Elapid Snakebite Research Articles

Acetylcholine-Binding Protein Affinity Profiling of Neurotoxins in Snake Venoms with Parallel Toxin Identification

Snakebite is considered a concerning issue and a neglected tropical disease. Three-finger toxins (3FTxs) in snake venoms primarily cause neurotoxic effects since they have high affinity for nicotinic acetylcholine receptors (nAChRs). Their small molecular size makes 3FTxs weakly immunogenic and therefore not appropriately targeted by current antivenoms. This study aims at presenting and applying an analytical method for investigating the therapeutic potential of the acetylcholine-binding protein (AChBP), an efficient nAChR mimic that can capture 3FTxs, for alternative treatment of elapid snakebites. In this analytical methodology, snake venom toxins were separated and characterised using high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) and high-throughput venomics. By subsequent nanofractionation analytics, binding profiling of toxins to the AChBP was achieved with a post-column plate reader-based fluorescence-enhancement ligand displacement bioassay. The integrated method was established and applied to profiling venoms of six elapid snakes (Naja mossambica, Ophiophagus hannah, Dendroaspis polylepis, Naja kaouthia, Naja haje and Bungarus multicinctus). The methodology demonstrated that the AChBP is able to effectively bind long-chain 3FTxs with relatively high affinity, but has low or no binding affinity towards short-chain 3FTxs, and as such provides an efficient analytical platform to investigate binding affinity of 3FTxs to the AChBP and mutants thereof and to rapidly identify bound toxins.

Preclinical assessment of VPEAV, a new trivalent antivenom for elapid snakebite envenoming in the Philippines: Proteomics, immunoreactivity and toxicity neutralization

Snakebite envenoming is an important neglected tropical disease. Antivenom supply, however, remains limited in many parts of the world. This study aimed to examine the protein composition, immunoreactivity and neutralization efficacy of a new antivenom product (VINS Philippine Elapid Antivenoms, VPEAV) developed for the treatment of snakebite envenoming caused by the Philippine Cobra (Naja philippinensis), Samar Cobra (Naja samarensis) and King Cobra (Ophiophagus hannah). Size-exclusion chromatography, sodium-dodecyl sulfate-polyacrylamide gel electrophoresis and tandem mass spectrometry showed that VPEAV consisted of F(ab)’2 (∼90% of total antivenom proteins) with minimal protein impurities. Indirect ELISA showed varying immunoreactivity of VPEAV toward the different venoms (EC50 = 4–16 μg/ml), indicating distinct venom antigenicity between the species. In mice, the neutralization potency of VPEAV against the King Cobra venom was moderate (potency, P = 2.6 mg/ml, defined as the amount of venom completely neutralized per unit volume of antivenom). The potency was significantly lower against the N. philippinensis and N. samarensis venoms (P = 0.18–0.30 mg/ml), implying a higher dose may be needed for effective neutralization of the Naja venoms. Together, the findings suggest the potential and limitation of VPEAV in neutralizing the venom toxicity of the three Philippine elapid snakes.

A Case of Cobra Antivenom Therapy in a Patient Bitten by Elapid Snake in South Korea

Elapid snakes have neurotoxic venom which causes diverse neuroparalytic manifestations, including fatal respiratory failure. In South Korea, since elapid snakebites are very rare, the cobra antivenom, which is effective against neurotoxicity, was only introduced recently. Most physicians in South Korea have little experience in the treatment of patients who have been bitten by elapid snakes. A 19-year-old man was brought to the emergency department with sudden diplopia, 1 hour after a snakebite on the left 2nd finger. The patient presented with drowsiness and complained of mild dizziness and binocular diplopia. After 1 hour, he had sudden onset of dyspnea and dysphagia and appeared to be agitated. He was immediately intubated and received mechanical ventilation as he was unable to breathe on his own. A total of 2.5 mg of neostigmine diluted with normal saline was slowly infused, and 1 vial of cobra antivenom was infused for an hour, 5 times every 2 hours, for a total of 5 vials. He slowly recovered self-breathing; on the 3rd day of hospitalization, he showed tolerable breathing and was extubated. He was discharged without any neurological deficits or other complications.

Phospholipase A2 (PLA2) as an Early Indicator of Envenomation in Australian Elapid Snakebites (ASP-27).

Early diagnosis of snake envenomation is essential, especially neurotoxicity and myotoxicity. We investigated the diagnostic value of serum phospholipase (PLA2) in Australian snakebites. In total, 115 envenomated and 80 non-envenomated patients were recruited over 2 years, in which an early blood sample was available pre-antivenom. Serum samples were analyzed for secretory PLA2 activity using a Cayman sPLA2 assay kit (#765001 Cayman Chemical Company, Ann Arbor MI, USA). Venom concentrations were measured for snake identification using venom-specific enzyme immunoassay. The most common snakes were Pseudonaja spp. (33), Notechis scutatus (24), Pseudechis porphyriacus (19) and Tropidechis carinatus (17). There was a significant difference in median PLA2 activity between non-envenomated (9 nmol/min/mL; IQR: 7–11) and envenomated patients (19 nmol/min/mL; IQR: 10–66, p < 0.0001) but Pseudonaja spp. were not different to non-envenomated. There was a significant correlation between venom concentrations and PLA2 activity (r = 0.71; p < 0.0001). PLA2 activity was predictive for envenomation; area under the receiver-operating-characteristic curve (AUC-ROC), 0.79 (95% confidence intervals [95%CI]: 0.72–0.85), which improved with brown snakes excluded, AUC-ROC, 0.88 (95%CI: 0.82–0.94). A cut-point of 16 nmol/min/mL gives a sensitivity of 72% and specificity of 100% for Australian snakes, excluding Pseudonaja. PLA2 activity was a good early predictor of envenomation in most Australian elapid bites. A bedside PLA2 activity test has potential utility for early case identification but may not be useful for excluding envenomation.

Experience of Snakebite Envenomation by a Desert Viper in Qatar.

Crotaline and elapid snakebites are reported all over the world as well as in the Middle East and other countries around this region. However, data regarding snakebites and their treatment in Qatar are limited. This review paper is going to investigate the presentation and treatment of snakebite in Qatar. A good assessment helps to decide on the management of the snakebites envenomation. Antivenom and conservative management are the mainstays of treatment for crotaline snakebite. Point-of-care ultrasound (POCUS) has been suggested to do early diagnosis and treatment of soft tissue problems, such as edema and compartment syndrome, after a snakebite. The supporting data are not sufficient regarding the efficiency of POCUS in diagnosing the extent and severity of tissue involvement and its ultimate effect on the outcome. Further research is suggested in this case. Systemic complications, such as bleeding diathesis, can be managed by administering clotting factors and platelets.

Autonomic Dysfunction Manifesting as Severe Hypertension Following Cobra Envenomation: An Unusual Occurrence

Introduction: Envenomation due to an elapid snake (krait or cobra) bite is a common life-threatening medical emergency in India and is associated with significant morbidity and mortality. Common cobra (Naja naja) and common krait (Bungarus caeruleus) are the common snake species whose bites are associated with neuroparalysis, which is a key feature of envenomation. Autonomic dysfunction (AD) is another feature of envenomation with varied clinical presentations such as abdominal pain, vomiting, sweating, mydriasis, mild to moderate hypertension (HTN) or hypotension, and cardiac arrhythmia. The occurrence of AD manifesting as severe HTN and tachycardia is unusual following an elapid snake bite. This presentation has been frequently reported with krait envenomation but can also be observed with cobra envenomation.Case Report: We present the case of a 31-year-old male with common cobra (Naja naja) envenomation presenting with neuroparalysis along with severe HTN and tachycardia. The patient had a gradual and sustained recovery with anti-snake venom and other supportive care.Conclusion: Increasing incidences of cobra envenomation warrant that understanding its atypical presentation and its early recognition are of paramount importance as they may alter treatment decisions influencing the overall morbidity and mortality

Snakebite, dysautonomia and central nervous system signs

### Learning Point for Clinicians This report highlights that clinically significant and striking dysautonomia can rarely occur in elapid snakebites and when present in the absence of clear history of snakebite, can cause diagnostic confusion with other mimickers of neuroparalytic snakebite such as myasthenic crisis, Grave’s disease, botulism, Guillain–Barre syndrome and acute porphyria. One early morning in August 2011, a previously healthy girl of 17 years was brought to the emergency medicine department of our hospital with history of sudden onset drooping of upper eyelids, diplopia, difficulty in speaking, swallowing and breathing and weakness of limbs for 2 h. These symptoms were preceded by abdominal pain and vomiting. She was apparently alright the previous night and had slept outside her kutcha house on the ground. There was no history of similar illness in family or deliberate self-poisoning. On admission, she was found to be unconscious, cyanosed with poor respiratory efforts. Pupils were normal and reactive to light. She was intubated immediately and mechanically ventilated. After an …

Treatment of snakebite in Australia: The current evidence base and questions requiring collaborative multicentre prospective studies

Despite the wealth of anecdotes and case reports there are fundamental questions of management of snakebite in Australia that remain unresolved or for which the current evidence is limited. The efficacy in the field, potential limitations and possibility of improvements in pressure immobilisation first aid need objective studies in humans. Optimal bandage sizes, stretch and pressure for different sized limbs need further evaluation, as does the use of pressure pads. Better definitions of specific clinical envenoming syndromes attributable to individual snake species are required, including elucidation of within-genus variations, similarities and differences. Venom studies suggest this is especially important for species within the brown snake ( Pseudonaja) and death adder ( Acanthophis) genera. Appropriate antivenom types, doses and dosing intervals for individual snake species should be more formally studied in patients. Especially important are confirmation of the need for higher doses of brown snake antivenom, while possibly limiting unnecessarily high doses, confirmation of the critical importance of early antivenom use to prevent pre-synaptic neurotoxicity in Taipan and tiger snake bites and ascertainment of whether larger doses of antivenom are unhelpful in Taipan bites after specified time delays. Confirmation of clinical efficacy and dosing recommendations for use of tiger snake ( Notechis) antivenom in envenoming from Australian copperhead ( Austrelaps spp.), broad headed ( Hoplocephalus spp.) and rough-scaled snakes ( Tropidechis carinatus) also require formal study in patients. Other examples of clinical relevance of cross-specificity of current and future monospecific antivenoms and whether there are geographical variations in antivenom responses within species will require elucidation. Prospective multicentre collaborative studies with predefined data collection and serial venom level assays are proposed as the way forward in Australia to help resolve therapeutic uncertainties and to establish a firmer evidence base for best-practice treatment guidelines for Australasian elapid snakebite.

Elapid snakebite as a cause of severe hypertension

Snakebite is a common medical emergency in tropical countries, however, autonomic dysfunction is an uncommon manifestation of snakebite. The authors present an unusual manifestation of severe neurotoxic snake envenomation: severe hypertension requiring intravenous antihypertensives. A review of the literature on autonomic dysfunction in neurotoxic snake envenomation is also presented.

Struan Sutherland's “Rationalisation Of First-Aid Measures For Elapid Snakebite”— A Commentary

The evolution of theory and practice in toxinology andthe personalities involved holds as much fascination asthe creatures that inflict these potentially mortal injuries.Perhaps the earliest text on snakebite is the papyrus heldat the Brooklyn Museum of Art. Dating from DynastyXXX or the early Ptolemaic Period (305

Rationalisation of First-Aid Measures for Elapid Snakebite

Summary The plasma of monkeys envenomated with tiger snake (Notechis scutatus) venom was monitored by radioimmunoassay for both crude venom and a neurotoxin. When the injected limb was immobilised and a pressure of 55 mm Hg applied to the injection site, only very low levels of circulating venom or neurotoxin were detectable. In practical terms, venom movement can be effectively delayed for long periods by the application of a firm crepe bandage to the length of the bitten limb combined with immobilisation by a splint. Pressure alone or immobilisation alone did not delay venom movement.

Envenoming by the Common Krait ( Bungarus caeruleus) and Asian Cobra ( Naja naja): Clinical Manifestations and Their Management in a Rural Setting

Villagers are commonly poisoned by kraits and cobras in India, and resulting deaths are common. An inadequate understanding of appropriate snakebite treatment often delays proper treatment of those who are bitten. A lack of simple airway management equipment such as resuscitation bags and laryngoscopes compounds the difficulty in treating many patients and increases mortality in neurotoxic (elapid) venom poisoning. This article discusses the clinical signs and symptoms of krait and cobra envenoming and medical intervention in a rural setting. We enrolled 30 subjects of presumed snake envenoming (krait = 23 cases, cobra = 7 cases). Details of the bite site, the subject's activities at the time of the bite, local manifestations, systemic involvement, progress of venom poisoning, and subsequent response to treatment were collected on a standard data form. The type of snake was confirmed either by analyzing the killed specimen or by combining clinical findings and identification by the subject or bystanders when presented with preserved specimens. Of 23 subjects (11 male, 12 female) bitten by kraits, 2 were deceased upon arrival, 7 died in the hospital, and 14 recovered. Of the 14 survivors, 4 required artificial respirations with a resuscitation bag, antivenom, and anticholinesterase drugs. One had a dry bite. The remaining 9 recovered with supportive treatment only. Of 7 subjects (5 male; 2 female) encountering cobras, 2 who had been bitten were deceased upon arrival at the hospital, and 1 died suddenly of an apparent cardiac arrest after seeing a hooded cobra on a road (there was no evidence of a bite site on this individual). Four subjects recovered with antivenon, anticholinesterase drugs, and/or artificial respiration. Early administration of antivenom prevents respiratory paralysis after elapid snake bite. Patients with evidence of respiratory insufficiency after neurotoxic venom poisoning require rapid intubation and artificial ventilation. Anticholinestrase agents may help reverse neuromuscular dysfunction caused by elapid envenoming and may accelerate recovery.

Mistakes are lessons of the past

A 16-year-old boy was bitten on his finger by a krait at 0300 h when sleeping on the floor of his hut. He reported to my clinic at 0500 h. He walked into my examination room, but he had bilateral ptosis, bulbar palsy, and was unable to talk. I gave him antivenom and intravenous atropine and neostigamine. As soon as I removed the intravenous needle, he vomited, aspirated, and died. A patient paralysed from an elapid snake bite should be treated in a semi-prone position and intubated.

Sam splint for wrap and immobilization of snakebite

Figure 1. Demonstrates the use of a single Sam splint in wrap and immobilization of a lower extremity. A, Left lower extremity. The 2 black marks on the dorsum of the foot indicate the fang marks and the site of envenomation. B, The lower extremity is wrapped to above the knee with a compression bandage. C, Using a single Sam splint, the splint is placed behind the leg. The foot is placed in a neutral position. The knee is placed in a comfortable position. D, A second wrap is applied external to the splint holding the splint firmly in place. E, Wrap and immobilization are complete. Figure 2. An alternate and perhaps more stable immobilization is achieved using 2 Sam splints. A, The first Sam splint is placed over the wrap on the medial side of the leg. It extends above the knee and wraps around the dorsum of the foot. B, A second Sam splint is applied on the lateral aspect and is also wrapped around the dorsum and up the medial aspect. C, An additional wrap is applied external to this, holding it in position and completing the wrap and immobilization. Wrap and immobilization as a lymphatic retardant (pressure-immobilization) was described and promoted by S. K. Sutherland for the management of Australian elapid snakebite.1–4 Its use has been expanded to most elapid bites with theoretical concern expressed for viperid bites and bites by those elapids with substantial proteolytic activity. The pressure component of the technique is readily achieved with numerous commercially available elasticized compression dressings such as Ace wrap (Medline Industries, Mundelein, IL) or Coban (3M, St Paul, MN). The immobilization portion is not always readily available. An IV board will serve the purpose, but as most bites occur on the lower extremities, a longer, thicker, often-unavailable leg board is required. An IV board is made of inexpensive materials, materials that deteriorate with sun, heat, and time. As most bites occur in the wilderness, one might think a stick would do, but it is difficult to find a straight stick of the right proportions, particularly in times of distress. The Sam splint (The Seaberg Company, Inc, Newport, OR) is a light, foam-covered strip of aluminum. It is designed as an extremity splint for skeletal injury. It is readily available in first-aid and wilderness medical kits. The 36-inch splint is probably the single most versatile of the Sam splints. The figures that follow demonstrate its potential for use in pressure-immobilization. Absent field experience, it appears to be an ideal material. Figure 1 demonstrates the use of a single Sam splint in the wrap and immobilization of a lower extremity. Figure 2 demonstrates the use of 2 Sam splints in the wrap and immobilization of a lower extremity.

Conus geographus envenomation

Human envenomation by the aquatic snail genus Conus is an infrequent but potentially fatal injury amongst divers and shell collectors in the Indian and Pacific Oceans. As with other causes of neurotoxic envenomation such as Elapid snakebites, the onset of paralysis may be rapid. Death occurring within 1 h of injury has been reported. Prompt diagnosis and resuscitation, including airway protection and respiratory support, if necessary, may be lifesaving. We describe a non-fatal case of envenomation due to Conus geographus treated at Honiara Central Hospital, Solomon Islands. A 24-year-old male nurse was admitted with a 12-h history of progressive generalised weakness and poor coordination. The previous night, while collecting seashells, he had suddenly felt a mild stinging sensation in his right hand. His systemic symptoms began about 30 min after this local injury. On examination he had a small puncture wound on the middle finger of his right hand, without erythema or swelling. He was dysarthric, had bilateral ptosis, and an absent gag reflex. All peripheral muscle groups were weak, and his coordination was impaired without cerebellar features. His peak expiratory flow rate was 290 L/min (predicted 600 L/min). The remainder of his physical examination was normal. The shell responsible for the injury was recovered by his relatives (figure). He was admitted for observation and a portable pulse oximeter was used to monitor the adequacy of his ventilation. His oxygen saturation remained above 95% on room air. 12 h after admission he developed acute urinary retention for which he required catheterisation. Although weak, he could walk unaided after 48 h. He was discharged after 72 h at which time his physical examination was normal. When reviewed at medical outpatients a month later he had no complaints. Recorded stings by cone shells are rare. Before 1980, 16 fatalities had been recorded, 12 of which were due to C geographus. It is estimated that one quarter of all stings from this species may prove fatal. Two other species, C textile and C marmoreus, have also been reported to kill human beings, although the plausibility of these reports has been questioned on the basis of venom studies on dissected shells. Nocturnally active, carnivorous cone shells are widely distributed in tropical and subtropical waters. They are often found in shallow waters under rocks, along reefs and crawling on sand. Most human stings occur when a collector attempts to clean a freshly-caught shell, or to place it in his or her pocket. The venom is injected into the shell’s natural prey or its human victim through a harpoon-like tooth or radula. The active components, conotoxins, are predominantly polypeptides of less than 30 aminoacids. Their paralytic actions include postsynaptic blockade of the acetylcholine receptor, as well as inhibition of motor endplate depolarisation by sodium-ion channel blockade. Presynaptically, other conotoxins inhibit acetylcholine release by blockade of voltage-gated calcium ion channels. Non-paralytic toxins also exist but their actions, if any, are unknown. Despite efforts to develop an antivenom, there is no specific treatment for cone-shell poisoning and management is essentially supportive. Paralysis, when it occurs, is generally reversible within 24 h, so mechanical ventilation may be justifiable in even the most basic health-care settings. A survey of health workers at our National Referral Hospital revealed little knowledge of this condition. Our patient was a registered nurse who had lived by the sea all his life and supplemented his income by collecting shells, yet he was unaware of the dangers involved. The most likely explanation for such widespread lack of awareness is the rarity of serious envenomation. However, mild cases may go unrecognised or unreported, and fatalities may be misattributed to drowning.`

Coagulopathy following Australian elapid snakebite: a review of 20 cases: J. White, B. Duncan, C. Wilson, V. Williams and J. Lloyd (State Toxinology Services, and Department of Haematology, Adelaide Children's Hospital, North Adelaide 5006; Department of Haematology, Institute of Medical and Veterinary Science, Adelaide 5000, Australia).

Coagulopathy following Australian elapid snakebite: a review of 20 cases: J. White, B. Duncan, C. Wilson, V. Williams and J. Lloyd (State Toxinology Services, and Department of Haematology, Adelaide Children's Hospital, North Adelaide 5006; Department of Haematology, Institute of Medical and Veterinary Science, Adelaide 5000, Australia).

Lymphopenia following Australian elapid snake bite: Julian White, 1Bruce Duncan2 and Vaughan Williams1 ( 1Haematology Department, Adelaide Children's Hospital, North Adelaide, S.A. 5006 Australia, and 2Haematology Department, Institute of Medical and Veterinary Science, Adelaide, S.A. 5000, Australia)

Lymphopenia following Australian elapid snake bite: Julian White, 1Bruce Duncan2 and Vaughan Williams1 ( 1Haematology Department, Adelaide Children's Hospital, North Adelaide, S.A. 5006 Australia, and 2Haematology Department, Institute of Medical and Veterinary Science, Adelaide, S.A. 5000, Australia)