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SUMMARY

Poisonous snakebite is a potentially serious accident. It can lead to severe pain or other problems, and in the rare instance even death. However in North America it is not nearly as dangerous as most believe. Snakes seldom bite humans and even when they do so, their bites are seldom fatal. There is no need to allow fear of snakes to ruin your enjoyment of the outdoors.

Snakes will usually avoid you if you give them a chance. Try to be sure they know you are coming. Don't reach into places they might hide. Be careful turning over rock and boards in snake country. Leave snakes alone; there is no simple rule to identify which are poisonous. The same advice applies to dead snakes and detached heads - reflex bites are as dangerous as bites from live snakes.

At least half of all bites are caused by foolish behavior: handling or taunting venomous snakes, or failing to move away from a venomous snake once it has been sighted.

If someone is bitten:

The following treatment protocol is provided by Jeff Isaac and Peter Goth in The Outward Bound Wilderness First Aid Handbook, Lyons and Burford, 1991.

"Transport the patient as quickly as possible to antivenin (antidote). Although local discomfort may be severe, systemic signs and symptoms may be delayed for two to six hours following the bite. Walking your patient out is reasonably safe unless severe signs and symptoms occur. It is also significantly faster than trying a carry. Splint the affected part if possible.

Expect swelling. Remove constricting items such as rings, bracelets, and clothing from the bitten extremity.

Do not delay. Immediately following the bite of a snake thought to be poisonous, evacuation should be started. It can always be slowed down or canceled if it becomes obvious that envenomation did not occur, or the snake is not poisonous.

Most medical experts agree that traditional field treatments such as tourniquets, pressure dressing, ice packs, and "cut and suck" snakebite kits are generally ineffective and are possibly dangerous. Poisonous snakebite is one of those conditions that you cannot treat in the field. Don't waste valuable time trying."

If it is going to be more than one hour to transport, you should consider rinsing and disinfecting the wound. [End of Summary]

ACKNOWLEDGEMENTS

At the outset we would like to thank the following for their helpful comments and suggestions:

K.V. Kardong at the Dept. of Zoology, Washington State University Keith Conover, M.D., Dept. of Emergency Medicine, University of Pittsburgh loosemore-sandra@CS.YALE.EDU (Sandra Loosemore) blazekm@a.cs.okstate.edu pholland@iastate.edu (Paul Hollander) KLEINSCHMIDT@MCCLB0.MED.NYU.EDU (Jochen) CWA@NAUVAX.UCC.NAU.EDU (Curt Anderson) ed@titipu.meta.COM (Edward Reid) Paul Moler, a professional herpetologist with the Florida Dept. of Game and Freshwater Fish.

REFERENCES

This posting only scratches the surface. The following sources will provide more information:

_The Outward Bound Wilderness First-Aid Handbook_ Jeff Isaac, P.A.-C. and Peter Goth, M.D. Lyons and Burford, 1991. Perhaps the best first aid book around at this time.

_Medicine for Mountaineering_, (referred to as 'MFM' throughout this article) Third Edition 1985. James A. Wilkerson, M.D. ed. The snakebite section starts on p234. The section on treatment is now somewhat dated.

_A Field Guide to Western Reptiles and Amphibians_, Robert C. Stebbins, Houghton Mifflin, 1966. A good guide to snakes and other reptiles including descriptions, color illustrations and maps of their ranges. Part of the Peterson Field Guide Series. Covers only the western U.S.

_Rattlesnakes_, Laurence M. Klauber, University of California Press, 1982. This is a condensation of a 2 volume series on the same topic.This book does not provide as much identification information as does Stebbins, but it does include range maps. It provides a lot of interesting information about many topics ranging from the snake life cycle to collections of folklore and misinformation.

Russell, Findlay E. 1980. _Snake venom poisoning in the United States_, Annual Review of Medicine, 1980, 31:247-59.

Kurecki, Barnard A. and H. James Brownlee._Venomous snakebites in the United States_, The Journal of Family Practice, 1987, 25(4):386-92.

Gold, Barry S. and Willis A. Wingert._Snake venom poisoning in the United States: A review of therapeutic practice_, Southern Medical Journal, June 1994, 87(6):579-89.

Downey, Daniel J., George E. Omer, and Moheb S. Moneim._New Mexico rattlesnake bites: Demographic review and guidelines for treatment_, The Journal of Trauma, 1991, 31(10):1380-86.

Curry, Steven C. et al., _The legitimacy of rattlesnake bites in central Arizona_, Annals of Emergency Medicine, 1989, 18(6):658-63.

Iserson, Kenneth V._Incidence of snakebite in wilderness rescue_, Journal of the American Medical Association, Sept 9, 1988, 260(10): 1405.

Antivenin (Crotalidae) Polyvalent under Wyeth-Ayerst Laboratories, in _Physicians Desk Reference_, Medical Economics Data: Montvale, NJ. 1995.

Antivenin (Micrurus fulvius) under Wyeth-Ayerst Laboratories, in _Physicians Desk Reference_, Medical Economics Data: Montvale, NJ. 1995.

Berkow, Robert (ed)._The Merck Manual of Diagnosis and Therapy. 14th Ed._, Merck, Sharpe and Dohme: Rahway, NJ, 1982.

J.L. Behler and F. Wayne King. _The Audubon Society Field Guide to North American Reptiles and Amphibians_. Alfred A. Knopf: New York, 1979.

_Conant, R. 1975. A field Guide to Reptiles and Amphibians of Eastern and Central North America_, Houghton Mifflin Company;Boston. Covers the eastern U.S. but there is also a Western edition by Stebbins (see above).

Minton, Sherman A. Poisonous Snakes and Snakebite in the U.S.: A Brief Review. Northwest Science, 61(2): 130-37, 1987.

INTRODUCTION

Snakebite is always a hot topic. In what follows we will attempt to describe prevention and treatment of bites by poisonous snakes in North America as well as the effects of such bites. Be aware that we are dealing with overreaction and hype here. Popular literature, folklore, and movies have greatly exaggerated both the probability of snakebite and the likely outcome should it happen. Humans are much less likely to get bitten than many people believe. Furthermore snakebite, while serious, is not the death sentence often implied. Snakes, poisonous and otherwise, have excited a lot of aversion and superstition over the ages, resulting in unwarranted fear and sometimes even panic. This fear and panic can lead to:

Improper treatment of those cases which need treatment for envenomation.

Dangerous overtreatment for bites in which envenomation does not occur.

Worsening the outcome of snakebites due to panic.

Unnecessary and dangerous treatment of bites by nonvenomous snakes.

Unnecessary, expensive, and dangerous rescue operations.

Unnecessary destruction of snakes and their habitat.

Snakebite in the U.S. should be treated conservatively. There is no need to jump in with knives, tourniquets, ice, or compression bandages. There is no need to try to suck out the venom by mouth. Carrying out any of these extreme procedures has the potential to do far more harm than good. We will explain later in this FAQ the reasons that such extreme measures do not form part of the therapy for snakebite. Victims should be given only the appropriate treatment and then be rapidly evacuated to medical facilities.

Wilkinson in Medicine for Mountaineering has this to say,

"About no other medical subject has so much been written when so little has been known!"

"Poisonous snakebites are unquestionably serious, potentially deadly accidents. Nonetheless, the danger from a single bite has been greatly exaggerated, particularly in the United States, where an average of less than fifteen people die each year as the result of bites by poisonous snakes. Less than one percent of poisonous snakebites in this country are lethal. In other parts of the world poisonous snakes are a more serious problem. Many of the snakes in those areas have a much more toxic venom, treatment is less successful, and sophisticated medical care is less available." (MFM p234)

Of course severity will vary with species as well as with the individual snake. Larger snakes of the same species tend to have more venom (although the larger snake may have learned to ration its venom while a younger animal may be more likely to inject the full load). In North America we do not have the really nasty varieties of snakes found in some parts of the world. There is no reason to panic when someone is bitten by a snake. Even the "three nasties" described below are not nearly as dangerous as the cobras, black mambas and death adders found outside the U.S.

VARIOUS SNAKES AND THEIR EFFECTS:

Venomous snakes in the U.S. all belong to one of two families:

Crotalids (pit vipers): copperhead cottonmouth or water moccasin the numerous species of rattlesnakes

Elapids coral snake (eastern and Arizona species)

Crotalids have the most efficient injection mechanism of any snake. They are equipped with long hollow fangs and a system to inject venom through those fangs. They have the ability to inject large volumes of venom quickly. Crotalid fangs can fold back into the mouth; lack of visible fangs does not necessarily mean an unarmed snake. Most crotalids have venom that is less toxic than that of coral snakes. Crotalids, however, are the more dangerous group because (a) they are more likely to bite a human, (b) they can inject venom much more efficiently, and (c) they are usually larger and have more venom to use.

Elapids on the other hand have grooved fangs. This is a much less efficient injection mechanism. They chew to get the venom into the victim. The size of coral snakes limits them to biting fingers or loose folds of skin. The elapidae include some of the world's nastiest critters: the black mamba, the death adder, and the cobra.

The two species of coral snakes in North America are about as mild as poisonous snakes can be. They are not aggressive. Children have reportedly played with coral snakes for hours without being bitten, but no record exists of how many parental heart attacks this has caused! The venom is potent, however, and treatment should be given for bites which do occur. Coral snake bites make up less than 2% of all U.S. snakebites. In fact, Gold and Wingert report that fewer than 25 of all reported venomous snakebites per year are from coral snakes. There have been no known fatalities from coral snake bites since the development of the _Micrurus fulvius_ antivenin (Wyeth-Ayerst Laboratories).

The Arizona coral snake (Micruroides euryxsanthus) is less dangerous than the eastern coral snake (Micrurus fulvius). It is smaller and would have a hard time biting a person even if inclined to do so. The rare bites which do occur should be treated the same as bites from the eastern coral snake.

VENOMS:

Snake venom usually contains two types of poison: hemolytic toxins which attack the walls of blood vessels and neurotoxins which attack the nerves.

Hemolytic toxin attacks blood vessel walls, allows serum to escape into the surrounding tissues, and causes clotting within the vessels. The result is severe swelling, pain, and discoloration at the site of the bite. In the few cases where hemolytic toxins cause death, the actual cause is likely to be shock. The effects of hemolytic toxin are immediate and primarily localized. Symptoms will be obvious.

Neurotoxins produce much less obvious immediate symptoms, at times fooling the victim into believing envenomation has not occurred. But systemic symptoms can appear later. Neurotoxins produce much less local reaction than do hemolytic toxins. On the other hand, they can affect nerves quite removed from the site of the bite. In extreme cases they can cause respiratory arrest, although this is uncommon with the bites from most North American snakes. However, respiratory distress without actual arrest may to occur in neurotoxin victims. Less severe symptoms from neurotoxins include tingling or prickly feelings and eyelid paralysis.

All snake venom probably has some of each kind of toxin. But, most pit vipers have a higher fraction of hemolytic toxin, and elapids have more neurotoxin. The Mojave rattlesnake, a pit viper, is an exception; see below. The potency of venom will vary, with species, with time of year and with geographic area.

The typical snake mouth is no cleaner than a human's. So, they tend to induce microbial contamination into bites. Although it is common for a snake to bite without injecting venom, microbial contaminants will always be present and should always be treated. Such contamination seems to be much less of a problem in bites by nonvenomous snakes, perhaps because their bites do not penetrate so deeply.

FIVE SPECIAL CASES:

FIVE varieties deserve special mention: A single bite from a copperhead is not very dangerous. The diamondbacks (eastern and western species) and the Mojave rattlesnakes deserve attention because they are particularly dangerous. The speckled rattlesnake should also be mentioned because bites >from it, like those from the Mojave, may not produce local pain or other reaction. (It is worth noting, however, that Findlay Russell points out that pain is not always associated with an envenomated bite from any variety of snake).

The copperhead has probably the mildest venom of any poisonous snake in the U.S. Adults bitten by a single copperhead usually need only supportive therapy and good cleansing and disinfection of the wound. A study of 400 victims of copperhead bites found only 2 deaths, both the result of simultaneous bites by 3 or more snakes. About 3,000 bites a year are inflicted by copperheads. You would probably want treat a copperhead bite pretty much as any other pit viper bite, but would be able to reassure the patient a bit more and would not be as concerned if medical help were not readily available. This not to say that a copperhead bite won't hurt, it will. These bites are still serious but are unlikely to be life threatening. Gold and Wingert state that "It [antivenin] is unnecessary in most cases of copperhead bite and pygmy rattlesnake bites.

The diamondbacks, on the other hand, are potentially deadly. Both the eastern and western versions are huge, the western species compensating for its slightly smaller size with a more potent venom. MFM lists the eastern diamondback as an aggressive snake and claims it is responsible for more human deaths than any other U.S. snake. Others dispute this. Paul Moler argues it is not particularly aggressive and quotes some numbers which indicate that it is unlikely to lead in killing people.

The Mojave rattler is dangerous in spite of its size. This little rascal is armed with a very potent venom, high in neurotoxins. Pain and other local responses to the bite may be mild, but the systemic response may be marked. Initial reaction is usually mild with severe symptoms coming 12 to 16 hours after the bite. The early symptoms could easily fool one into believing there was no problem. By the time severe symptoms appeared the best time for treatment would have passed. The Mojave rattlesnake also has a couple of close relatives south of the border, the Mexican west coast rattler and the South American tropical rattlesnake, also known as cascabel or neotropical rattlesnake. They provide problems at least equal to those of the Mojave version.

It is worth mentioning that bites from other North American venomous snakes may yield little local pain, swelling, or other reaction following envenomation. This true of bites from the speckled rattlesnake,_Crotalus mitchelli_, and possibly also of bites from the rock rattlesnake, _Crotalus lepidus_, and tiger rattlesnake, _Crotalus tigris_ (Minton, 1987). If you know that you have been bitten by one of these snakes, it is probably best to assume that you have been envenomated and procede to a hospital.

Envenomated bites from either the diamondback or the Mojave rattler are serious, possibly even deadly. Do your level best to evacuate the victim quickly to medical facilities.

There is of course a wide variety of poisonous snakes throughout the world. We can't discuss them all here. They are generally confined to warmer climates in places such as Australia, Africa, the Indian subcontinent, and Southeast Asia. Many of these snakes much more dangerous than those native to the North America. There are some exceptions with more northerly ranges. For example, the habitat of the European viper extends to the Arctic Circle. It is not, however, as dangerous as some of the snakes inhabiting warmer climates. If you plan to engage in wilderness activities overseas you should research their venomous snakes.

MFM does have some information on other areas as well as a list of central medical facilities which can provide more information. If you are not familiar with the snakes in an area, assume they are dangerous (especially in warm climates). If you are bitten by an exotic snake in the U.S. (a pet, a zoo specimen, or a research specimen) your physician will want to contact a referral center for information on treatment and antivenin availability. Some such sources include the Antivenin Index in Tucson AZ (602-626-6016), the Oklahoma City Zoo (405-424-3344), the Rocky Mountain Poison Center (303-629-1123), or the New York City Snakebite Emergency Center (718-430-6494).

If your physician desires more information on the two antivenins used for the treatment of North American snakebites, he can contact the manufacturer:

Professional Service Wyeth-Ayerst Laboratories PO Box 8299 Philadelphia, PA 19101 (610) 688-4400, or (800) 950-5099

NONVENOMOUS SNAKES

Snakes regarded as nonvenomous are not necessarily completely safe. The saliva of many of these snakes can contain the same toxins as the venom of their more feared relatives. Some snakes such as the gopher snake lack anything resembling venom, and others such as the hognose and garter snakes have saliva which could be considered a mild venom. After all, true snake venom is just modified saliva anyway. These so-called nonvenomous snakes lack an efficient means of delivering their saliva/venom to a human victim. Yet there are recorded cases of them envenomating and even killing people. The victims tend to be people who regularly handle snakes either professionally or as a hobby.

The most common reaction to such a bite (at least in the U.S.) is the swelling, pain, and discoloration caused by hemolytic toxins. But neurotoxins have also been identified in the saliva of some of these snakes.

More information on this subject can be found in several references. One we were able to locate was, Sherman A. Minton, Jr. "Beware: Nonpoisonous Snakes," _Natural History_, 87: 56, Nov 1978.

IDENTIFICATION:

Rule One: Leave snakes alone. There is no reliable rule to distinguish which snakes are venomous and which are not. Characteristics vary greatly depending on locale and occasional individuals have atypical coloration or pattern.

Rule One, Expanded: Unless you are engaged in legitimate biological research, leave undisturbed all wildlife you encounter in the wilderness.

Coral Snakes

It is useful to be able to identify the dangerous species of snakes. However it is not always easy. Coral snakes are probably the easiest to properly identify, they are small (usually no more than about 30 inches long, sometimes up to 40 inches), thin, brightly colored, and have small heads. They can be distinguished from the nonvenomous king snake and other harmless mimics by the presence of adjacent red and yellow bands. Milk snakes, king snakes, and the other mimics have adjacent red and black bands:

Red touch yellow - kill a fellow Red touch black - venom lack.

Another mnemonic is to think of a traffic light. If red is adjacent to yellow, stop!

There are two species, the Arizona coral snake (Micruroides euryxanthus) and the eastern coral snake (Micrurus fulvius).

Bebler and King describe the Arizona coral snake (Micruroides euryxanthus) as follows:

"Description: 13-21 inches. Blunt-snouted and glossy, with alternating wide red, wide black, and narrow yellow or white rings encircling the body. Head uniformly black to angle of jaw. Scales smooth, in 15 rows. Anal plate divided.

Habitat: Rocky areas, plains to lower mountain slopes; rocky upland desert especially in arroyos and river bottoms; sea level to 5900 feet.

Range: C. Arizona to sw New Mexico south to Sinaloa, Mexico.

This snake emerges from a subterranean retreat at night, usually during or following a warm shower. When disturbed by a predator, it buries its head in its coils, raises and exposes the underside of its tail, and may evert its cloacal lining with a popping sound. Eats blind snakes, other small snakes."

Bebler and King describe the eastern coral snake (Micruroides fulvius) as follows:

"Description: 22-47 inches. Body encircled by wide red adn black rings separated by narrow yellow rings. Head uniformly black from tip of blunt snout to just behind eyes. Red rings usually spotted with black. Scales smooth and shiny in 15 rows. Anal plate divided.

Habitat: Moist, densely vegetated hammocks near ponds or streams in hardwood forests; pine flatwoods; rocky hillsides and canyons.

Range: Se. North Carolina to s. Florida and Key Largo, west to s. Texas and Mexico.

Usually seen under rotting logs or leaves or moving on surface in early morning or late afternoon. Feeds on small snakes or lizards."

Pit Vipers

Pit vipers are a bit more difficult. Of course the presence of rattles tells you that you are dealing with a venomous snake, but absence thereof gives no assurance to the contrary. Copperheads and cottonmouths have no rattles, and even rattlers sometimes loose their rattles. The presence of fangs indicates a venomous snake, but these may be folded back in the mouth and difficult to detect. The fangs may even be broken off. The easiest indicator (but one which requires practice, maybe in a zoo) is the characteristic heavy body and triangular head of the pit viper. Although some nonvenomous snakes also have these characteristics it is always best to treat a snake with caution.

In a dead snake you could look for the pit after which the pit viper is named. This will be between the eye and nostril, one on either side of the head. Another sure indicator is the scales behind the anal plate. Pit vipers have a row of single scales reaching across the underside of their bodies behind the anus while most other snakes have a double row of scales, joining in about the middle. Some references suggest checking the pupils of the snake's eyes for identification. Pit vipers will have vertical slit pupils. If the snake has round pupils it is not a pit viper. These fine characteristics are probably only useful in identifying a dead snake. One wouldn't want to pick up a live one to look at its underscales or its pupils.

One good indicator of the type of snake is the location. Snakes don't wander far from home. They tend to have a limited range and will not survive outside the conditions they prefer. Except in the case of an exotic pet you will not find them in areas far removed from their normal range. You simply won't find a Mojave rattler in Ohio or an eastern diamondback in Colorado. Several of the books listed above describe the ranges for various species, usually with maps.

Body markings are rarely sufficient for identification by the inexperienced. It takes a lot of practice to learn to distinguish between various species, some of which are quite similar externally. Furthermore, individuals of the same species can have varying shades of color, making such identification even more difficult. See the references listed above for pictures and other help in identification. If you are concerned about venomous snakes, get a book on herpetology and study it. Visit zoos and talk with specialists. You will not become an expert by reading usenet.

Again, the best rule is, leave snakes alone! Getting close enough to identify pits or scales is dangerous. You might then be able to also examine the fang marks on your body!

Copperhead

Bebler and King describe the copperhead (Agkistrodon contortrix) as follows:

"Description: 22-52 inches. Stout-bodied; copper, orange, or pink-tinged, with bold chestnut or reddish-brown crossbands constricted on midline of back. Top of head unmarked. Facial pit between eye and nostril. Scales weakly keeled, in 23-25 rows. Anal plate single.

Habitat: Wooded hillsides with rock outcrops above streams or ponds; edges of swamps and periodically flooded areas in coastal plain; near canyon springs and dense cane stands along the Rio Grande; sea level to 5000 feet.

Range: Sw. Massachsetts west to extreme se. Nebraska south to Florida panhandle and sc. and west to Texas.

It basks during the day in spring and fall, becoming nocturnal as the days grow warmer. Favored summer retreats are stonewalls, piles of debris near abandoned farms, sawdust heaps, and rotting logs, and large flat stones near streams.... In fall, copperheads return to their den site, often a rock outcrop on a hillside with a southern or eastern exposure."

Cottonmouth

Bebler and King describe the cottonmouth or water moccasin (Agkistrodon piscivorus) as follows:

"Description: 20-74 inches. A dark, heavy-bodied water snake; broad-based head is noticeably wider than neck. Olive, brown or black above; patternless or with serrated-edged dark crossbands. Wide light-bordered, dark brown cheek stripe distinct, obscure, or absent. Head flat-topped; eyes with vertical pupils (not visible from directly above as are eyes of harmless water snakes); facial pit between eye and nostril. Young strongly patterned and bear bright yellow tipped tails. Scales keeled, in 25 rows.

Habitat: Lowland swamps, lakes, rivers, bayheads, sloughs, irrigation ditches, canals, rice fields, to small clear rocky mountain streams; sea level to ca. 1500 feet.

Range: Se. Virginia south to upper Florida Keys, west to s. Illinois, s. Missouri, sc. Oklahoma and c. Texas. Isolated population in nc. Missouri.

When annoyed, the cottonmouth tends to stand its ground and may gape repeatedly at an intruder, exposing the light cotton lining of its mouth. Also called trap jaw or water moccasin. Unlike other water snakes, it swims with head well out of water. Although it may be observed basking during the day, it is more active at night. Preys on sirens, frogs, fishes, snakes, and birds."

Speckled Rattlesnake

Bebler and King describe the speckled rattlesnake (Crotalus mitchelli) as follows:

"23-52 inches. Pattern and color vary greatly; generally has a sandy, speckled appearance. Back marked with muted crossbands or hexagonal to diamond shaped blotches formed by small clusters of dots. Large scale above eye ptted, creased, or rough-edged; or rostral scale separated from preanals by row of tiny scales. Scales keeled, in 23-27 rows.

Habitat: Prefers rugged, rocky terrain, rock outcrops, deep canyons, talus, chaparral amid rock piles and boulders, rocky foothills; sea level to 8000 feet.

Range: Extreme sw. Utah, s. Nevada and s. California south into nw. Sonora and throughout Baja California.

Active during the day in spring and fall, at night in summer. Eats ground squirrels, kangaroo rats, white-footed mice, birds, and lizards."

The Three Nasties

There are three species worth extra attention if you frequent their ranges. These all have the venom to make you pay dearly should you upset them. Different sources give different assessments of the dispositions of the eastern diamondback and the Mojave rattler. Some list them as short tempered and quick to strike humans, while others say that they are not very aggressive. There is, however, general agreement that both of these plus the western diamondback pack a nasty wallop if they do bite. It is useful to know if you are in their range and be able to recognize them in order to get proper treatment should someone get bitten.

While a major distinguishing feature of both diamondbacks (at least in the adult snake) is their size, this may be an unreliable indicator. Even experts have a difficult time estimating the size of a live snake, a problem compounded when a novice unexpectedly encounters one. Size estimates are typically quite generous to say the least. If the snake is dead and can be measured you can get useful information. Most of the danger of a diamondback comes from its size and the quantity of venom anyway. It won't make much difference if it is a juvenile diamondback or an adult of some other species (except the Mojave).

Various authors do not agree on which is the most dangerous. Some claim this honor for the eastern diamondback, and some for the western version. The eastern species is larger and has more venom but its western cousin has a more potent venom. The Mojave rattlesnake is also a good candidate for the most dangerous snake in the U.S Its very potent venom with the delayed action make it a real danger. Not that it matters much, one would not want to be bitten by any of the three.

Eastern Diamondback (Crotalus adamanteus)

According to Conant's Reptiles & Amphibians of Eastern/Central U.S. , "33-72 inches; record 96 inches [Bebler and King give the range as 36 to 96 inches]. An ominously impressive snake to meet in the field. The diamonds, dark brown or black in color, are strongly outlined by a row of cream-colored or yellowish scales. Ground color olive, brown, or almost black. Pattern and colors vivid in freshly shed specimens; dull and quite dark in those preparing to shed. Only rattler within its range with 2 prominent light lines on face and vertical light lines on snout.

At home in the palmetto flatwoods and dry pinelands of the South. Occasionally ventures into salt water, swimming to outlying Keys off the Florida coast. Some snakes will permit close approach without making a sound, whereas others, completely concealed in palmettos or other vegetation, will rattle when dogs or persons are 20 or 30 feet away. Many stand their ground, but when hard pressed they back away, rattling vigorously but still facing the intruder. Frequently they take refuge in burrows of gopher tortoises, in holes beneath stumps, etc. Rabbits, rodents, and birds are eaten.

Range: Coastal lowlands from se. N. Carolina to extr. E. Louisiana; all of Florida, including the Keys."

According to Behler and King's Audubon herpetology guide:

"Our largest rattler. Heavy-bodied with large head sharply distinct >from neck. Back patterned with dark diamonds with light centers and prominently bordered by a row of cream to yellow scales. Prominent light diagonal lines on side of head. Vertical light lines on snout. Scales keeled, in 27-29 rows."

Range and habitat same as above, but get this,

"Give it a wide berth; most dangerous snake in North America! Venom highly destructive to blood tissue. Stumpholes, gopher tortoise burrows, and dense patches of saw palmetto often serve as retreats. Their numbers have been substantially reduced by extensive land development and by rattlesnake hunters. Eats rabbits, squirrels, birds"

The following descriptions of the Mojave and western diamondback are taken >from Stebbins's book:

Western Diamondback Rattlesnake (Crotalus atrox)

"Identification: 30-89 inches. The largest western rattlesnake. Above: gray, brown or pink with brown diamond or hexagonal blotches on the back and fainter smaller blotches on the sides. Markings often indefinite and peppered with small dark spots, giving an overall speckled or dusty appearance. Tail set off from the rest of the body by broad black and white rings, about equal in width; hence sometimes called the "coontail" rattler. A light diagonal stripe behind the eye intersects the upper lip well in front of the corner of the mouth. Young: 9-14 inches, markings more distinct than in adult.

Frequents a variety of habitats in arid and semiarid regions from the plains into the mountains - desert, grassland, brushland, woodland, rank growth of river bottoms, rocky canyons, and lower mountain slopes. Crepuscular and nocturnal, but also abroad in daytime. Perhaps the most dangerous North American serpent, often holding ground and boldly defending itself when disturbed. Live-bearing.

Range: SE California to E Oklahoma and E Texas, south to Isthmus of Tehauantepec. Old records for central Arkansas and Trinidad, Las Animas Co., Colorado. Sea level to 7000 feet."

Mojave Rattlesnake (Crotalus scutulatus)

"Identification: 24-51 inches. Well-defined, light-edged dark gray to brown diamonds, ovals, hexagons down middle of back; light scales of pattern usually entirely light-colored. Ground color greenish gray, olive green, brownish, or yellowish. A white to yellowish stripe extends from behind the eye to a point behind the corner of the mouth except at extreme southern end of range. Tail with contrasting light and dark rings; dark rings narrower than light rings. Enlarged scales on snout and between the supraoculars.

Chiefly inhabits upland desert and lower mountain slopes, but ranges to about sea level near the mouth of the Colorado river and to high elevations in the Sierra Madre Occidental. Habitats vary--barren desert, grassland, open juniper woodland, and scrubland. This rattler seems to be most common in areas of scattered scrubby growth such as creosote bush and mesquite. Not common in broken rocky terrain or where vegetation is dense. Eats kangaroo rats and other rodents; and probably other reptiles. AN EXTREMELY DANGEROUS SNAKE; EXCITABLE AND WITH HIGHLY POTENT VENOM.

Range--S. Nevada to Puebla, near southern edge of Mexican Plateau; western edge of Mojave Desert, Calif. to extreme w. Tex. From near sea level to around 8300 feet."

In case of a bite it may be important to distinguish between the diamondback and the Mojave. The ranges of the species overlap and if you are in the area of overlap you may not know which was the culprit. The distinction is important in the case of a bite with little or no local reaction. In a diamondback bite, lack of reaction within 4 to 6 hours indicates that envenomation did not occur. However if a Mojave was the culprit no such assumption can be made and systemic reaction may occur 12-16 hours later. The two species are very similar in appearance. The relative width of light and dark tail bands may be the best way to distinguish between the two. If uncertain, assume the snake was a Mojave and treat accordingly.

Other similar snakes include the speckled and western rattlesnakes (there are several sub-species of the speckled). Their ranges also overlap those of the Mojave and diamondback.

Mojave venom can be up to 20 times the as potent as diamondback venom, although its quantity will typically be about 1/6 that of a diamondback. Specific references to Mojave and its unusual venom are:

_The Venomous Reptiles of Arizona_, (Arizona Game and Fish) pp 55-56.

_Journal of Herpetology_, Vol 23 no. 2, pp 131ff (1989)

_Herpetologica_, vol 47 No. 1 (March 1992) pp 54ff

One other note on the Mojave: There is a central Arizona version which can be considered a subspecies. The principal difference between it and its more widely distributed cousins is that its venom is very similar to diamondback venom. This therefore makes it less dangerous than other Mojaves. There are also hybrids which have components from both venom types. Hybrids present the particular danger of a local reaction which may fool victims and medical personnel into believing the culprit was a some other rattler until the systemic reaction due to neurotoxin sets in later. Even experts can't tell the difference between different varieties of Mojave except by analyzing the venom.

There are a number of other species of rattlesnakes in North America. Information on their identification can by found in the Peterson or Audubon field guides.

EPIDEMIOLOGY: THE RISK OF SNAKEBITE

Your risk of being bitten be a snake is small, and so too is your risk of dying if bitten. Findlay E. Russell writes in Ann Rev Med 1980, 31:247-59.,

"Although there are an estimated 45,000 bites by all snakes in the United States each year, only about 6680 persons are treated for snake venom poisoning. However, it can be expected that at least 1000 additional bites by venomous snakes occur each year and that they are either not treated or go unreported. During the past five years, the number of deaths from snakebite in the United States has ranged between 9 and 14. Most of the deaths occurred in children, in the elderly, in untreated, mistreated, or undertreated cases, in cases complicated by other serious disease states, or in members of religious sects who handle serpents as part of their worship exercises and refuse medical treatment. Almost all reported deaths have been attributed to rattlesnakes."

In a second article (When a snake strikes, Emergency Medicine, 1990, 22:21-43.), Russell states,

"25% of all pit viper bites do not result in envenomation and another 15% are so trivial, they require only local cleansing and tetanus prophylaxis."

Kurecki and Brownlee write in The Journal of Family Practice 1987 25(4):386-392,

"Approximately 75 percent of all snakebites occur in people aged between 19 and 30 years, 1 percent to 2 percent occur in women, and less than 1 percent occur in blacks. Approximately 40 percent of all snakebites occur in people who are handling or playing with snakes, and 40 percent of all people bitten had a blood alcohol level of greater than 0.1 percent. Sixty-five percent of snakebites occur on the hand or fingers, 24 percent on the foot or ankle, and 11 percent elsewhere. One case was reported of a snakebite on the glans penis."

So it seems that getting drunk and messing about snakes is a big cause of getting bitten. It also seems that male yahooism is a precursor to snake toxin poisoning. Women are unlikely to get themselves bitten, and if they do get bitten, it is unlikely that they got that way by doing something stupid. Here is some more interesting data on that point from Curry et al. in Annals of Emergency Medicine 1989 18(6):658-63:

"We reviewed medical records of 85 consecutive snakebite victims cared for at a single medical center to determine legitimacy of snakebites. A bite was considered illegitimate if, before being bitten, the victim recognized an encounter with a snake but did not attempt to move away >from the snake. A legitimate bite was said to have occurred if a person was bitten before an encounter with a snake was recognized or was bitten while attempting to move away from a snake. The study group was made up of 75 male (87.2%) and 11 female (12.8%) victims. Seventy-four percent were 18 to 50 years old, and 15% had been bitten previously. Only 43.4% of all bites were considered legitimate, and pet (captive) snakes accounted for almost one third of all illegitimate bites. The ingestion of alcoholic beverages was associated with 56.5% of illegitimate bites versus 16.7% of legitimate bites. While 74.4% of bites were to upper extremities, only 27% of upper extremity bites were legitimate. All bites to the lower extremities were legitimate. Of 14 individuals bitten by pet snakes, all were men and 64.3% were under the influence of alcohol at the time of the bite. In our patient population, the data suggest that a 16% reduction in rattlesnake bites would result if rattlesnakes were not kept as pets, and more than one half of all rattlesnake bites would be eliminated if persons simply would attempt to move away from a rattlesnake after an encounter is recognized".

It is worth noting that only one woman in Curry et al.'s study group received an illegitimate bite.

PREVENTION:

Obviously the best prevention is to avoid getting bitten. It helps that humans are not the natural prey of any venomous snake. We are a bit large for them to swallow whole and they have no means of chopping us up into bite size pieces. Nearly all snakebites in humans are the result of a snake defending itself when it feels threatened. In general snakes are shy and will simply leave if you give them a chance. Remember, MOST BITES HAPPEN TO PEOPLE WHO FAIL TO MOVE AWAY FROM SNAKES ONCE THEY SEE THEM. So don't pick up, torment or otherwise mess about with venomous snakes. In light of the Curry data, avoiding alcohol or drug intoxication in snake country would be a good idea. Many, many bites are associated with intoxication.

Another basic rule is to be sure the snake knows you are coming. Walk heavily; they may sense ground vibrations better than sound. If they sense your presence they will almost always leave before you even know they are there. (This may not apply in other parts of the world. Some of the more potent snakes may protect their territory as well as their bodies.)

If you do unexpectedly confront a snake, stay calm, back away and do nothing to threaten it. (This assumes of course that the surprise didn't cause you to jump well beyond the snake's reach. It's amazing what the human body can do in such circumstances.)

Don't run around barefoot in snake country, especially after dark. During warm weather snakes will be most active at night and will defend themselves if stepped on or if you walk too close and they sense danger. MFM lists going barefoot and gathering firewood after dark as two common activities leading to snakebite. Going barefoot not only exposes your feet, it also makes your footsteps quieter so you are less likely to be felt. You could invest in a pair of snakeproof boots but any high top leather boot is probably adequate. Long pants will also help since the snake has difficulty biting through a fold of your clothing.

Remember that snakes like to hide under rocks, logs, and brush to protect themselves from sun or cold. Be very careful in snake country about moving such objects or reaching into anywhere a snake might hide. A snake might well perceive your actions as aggressive and defend itself. There may be more than one snake in the same place and, taken by surprise, they may strike without warning. Furthermore snakes will be more likely to bite your unprotected hand rather than a leg or foot protected by clothing. Remember, according to Curry, 74.4% of bites are to the upper extremities.

Rock climbers should be careful in snake country. Snakes like to sun themselves on ledges and it can be a real eye-opener to poke your head up and stare one in the eyes. And while you won't find them in the middle of a 5.12 face you may find them in cracks and on ledges. Remember, the mice and rats which inhabit many cliff areas mean food to a snake and so attract them. Small rock outcrops scattered around on foothills are prime snake territory, so be particularly careful when you go bouldering.

Be careful entering old buildings such as mining cabins. They make nice homes for snakes.

Obviously you should not handle or tease poisonous snakes. Less obvious is the danger of handling them when they are dead. A reflex strike from a dead snake can be just as dangerous as a bite by a live one. This warning also applies to detached heads of dead snakes.

The degree of protection afforded by responsible behavior and protective clothing (boots, long pants) is remarkable. Iserson in JAMA reported on the incidence of snakebite in three groups of experienced outdoor workers. Members of the Southern Arizona Rescue Association worked 115,000 person-hours in the field without a snakebite. The personnel at the La Selva Biological Station in Costa Rica (habitat of the fer de lance, a venomous crotalid) worked for 350,000 person-hours in the field without a bite. The graduate students at the Organization for Tropical Studies, also in Costa Rica, worked 660,000 person-hours in the field with only one bite.

Russell has something to say about this as well, "Few bites occur in backpackers, serious hunters, or fishermen...In the past 20 years, there has been only one backpacker in the Sierras of California, who I know of, who was bitten by a rattlesnake, and this happened when he was changing a tire at the end of his hike."

ENVENOMATION

In the article -When a snake strikes- ( Emergency Medicine, 1990, 22:21-43.), Russell states,

"25% of all pit viper bites do not result in envenomation and another 15% are so trivial, they require only local cleansing and tetanus prophylaxis."

Kurecki and Brownlee report that,

"Coral snakes lack retractable fangs. Instead they rely on fixed retroverted teeth to gnaw into the flesh of their prey. They must penetrate the skin long enough for their venom to be deposited around their teeth and into the wound. This envenomation mechanism is much less efficient than that of pit vipers; consequently, 50 percent of coral snakebites are dry."

The severity of the reaction to a snakebite depends on the degree of envenomation. Downey, Omer and Moneim describe a system whereby,

"grade 0 means there is no envenomation and indicates swelling and erythema [redness] around the fang marks of 40 cm with systemic signs, and grade 4 indicates severe systemic signs including coma and shock."

In their series of 36 patients, there were no grade 0 bites, five grade 1 bites, 27 grade 2 bites, three grade 3 bites, and no grade 4 bites. So, this study suggests that most victims of snakebite will have a moderate local reaction with mild systemic signs. Life-threatening consequences such as shock are unlikely.

SIGNS AND SYMPTOMS

Gold and Wingert describe the signs and symptoms associated with an envenomated snakebite:

"Panic is the most common reaction to a snakebite. As a result, the victim may become emotionally unstable with thoughts of imminent death, or conversely, the victim may enter a state of extreme lethargy and withdrawal. Fear may cause such symptoms as nausea, vomiting, diarrhea, dizziness, fainting, tachycardia [rapid hert rate], and cold, clammy skin. It is important that autonomic [flight or fight] reactions not be mistaken for systemic symptoms and signs resulting from a bite. Such an error could lead to unwarranted treatment. The primary local symptoms and signs of most pit viper envenomations are fang punctures, pain, edema [swelling], and erythema [redness] or ecchymoses [bruising] of the bite site and adjacent tissues. There may be one or more puncture wounds, depending on the number of fangs the snake had, the accuracy of the strike, and the number of strikes inflicted. Superficial lacerations produced by fangs do not usually result in envenomation, because the discharge orifice of the fang lies slightly proximal to the tip. Teeth marks, other than fang punctures, may or may not be present. There may be moderate pain in or around the local bite site in about 90% of pit viper envenomations. Exceptions are the bites from the Mojave rattlesnake and the speckled rattlesnake, which cause little or no pain. ...The pain, which had been described as sharp and burning in character, usually develops within 5 minutes after inoculation [injection] of the venom. Edema and erythema or ecchymoses are characteristic of pit viper envenomation and usually occur within 30 minutes of the bite, evolving both proximally and distally as the venom spreads. If edema and erythema have not manifested within 8 hours after a snakebite, it is generally safe to assume that the patient has not been envenomated. Frequently, there are signs of lymphangitis [inflammation of the lymphatic system] with tender regional lymphadenopathy [disease of the lymph nodes]. Frequent systemic manifestations after bites by eastern, timber, and western diamondback rattlesnakes are perioral parathesias extending to the face and scalp with tingling of the fingertips and toes. According to Russell, the most frequent diagnostic findings after bites by the Pacific rattlesnake are complaints of a 'minty,' 'rubbery', or 'metallic' taste in the mouth and 'tingling of the lips.' ...Skeletal muscle fasciculations [tics, spasms] in the bitten area, face, neck, and back may occasionally become generalized."

Russell describes the effects of coral snake envenomation,

"The bite is usually associated with some pain, although it may be minor and transitory in nature. Swelling is either absent or very minor. Parathesia [abnormal sensation] is sometimes noted around the bitten area, and some weakness of the part may become evident within several hours of the poisoning. The patient may complain of drowsiness, apprehension, and weakness. Muscular incoordination may develop, and muscle fasciculations [tics, spasms] and tremor of the tongue may be seen. Increased salivation and difficulties in swallowing and phonation [speech pronunciation], as well as visual disturbances, respiratory distress and failure, a bulbar [brainstem] type of paralysis, convulsions, and shock may develop."

FIELD TREATMENT

Now, what about treatment? What do you do if you or a member of your party becomes one of the unfortunate few to actually get bitten?

The first thing is to remain calm. Remember, snakebite is not usually deadly in spite of all the hype about it. Even without treatment you will almost certainly recover. If you can identify the snake do so. If it is dead, take it with you to the hospital in a safe container to be sure of getting the right antivenin. Do not risk more bites in order to kill it. Remember the first rule of rescue: Do not create any more victims or risk further injury to the current victim.

Trained first aiders base their treatment of patients on a protocol: a simplified set of procedures. We describe below two different protocols for the treatment of snakebite.

A Wilderness Protocol

The following treatment protocol is provided by Jeff Isaac and Peter Goth in The Outward Bound Wilderness First Aid Handbook, Lyons and Burford, 1991. This same protocol is taught to Wilderness First Responders and Wilderness Emergency Medical Technicians certified by the National Association for Search and Rescue:

Expect swelling. Remove constricting items such as rings, bracelets, and clothing from the bitten extremity.

Do not delay. Immediately following the bite of a snake thought to be poisonous, evacuation should be started. It can always be slowed down or cancelled if it becomes obvious that envenomation did not occur, or the snake is not poisonous.

Boy, this is an awfully simple protocol! Doesn't seem to leave much for the first aider with an anxious desire to do something to occupy himself with. Well, at least they suggest you could make a nice splint.

Actually, a first responder, EMT, or other trained person would know that there would be a number of other steps to field treatment that were not explicitly stated in this protocol. He might want to evaluate the patient's ABC's, take a history, record the time and events associated with the bite, thoroughly evaluate and document the chief complaint, conduct a physical exam, develop a plan for treatment and evacuation, and begin recording a regular series of vitals. He would also record all changes in signs and symptoms with the time that they occurred. None of these activities, however, would be allowed to interfere with moving the patient to definitive care (antivenin). Folks with a lesser set of skills would want to do what they could.

As part of the history, the first aider should ask whether the patient has (a) asthma, hay fever, hives, or other allergies, (b) allergic reactions upon exposure to horses, or (c) prior injections of horse serum. The two antivenins in use in North America are both raised in horses, and patients with allergies to horses or horse serum can exhibit adverse reactions (see the discussion of hospital care below). The first aider should also ask whether the patient has been bitten by venomous snakes in the past, and, if so, whether he received antivenin and what the reaction to it was. Finally he should inquire when the patient last received a tetanus booster.

Don't forget to wear rubber gloves when handling patients, for your safety and theirs. Playtex dishwashing gloves are a good choice for wilderness use, but disposable latex surgeon's gloves work fine too. If it is necessary to assist a patient's respirations, use a pocket mask.

If the group is sufficiently large, it might be best to send two runners ahead to summon aid. At the very least, it would be nice to have an ambulance waiting at the trailhead. There is a maxim in wilderness first aid: move the patient to treatment, and move treatment to the patient. The best evacuation strategies will cause both of these things to happen simultaneously.

If it is going to be more than 1 hour to hospital treatment, you may choose to rinse and disinfect the wound. More on how to do this follows below.

An Urban Protocol

The following more elaborate protocol is taken from the -Emergency Medical Technician 1A Protocols- for Fresno County in California. The protocol is designed for EMS personnel in an urban setting:

"I. Priorities

A. Assessment. Vital signs, site of wound, measure the circumference of the extremity, mark and record, note extent of swelling and record time.

B. Keep patient quiet and reassure.

If snake is available and dead, place in a secure container and bring to the emergency department. Use caution. Do not engage in a search for the snake.

C. Code 3 transport [lights, siren] is indicated for patients in shock, uncontrolled bleeding or with concurrent severe injuries.

Code 2 [normal driving, no lights, siren] transport for patients with stable vital signs without immediate life threat.

[Folks that choose to transport a snakebite victim by personal auto to a hospital should note these instructions. Life-threatening systemic reactions are rare with snakebite, so safe driving within the speed limit is the way to go. Given the amount of panic associated with snakebite, it might be best to allow an ambulance transport the patient, and thereby reduce the risk of an automobile accident]

II. Treatment

A. Oxygen 6 L/min by nasal cannula. [If not trained in O2 delivery, then don't do this, RP]

B. Apply elastic bandage 2-5 inches proximal to the bite if transport >10 minutes. Do not apply to hand or foot. No other tourniquet should be used. This should be applied to a tightness which allows you to slip one finger underneath.

C. Immobilize affected extremity at or slightly below the level of the heart.

D. Keep patient at rest.

E. Mark area of swelling with pen line and record time.

III. Further Evaluation

A. If the snake was an exotic pet or zoo animal (e.g. coral snake, cobra, krait), neurotoxic symptoms may precede local reactions. Observe for mental status change, respiratory depression, convulsions, or paralysis.

B. Do not allow any person to apply ice or cooling. Do not allow incision of the wound.

C. The best course of action following envenomation is rapid transport to the emergency department where intravenous antivenin can be administered.

D. Reassure patient. Mortality from snakebite is rare, particularly in young, healthy patients."

Once again, this protocol does not mention all the neat things that trained EMS folks do for every patient. See the discussion following the wilderness protocol above.

So two quite different approaches. One, designed for the wilderness, allows the patient to walk toward treatment. The other, designed for an urban setting with ready access to the EMS system, had the patient remain at rest, with the wound immobilized at or below the level of the heart.

Which to follow? It is up to you to decide. But, a few comments that may help are listed below.

FIELD TREATMENT: AREAS OF DISAGREEMENT

Keep the Patient Immobilized, Wound at or below Level of Heart

We described one field treatment procedure, designed for the wilderness, that allows the patient to walk toward treatment. The other, designed for an urban setting with ready access to the EMS system, required the patient remain at rest, with the wound immobilized at or below the level of the heart.

In the urban setting, nothing is to be lost by the "keep patient at rest" approach. But in deciding what to do where help is an hour or more away, here are a few thoughts: (1) Antivenin is the definitive therapy for snakebite. Kurecki and Brownlee say,

"Remember, based on the current literature, the single most effective course of action following a pit viper bite is rapid transport to an emergency department because the intravenous administration of antivenin remains the definitive and only therapy of proven value. The best first aid is a set of car keys."

(2) The systemic reactions to snakebite are often delayed, giving a window that can be used to have the patient aid in his own rescue. Here is what Gold and Wingert say,

"Several hours usually elapse after the bite before the severe toxic effects of the venom ensue. According to Parrish [Am J Med Sci, 1963, 245:129-41.], of 138 people who died from snakebites over a 10-year period, only 4% died within 1 hour and only 17% died within 6 hours. The majority (64%) died 6 to 48 hours after the bite. Victims of snakebites who received medical attention within the first 2 hours after being bitten have an excellent chance of survival."

(3) There is little evidence in the literature that activity can worsen the outcome associated with snakebite (Keith Conover, personal communication). (4) There is little evidence in the literature that keeping the bitten extremity at or below the level of the heart has an effect on the outcome due to snakebite (Keith Conover, personal communication). (5) Evacuating a patient from the wilderness who is kept at rest necessitates a BIG rescue effort. It poses a potential risk to the rescuers themselves. (6) Waiting for a big rescue to be organized and executed could delay getting the patient to antivenin. (7) There is a tradition of self-rescue in mountaineering and other backcountry sports.

Constriction Bands

Most authorities agree that a constriction band may be of benefit. Here is what Gold and Wingert say,

"If the anticipated delay in treatment is several hours and evaluation is done within 5 minutes of the snakebite, a constriction band may be applied about 5 cm above the bite or just proximal to the closest joint. The band should be tight enough to occlude lymphatic flow, yet loose enough so as not to impede arterial or venous circulation. The pulses distal to the bite should be palpated frequently to ascertain flow, and the band should be loosened, but not removed, if too tight."

A constriction band is not a tourniquet!! If you are not confident that you can assess vascular function in an extremity, then you should not carry out this procedure. Swelling will cause this band to become tighter. It is going to require constant monitoring, and the band will have to be loosened as necessary. Forget to monitor or fail to properly assess vascular function, and you could cause permanent disability. Do not apply a constriction band directly to a digit, foot, or hand.

Wound Cleaning

The two protocols listed in the section on treatment do not mention cleaning the bite wound. However, if it is going to be an hour or two to get the patient to the hospital, you might consider cleaning the wound. Here is what Wilkinson in MFM says,

"The skin should be washed and swabbed with an antiseptic. (Such obvious measures to reduce contamination are frequently neglected, resulting in infections which are responsible for a large part of the residual damage >from snake bites. The bacteria that cause tetanus and gas gangrene have both been isolated from the mouths of poisonous snakes.)"

Providone-iodine solution (10% in water, trade name Betadine) diluted 1:10 in clean water to make a 1% final concentration makes a fine antiseptic solution.

Extractor Devices

The Sawyer's Extractor is a spring-loaded piston that attaches to any of several sizes of cylindrical vacuum chambers. Although neither of the two treatment protocols above suggest its use, many authorities suggest it might be useful. Gold and Wingert state,

"A number of field studies have shown that a Sawyer's Extractor (Sawyer's Products, Safety Harbor, Fla), which provides about one atmosphere of negative pressure, is effective in extracting venom from the bite site, provided it is applied within the first 5 minutes after the victim is bitten. Suction should then be continued during the first 30 to 60 minutes after a bite."

FIELD TREATMENT: 'THERAPIES' TO AVOID

Incisions

Don't use them. Gold and Wingert say,

"The use of ice, tourniquets, incision and suction, and electric shock therapy as part of emergency field therapy should be strictly discouraged."

Similarly, Kurecki and Brownlee say,

"The complications of incision and suction, especially in the hands of the untrained person who does not know the anatomy of the body, include damage to underlying structures, vascular compromise to the extremity, and infection. The blade in a snakebite kit is of sufficient size and quality to damage underlying blood vessels, nerves, tendons, and muscles. It has never been shown in a clinical trial that incision and suction improves motality, although morbidity through improper incision is increased."

If you have one of those little green snakebite kits, you might as well discard it. The little sharp knives are dangerous to use, and the suction developed by the little rubber cups is insufficient to be of benefit. See the discussion of extractor devices above. While you are discarding dangerous implements from your first aid kit, you might as well throw out those ammonia inhalants and salt tablets too.

Oral Suction

Do not try to suck venom from a wound by mouth. You might cause a severe infection in the wound due to bacteria from your mouth. And, you do not want to take a risk of absorbing venom through a cut, or a sore, or bleeding gums. Finally, given the risk of blood-borne pathogens such as hepatitis and AIDS, putting your mouth to a wound on another person is an unwise practice.

It is worth repeating here: use gloves when handling patients, particularly if they have a wound. Use a pocket mask if you assist respirations.

Tourniquets

Don't use them. Gold and Wingert say,

"The use of ice, tourniquets, incision and suction, and electric shock therapy as part of emergency field therapy should be strictly discouraged. Dart [Dart, R. and Russell, F.E.-Animal Poisoning-. in Principles of Critical Care. Hall, Schmidt and Wood (eds). New York, McGraw-Hill, 1992, 2163-71.] studied 94 snakebite victims at University of Arizona. Of 18 patients who had used a tourniquet, problems developed in 8; 6 had tissue loss, and 2 had permanent disability resulting directly from the use of a tourniquet."

See the discussion above of constriction bands.

Compression Wraps

In North America, don't use them. For the same reasons as tourniquets. In Australia, the bites of the elapids they have there have a greater potential for fatal outcome. Physicians there have used compression wraps with success. Inquire about local procedures when you travel.

Electrical shock

Don't use it. Electrical shock was tried experimentally for a time, and several portable devices were developed. These still turn up in use from time to time at rattlesnake roundups and the like. No research data ever emerged that supported the use of electric shock.

Ice or Cold Packs

Don't use them. Here is what James Wilkerson says in Medicine for Mountaineering (3rd Ed):

"Packing an extremity bitten by a poisonous snake in ice or snow probably would not be possible in most wilderness situations because snakes do not inhabit areas where ice and snow are available. However, such therapy for poisonous snake bite has been recommended in the past. The basis of such therapy was the assumption that the active components of snake venom were enzymes, the activity of which would be reduced by cooling. However, subsequent studies have determined that most of the toxins in snake venom are peptides, which are not inactivated by cooling. Additionally, since snakes are cold blooded animals, their enzymes remain active at temperatures at which a warm blooded human's defenses are immobilized. Furthermore, some enzymes are driven deeper into warmer tissues by cooling the skin.

Few physicians advocate local cold therapy; even fewer would deny that its use outside the hospital as a technique for emergency care has caused the loss of many limbs."

Cold causes increased local tissue destruction when applied to North American pit viper bites. See the following references:

Sullivan JB Jr, Wingert WA. Reptile Bites. in Auerbach PS, Geehr EC, Ed Management of wilderness and environmental emergencies. 2nd ed. St. Louis: C.V. Mosby Co., 1989:479-511.

Gill KA Jr. The evaluation of cryotherapy in the treatment of snake envenomation. So Med J 1968;63:552-6.

Durand LS, Rodeheaver GT, Edlich RF. Poisoning by pit vipers. W Va Med J 1982;78(7):162-7.

HOSPITAL CARE

The definitive care in the hospital will be i.v. administration of antivenin. The number of vials of antivenin administered will depend on the severity of the envenomation. Snakebite patients who were not envenomated or who were bitten by a copperhead may not receive antivenin.

There are two antivenins in common use in the United States. Both are manufactured by Wyeth-Ayerst Laboratories and are created by injecting venom into horses, and then collecting the resulting immune serum.

Antivenin (Crotalidae) Polyvalent is developed by injecting a mixture of the venoms of eastern diamondback, western diamondback, cascabel (tropical rattlesnake), and fer-de-lance into horses. This antivenin is used for treating the effects of bites from crotalids native to North, Central, and South America, as well as Japan and Korea.

Antivenin (Micrurus fulvius) is developed by injecting the venom of the eastern coral snake into horses. It is used for treating the bites of both eastern and Arizona coral snakes.

There is a potential for a dangerous reaction to antivenin in patients who have an allergy to horses or horse serum. For this reason antivenin is only administered in a hospital, and the physician makes every effort to rule out allergy before he administers the antivenin. The adverse consequences of antivenin administration in patients allergic to horses include shock, anaphylaxis, and serum sickness.

If your physician desires more information on the two antivenins used for the treatment of North American snakebites, he can contact the manufacturer:

Professional Services Wyeth-Ayerst Laboratories PO Box 8299 Philadelphia, PA 19101 (610) 688-4400, or (800) 950-5099

Also while in the hospital, the bite wound will be cleaned, and the patient will subjected a battery of laboratory tests. Any of a variety of drugs and i.v. fluids may be administered including D5W, saline, plasma, blood products, antiphylaxis agents, sedatives, analgesics, and antibiotics.

The patient may receive a tetanus booster. Continuing wound care will include cleansing, and may include surgical treatment of the wound area. If movement or strength of an extremity is compromised, patients may receive physical therapy.

COMPLICATIONS

Downey, Omer and Moneim reported 68 complications in their study group of 36 snakebite victims. The most frequent was compartment syndrome (increased pressure within a closed body compartment, interfering with function), which occurred in 25 patients. All 25 received surgical intervention (fasciotomy). The breakdown of all complications was as follows:

Compartment syndrome 25 Carpal tunnel syndrome 1 Reduced range of motion 9 Reduced sensation 4 Thrombosed digital artery 1 Wound infection 4 Tendon necrosis 1 Digit amputation 1 Abnormal coagulation studies 7 Thrombocytopenia 4 Postoperative anemia 4 Serum sickness 4 Hypotension 3 Pleural effusion 1

The length of hospital stay ranged from 1 to 31 days; the median was 5 days.

GLOSSARY

The definitions below are simplified; you would find more subtle and complex definitions in dictionaries of biology or medicine.

anemia Abnormally low number of red blood cells in the blood.

antivenin Antiserum used to treat the victims of snakebite. Manufactured by hyperimmunizing horses with snake venom.

autonomic reaction Flight or fight reaction.

bulbar Pertaining to the brainstem. Bulbar functions include the maintenance of heart rate and breathing.

carpal tunnel syndrome

coagulation Clotting of blood.

compartment syndrome The effect of swelling within a closed body space.

crepuscular Active at twilight.

crotalid A member of the snake subfamily Crotalinae, the pit vipers.

distal Toward the periphery of the body and away from the central axis. Opposite: proximal.

ecchymoses Bruising.

edema Swelling

elapid A member of the snake family Elapidae, which includes the coral snakes and other venomous snakes with immovable hollow fangs at the front of the mouth.

envenomation Injection of venom.

erythema Redness.

fasciculations Tics or spasms.

hemolytic toxin Poison which attacks the blood.

hybrid The offspring deriving from the mating of members of two different species.

hypotension Low blood pressure.

inoculation Injection.

lymphadenopathy Disease of the lymph nodes.

lymphangitis Inflammation of the lymph nodes.

nasal cannula A hoop of plactic tubing with two open nozzles which insert into the nostrils. Used for the delivery of oxygen.

necrosis Death of tissue.

neurotoxin Poison which attacks nervous tissue.

parathesias Abnormal sensations.

perioral Around the mouth.

phonation Speech pronunciation.

pleural effusion Escape of fluid into the space outside the lungs and inside the chest wall.

prophylaxis Prevention.

protocol Procedure or rules of action.

proximal In the direction of the central axis of the body. Opposite: Distal.

serum The watery component of blood.

serum sickness An allergic reaction after administration of a foreign serum.

shock The life-threatening systemic reaction to inadequate perfusion of the tissue with oxygenated blood. Not the same as an autonomic reaction.

tachycardia Fast heart rate.

tetanus An infectious disease due to the toxin of tetanus bacteria growing at the site of an injury.

thombosed Containing a blood clot (a thrombosis).

thrombocytopenia Abnormal decrease in the number of blood platelets.

toxin A poison. Syn: venom.

venom A poisonous secretion of certain plants and animals. Syn: toxin.

DISCLAIMER

This FAQ does not constitute professional medical advice. It is merely a compilation of information available in the literature. If you need professional medical advice on snakebite or any other topic, consult your physician.

----------------------------------------------------------- (Written by Hal Lillywhite. Last update: 14 February 1994) (Revised by Richard Penny. Last update: 9 August 1995)

>From "Last Chance to See"

"Oh, you don't have to worry about identifying Tasmanian snakes. They're all poisonous." ... "So what do we do if we get bitten by something deadly, then?" I asked. He blinked at me as if I were stupid 'Well what do you think you do?' he said. 'You die of course. That's what deadly means.' 'But what about cutting open the wound and sucking out the poison?' I asked. 'Rather you than me,' he said. 'I wouldn't want a mouthful of poison. All those blood vessels beneath the tongue are very close to the surface so the poison goes straight into the bloodstream. That's assuming you get much of the poison out, which you probably couldn't. And in a place like Komodo it means you'd probably quickly have a seriously infected wound to contend with as well as a leg full of poison. Septicaemia, gangrene, you name it. It'll kill you.' 'What about a tourniquet?' 'Fine if you don't mind having your leg off afterwards. You'd have to because it would be dead. And if you can find anyone in that part of Indonesia who you'd trust to take your leg off then you are a braver man than me. No, I'll tell you: the only thing you can do is apply a pressure bandage direct to the wound and wrap up the whole leg up tightly, but not too tightly. Slow the blood flow but don't cut it off or you'll lose the leg. Keep the leg or whatever bit of you it is you've been bitten in, lower than your heart and your head. Keep very, very still, breathe slowly and get to a doctor immediately. If you're in Komodo that mean a couple of days, by which time you'll be well dead. 'The only answer, and I mean this quite seriously, is don't get bitten. There is no reason why you should. ... No, the things you really need to worry about are the marine creatures.' 'What?' 'Scorpion fish, stonefish, sea snakes. Much more poisonous than anything on land. Get stung by a stone fish and the pain alone can kill you. People drown themselves just to stop the pain.' ... 'Is there anything you do like?' 'Hydroponics.' 'No I mean are there any venomous creature you're particularly fond of?' He looked out of the window for a moment. 'There was,' he said, 'but she left me.' --Douglas Adams, Chapter 2 "Here Be Chickens," in Last Chance to See

An older copy of this file (check last modified dates) can be found at: ftp: sunSITE.unc.edu: pub/academic/agriculture/sustainable_agriculture/health-safety-FAQs

MEDICINE FOR MOUNTAINEERING. Forth Edition. Edited by James. A. Wilkerson. MD. The Mountaineers. ISBN: 0-89886-331-7