AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

INTRODUCTION

Section 2 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Background

To many people, the cobra is the quintessential venomous snake. Cobras discussed in this article include species in the genus Naja and other similar venomous snakes, such as Ophiophagus hannah (king cobra), Hemachatus haemachatus (ringhals), Walterinnesia aegyptia (desert black snake), Boulengerina species (water cobras), and Pseudohaje species (tree cobras).

Most cobras are large snakes, 1.2-2.5 m in length. The king cobra, which may reach 5.2 m, is the largest venomous snake in the world. Cobras live throughout most of Africa and southern Asia. Their habitats vary. Some species adapt readily to life in cultivated areas and around villages.

When encountered, cobras usually try to escape but occasionally defend themselves boldly and may appear aggressive. Most of these snakes elevate the head and spread the neck as a threat gesture. However, a number of other snakes, venomous and nonvenomous, use this defense as well.

Most snakebites are inflicted on body extremities. Because cobras are popular as show snakes, bites on the hands and fingers are common.

By far, rural agricultural workers and other people in Asia and Africa receive most bites while working outdoors without protective footwear. In North America and Europe, captive snakes usually cause bites, zookeepers and amateur collectors being at greatest risk.

Not all snakebites result in envenomation. In the case of cobras, the percentage of blank bites may be quite high, 45% in one series of 47 cases from Malaysia. In another series, 1 of 3 snake charmers bitten by large king cobras showed no signs of envenomation.

In addition to biting, some cobra species have a unique defense; they eject jets of venom toward an enemy, usually at the eyes. The fangs of these species are specially modified with the discharge orifice on the anterior face rather than at the tip. The effective discharge range of a large snake is at least 3 m. The ringhals and certain African species of Naja are the most effective spitters, but the spitting behavior also is observed among some Asian Naja species.

Pathophysiology

Cobra envenomation is an extremely variable process. The envenomations of some species cause profound neurological abnormalities (eg, cranial nerve dysfunction, abnormal mental status, muscle weakness, paralysis, and respiratory arrest). With other snakes, local tissue damage is of primary concern.

Necrosis is typical of bites by the African spitting cobras (Naja nigricollis, Naja mossambica, Naja pallida, and Naja katiensis), Naja atra (the Chinese cobra), Naja kaouthia (monocellate cobra), and Naja sumatrana (Sumatran spitting cobra). Although the venoms of these cobras contain neurotoxins, necrosis often is the chief or only manifestation of envenoming in humans. Occasionally, a combination of neurologic dysfunction and tissue necrosis is observed.

Cobra venoms have been studied extensively. As with all snake venoms, they are multicomponent systems whose toxins are mostly proteins and polypeptides.

Venoms can be divided into the following categories:

• With most species, excluding some of the African spitting cobras, the most clinically significant toxins are postsynaptic neurotoxins that competitively bind to nicotinic acetylcholine receptors to produce depolarizing neuromuscular blockade. One group in this category has 60-62 amino acids and 4 disulfide bridges. Another has 71-74 amino acids and 5 disulfide bridges.
• The second venom category comprises so-called cardiotoxins, which are actually generalized cell-membrane poisons that produce irreversible cell depolarization. Such depolarization may cause dysrhythmia, hypotension, and death.
• Toxins in the third category activate complement via the alternative pathway (C3-C9 sequence).
• The fourth category is composed of enzyme toxins, such as phospholipase A₂ (variable toxicity), hyaluronidase (facilitates tissue dispersion of other toxins), L-amino acid oxidase (gives many venoms a characteristic yellow coloration), and acetylcholine acetylhydrolase (unknown toxicity). Other proteolytic enzymes are found in the venom of the king cobra.

Naja philippinensis (Philippine cobra) venom is the most toxic, with a subcutaneous median lethal dose (LD₅₀) of 0.14 mg/kg in mice. In comparison, the corresponding LD₅₀ for Naja naja (Indian cobra) venom is 0.29 mg/kg, for Naja haje (Egyptian cobra) venom is 1.75 mg/kg, for king cobra venom is 1.73 mg/kg, and for Naja nigricollis (black-necked spitting cobra) venom is 3.05 mg/kg.

An additional, unique form of toxicity with some Asian and African species is acute ophthalmia, which occurs when venom is spit into the eyes. Spitting cobras can spit venom into a person's eyes from up to 3 m away. Immediate and intense pain results, with blepharospasm, tearing, and blurring of vision. Systemic toxicity does not occur with eye exposure, but corneal ulcerations, uveitis, and permanent blindness have been reported in untreated cases.

About half of the cases ascribed to the African spitting cobras (N nigricollis, N mossambica, N pallida, N katiensis) showed corneal ulceration, and some patients experienced permanent visual impairment or blindness. Cases ascribed to the Asian spitting cobras and the African ringhals are usually less severe.

Frequency

United States

Envenomations result from human interaction with cobras in zoos, research laboratories, and private collections in the United States and other countries where cobras lack natural habitat. In a series of 54 consultations regarding bites by nonnative snakes in the United States, 23 involved cobras. One fatality occurred, and 7 other cases involved serious envenoming. In Russell's 1980 series, cobras inflicted 18 of the 85 bites by non-native snakes. No comparable data are available for other nations, though it was reported that only 3 cobra bites among 32 bites inflicted by nonnative venomous snakes occurred in Britain (rattlesnakes were implicated most often in this series).

International

Snakebites are a significant medical problem in parts of Africa and Asia. In West Africa, the annual bite incidence is 40-120 bites per 100,000 population. Two rural Congolese regions report an annual incidence of 430 bites per 100,000 population. In a 7-year survey, the Natalese incidence was 24 bites per 100,000 population.

Mortality/Morbidity

In India, the annual mortality incidence is 5.6-12.6 per 100,000 population. At one time, Burma listed snakebite as its fifth leading cause of death. More recently, the annual mortality incidence was 3.3 per 100,000 population. Data from Thailand and Malaysia in the 1980s demonstrate an annual mortality incidence of 0.1 per 100,000 population.

• Determining the exact contribution of cobras to overall snakebite morbidity and mortality is difficult. In most cases, bitten individuals are unable to identify the snake. In India, the tendency is to ascribe all fatal or serious bites to cobras. Physicians are also likely to attribute all bites with neurotoxic symptoms to cobras.
• In a Thai survey, cobras made up 17% of the 1145 snakes identified in bites and were responsible for 25% of the fatalities associated with those bites. In northern Malaysia, cobras accounted for 23 of 854 bites in which the snake was identified. In a survey in Taiwan, cobras were blamed for 100 of 851 bites in which the snake was identified; none was fatal. Cobras accounted for 2 of 95 bites on a Liberian rubber plantation. The ringhals was responsible for 18 of 314 envenomations in Natal. Based on patients' symptoms alone, 18 other bites in this series were ascribed to cobras.
• King cobra bites are considered more serious than bites from other cobra species because of the greater volumes of injected venom and the more rapid onset of neurotoxic symptoms. Mortality is also higher. In a series of 35 cases, 10 deaths occurred. Ringhals bites are similar to other cobra bites but are less serious both locally and systemically. Deaths are rare. A medical report of 4 bites by the desert black snake described relatively mild symptoms and reported recovery without specific treatment. Anecdotal reports of fatal bites exist. No medical accounts of bites by water cobras or tree cobras exist. Anecdotal evidence suggests both are dangerous.

Sex

Because of increased exposure to snakes, men are bitten more often than women.

CLINICAL

Section 3 of 11  

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History

The onset of symptoms and signs following a cobra bite can be extremely variable.

• Immediate, local pain (almost always present)
• Soft tissue swelling (may be progressive)
• Neurologic findings, which may begin early and be rapidly progressive (in anecdotal cases, victims have suffered respiratory arrest in a matter of minutes) or may be delayed in onset as long as 24 hours
• Alteration of mental status (eg, drowsiness, occasionally with euphoria)
• Complaints related to cranial nerve dysfunction, such as ptosis (often one of the earliest neurotoxic findings), ophthalmoplegia, dysphagia, and dysphasia
• Profuse salivation, nausea, vomiting, and abdominal pain
• Paresis of neck and jaw muscles and generalized muscular weakness followed by flaccid paralysis
• Shortness of breath, respiratory failure (muscular paresis and accumulated secretions)
• Chest pain or tightness
• Eye pain, tearing, blurred vision (with eye exposure to venom from spitting cobras)

Physical

• Impending respiratory failure
• • Respiratory distress or weakness
  • Cyanosis
• Neurologic dysfunction
• • Altered mental status
  • Ptosis (may be the earliest sign of systemic toxicity)
  • Generalized weakness or paralysis
• Cardiovascular collapse
• • Hypotension
  • Tachycardia or bradycardia
• Soft tissue edema
• Signs of necrosis usually appear within 48 hours of the bite.
• • The area around the fang punctures darkens.
  • Blistering may follow.
  • Necrosis is usually confined to the skin and subcutaneous tissue but may be quite extensive.
  • A putrid smell is characteristic.
• Acute inflammation of the eye follows venom-spitting exposure and is characterized by ocular congestion, edema of the conjunctiva and cornea, and a whitish discharge.

DIFFERENTIALS

Section 4 of 11  

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• Miscellaneous
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WORKUP

Section 5 of 11  

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Lab Studies

• Laboratory studies offer no diagnostic benefit. Baseline labs (eg, complete blood count [CBC], electrolyte tests, renal function studies, coagulopathy panels) may be reasonable in severe bites or if the patient has significant underlying medical problems. Coagulopathy is rare with cobra bites, though prolonged bleeding and failure of clot retraction have been reported following bites by African spitting cobras.
• Arterial blood gas (ABG) determinations may be helpful if the patient's respiratory status is questionable.
• In some regions of the world, researchers are developing immunologic tools, such as enzyme-linked immunosorbent assays (ELISAs), to aid in species identification and possibly in severity grading.

Imaging Studies

• A chest radiograph benefits patients who have severe envenomations, require intubation, or show evidence of cardiorespiratory failure.

Other Tests

• An electrocardiogram (ECG) should be obtained if the victim complains of chest pain or if there is evidence of dysrhythmia.

TREATMENT

Section 6 of 11  

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Prehospital Care

Prompt movement of the victim to a medical facility capable of rendering advanced care, including airway support and antivenom administration, is critical.

• Make every effort to specifically identify the envenomating species; this will aid further management and is vital in determining the proper antivenom to be administered.
  • If the patient is bitten by a wild snake, the snake should be killed and brought to the admitting institution if it is possible to do so safely. Knowledge of the snake fauna of an area and habits of the various species may help in identification. Fairly accurate ELISA tests for identification of snake venoms in wound aspirate, serum, urine, and other body fluids have been developed but are not generally available in regions where cobras live.
  • If the bite occurs in a research or zoo setting, the cage identification card should be brought to the hospital. If available, species-specific antivenom should be sent with the patient.
  • If a captive cobra in a private collection inflicts the bite, identification may be more straightforward. Unfortunately, tremendous controversy exists among experts regarding taxonomy of cobra species and becomes amplified in the lay herpetoculturist community. A private collector who presents after being bitten by his or her captive "Thai cobra" may have been envenomed by any 1 of at least 3 different species, each with different clinical consequences. Thus, expect a variety of physiologic abnormalities and enlist professional help (eg, from a local zoo) to obtain prompt, accurate identification of the snake.
• In some regions of the world, clothing is wrapped around a bitten extremity proximal to the bite site. However, prolonged use of arterial tourniquets is unwise and has caused loss of limb function. A completely occlusive tourniquet is reasonable when a victim has been bitten by a highly toxic snake, such as a cobra, and is a short distance from medical care.
• An alternative first aid procedure is the Australian pressure immobilization technique. This technique has been shown to be helpful in delaying systemic absorption of elapid venoms, but its use in cobra bites remains controversial. An elastic compress (eg, Ace wrap, clothing, crepe bandage) is wrapped rapidly around the bitten extremity, beginning distally and progressing proximally to encompass the entire limb. The compress is as tight as one used for immobilization of a severe ligamentous sprain. Then, the extremity is splinted and kept at heart level. Research shows that, in simulated snakebite scenarios, individuals tend to underestimate the degree of tension required for the wrap to be effective.
• Incisions are not helpful. Using a mechanical suction device is unlikely to return any significant amount of venom, and it could increase local tissue damage when a necrotizing venom is involved. Suction should, therefore, be avoided.
• Avoid cooling measures and ice application. They have been associated with increased necrotic complications.
• If venom is spit into the eyes, immediately and copiously irrigate them with any bland fluid, such as water, saline solution, or milk.

Emergency Department Care

• Assess the patient's airway and breathing. Aggressively manage any signs of impending respiratory failure with endotracheal intubation to prevent aspiration.
• Immediately institute cardiac and pulse oximetry monitoring and closely monitor the patient's vital signs.
• Start, at an appropriate rate, at least 1 large bore line with normal saline or Ringer's lactate.
• Grading scales for judging the severity of viper venom poisoning rely heavily on local findings, which are variable in cobra bites; they should not be used. All persons who have been bitten by a cobra should be treated as if a severe envenomation has occurred.
• Antivenom is the only proven therapy for significant snakebites. About 20 laboratories in Africa, Asia, and Europe produce cobra antivenoms. Some are monovalent, but most are polyvalent against venoms of all the important snakes of a nation or region. However, the quality varies, and no international standards of purity or effectiveness exist. In the United States, no cobra antivenom has FDA approval. All are considered experimental drugs. Antivenoms are largely ineffective in preventing or ameliorating the necrosis caused by many cobra venoms.
• • If the envenomating species has been determined, a resource, such as the Antivenom Index (published and maintained by the American Association of Zoological Parks and Aquariums and the American Association of Poison Control Centers), can be accessed by calling a regional poison control center or the Arizona Poison and Drug Information Center (from outside Arizona, 520-626-6016; from Arizona only, 800-362-0101). This document lists the preferred antivenoms available for most medically important venomous snakes around the world and has information about where these sera can be obtained in the United States (usually zoos or serpentariums). Once the antivenom is located, the physician may need assistance from the police or military to facilitate its rapid transport.
  • If possible, the antivenom should have antibodies against venom of the cobra species that inflicted the bite. However, shared venom antigens among cobra species exist, and heterologous antivenoms may be effective. Venoms of the African spitting cobras are among the most difficult to neutralize by nonspecific antivenoms. Notechis (Australian tiger snake) antivenom proved effective in animal experiments against 9 of 11 cobra venoms, exceptions being ringhals and Chinese cobra venoms. Apparent effectiveness of tiger snake antivenom in clinically treating cobra bites has been shown in a few cases.
• If the patient arrives with some device applied in an attempt to limit spread of the venom, such as a tourniquet, constriction band, or pressure device, quickly assess the patient to determine if any evidence of systemic toxicity is present. Assess the presence of distal pulses below the ligature. If symptoms are present and antivenom is available, start the antivenom before removing the tourniquet device. If symptoms are absent and antivenom is available, remove the device and observe the patient closely for symptoms or signs of toxicity. If toxicity signs occur, administer antivenom promptly. If the tourniquet is totally occluding arterial flow, apply a more loosely fitting device, such as a proximal constriction band, as tightly as one would for a phlebotomy. A pressure/immobilization device may also be used. In either case, release the tourniquet.
• When applicable, initiate and continue irrigation of the eyes with saline. Applying several drops of a topical ophthalmic anesthetic agent may reduce pain and aid in irrigation. The topical use of 1:1000 epinephrine solution is reported to relieve pain promptly. A fluorescein-aided slit lamp examination helps to find evidence of corneal damage. A brief course of topical ophthalmic antibiotics may be prescribed.

Consultations

• Toxicologist or expert in snake venom poisoning
• Regional poison control center or the Arizona Poison and Drug Information Center (from outside Arizona, 520-626-6016; from Arizona, 800-362-0101).
• A local zoo or museum may be able to assist in species identification and may have appropriate antivenom in stock.
• An ophthalmologist should evaluate any patient who has suffered eye exposure to spitting cobra venom.
• General surgeon or plastic surgeon for necrotic wounds

MEDICATION

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The definitive therapy for cobra venom poisoning is antivenom administration, which should be started as soon as possible if evidence of systemic envenoming is present. If specific antivenom is not rapidly available, the patient must be supported using conservative measures alone. Measures include securing the airway and supporting respirations as necessary. Hypotension should be treated initially with intravenous fluids (initially crystalloids but if blood pressure/tissue perfusion fails to improve, then albumin). If hypotension persists after the intravascular volume is replete, vasopressor agents may be necessary.

Evidence supports the use of cholinesterase-inhibiting drugs, such as edrophonium and neostigmine, as a temporizing measure in a situation of severe cobra venom poisoning with significant neurologic abnormalities until antivenom can be obtained.

Administer antivenom according to the manufacturer's instructions. While most currently available commercial antivenoms are of equine origin, work is currently underway in several countries to produce new, fragment antigen binding (Fab)-based ovine antivenoms for various cobra species. These new antivenoms may be much safer to use, with less risk of allergic phenomena.

As with any form of bite, update the tetanus status as necessary. Antibiotic prophylaxis is not necessary.

Drug Category: Antivenom

Imparts passive immunity to the victim against the venom components of the snake(s) for which it is manufactured. The heterologous antibodies bind with venom antigens and block their deleterious effects.

Drug Category: Antihistamines

Antihistamines (H1 and H2 blockers) may blunt or prevent an acute allergic reaction when given before the administration of antivenom. If an anaphylactic/anaphylactoid reaction occurs despite pretreatment, further antihistamine dosing may be required. These agents are useful in managing pruritus in cases of delayed serum sickness, which may appear days to weeks following antivenom treatment.

Drug Category: Cardiovascular agents

Useful in treating acute allergic reactions that may occur with antivenom administration and in supporting the blood pressure and tissue perfusion of hypotensive patients with shock unresponsive to IV fluids alone.

Drug Category: Corticosteroids

Essential for management of both acute and delayed allergic phenomena following antivenom administration. Corticosteroids have no primary role in the management of snake venom poisoning.

Drug Category: Cholinesterase inhibitors

May be effective in temporarily reversing muscle weakness until antivenom can be obtained. Their use might obviate intubation, but airway protection should not be delayed if there is any doubt of the patient's respiratory status or ability to protect his or her airway.

Drug Category: Immune globulins

Consists of administration of immunoglobulin pooled from serum of immunized subjects.

Drug Category: Tetanus toxoid

Used to induce active immunity against tetanus.

FOLLOW-UP

Section 8 of 11  

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Further Inpatient Care

• Admit all cobra snakebite patients to closely monitored settings, whether or not antivenom is given.
• Observe asymptomatic patients for at least 24 hours. Delayed signs and symptoms may occur.
• If signs or symptoms of envenomation progress after first administration of antivenom, further antivenom may be required.
• Continue to administer systemic antihistamines and steroids to a patient experiencing an acute allergic reaction to antivenom until patient is stable.
• Aspirate bullae
• • If necrosis occurs, initiate standard, conservative wound care (eg, cleansing, splinting, debridement as necessary).
  • Secondary bacterial infections may occur and are usually caused by gram-negative bacilli, such as Proteus, Pseudomonas, and Enterobacter species. Initial antibiotics should cover gram-positive and gram-negative organisms. Culture results should determine use of further antibiotics.
  • Occasionally, debridement, amputation, or grafting of tissue is required.
• Warn patients who have received antivenom about the signs and symptoms of delayed serum sickness. If these signs or symptoms develop after discharge, evaluate patient promptly for initiation of systemic steroids and diphenhydramine as outlined above.

Further Outpatient Care

• Patients with necrosis need continued outpatient management of their wounds and should be warned about the signs and symptoms of infection. Continued outpatient physical therapy may be necessary.
• Patients who received antivenom should be aware of the signs and symptoms of delayed serum sickness and should return if they develop.
• Patients who have experienced acute ophthalmia following spitting cobra venom exposure should have outpatient ophthalmologic follow-up to monitor for complications such as uveitis or corneal ulceration.

Transfer

• People bitten by cobras should be cared for in a facility capable of intensive monitoring.

Deterrence/Prevention

• Professional snake keepers should use standard safety techniques (eg, locked cages, trap boxes, protective eyewear) when dealing with cobras and other species that spit venom.
• Amateurs should refrain from keeping exotic venomous snakes in their collections. If they keep such snakes, they should know the specific species they keep, the appropriate antivenom type, and where it can be obtained in an emergency. Preferably, amateurs should maintain their own supply of appropriate antivenom, but this may be difficult (due to regulations related to importing foreign antivenoms into the country) and expensive.
• Travelers in regions where cobras are indigenous should wear protective clothing (long pants and footwear), avoid areas where snakes seek cover, and know the location of the nearest source of medical care in case they are bitten.

Complications

• Respiratory failure/arrest
• Cardiovascular collapse
• Prolonged neuromuscular weakness
• Tissue necrosis
• Antivenom-related complications
• • Anaphylactoid reactions
  • Delayed serum sickness

Prognosis

• Many patients recover with no specific treatment.
• The neurotoxic effects of cobra venom are completely reversible, though recovery may take up to 6 days.
• Reports of death within 1 hour of cobra bite exist, but a timeframe of 2-6 hours is more typical of fatal cases.
• With sound supportive care (eg, prevention of aspiration) and appropriate, prompt antivenom administration, anticipate recovery from cobra envenomation.

Patient Education

• Advise amateur herpetoculturists bitten by a venomous snake in their collection to not keep such animals. If they previously have received antivenom, their risk for an allergic reaction may be increased should antivenom use be required again in the future.
• For excellent patient education resources, visit eMedicine's Bites and Stings Center. Also, see eMedicine's patient education article Snakebite.

MISCELLANEOUS

Section 9 of 11  

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Medical/Legal Pitfalls

• Considering the potential delay in onset of signs and symptoms, do not discharge patients with a possible cobra bite until they have been observed for 24 hours.
• Acute or delayed allergic reaction associated with antivenom use is always a risk. If possible, obtain the patient's consent to administer antivenom, and be immediately available throughout administration to intervene if necessary.
• Failure to aggressively manage a patient's airway in the face of impending respiratory failure may lead to aspiration, with its attendant complications.
• Foreign-produced antivenoms for snakes not native to the United States are not FDA-approved, and some medicolegal risk may be associated with their use. Conversely, failure to use such a product in a significantly envenomed patient could also put the physician at medicolegal risk.

Special Concerns

• Treatment of a patient with significant cobra venom poisoning and evidence of acute allergy to antivenom (positive skin test or reaction on administration of antivenom) is difficult. Weigh the risks and benefits of proceeding with antivenom. Options include the following:
• • Maximally premedicate the patient with drugs that might blunt or prevent anaphylaxis (eg, H1 and H2 blockers, steroids), and begin the infusion very slowly and in a very dilute state.
  • Admit the patient to an intensive care facility, establish invasive hemodynamic monitoring (arterial line), maximally premedicate the patient as above, establish an additional line with an epinephrine infusion, and administer very dilute antivenom at a slow rate. Epinephrine infusion can be titrated with the antivenom to prevent an anaphylactic reaction. This technique should be used only in consultation with an intensivist, a toxicologist, or an expert in snake venom poisoning.
  • Rely on supportive care measures only, including aggressive airway and respiratory management.

MULTIMEDIA

Section 10 of 11  

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• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Media file 1:  Naja atra (Chinese cobra). Photo by Sherman Minton, MD.
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Media file 2:  Naja kaouthia (Monocellate cobra). Photo by Sherman Minton, MD.
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Media file 3:  Naja nivea (Cape cobra). Photo by Sherman Minton, MD.
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Media file 4:  Necrosis from a cobra bite. Photo by Sherman Minton, MD.
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Media file 5:  Necrosis from a Naja atra (Chinese cobra) bite. This resulted in a severe deformity. The patient had few systemic signs or symptoms. Photo by Sherman Minton, MD.
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Media file 6:  The Australian pressure immobilization technique. This technique has been shown to be helpful in delaying systemic absorption of elapid venoms, but its use in cobra bites remains controversial. See Image 7 for Figures 4-6. Figure 1: Apply a broad-pressure bandage over the bite site as soon as possible. Do not take off jeans because the movement of the doing so assists venom to enter the bloodstream. Keep the bitten leg still. Figure 2: The bandage should be as tight as would be applied to a sprained ankle. Figure 3: Extend the bandage as high as possible.
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Media file 7:  The Australian pressure immobilization technique. This technique has been shown to be helpful in delaying systemic absorption of elapid venoms, but its use in cobra bites remains controversial. See Image 6 for Figures 1-3.Figure 4: Apply a splint to the leg.Figure 5: Bind the splint firmly to as much of the leg as possible. If the bandages and splint are applied correctly, they will be comfortable and may be left on for several hours. They should not be taken off until the patient has reached medical care. The doctor will decide when to remove the bandages. If venom has been injected, it will move into the bloodstream quickly once the bandages are removed. The doctor should leave the bandages and splint in position until he or she has assembled appropriate antivenom and drugs that may need to be used when the dressings and splint are removed.Figure 6: For bites on a hand or forearm, bind to the elbow with bandages, use a splint to the elbow, and use a sling.
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Media file 8:  Table of antivenom choices for cobra bites.
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Media file 9:  Cobra antivenoms and their manufacturers (part 1).
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Media file 10:  Cobra antivenoms and their manufacturers (part 2).
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REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

• Bush SP, Hegewald KG, Green SM, et al. Effects of a negative pressure venom extraction device (Extractor) on local tissue injury after artificial rattlesnake envenomation in a porcine model. Wilderness Environ Med. 2000;11(3):180-8. [Medline].
• Gold BS. Neostigmine for the treatment of neurotoxicity following envenomation by the Asiatic cobra. Ann Emerg Med. Jul 1996;28(1):87-9. [Medline].
• Lifshitz M, Maimon N, Livnat S. Walterinnesia aegyptia envenomation in a 22-year-old female: a case report. Toxicon. Mar 2003;41(4):535-7. [Medline].
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• Low BW, Corfield BWR. Acetylcholine receptor alpha-toxin binding site - theoretical and model studies. Asia Proc J Pharmacol. 1987;2:115-27.
• Minton SA. Bites by non-native venomous snakes in the United States. Wilderness Environ Med. 1996;4:297-303.
• Minton SA Jr. Paraspecific protection by elapid and sea snake antivenins. Toxicon. Jul 1967;5(1):47-55. [Medline].
• Norris RL, Ngo J, Nolan K. Physicians and lay people are unable to apply pressure immobilization properly in a simulated snakebite scenario. Wilderness Environ Med. 2005;16(1):16-21. [Medline].
• Reid HA, Thean PC, Martin WJ. Epidemiology of snake bite in north Malaya. Br Med J. 1963;1:992-997.
• Reid HA. Cobra bites. Br Med J. 1964;2:540-545.
• Reid HA. Bites by foreign venomous snakes in Britain. Br Med J. Jun 17 1978;1(6127):1598-1600. [Medline].
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Article Last Updated: Jan 4, 2007