Copyright 2002
Wilderness Drum, Inc.
All rights reserved

Wilderness Emergency Care
Thoughts on Snakebite
Steve Beyer

Pit vipers      Coral snakes      Neotropical snakes

Coral Snakes

The other great family of snakes in the United States are the Elapidae or coral snakes. Coral snakes are related to cobras and several types of Australian venomous snakes. In North America, there are two species of coral snake – the western coral snake, found in Arizona and New Mexico, and the eastern coral snake, found from coastal North Carolina through the Gulf states to western Texas.

Elapids are different from the Crotalids or pit vipers in a number of significant ways. Coral snakes have very short fangs in the front of a small mouth. The small mouth and fangs make it hard for a coral snake to bite anything other than a finger, toe, or fold of skin. Pit vipers strike and release, but coral snakes hang on and chew. And while Crotalid venom causes rapid tissue necrosis, Elapid venom slowly attacks the central nervous system. These differences mean that you treat a coral snake bite differently than you would a pit viper bite. In particular, for Elapid envenomation,

• the use of a Sawyer Extractor appears to be of little benefit, and
   
• the use of the Australian pressure-immobilization technique has become accepted as a standard treatment. Since Elapid venom is a systemic neurotoxin, wrapping the entire bitten extremity can help delay systemic absorption of the venom, but, unlike Crotalid venom, will not cause local tissue necrosis.

North American coral snakes are generally shy and docile, and they do not attack unless deliberately provoked. Fewer than forty percent of Elapid bites result in significant envenomation. Fatalities are rare.

When an envenomation occurs, the bitten extremity starts to become weak and numb after about an hour. In the following hours, the signs and symptoms of central nervous system poisoning begin to appear – nausea, vomiting, weakness, muscle twitching, tingling in the extremities, slurred speech, increased salivation, and difficulty swallowing and breathing. In the worst case, depression of the central nervous system can lead to respiratory and cardiac paralysis and death.

A significant problem is that it is often hard to know whether the person bitten has been envenomated or not. The fang marks can be hard to see, although sometimes you can squeeze blood from the tiny puncture sites. Local swelling is usually minimal. There are often many nonvenomous mimics of coral snakes in the same area, so it can be difficult to know whether the biting snake was venomous or not. It can take more than an hour for the bitten extremity to feel weak or numb, and sometimes as long as twelve hours before the victim feels sick enough to need help.

So, if someone has been bitten by something that may have been a coral snake, it is important to begin treatment and observation right away, and to give serious consideration to evacuation, even in the absence of signs and symptoms, and even if you might feel foolish later if nothing happens. Treatment for Elapid envenomation in the wilderness is as follows:

• Keep the patient calm and with as little movement as possible. Provide lots of support and encouragement.
   
• Clean and flush the wound with clean water and apply a sterile dressing.
   
• Wrap the bitten limb with an elastic bandage, at about the same tension as would be used on a sprained ankle. Start wrapping about four inches above the bite and wrap away from the body toward the hand or foot. If you have an additional elastic bandage, you can then wrap in the other direction, starting about four inches below the bite and wrapping toward the body. This should help to immobilize the venom. The wrapping should be loose enough so that you can slip a finger underneath, and you should check the peripheral pulses to make sure there is no constriction of blood flow. Remember that the venom spreads through the lymphatic system, which lies close to the surface of the skin, so that great pressure is not necessary in order to constrict its flow.
   
• Splint the limb and keep it at about heart level.
   
• Encourage the patient to drink frequent small amounts of water.
   
• Provide basic life support and treat for shock as necessary.
   
• Transport as quickly as possible to definitive medical care, where antivenom and appropriate facilities for its administration may be available.

As with Crotalid bites, the use of alcohol, incisions, electric shock, sucking, and ice are not recommended.

Again, I am not persuaded that Elapid antivenin should be administered in the field. First, of course, there are the issues of contamination, sepsis, and anaphylactic shock, just as with Crotalid antivenin. Second, Elapid antivenin is specific for closely related species of snakes, and there is no benefit – but the same risk – in administering antivenin developed for unrelated snakes. For example, the only antivenin available in the United States is Antivenin (Micruris fulvius) manufactured by Wyeth-Ayerst, for use with bites by the eastern coral snake. There is no antivenom available for the western coral snake, and care for victims of this snake is entirely supportive. There are other antivenoms produced in other countries, such as Costa Rica, Brazil, and India, for Elapidae species found there.

< Previous       Next >

Back to the top
Return to Writings Page