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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:

"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
cancelled 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."

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