difference. Duration of mechanical ventilation was less with the national protocol (24 vs. 43.5 h). Significantly less amount of ASV was used with the national protocol (224 vs. 982 ml) per patient. There were no mortality or permanent neurological sequelae with either regimen. INTERPRETATION & CONCLUSIONS: In this preliminary study, it was found that the national ASV protocol was as effective as the conventional regimen for neurotoxic snake bites. However, the findings need to be tested in a larger randomized controlled trial for definitive conclusions.

Incidence & prognosis of acute kidney injury in individuals of snakebite in a tertiary care hospital in India.

BACKGROUND & OBJECTIVES: The snakebites are considered to be an occupational hazard in agriculture workers and the snake handlers, resulting in a considerable morbidity, mortality and economical implications. This study was conducted to determine the incidence, clinical presentation, renal injury and clinical outcome in snakebite victims who developed acute kidney injury (AKI). METHODS: This hospital-based prospective, observational study was done on 100 cases who were admitted for the management of snakebite and found to develop AKI in a tertiary care hospital at Hyderabad, India. Renal function tests, complete blood picture, urine routine examination, ultrasound examination of abdomen and coagulation profile were done and the prognosis was assessed by noting recovery, mortality, morbidity and/or progress to chronic stage. RESULTS: A total of 100 patients with a mean age of 43.80±12.63 yr (range 18-70); 62 males and 38 females were studied. All had bites on lower limbs. A total of 86 patients arrived in the hospital within 24 h, and 14 arrived after 24 h. Oliguria was found in 60, bleeding tendencies in 64, haemodynamic instability noted - tachycardia in 86. Systolic blood pressure (BP) was <120 mm Hg in 68 and BP was not recordable in four patients. Twelve patients were in stage III kidney disease and needed haemodialysis. Of the 100 cases of snakebite-induced acute kidney failure, 86 recovered and six died. On follow up, after six months eight patients developed chronic kidney failure. INTERPRETATION & CONCLUSIONS: A cascade of events tends to occur in severe haemotoxic envenomation such as bleeding disorders, hypotension/circulatory shock, intravascular haemolysis, disseminated intravascular coagulation and acute respiratory disease syndrome (ARDS). The findings of this study showed that early hospitalization, quick antisnake venom administration and adequate supporting care provided promising results.

Delayed hematologic toxicity following rattlesnake envenomation unresponsive to crotalidae polyvalent antivenom.

North American rattlesnake envenomations are known to produce coagulopathies and thrombocytopenia. However, the occurrence of delayed hematologic toxicity (less than seven days after envenomation) is poorly characterized in the medical literature. While the recurrence of hematologic derangements has been documented following envenomation, it is usually in the absence of clinically significant bleeding. Although commonly recommended to treat delayed coagulopathies, the effectiveness of crotalidae polyvalent immune Fab ovine (CroFab®) in managing this condition remains in question and warrants further investigation and exploration. We describe the case of a 19-year-old male who presented following rattlesnake envenomation at a church service who was treated with antivenin for 48 h and discharged home only to return four days later with profound thrombocytopenia, coagulopathy, and clinically significant bleeding.

Prolonged Coagulopathy, Ecchymoses, and Microangiopathic Hemolytic Anemia Following Hump-Nosed Pit Viper (Hypnale hypnale) Bite in Sri Lanka.

A 74-year-old previously healthy woman was bitten by a hump-nosed pit viper (Hypnale hypnale) at dusk causing incoagulable blood lasting for 6 days. Further, she developed ecchymoses over her forearms, upper arms, hands, and lower back on day 4 after the snakebite, and microangiopathic hemolytic anemia (MAHA). Features of this nature are rare after hump-nosed pit viper bite.

The Related Risk Factors Analysis of Snake-Bite Induced Acute Kidney Injury.

BACKGROUND The pathogenic mechanism of snake-bite induced acute kidney injury (AKI) remains unclear. Analyzing the risk factors for snake-bite induced AKI may provide the guidance needed for AKI prevention and early treatment. MATERIAL AND METHODS This retrospective study included 119 snake-bite patients who were hospitalized at the emergency department of Sichuan Provincial People's Hospital from January 2011 to September 2013. The patients were divided into AKI and non-AKI groups according to the 2012 Kidney Disease: Improving Global Outcomes (KDIGO) guideline. Gender, age, and clinical examination data of the patients were recorded. The Mann-Whitney U test and Fisher exact test were performed to analyze the collected data; preliminary analysis of independent risk factors was performed with multivariate logistic regression. RESULTS Among the snake-bite patients, 98.3% were farmers. The mean age of patients was 46±12 years. Of the 119 patients (13.4%), 16 suffered from AKI. There were statistically significant differences between the AKI and non-AKI groups with respect to age, time interval from snake bite to antivenin therapy, creatine kinase, blood myoglobin, advanced age, regional lymphadenopathy, incision drainage, and hemoglobin. Preliminary analysis with multivariate logistic regression showed that advanced age and increased time interval from snake bite to antivenin therapy might be independent risk factors for snake-bite induced AKI. CONCLUSIONS Age, time interval from snake bite to antivenin therapy, creatine kinase, blood myoglobin, advanced age, regional lymphadenopathy, incision drainage, and hemoglobin were risk factors for snake-bite induced AKI. Advanced age and delayed antivenin therapy might be independent risk factors for snake-bite induced AKI.

Comparative Studies of Structural and Functional Properties of Snake Venom Metalloproteinases.

Snake venom metalloproteinases (SVMPs) induces local and systemic effects on patients suffering from snakebite, degrading extracellular matrix (ECM) proteins such as collagen, gelatin, elastin, laminin, fibronectin, nidogen (entactin), and thrombospondin that cause local hemorrhage and tissue damage. They cleave or activate coagulation factors such as fibrinogen, fibrin, prothrombin, factor V, factor IX, factor X and protein C that bring about systemic coagulopathy. SVMPs and their truncated forms cleave or interfere with platelet adhesive proteins such as vWF, fibrinogen and collagen, and cleave or interfere with platelet receptors such as GPVI, alpha2beta1, GPIb, GPIX, and GPIIbIIIa that result in platelet aggregation defect. SVMPs induce cancer cell line to form morphological changes and apoptosis in vitro concordant with skin necrosis after snakebite in some cases. These local effects caused by SVMPs have no certain treatments, even with commercial anti-venom. SVMPs researches are focusing on their inhibitors, measurement and replacement of blood coagulation factor defects, or anti-cancer drug.

Pharmacological activity of Costus spicatus in experimental Bothrops atrox envenomation.

CONTEXT: Medicinal plants encompass a rich source of active compounds that can neutralize snake venoms or toxins. Costus spicatus (Jacq.) Sw. (Costaceae) is used by the Amazonian population to treat inflammation, pain and other pathological manifestations. OBJECTIVE: To evaluate the influence of C. spicatus aqueous extract on edema, peritonitis, nociception, coagulation, haemorrhage and indirect haemolytic activity induced by Bothrops atrox venom (BAV). MATERIALS AND METHODS: Dried and pulverized leaves were extracted with distilled water. Envenoming was induced by administration of B. atrox snake venom in Swiss Webster mice. The experimental groups consisted of BAV (at the minimum dose to induce measurable biological responses) and C. spicatus extract (CSE, 1.25, 2.5, 5.0, 7.5 and 10 mg/kg/25 µl phosphate-buffered saline) administered individually and in combination (BAVCSE). PBS was used as a control. In vitro assays were also conducted in order to evaluate phospholipase A2 coagulant activities (indirect haemolytic method). RESULTS: CSE significantly reduced the venom-induced edema and nociception at all concentrations tested and inhibited migration of inflammatory cells at the three least concentrations (5.0, 7.5 and 10 mg/kg/25 µl PBS). CSE was not effective in inhibiting coagulant, haemorrhagic and indirect haemolytic activities of the venom. DISCUSSION AND CONCLUSION: The data suggest that CSE could exhibit a central mechanism for pain inhibition, and may also inhibit prostaglandin synthesis. These findings corroborate the traditional administration of C. spicatus decoction to treat inflammatory disorders, including those caused by B. atrox envenomation.

Snakebite Envenoming by Sochurek's Saw-scaled Viper Echis Carinatus Sochureki.

A snake breeder, 47-years-old man, was bitten by the saw-scaled viper (Echis carinatus sochureki). After admission to Toxinology Centre, within 1.5 h, laboratory evaluation showed clotting times prolonged to non-measurable values, afibrinogenaemia, significantly elevated D-dimers, haemolysis and myoglobin elevation. Currently unavailable antivenom was urgently imported and administered within 10 hours. In 24 hours, oligoanuric acute kidney injury (AKI) and mild acute respiratory distress syndrome (ARDS) developed. Despite administration of 10 vials of urgently imported Polyvalent Snake Antivenom Saudi Arabia, the venom-induced consumption coagulopathy (VICC) and AKI persisted. Another ten vials of antivenom were imported from abroad. VICC slowly subsided during the antivenom treatment and disappeared after administration of total 20 vials during 5 day period. No signs of haemorrhage were present during treatment. After resolving VICC, patient was transferred to Department of Nephrology for persisting AKI and requirement for haemodialysis. AKI completely resolved after 20 days. Despite rather timed administration of appropriate antivenom, VICC and AKI developed and the quantity of 20 vials was needed to cease acute symptoms of systemic envenoming. The course illustrates low immunogenicity of the venom haemocoagulation components and thus higher requirements of the antivenom in similar cases.

Neurological Involvement and Hepatocellular Injury Caused by a Snake With Hematotoxin Envenomation.

Venomous snakes with hematotoxin-Russell's viper (Daboia spp), Malayan pit viper (Calloselasma rhodostoma), and green pit viper (Cryptelytrops albolabris and C macrops, previously named Trimeresurus spp) are commonly found in Thailand. Coagulation factor activation, thrombocytopenia, hyperfibrinolysis, and disseminated intravascular coagulation are the main mechanisms of hemorrhaging from these snake bites. The neurological involvement and hepatocellular injury after Russell's viper bites were reported in Sri Lanka, but there is no report from Southeast Asia. This case was a 12-year-old hill tribe boy who had ptosis and exotropia of the left eye, respiratory distress, and prolonged venous clotting time, prothrombin time, and activated partial thromboplastin time; low fibrinogen and platelet count; and transaminitis after being bitten by a darkish-colored snake. He did not respond to antivenom for cobra, Malayan pit viper, or Russell's viper. However, his neurological abnormalities, respiratory failure, and hepatocellular injury improved, and coagulopathy was finally corrected after receiving antivenom for green pit viper. The unidentified snake with hematotoxin was alleged for all manifestations in this patient.