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Two types of poisonous snakes are indigenous to the United States: pit vipers (rattlesnake, cottonmouth [water moccasin], copperhead) and coral snakes. Their distributions are as follows:

Northeast: Cottonmouth, copperhead, timber rattlesnake.
Southeast: Cottonmouth, copperhead, eastern diamondback rattlesnake, pygmy rattlesnake, eastern coral snake.
Central: Cottonmouth, copperhead, massasauga rattlesnake, timber rattlesnake, prairie rattlesnake.
Southwest: Cottonmouth, copperhead, pygmy rattlesnake, massasauga rattlesnake, northern black-tailed rattlesnake, prairie rattlesnake, sidewinder, Mojave rattlesnake, western diamondback rattlesnake, red diamondback rattlesnake, Texas coral snake, Sonoran coral snake.
Pacific Coast: Northern Pacific rattlesnake, southern Pacific rattlesnake, Great Basin rattlesnake, western diamondback rattlesnake, red diamondback rattlesnake, sidewinder, Mojave rattlesnake.

In the United States, 98% of venomous bites are from pit vipers. In addition, many "non-venomous" species, such as colubrid (rear-fanged) snakes (including the red-neck keelback), are capable of producing venomous bites. There are no indigenous venomous snakes in Hawaii or Alaska.

Pit vipers are typified by rattlesnakes, which have a characteristic triangular head, vertical elliptical pupils ("cat's eyes"), two elongated and hinged fangs in the front part of the jaw, heat- (infrared-) sensing facial pits on the sides of the head midway between and below the level of the eyes and the nostrils, a single row of scales on the underbelly leading to the tail (not seen in nonpoisonous snakes), and rattles on the tail. The snake's age is not determined by the number of rattles, since molting may occur up to four times a year. Because fangs are replaced every 6 to 10 weeks in the adult rattlesnake, bites may demonstrate from one to four large puncture marks. An adult pit viper can strike at a speed of 8' (2.4 m) per second. The rattlesnake may strike without a preliminary warning rattle.

Coral snakes are characterized by their color pattern, with red, black, and yellow or white bands encircling the body. A general rule is"red on yellow kill a fellow [venomous]; red on black venom lack [non-venomous]." The fangs are very short and fixed; the snakes have round pupils, and they bite with a chewing, rather than striking, action.

Signs of Envenomation
Most snakebites do not result in envenomation, because either the snake does not release venom, the skin is not penetrated, or the venom is not potent. Therefore, it is important to recognize the signs of envenomation, in order to avoid needless worry, evacuation, and improper therapy.

The most common signs of envenomation are:
Pit Vipers
1. One or more fang marks. Most snakebites (venomous and non-venomous) will demonstrate rows of markings from the teeth. In the case of venomous snakes, there will be one to four larger distinct markings from the elongated fangs that inoculate the victim with venom. Venomous snakebite wounds tend to bleed more freely than bites from animals and insects.
2. Burning pain at the site of the bite. This may not be present with the bite of the Mojave rattlesnake.
3. Swelling at the site of the bite. This usually begins within 5 to 10 minutes of envenomation and may become quite severe. This may not be pre sent with the bite of the Mojave rattlesnake.
4. Numbness and tingling of the lips, face, fingers, toes, and scalp 30 to 60 minutes after the bite. This can also be present if the victim hyperventilates with fear and excitement. If a victim of a snakebite has immediate symptoms, these are likely to be due to hyperventilation.
5. Twitching of the mouth, face, neck, eye, and bitten extremity muscles 30 to 90 minutes after the bite.
6. Rubbery or metallic taste in the mouth 30 to 90 minutes after the bite.
7. Sweating, weakness, nausea, vomiting, and fainting 1 to 2 hours after the bite. Additional symptoms include chest tightness, rapid breathing rate (20 to 25 breaths per minute), rapid heart rate (125 to 175 beats per minute), palpitations, headache, chills, and confusion.
8. Bruising at the site of the bite. This usually begins within 2 to 3 hours. Large blood blisters may develop within 6 to 10 hours.
9. Difficulty breathing, increased bleeding (bruising, bloody urine, bloody bowel movements, vomiting blood), and collapse 6 to 12 hours after the bite.

Coral Snakes
1. Burning pain at the site of the bite may be present or absent. There is generally very little local swelling or bruising, and certainly much less than that seen with the bite of a pit viper.
2. Numbness and/or weakness of a bitten arm or leg within 90 minutes.
3. Twitching, nervousness, drowsiness, giddiness, increased salivation and drooling in 1 to 3 hours. Vomiting may occur.
4. Slurred speech, double vision, difficulty talking and swallowing, and impaired breathing within 5 to 10 hours.
5. Death from heart and lung failure.

Treatment of Snakebite
If a person is bitten by a snake that could be poisonous, act swiftly. The definitive treatment for serious snake venom poisoning is the administration of antivenin (sometimes called"anti-venom"). The most important aspect of therapy is to get the victim to an appropriate medical facility as quickly as possible.

1. Don't panic. Most bites, even by venomous snakes, do not result in medically significant envenomations. Reassure the victim and keep him from acting in an energy-consuming, purposeless fashion. If the victim has been envenomed, increased physical activity may increase his illness by hastening the spread of venom.
2. Retreat out of the striking range of the snake, which should be considered to be the snake's body length (for pit vipers, it is approximately half the body length). A rattlesnake can strike at a speed of 8' (2.4 m) per second.
3. Locate the snake. If possible, identify the species. If you cannot do this with confidence (which is really only important for the Mojave rattlesnake and coral snake), kill the animal with a blow on the neck from a long, heavy stick. Collect the snake and bring it along for proper identification. Doing this may be extremely important in estimating the amount of antivenin necessary; however, never delay transport of the victim in order to capture a snake. Take care to carry the dead animal in a container that will not allow the head of the snake to bite another victim (the jaws can bite in a reflex action for 20 to 60 minutes after death). If you are not sure how to collect the snake, it is best just to get away from it, to avoid creating an additional victim.
4. Apply the Extractor suction device according to the manufacturer's instructions. This removes venom without the need for a skin incision.
5. Splint the bitten body part, to avoid unnecessary motion. Allow room for swelling within the splint. Maintain the bitten arm or leg at a level below the heart. Remove any jewelry that could become an inadvertent tourniquet.
6. Transport the victim to the nearest hospital.
7. Do not apply ice directly to the wound or immerse the part in ice water An ice pack placed over the wound is of no proven value. Application of extreme cold can cause an injury similar to frostbite.
8. If the victim is more than 2 hours from medical attention, and the bite is on an arm or leg, use the pressure immobilization technique (figure 165): Place a 2" x 2" (5 cm) cloth pad (1/4", or 0.6 cm, thick) over the bite and apply an elastic wrap firmly around the involved limb directly over the padded bite site with a margin of at least 4 to 6" (10 to 15 cm) on either side of the wound, taking care to check for adequate circulation in the fingers and toes (normal feeling and color). An alternative method is to simply wrap the entire limb at the described tightness with an elastic bandage. The wrap is meant to impede absorption of venom into the general circulation by containing it within the compressed tissue and microscopic blood and lymphatic vessels near the limb surface. You should then splint the limb to prevent motion. If the bite is on a hand or arm, also apply a sling. An alternative to the pressure immobilization technique is a constriction band (not a tourniquet) wrapped a few inches closer to the heart than the bite marks on the bitten limb. This should be applied tightly enough to only occlude the superficial veins and lymph passages. The band may be advanced periodically to stay ahead of the swelling. It is of questionable usefulness if 30 minutes have intervened between the time of the bite and the application of the constriction band (or pressure immobilization technique).
9. The only indications for incision and suction are if all four of the following conditions are present: The bite is from a rattlesnake, the victim is more than 1 hour from medical care, the Extractor cannot be applied, and the procedure can be performed within 5 minutes of the bite. The incisions should be made only by a person experienced in the procedure with a razor blade or sharp knife directly over the fang marks, in a parallel fashion (not crisscross), 1/8'' to 1/4'' (0.3 to 0.6 cm) long and i/8" to 1/4'' deep (just through the skin). The purpose is to enlarge the fang marks and facilitate suction. Apply suction for 30 minutes with the rubber device from a snakebite kit—use your mouth only as a last resort. The impression of most snakebite experts is that incision and suction are of little value and probably should be abandoned. It appears that little venom can actually be removed from the bite site unless a perfectly placed incision is made immediately after the bite and followed by superb suction. Furthermore, mouth contact with a crisscross incision invariably creates a nasty infection that leaves a noticeable scar; there is also the risk of transmission of blood-borne disease.
10."Snakebite medicine" (whiskey) is of no value and may actually be harmful if it increases circulation to the skin.
11. There is not yet scientific evidence that electrical shocks applied to snakebites are of any value. To the contrary, there are experiments that refute this concept.
12. The bite wound should be washed vigorously with soap and water, and the victim treated with dicloxacillin, erythromycin, or cephalexin. Watch for an allergic reaction caused by the snakebite. Once the victim is in the hospital, the severity of envenomation will be ascertained, and the victim treated with antivenin if necessary. Such therapy must be carried out under the supervision of a physician, because serious allergic reactions to presently available antivenins are common.

Avoiding Poisonous Snakes
1. Avoid the known habitats of poisonous snakes, such as rocky ledges and woodpiles.
2. Do not reach into areas that you cannot visually examine first. Walk on clearly marked trails, and use a walking stick to move suspicious objects. Do not reach blindly behind rocks.
3. Wear adequate protective clothing, particularly boots to cover your feet and lower legs.
4. Never hike alone in snake territory. Carry the Extractor, an elastic wrap, and a SAM Splint.
5. Avoid hiking at night in snake territory. Carry a flashlight and walking stick.
6. Do not handle snakes unless you know what you are doing. Remember that you can be bitten and envenomed by seemingly dead or non-venomous snakes.

Nonpoisonous Snakes
Many snakes (for example, the gopher snake and king snake) are non-venomous and do not create serious medical problems with a bite. However, identifying a snake from the bite puncture wounds is often extremely difficult for the amateur. Unless the snake can be positively identified as a non-venomous species, the victim should be considered to have been bitten by a poisonous snake and managed appropriately. The snake should be captured for identification. If the snake is known to be non-venomous, the wound should be washed vigorously with soap and water, and the victim treated with dicloxacillin, erythromycin, or cephalexin.

Published: 29 Apr 2002 | Last Updated: 15 Sep 2010
Details mentioned in this article were accurate at the time of publication
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