What You Need To Know About Snakebites

Eastern coral snake, photo courtesy of Norman Benton, CC-BY-SA 3.0

The Wilderness Medical Society held its annual meeting at  Snowmass last summer July 23-28, 2010. There were numerous terrific educational  sessions. In a series of posts, I am going to highlight some of what we learned  from the presenters.

Jonathan Allen gave a presentation on venomous snakebite  management. Here are some facts to remember:

Snakebite Statistics

Approximately 15 percent of the 3,000 snake species  worldwide are dangerous to humans. There are annually 400,000 to 2,000,000  envenomations from snakebite worldwide, with 20,000 to 100,000 deaths. In the  U.S., there is at least one species of venomous snake in every state except  Alaska, Maine, and Hawaii. There are  approximately 20 venomous species, including pit vipers and coral snakes, and  an estimated 6,000 to 7,000 venomous snakebites each year, including six to 10  deaths. Perhaps only 20 percent of bites are reported.

Deaths from snakebites typically occur in elder victims, in victims  who do not receive antivenom or in victims who receive inadequate amounts of  antivenom. Ninety-eight percent of bites are on the victima??s limbs, usually the  arms or hands.

Coral Snakebites

Venomous coral snakes in North America can be recognized by  the pattern of red bands bordered by yellow bands. a??Red on yellow, kill a  fellow; red on black, venom lack.a?? The venom of the Texas coral snake is  generally less toxic than that of the Eastern coral snake (pictured above). The Sonoran coral  snake is small; the limited volume of venom it can deliver makes its bite  relatively insignificant.

Because a significant coral snake envenomation can have  serious symptoms that are delayed or gradual in onset, anyone who has a  suspected coral snake bite should be transported to appropriate medical care  (typically, an emergency department) even if no signs or symptoms are present.  If a person has been bitten by an Eastern coral snake and has any sign of  neurotoxicity, antivenom should be administered as soon as possible. North  American Coral Snake Antivenom (NACSA) is produced by Wyeth; production ceased  in 2006, so very little of this product is available. A Mexican product, Coralmyn,  which is effective against both the Eastern and Texas coral snakes, is not  available in the U.S. Antivenom is usually not needed for most bites from the  less toxic Texas coral snake, and supportive care alone without antivenom is  the appropriate therapy for Sonoran coral snake bite.

Crotalid Snakebites

Western diamondback (a type of crotalid), photo courtesy of Clinton & Charles Robertson, CC-BY-SA 2.0

Crotalid snakes (such as rattlesnakes) have fangs with a  deep groove through which venom flows. The fangs can be folded into the snakea??s  mouth, or hyperextended up to 180 degrees. The fangs move independent of each  other, and the snake can control whether or not to inject venom and how much to  inject. The venom of crotalids varies between species, can vary within a  species, and is very stable to temperature changes and drying.

One quarter of all pit viper bites are a??drya?? and do not  result in envenomation. When envenomation does occur, youa??ll notice pain,  redness and swelling near the bite site occurring within 30 to 60 minutes. Over  several hours, blisters (often bloody) occur, sometimes with inflammation in  the lymphatic system. In three to six hours, there can be extensive bruising.

What to Do if Someone  is Bitten by a Snake

When someone is bitten by a crotalid snake, one should limit  motion of the bitten part (such as by using a splint), try to limit walking,  remove jewelry and constrictive clothing that might cut off circulation if  swelling were to occur, and use acetaminophen for pain. The next step is to transport  the victim to the emergency department. Useless and potentially harmful first  aid maneuvers include tight tourniquets, incision and suction, venom extraction  devices, electric shock, immersion into crushed or cubed ice or ice water, and  application of papain or meat tenderizer.

A severe allergic reaction may occur following a snakebite.  This is treated in standard fashion with drugs such as epinephrine,  antihistamines, and steroids.

Exotic Snakes

Exotic snakes imported into the U.S. can certainly bite  victims. The symptoms of envenomation are often different than those from North  American venomous snakes, and include flaccid (a??floppya??) paralysis, muscle  tissue breakdown, severe bleeding disorder, kidney failure, tissue death at the  bite site, infection or abscess at the bite site, and allergic reactions.

                       
                       

This post, What You Need To Know About Snakebites, was originally published on
                        Healthine.com by Paul Auerbach, M.D..