Saturday, August 25, 2007


Ajolote: Mexican reptile of the genus Bipes. It and several other tropical burrowing species are placed in the Amphisbaenia, a group separate from lizards and snakes among the Squamata. Unlike the others, however, which have no legs, it has a pair of short but well-developed front legs. In line with its burrowing habits, the skull is very solid, the eyes small, and external ears absent.

How Snakes Survive Starvation

Science Daily — Starving snakes employ novel survival strategies not seen before in vertebrates, according to research conducted by a University of Arkansas biologist.
“These animals take energy reduction to a whole new level,” said Marshall McCue, a graduate student in biological sciences in the J. William Fulbright College of Arts and Sciences. He reported his findings in the journal Zoology.

While scientists knew that some snake species could survive for up to two years without a meal, no studies have examined the physiological changes that take place when a snake goes for prolonged periods without food. McCue examined three snake species – the ball python, the ratsnake and the western diamondback rattlesnake – to study their responses to prolonged periods without food.

The 62 snakes studied went about six months without eating – a time period that could well be duplicated in the wild, where food supplies can be scarce. McCue then looked at physiological, compositional and morphological changes in the snakes.

The results showed that the snakes could lower their standard metabolic rates, some by up to 72 percent.

“Snakes already had low energy demands. We didn’t know they could go lower,” McCue said.

Another surprising finding: The snakes continued to grow despite the lack of food – a counterintuitive finding, but a measurement that again does not appear in the research literature.

“To me, this suggests that there must be a strong selective advantage to growing longer,” McCue said. It also means the snakes have become extremely efficient in their ability to use available resources.

To illustrate the strategies employed by snakes to combat starvation, McCue uses an economic analogy of supply and demand.

“When you’re cut off from resources, you are an organism that still needs to expend energy,” he said. The “demand” end is met by decreasing their metabolic rate. The “supply” end must be met by frugal use of resources they have at hand for energy, which comes from within.

The body composition of snakes includes water, ash, protein, fats and carbohydrates. McCue found that the snakes used up selected fat stores first during starvation, but he also found crucial differences between the snake species. The ratsnakes, which typically have a more abundant rodent supply in their natural environment, began to break down proteins faster than the pythons or rattlesnakes.

“The protein use was higher in the snakes less well adapted to starvation,” McCue said.

Snakes are relatively new on the world scene, having been around for about 100 million years. Yet they currently comprise about half of all reptile species.

“Snakes are very evolutionarily successful,” McCue said. Understanding the physiology that allows them to succeed in low-energy environments will help scientists further their understanding of the snakes’ evolution and their adaptation to their current ecosystems.

Note: This story has been adapted from a news release issued by University of Arkansas, Fayetteville.

Friday, August 24, 2007

King cobra Antivenin in India

Two Kinds of King cobra Antivenin is available. Red cross in Thailand manufactures one, and the Central Research Institute, Himachal Pradesh in India manufactures another.

Central Research Institute

[ TOC ]
Distt. Solan
Kasauli, Himachal Pradesh, India 173 204
Antivenoms equine derived; liquid (2-year shelf life) and lyophilized (5-year shelf life).
Dr. Rakesh Sehgal, Director
91-1-792-272114, 91-1-792-272046
91-1-792-272016, 91-1-792-272049

Ophiophagus hannah Antivenom

[ TOC ]
Venom Research Unit (Vietnam)
Antivenom Notes
F(ab')2 - immunoglobin. Production status unclear; the director left the organization in 2004.
Printed Notes
Equine-derived, liquid, 10 ml vials, 5-year shelf life. Initial recommended dose: 60 ml i.v. Cost (local) was US$20.00 ca. 2001.
Effective Against
Scientific Names:
Ophiophagus hannah,

King Cobra antivenin

[ TOC ]
Queen Saovabha Memorial Institute
Antivenom Notes
Producer also known as "Science Division, Thai Red Cross Society ."
Printed Notes
Equine-derived, lyophilized, 10 ml vials; five-year shelf life. Cost (local) was US$40.00/10 ml. vial in 2000. Initial recommended dose: 20-40 ml i.v.
Effective Against
Scientific Names:
Ophiophagus hannah,
SII Polyvalent Antisnake Venom Serum
[ TOC ]
Serum Institute of India
Antivenom Notes
Found efficacious in vivo against venoms of Echis leucogaster, E. occelatus, and Naja melanoleuca. Claimed effective for Indian Trimeresurus spp. and "Expected to cover Hypnale spp."
Printed Notes
Equine-derived, lyophilized, 10 ml. vials, five-year shelf life. Recommended initial dose: 20 ml, i.v. or i.m. List price est. at US$11.30/vial ca. 2004. Also known as "Anti Snake Venom Serum (Asia)"
Effective Against
Scientific Names:
Bungarus caeruleus, Bungarus ceylonicus, Bungarus fasciatus, Daboia russelii, Echis carinatus multisquamatus, Naja naja, Ophiophagus hannah,

Types of Venomous Snakes

There are three types of venomous snakes:

Opisthoglyph: These are the rear-fanged snakes, the fangs are enlarged rear teeth with a 'groove' that venom flows down while they are swallowing the prey item. They are mostly harmless or mildly venomous but there are two BIG exceptions. The Boomslang (Dispholidus typus) and the Twig snake (Thelotornis kirtlandi) have killed humans before. Other good examples of this type of snake are the Mangrove (B. dendrophila) and Hognose snakes (Heterodon ssp.)

Proteroglyphs: These are the fixed front fang snakes. These snakes have small non-movable front fangs. When they bite they hang on and 'chew' to envenomate the prey. Obvious examples of this type of snake are the cobras (Naja), kraits (Bungarus), mambas (Dendroaspis), and coral (Micrurus) snakes. These are some of the deadliest snakes in the world.

Solenoglyph: These snakes have movable front fangs. The fangs fold back into the mouth until they are needed. This is what makes these snakes more dangerous work with. They can grab on to your hand like a cobra would but they can also open their mouth almost 180 degrees with the fangs extended straight out. This enables them to strike at any portion of your body because it is more of a 'stab' than a bite. Examples include rattlesnakes (Crotalus), eyelash vipers (Bothriechis), gaboon vipers (Bitis), cottonmouths and copperheads (Agkistrodon)

Thursday, August 23, 2007

Snake Venom:Bungarotoxins

Wednesday, August 22, 2007

Abandoned Eggs of King cobra preserved

KalingaTimes Correspondent
Kendrapara (Orissa), Aug 22: The forest personnel have preserved 'abandoned' eggs of a rare king cobra in the wildlife museum after the reptile recently nested along the swampy patches of Bhitarkanika wildlife sanctuary.

For the first time, wildlife researchers had spotted the nest of a king cobra in the mangrove forest area.

The reptile had abandoned two eggs that were later collected and preserved in the local museum after being chemically treated.

"The king cobra eggs have found a pride of place in the museum. Reptile researchers are taking care for its prolonged preservation," said forest officials.

Though venomous king cobras abound in the mangrove forest region, never before cobras' nest had been sighted.

The forest protection staff while on duty had stumbled upon a 12-foot-long female king cobra in dense mangrove cover.

The reptile was on vigil protecting the nest from natural predators like estuarine crocodiles.

Later, after having received the good news, the forest staffs were asked to keep watch on the nest and ensure its safety.

Babies had emerged from the nest. The mother tended to the babies for about an hour. Later it swiftly disappeared into the forest taking the babies in tow, according to forest staffs who witnessed the rare

Initially, the mother was scared of human interference and had become restless. But later the reptile regained composure after it found that there was no threat to the nest from the forest staff.

Two of the eggs that did not hatch were left behind in the nest by the mother.

Monday, August 20, 2007

When Cobras Spit, There's Not A Dry Eye In The House

Science Daily — The red Mozambique spitting cobra stiffens, fixing its gaze on the victim's face, which is moving backwards and forwards in front of it. For several seconds it remains erect like this; then its head flashes forwards. For an instant the fangs in front of its pale pink throat are visible in its wide-open mouth, as they squirt the venom at high pressure towards the victim. On the plastic visor two red spiral patterns appear. The eyes behind it look surprisingly unperturbed. "I sprayed the visor beforehand with rhodamine," Katja Tzschätzsch calmly explains, "It's a pigment which dyes liquids red. This makes the traces of venom easier to see."
In her undergraduate dissertation the trainee teacher investigated what spitting cobras aim at when spitting. "In the literature it often says: they aim at the eyes," her supervisor Dr. Guido Westhoff, junior lecturer in Professor Horst Bleckmann's team, explains. "However, up to now nobody has investigated it." The cocktail of toxins partly consists of nerve poisons, but also contains components which are harmful to tissue. Through a narrow channel in their fangs the snakes can spray the liquid at high pressure similar to a bullet in the barrel of a gun. If they manage to hit an eye, the sensitive cornea reacts with severe stinging pain. In the worst case these burns can ultimately lead to blindness.

As guinea pigs Katja Tzschätzsch used four Mozambique and six black-necked spitting cobras from the animal house in Schloss Poppelsdorf. In her experiments she either stood face to face with them herself protected only by a plastic visor or she used photos. In addition, for both species she recorded the spitting process using a high-speed video camera. "The snakes really do spit only at moving faces," was her first finding; "movements involving the hand elicited no response from any of the snakes." Only two cobras reacted to the photos. These even spat when Katja touched up the photo, taking out one eye. And even when both eyes were removed, one of the black-necked cobras still remained aggressive. The conclusion: "For really reliable results we would need a larger sample."

Always straight at the eyes

The evaluation of the traces of venom on the photos and the visor revealed how accurate the aim of both species of snake was: the black-necked spitting cobras hit at least one eye eight out of ten times, with the red Mozambique spitting cobras even reaching the target in 100 per cent of cases. However, there was a clear difference in the traces left by the two species: whereas the black-necked cobra sprayed its venom, the attack by the red Mozambique cobra is reminiscent of something shot from a double-barrelled water pistol.

What is decisive for the high degree of accuracy is a pattern of behaviour which researchers were able to observe in both species. "In super slow motion it is clearly visible that the snakes move their heads rapidly when squirting the toxin," Dr. Westhoff explains. "Rather like we do when we wish to use a garden hosepipe to water the flowers of an entire flowerbed." In this way the venom is spread out over a larger area; the chance that it will hit one eye increases.

However, Dr. Westhoff would like to scotch one prejudice: "Cobras only spit when they feel threatened, not to kill their prey," he says; "anything else is a myth." They kill their prey like other poisonous snakes do, by biting them and thereby injecting the venom into their bloodstream, which then proves fatal. Human beings are not on their list of potential prey; even so, these snakes are dangerous even when they are still very young. Dr. Westhoff reveals, "I was once attacked by a spitting cobra which had just emerged from its shell it practically spat at me out of its shell."

Note: This story has been adapted from a news release issued by University Of Bonn.

Sunday, August 19, 2007

Rattlesnake Country(animal planet)

Loma Linda is an expanding Southern Californian town on the cusp of two harsh worlds. It occupies a scorched hinterland where the urban sprawl of Los Angeles ends and the great South Western deserts begin.

This is rattlesnake country – home to two separate species: the Southern Pacific rattlesnake, and the Red Diamond rattler - with Loma Linda representing the northern perimeter of its range.

Both are capable of causing agonising pain, permanent disability, and the need for amputation with even the most casual strike. In extreme cases - without correct medical attention - they are quite capable of killing a man.

Within a few hours drive of Loma Linda are four other species of rattlers - Mojave, Sidewinder, Speckled, and Western Diamondback…. not forgetting the other potentially lethal creatures that lurk in these parts, like black widow spiders and scorpions.

Where a burgeoning human population encroaches on the natural habitat of deadly predators that have been around these parts for millions of years there’s bound to be problems…

Rescue Team
Loma Linda’s University Medical Centre is home to Venom ER – a unit dedicated to saving the lives of snake bit victims and other poisonous creature-related crises.

The envenomation specialist here is Dr Sean Bush – a pony-tailed professor who speeds between shifts in his vintage Mustang muscle car. But that’s where the fun ends and the serious stuff begins.

With the local population growing by 6% a year and rattlesnakes already in their back gardens, Venom ER isn’t a place for relaxation.

Unfortunately, snakebites don’t always happen at the most convenient moments - the snake rescue team covers over 100,000 sq km – most of it wilderness. Wasted time is perhaps the biggest threat to a victim’s life.

Over 100 paramedics and fire department operatives are on hand to rush the victims to Loma Linda Venom ER. And the quickest way is by helicopter. In fact, Venom ER’s chopper crew are so in demand, they cover on average 50,000 miles every year flying life saving missions.

Strike Out
Fortunately, not all snake strikes are emergencies – in many cases the snake may not puncture the skin. Even when it does it may not release any venom at all. This is known as a dry bite.

All too often, though, the fangs do the job for which they were intended. In an instant the snake injects a lethal cocktail of proteins and enzymes straight into the victim’s bloodstream like a hypodermic syringe.

With a Southern Pacific rattler bite, huge amounts of swelling forms almost immediately around the bite. A wounded limb gradually turns a stomach-churning shade of black as the venom destroys tissue and begins killing the victim; essentially digesting it from within.

DR Bush explains the subsequent deadly pattern: “Creatine kinase (CK) is an enzyme molecule that’s inside the muscle cell. And as the muscle cells are destroyed and they rupture the CK leaks out into the blood stream and flood the kidney and clogs them up.”

In the treatment room Dr Bush flushes the patient’s body with fluids and keeping the vital organs working. The patient is also administered with antivenom – antibodies that are harvested from animals like horses, rabbits and goats that have an immune response to venom.

Disaster Recovery
Contrary to popular belief, antivenins aren’t a miracle cure. For a start it’s hard to predict the impact of a bite from the snake’s size – as even the venom effects for bites of individuals the same each species can vary.

Because all our metabolisms are different, we all have a different reaction to the venom - making the effects on victims almost impossible to predict.

Scientists now believe that venom is far more complex than first imagined – essentially, it seeks out a weakness in the victim’s constitution which the venom can exploit.

One of Dr Bush’s most memorable cases was a patient who was bitten by an escaped ‘pet’ Southern Pacific rattlesnake. It began with an agonising 15 second bite that almost cost him his life.

After 70 hours on the critical list and a week in intensive care, the patient’s body was still suffering violent tremors, as if it was possessed by a demon - five days after the man had been bitten. He was given 58 vials of the Crofab antivenin; to Dr. Bush's knowledge, a world record.

It can be a long and agonising road to recovery after a rattle snake bite – providing the victim is lucky enough to make it to Venom ER, that is.

Venom ER (animal

Snakes have symbolised all that is bad on this planet of ours since the dawn of humanity – they’re the original bête noir. These reptiles slither and slide, hide in holes and peer out with glassy, unblinking eyes. Then there’s the forked tongues flicking between a pair of sharp fangs.

But is this a good enough reason for our primeval fear and loathing? The experts don’t think so.

But the facts remain: venomous snakes are amongst the deadliest animals on earth. They can strike without warning – some with bites so noxious they dissolve human skin on contact. They kill over 100,000 people worldwide each year - more than are killed from all other animal attacks combined.

…And still the experts tell us we’re over reacting. How can this be?

Well for starters, the majority of snakes catch their prey and suffocate it by means of constriction. Out of approximately 2500 species of snake, less than a quarter are actually venomous.

Armed Response
Mike Cardwell is a Deputy Chief Sheriff who works closely with the Loma Linda’s Venom ER. He’s conducted a long term study of over 1,200 Mojave rattlesnakes - arguably, one of the world’s most infamous reptile families. Their fearsome reputation for aggression, he says is misplaced. Rattlesnakes have relatively weak venom when compared to the world's other vipers and cobras.

“These snakes never show any aggression to us. They usually sit still; they occasionally rattle or crawl away, and sometimes they come over and sniff our equipment or sniff our feet without showing any aggression.”

Rattlesnakes strike fast but don’t have more than a metre range. Outside their striking distance, we’re quite safe.

According to the University of Florida, 7000 venomous snake bites are reported annually in the United States. Out of those unfortunates, just 2 in every thousand prove to be fatal – more Americans die being struck by lightning. In fact, it’s estimated that as many as half the attacks are ‘dry bites’ – where no venom is transmitted.

Less than one percent of properly-treated snake bites in developed countries actually results in death.

Scientists believe that snakes produce venom with a voluntary action. So strikes against humans – which, they say, are too large to be legitimate prey - are likely to be a defensive reaction. It’s a warning an intimidating and superior threat to back off.

Cardwell agrees. He can’t imagine why anything that’s that close to the ground would pick a fight with another animal over 5 feet tall.

Lethal Injection
Snakes in the deserts of South Western America are essentially ambush specialists. They prey on lizards and small mammals that burrow into the sandy desert to escape from the heat of the sun.

All snakes have very strong saliva – this common trait allows them to swallow their prey whole and digest it chemically as it passes through their limbless bodies. But venomous snakes have another trick up their sleeves – or more accurately, their fangs.

A dedicated supply of proteins and enzymes is efficiently injected using their needle-like teeth, right into the bloodstream of their prey. The venom destroys tissue to kill the prey and starts the digestion before their quarry hits the ground. In fact, death doesn’t come immediately.

The snake’s victim will try to make its escape once it has been bitten - its progress hampered, however, by the debilitating and ultimately fatal dose of poison.

The snake simply follows the powerful scent of its own saliva. It finally catches its prey, devouring it whole without suffering any injuries that other predators frequently face from a meal that puts up too much of a fight.

What’s your Poison?
Snake venoms can be roughly divided into three types: hemotoxic and neurotoxic, and haemolytic. They are classified essentially by their effects on the victim’s body.

• Haemotoxins - breaks down vessels, and causes bleeding into internal body cavities.

• Neurotoxins - act on the nervous system; primarily effecting muscle reactions, digestion, sight, and breathing.

• Haemolysins – dissolve red blood cells and prevent their ability to clot.

However, venom is more complex than scientists had first imagined. Some snakes have a cocktail of two or more of these deadly ingredients.

It was initially thought that only a special group of Mojave rattlesnakes had neurotoxin venom. But then a different species presented itself to Venom ER with the same symptoms.

At first, the experts didn’t know whether the snakes were interbreeding or evolving. Though scientists haven’t mapped snake venom perfectly, they now believe venom properties are flexible – they can change daily; as a snake gets older; even depending on its last meal.

And so, the mysterious serpent saga continues…

Saturday, August 18, 2007

How snakes starve to live

New York, Aug 17 (IANS) Mystery shrouding a snake's ability to go without food for nearly two years may have been finally uncovered with researchers claiming to have cracked the mechanism behind their survival despite starvation.

The research, which reveals some previously unknown serpentine tricks, sheds light on how serpents managed to drag on since before the days of the dinosaur Tyrannosaurus rex, biologists were quoted as saying in the Nature magazine.

Biologist Marshall McCue at the University of Arkansas, Fayetteville, kept ratsnakes, pythons, and rattlesnakes in cages where they could not alter their activity levels - they were forced to be inactive.

They were also unable to reduce body temperature, stuck with the laboratory temperature of a steady 27C. The animals were then starved for a period of up to 168 days.

McCue measured the animals' oxygen consumption and found that they had somehow managed to reduce their resting metabolic demands by up to 72 percent.

'We had no idea that these animals could reduce their metabolic rates lower than their standard resting rate,' says McCue. 'It would seem that their pilot light, which we already thought to be as low as possible, actually goes much lower.

'In most starving animals, allowing lipid (the compound that make up fat) levels to fall below 10 percent body mass is a death sentence,' says McCue. But snakes were able to go down to five percent body fat before making a switch to protein consumption, he found, letting them hold on for longer without food.

'Even then, consuming their own proteins had little effect on their health because they had slowed down their metabolism so drastically,' he says. 'The ability to selectively utilise lipids at low levels, thereby conserving structural proteins, could be a key breakthrough in understanding starvation survival,' says physiologist Anthony Steyermark of the University of St Thomas, Minnesota.

How the snakes were lowering their metabolic rates, without lowering their temperature - and while staying alert enough to attempt to bite their captor - is a mystery.

McCue thinks the snakes may be reducing the density of energy-generating cell machinery called mitochondria in highly active tissues such as those in the liver and heart.

In addition, the snakes had a cunning way to stretch out their resources while enduring starvation.

All animals burn lipids - the compounds that make up fat - for energy when they run out of food.

But lipids have some essential functions in the body, forming crucial parts of cells and organs needed for nutrient transfer, for example. So as starvation progresses and fat reserves run low, most animals turn to protein in the body and begin using that as an energy resource instead. This essentially means that they begin to digest themselves - a process that can only be tolerated for a short while before resulting in death.

Biologists have long argued that there are two main tactics used by animals to weather a period of starvation.

The core body temperature can be reduced, as is the case in penguins that go through torpor to reduce their calorie use during the winter. Hibernating animals such as hedgehogs utilise another method - they stock up on food and then reduce activity levels. Some species, including polar bears, do both.

Friday, August 10, 2007

Scientist Discovers Why Cobra Venom Can't Kill Other Cobras(Tha National Georgraphic News)

Zoltan Istvan
National Geographic Channel
February 20, 2004

In a cobra hunt, every move counts.

Zoltan Takacs, a herpetologist and toxinologist (natural-toxins scientist), lunges at a 5-foot long (1.5-meter) Egyptian cobra slithering away in the dry East African grassland of Tanzania.

The cobra opens its hood—kicking up dust and hissing—and strikes, narrowly missing Takacs's right hand. Takacs jumps away, gathers himself, then quickly moves in and snares the cobra's head with a wooden stick.

In his field lab the Hungarian-born Takacs, who's been fascinated by snakes since childhood, extracts tissue samples from the cobra for genetic analysis. Based at the Yale University School of Medicine in New Haven, Connecticut, Takacs has developed an international reputation for unlocking secrets of venom that promise to have significant medical potential.

But Takacs must endure tremendous risks in the field. "I have to be extremely careful in this tropical wilderness—because I'm far from any hospitals," Takacs said. "Over the years I've lost three good friends and colleagues to snakebites."

Since high school, Takacs, who holds a doctorate in molecular pharmacology from Columbia University in New York, has traveled to more than a hundred countries to collect venomous snakes.

Animal neurotoxins are nature's deadliest weapons. Nearly all creatures, except cobras, die in minutes when cobra venom enters their bloodstreams. At his Yale lab, Takacs explores why.

Cobra Venom

"Neurotoxin is the main lethal component of the cobra venom," Takacs said. "It binds to a receptor on the muscle, therefore preventing the nerve impulses to induce muscle contraction, leading to the cessation of breathing, and death."

The target of cobra neurotoxin, called the acetylcholine receptor, appears to play a role in Parkinson's disease, schizophrenia, and myasthenia gravis, which debilitates the muscles.

"Snake venoms are extraordinary biological products, with importance in many different fields," said Rick Shine, professor of evolutionary biology at the University of Sydney in New South Wales, Australia. "Understanding their mechanisms of action can help us to design better drugs—as well as to reduce the immense suffering and mortality from bites to humans."

Venomous snakes come in two main families: vipers, such as rattlesnakes, and cobras, such as kraits, mambas, and sea snakes. During the 1970s scientists discovered that vipers' bloodstreams contain molecules that neutralize the lethal components of their own venom.
Cobras deal with their venom differently from vipers, the scientists suspected. During the 1990s studies were launched to find out why.

Snake venoms are complex mixtures of peptides, enzymes, and other toxins that target the nerves, muscles, and blood circulation and coagulation. A key to the research was finding how the toxins reacted with muscle receptors.

Lock and Key

Takacs cloned a cobra's acetylcholine receptor and compared it to acetylcholine receptors from other vertebrates (animals with spinal columns). At the molecular level this cobra receptor looked the same as those in the rest of the vertebrates—except for a single different amino acid.

Takacs' experiments showed that this single difference introduces a bulky sugar molecule onto the cobra receptor. The sugar masks the so-called binding site on the receptor surface—which prevents the neurotoxin from attaching.

"If the sugar is removed, then the cobra receptor will become sensitive to its own neurotoxin, just as other animals are," Takacs explained.

To prove his theory, Takacs and his colleagues engineered a mouse muscle receptor with a sugar molecule attached—and thus created a mouse receptor that resists cobra neurotoxin.

"Like a keyhole and a key—if you change the keyhole, the key will no longer fit into it," Takacs said. That's the secret to how the cobra avoids its own venom.

"These same venom [and receptor] molecules, once purified, characterized, redesigned, and cloned, can be used in medical research as possible drugs for treating strokes, heart attacks, and metastasis as well," said John C. Perez, a professor at the Natural Toxins Research Center at Texas A&M University-Kingsville.

"These venom and receptor molecules all have important biomedical applications, making Takacs's work much more than just studying snake venom," he added.

Postsynaptic α-Neurotoxin Gene of the Spitting Cobra, Naja naja sputatrix: Structure, Organization, and Phylogenetic Analysis

Fatemeh Afifiyan, Arunmoziarasi Armugam, Chee Hong Tan, Ponnampalam Gopalakrishnakone, and Kandiah Jeyaseelan1
Department of Biochemistry, Faculty of Medicine, National University of Singapore, 119260 Singapore
1Corresponding author.
Received November 2, 1998; Accepted January 19, 1999.

The venom of the spitting cobra, Naja naja sputatrix contains highly potent α-neurotoxins (NTXs) in addition to phospholipase A2 (PLA2) and cardiotoxin (CTX). In this study, we report the complete characterization of three genes that are responsible for the synthesis of three isoforms of α-NTX in the venom of a single spitting cobra. DNA amplification by long-distance polymerase chain reaction (LD-PCR) and genome walking have provided information on the gene structure including their promoter and 5′ and 3′ UTRs. Each NTX isoform is ~4 kb in size and contains three exons and two introns. The sequence homology among these isoforms was found to be 99%. Two possible transcription sites were identified by primer extension analysis and they corresponded to the adenine (A) nucleotide at positions +1 and −45. The promoter also contains two TATA boxes and a CCAAT box. Putative binding sites for transcriptional factors AP-2 and GATA are also present. The high percentage of similarity observed among the NTX gene isoforms of N. n. sputatrix as well as with the α-NTX and κ-NTX genes from other land snakes suggests that the NTX gene has probably evolved from a common ancestral gene.
[The genomic DNA sequences reported in this paper have been submitted to GenBank databases under accession nos. AF096999 toAF097001.]

Monday, August 6, 2007

Neurotoxins affecting neuroexocytosis

G Schiavo, M Matteoli, C Montecucco
Imperial Cancer Research Fund, London, United Kingdom.

Nerve terminals are specific sites of action of a very large number of toxins produced by many different organisms. The mechanism of action of three groups of presynaptic neurotoxins that interfere directly with the process of neurotransmitter release is reviewed, whereas presynaptic neurotoxins acting on ion channels are not dealt with here. These neurotoxins can be grouped in three large families: 1) the clostridial neurotoxins that act inside nerves and block neurotransmitter release via their metalloproteolytic activity directed specifically on SNARE proteins; 2) the snake presynaptic neurotoxins with phospholipase A(2) activity, whose site of action is still undefined and which induce the release of acethylcholine followed by impairment of synaptic functions; and 3) the excitatory latrotoxin-like neurotoxins that induce a massive release of neurotransmitter at peripheral and central synapses. Their modes of binding, sites of action, and biochemical activities are discussed in relation to the symptoms of the diseases they cause. The use of these toxins in cell biology and neuroscience is considered as well as the therapeutic utilization of the botulinum neurotoxins in human diseases characterized by hyperfunction of cholinergic terminals.

Pathophysiology of Snake Venom

Snake venoms are complex substances, chiefly proteins, with enzymatic activity. Although enzymes play an important role, lethal properties of venom can be due to certain smaller polypeptides. Most venom components appear to bind to multiple physiologic receptors, and attempts to classify venom as toxic to a specific system (eg, neurotoxin, hemotoxin, cardiotoxin, myotoxin) are misleading and can lead to errors in clinical judgment.

The venom of most North American pit vipers produces local effects and coagulopathy and other systemic effects. Results may include local tissue damage; vascular defects; hemolysis; a disseminated intravascular coagulation (DIC)–like (defibrination) syndrome; and pulmonary, cardiac, renal, and neurologic defects. Venom alters capillary membrane permeability, causing extravasation of electrolytes, albumin, and RBCs through vessel walls into the envenomated site. This process may occur in the lungs, myocardium, kidneys, peritoneum, and, rarely, the CNS. Initially, edema, hypoalbuminemia, and hemoconcentration occur. Later, blood and fluids pool in the microcirculation, causing hypotension, lactic acidemia, shock, and, in severe cases, multisystem organ failure. Effective circulating blood volume falls and may contribute to cardiac and renal failure. Clinically significant thrombocytopenia (platelet count < 20,000/μL) is common in severe rattlesnake bites and may occur alone or in combination with other coagulopathies. Venom-induced intravascular clotting may trigger defibrination syndrome, resulting in epistaxis, gingival bleeding, hematemesis, hematuria, internal hemorrhage, as well as spontaneous bleeding at the bite site and venipuncture sites. Renal failure may result from severe hypotension, hemolysis, rhabdomyolysis, nephrotoxic venom effects, or a DIC-like syndrome. Proteinuria, hemoglobinuria, and myoglobinuria may occur in severe rattlesnake bites. The venom of most North American pit vipers produces very minor changes in neuromuscular conduction, except for Mojave and Eastern diamondback rattlesnake venom, which may cause serious neurologic deficits.

Coral snake venom contains primarily neurotoxic components, which result in a presynaptic neuromuscular blockade, potentially causing respiratory paralysis. The lack of significant proteolytic enzyme activity accounts for the paucity of symptoms and signs at the bite site.

Sunday, August 5, 2007

General Do's And Don'ts of a Snake Bite


Remove everyone from risk.

Calm the patient. This is far more important than you may think! Nearly all snakebites are successfully treated in the US. Most poisonous snake bites are not fatal. Panic only increases danger to the victim by increasing heart rate, and it spurs carelessness among everyone.

Use your snakebite kit immediately. The first few minutes are the most effective for venom removal. Follow the instructions provided in the kit.

Seek medical help at once. Recent studies indicate the single most effective thing you can do is calmly transport the victim to a medical facility. In most cases, severe complications DO NOT occur until several hours after the bite. If you're deep in the wild, make wise use of your time, but don't rush.

Remove tight watches, sleeves, jewelry, etc. Cut these items off if you have to. Note that rings and bracelets are especially hazardous as they will severely restrict blood flow to their particular extremity once swelling begins. Amputation is a likely outcome if these items are not removed.

While enroute to a hospital, apply a loose yet constricting band between the bite and the heart. This is NOT a tourniquet and should not be any tighter than a semi-tight watch band.

Keep the patient still if possible and immobilize the injured limb with a splint.

Treat the site like a puncture wound. If possible, wash the wound with copious amounts of soap and water. Once at the hospital, a doctor will likely give the patient a tetanus shot in addition to other treatments.

Keep the affected extremity at heart level or lower.

Avoid alcohol. It only increases metabolism and impairs judgment.

DO NOT GIVE ANTIVENIN IN THE FIELD! Many snakebite victims experience allergic reactions to antivenin and this potential requires that the person giving the antivenin must be ready and able to provide advanced heart and lung support -- something only available at a hospital via trained medical personnel, sophisticated machines, and powerful drugs. Further, more than six vials are often needed to treat one bite. More drawbacks come into play when the detrimental effects of heat and agitation (due to carrying the vials in a backpack) are considered.

Don't kill the snake! It was only defending itself and such an attempt may produce yet another bite.

Don't try to capture the snake -- it's not necessary. There are only two types of venom -- neurotoxin and hemotoxin (antivenin for pit viper bites is the same for all species). Based on the geographic area and the patient's symptoms, a doctor will usually know which type of antivenin to use.

NEVER cut an "X" at the bite site. This is ineffective and increases trauma in the area of the wound.

NEVER suck out venom with the mouth. The person sucking poison from the wound with his/her mouth will absorb the poison through his/her gums the same way a person absorbs nicotine from chewing tobacco. Further, the human mouth carries at least 42 species of pathogen† and this action could give the snakebite victim a major infection.

Don't excite the victim or allow him/her to walk if avoidable. Doing so will increase venom circulation.

Never apply a tourniquet, constricting band, or "Australian Wrap," unless you are well-trained in its use. As with snakebite kits, recent studies suggest this is of no help and even detrimental. (If, for some reason you do apply one, write a capital T (for tourniquet) on the victim's forehead AND the TIME you applied it. Relax it for 1 minute every 15 minutes.)

Do not apply ice, a cold pack, or freon spray to the wound. This does not retard the spread of venom.

Never apply electrical stimulation from any device in an attempt to retard or reverse venom spread. Studies show this does NOT retard or reverse the spread of venom.

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

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:

A recent study 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 percent) and 11 female (12.8 percent) victims. Seventy-four percent were 18 to 50 years old, and 15 percent had been bitten previously. Only 43.4 percent 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 percent of illegitimate bites versus 16.7 percent of legitimate bites. While 74.4 percent of bites were to upper extremities, only 27 percent 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 percent were under the influence of alcohol at the time of the bite. In our patient population, the data suggest that a 16 percent 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.

What are the symptoms of poisonous bites?

If you get bit, DON'T PANIC. Many people who "died from a snakebite" actually died from something reckless they did while in a panicked state after being bit.While each individual may experience symptoms differently, the following are the most common symptoms of poisonous snake bites:

1.bloody wound discharge
2.fang marks in the skin and swelling at the site of the bite
3.severe localized pain
10.blurred vision
11.excessive sweating
13.increased thirst
14.loss of muscle coordination
15.nausea and vomiting
16.numbness and tingling
17.rapid pulse

How are snake bites treated?
Call for emergency assistance immediately if someone has been bitten by a snake. Responding quickly in this type of emergency is crucial. While waiting for emergency assistance:

Wash the bite with soap and water.
Immobilize the bitten area and keep it lower than the heart.
Cover the area with a clean, cool compress or a moist dressing to minimize swelling and discomfort.
Monitor vital signs.
If a victim is unable to reach medical care within 30 minutes, the American Red Cross recommends:

Apply a bandage, wrapped two to four inches above the bite, to help slow the venom. This should not cut off the flow of blood from a vein or artery - the band should be loose enough to slip a finger under it.
A suction device can be placed over the bite to help draw venom out of the wound without making cuts. These devices are often included in commercial snake bite kits.
Most often, physicians use antivenin -- an antidote to snake venom -- to treat serious snake bites. Antivenin is derived from antibodies created in a horse's blood serum when the animal is injected with snake venom. Because antivenin is obtained from horses, snake bite victims sensitive to horse products must be carefully managed.

Preventing snake bites:
Some bites, such as those inflicted when you accidentally step on a snake in the woods, are nearly impossible to prevent. However, there are precautions that can reduce your chances of being bitten by a snake. These include:

Leave snakes alone. Many people are bitten because they try to kill a snake or get too close to it.
Stay out of tall grass unless you wear thick leather boots and remain on hiking paths as much as possible.
Keep hands and feet out of areas you cannot see. Do not pick up rocks or firewood unless you are out of a snake's striking distance.
Be cautious and alert when climbing rocks.

King cobra nest sighted(The Statesman)

KENDRAPARA, July 30: Wildlife researchers have spotted the nest of a king cobra along the swampy patches of Bhitarkanika wildlife sanctuary. The sighting of nest of these reptile species is first of its kind within the internationally-acclaimed Ramsar wetland site, according to official sources.
Though venomous king cobras abound in the mangrove forest region. Never before, cobras’ nest had been sighted, said Mr. Ajay Kumar Jena, divisional forest officer, Rajnagar mangrove forest division.“It’s a chance discovery”, described Mr. Jena. The forest protection staff while on duty had stumbled upon a 12-foot-long female king cobra in dense mangrove cover. The reptile was on vigil protecting the nest from natural predators. Later after having received the good news, the forest staffs were asked to keep watch on the nest and ensure its safety. Yesterday, babies emerged from the nest. n SNS

What makes a rattlesnake's rattle...rattle?

The sound of a rattler's raspy buzz fills most hikers with dread -- and for good reason. Rattlesnakes, who belong to the pit viper family, are known for beating the pointy tips of their tails against the ground to ward off enemies.

A rattlesnake baby is born with what's called a "pre-button" at the end of its tail. When the rattlesnake sheds its skin (which happens about 10 days after birth and every few months thereafter), the skin gets caught on the pre-button and a button is formed. At the second shed, the first segment is formed and can now rattle slightly against the button. Each time the snake sheds, a new segment is added and the rattle gets longer and louder. The segments knocking against each other create the sound and allow a rattlesnake to rattle its tail in the air rather than beat it against the ground.

The rattle can be loud: its frequency can peak at 5,000 to 8,000 hertz (which is roughly equivalent to an ambulance siren) and at a loudness of 60-80 decibels from a distance of one meter.

However, as a rattlesnake gets older, the outer segments of the rattle sometimes become brittle and fall off. That's why you can never tell the age of a snake by the size of its rattle. Not that you were eager to examine them up close anyway.

History of Snakes

Snakes are the most modern of reptiles, first appearing in the fossil record during the time of the dinosaurs. It is thought that they evolved from ground dwelling or burrowing lizards that exploited the survival advantages to be found in a cylindrical, legless body. They gave up external ears and developed clear scales to shield their ever-open eyes from dust and damage. They evolved elongated internal organs, specialized muscles and resilient, scaled skins of varied pattern and color that provided camouflage and some limited protection from predators and the elements. They also evolved a host of instinctive behaviors that enabled them to find and catch prey, hide from predators, reproduce and survive in a great variety of climates. Tunnelling beneath dirt and sand, swimming in the seas, climbing in the crowns of trees and crawling on the land, snakes became integral components of varied ecosystems throughout the world. Some evolved infrared heat sensors to find prey in the darkness of night or burrow. Some developed venoms (and the apparatus to deliver them) of such exquisite complexity and design that - unlike most biochemical substances - they cannot yet be manufactured through biotechnology or genetic engineering. In short, snakes are incredibly successful, unique and remarkable animals, well deserving of our respect and admiration.

Why, then, do so many people burden themselves with an irrational, senseless fear of snakes and an unwarranted prejudice toward them? The answer lies in the power and longevity of myth.

For centuries, snakes have figured prominently in the religions, customs and folklore of people throughout the world. To early humans, snakes must have possessed seemingly magical, almost supernatural attributes. They had the ability to move without legs over and through all types of terrain, vegetation and water. They had the ability to find, capture and eat prey without the aid of appendages, as well as to periodically shed an old skin and the ravages of time to reveal a new, brightly hued mantle. They could arise in the spring, resurrected from the ice of winter, and, in a few cases, could cause sickness or death with a single bite. A science fiction writer could scarcely ask for a better model, so it is not surprising that snakes gave rise to all manner of tall tales and myths.

The fear of snakes is an old, deeply entrenched form of prejudice, born of ignorance and perpetuated through superstition and myth. It is time that we stop judging these fascinating reptiles on the basis of folklore and ignorance.

Snake Mythology

Cows, monkeys and dogs are revered by some cultures yet consumed as food by others. So, too, snakes are respected in some parts of the world and despised in others. The way that people feel about snakes is heavily influenced by cultural beliefs and mythology.

Some cultures held snakes in high esteem as powerful religious symbols. Quetzalcoatl, the mythical "plumed serpent," was worshipped as the "Master of Life" by ancient Aztecs of Central America. Some African cultures worshipped rock pythons and considered the killing of one to be a serious crime. In Australia, the Aborigines associated a giant rainbow serpent with the creation of life.

Other cultures have associated snakes with medicinal powers or rebirth. In India, cobras were regarded as reincarnations of important people called Nagas. Our modern medical symbol of two snakes wrapped around a staff, or 'caduceus,' comes from ancient Greek mythology. According to the Greeks, the mythical figure Aesculapius discovered medicine by watching as one snake used herbs to bring another snake back to life.

Judeo-Christian culture has been less kind to snakes. Tales of the Garden of Eden and the serpent's role in "man's fall from grace" have contributed to a negative image of snakes in western culture. In Appalachia, some Christians handle venomous snakes as part of ritual ceremonies, relying on faith to protect them from bites. Among Catholics, Saint Patrick is credited with ridding Ireland of snakes, a feat celebrated by many as a good thing.

Deep rooted cultural biases may be responsible, in part, for widespread fear and disdain for snakes. However, modern myths, from folk tales to plain old misinformation, also contribute to their negative image

Modern Myths
Size. Snakes are almost always described as larger than they really are. Stories about New England water snakes eight and ten feet long are simply not true. Northern water snakes rarely exceed three and a half feet in length, with the largest stretching only four and a half feet. While the black rat snake, our largest native snake, can reach lengths of just over eight feet, most New England snakes are less than three feet long.

Poisonous Snakes. The regularity with which people kill a snake first and ask questions later might lead you to believe that the world is overrun with venomous snakes. In fact, venomous snakes only make up about 10 percent of snake species worldwide, and in Massachusetts only two of the state's fourteen species of snakes are venomous (timber rattlesnake and northern copperhead). Both are rare, reclusive and generally confined to isolated areas.

Folk Tales. Folk tales about snakes are handed down from generation to generation and include such things as snakes that charm prey, swallow their young for protection, poison people with their breath, roll like hoops, and suck milk from cows. These folk tales could be just interesting and amusing stories except that many people still believe them. As we learn more about the true nature of snakes, we can begin to base our perceptions of them on fact rather than fiction.

Hoop Snakes
Myth: When frightened, hoop snakes will bite their tails and roll downhill like a wagon wheel.

Reality: Anatomically, snakes are not well equipped for rolling and there are no reliable accounts of this ever occurring. The hoop snake myth may have been associated originally with mud snakes found in the southern United States. Mud snakes will occasionally lie in a loose coil shaped like a hoop, but they slither away from danger like other snakes.

Swallowing Young
Myth: When confronted with danger, mother snakes swallow their young, spitting them out later once danger has passed.

Reality: Parental care is not very well developed in snakes and there is no evidence that mother snakes protect their young in this way. The myth may result from the fact that some snakes eat young snakes of their own species or of other species, though usually not their own brood.

Charming Snakes
Myth: Snakes have the ability to charm prey, especially birds, so they cannot flee.

Reality: There is no evidence that snakes charm their prey. Small animals may become "frozen with fear" when confronted by snakes but they are not charmed. Birds may flutter about in front of a snake in an attempt to lure it away from their nests; occasionally a bird may actually be captured by the snake, giving the impression that it was charmed. The fact that snakes never blink may also have played a role in this myth's origin.

Sucking Milk
Myth: Milk snakes are so named because of their ability to suck milk directly from the udders of cows.

Reality: Although milk snakes are common around barns that house cows, they completely lack the anatomy necessary to suck milk (or anything else for that matter). Barns are attractive to milk snakes because they provide abundant food in the form of small rats and mice.

Poisonous Breath
Myth: Puff adders (hognose snakes) mix poison with their breath and can kill a person at a distance of twenty-five feet.

Reality: Although the bite of a hognose snake can produce swelling and a burning sensation, these snakes rarely bite people and are not considered venomous. When confronted, they do puff themselves up and hiss, but their breath is harmless.

Cottonmouths in New England
Myth: Swimmers in New England are advised to watch out for venomous cottonmouths, also known as water moccasins.

Reality: Simply put, there are no water moccasins in New England. The cottonmouth, or water moccasin, is a venomous snake of the southeastern United States that occurs no farther north than the Great Dismal Swamp of Virginia. Many people mistake non-venomous water snakes for water moccasins.

Snake Venom May Slow Cancer Growth, Studies Hint

Jennifer Hile
National Geographic Channel,June 1, 2004

Preliminary research shows a natural compound in some snake venoms may prevent the growth of cancerous tumors, potentially transforming one of nature's deadliest toxins into a curative agent.

"Snakes use venom to alter biological functions, and that's what medicine does too," explained John Perez, director of the Natural Toxins Research Center at Texas A&M University-Kingsville. "This is why venoms have always been of interest to medical researchers."

Today roughly a dozen diagnostic tests and drugs are derived from snake venom, according to Zoltan Takacs, a toxinologist (natural-toxins scientist) and herpetologist based at the Yale University School of Medicine in New Haven, Connecticut.

ACE inhibitors, a class of drugs used to treat high blood pressure and other cardiovascular disorders, were developed from the venom of a Brazilian snake. Scientists anticipate that this is just the beginning.

Of the nearly 3,000 species of snakes in the world, about 650 are venomous. Ten of the most deadly live in Australia, making it a logical base for new experiments.

"We knew Australia could be a rich source of drugs because there are so many venomous creatures here," said Tony Woods, a biologist at the University of South Australia in Adelaide. Woods is co-leader of a project to investigate whether the toxins in venom can be used to destroy blood vessels that feed cancerous tumors.

The Power of Nature's Toxins

Venoms are exquisitely complex, composed of as many as a hundred different peptides, enzymes, and toxins. Not only are the venoms of every snake species different, there are also subtle variations within each species.

"There are differences between [venoms of] juveniles and adults, and even among different geographic regions," Takacs said. "These differences may be due to different evolutionary pressures, like different ancestry, prey, and environments."

The variations between venom types and the number of venomous snakes worldwide create a rich molecular hunting ground for researchers, like Woods, seeking to design new drugs.

"A tumor is made of tissue," Woods said. "Like tissue in any part of the body, if you can prevent it from developing a blood supply, or interfere with that supply, then you will have an effect on the growth of that tissue."
Woods is working with Michael Venning, a pharmacologist at the University of South Australia, and graduate student Emma Bateman. Peter Mirtschin, a toxinologist at Venom Supplies in Tanunda, South Australia, is providing the venom directly from the snakes.

Woods's group has found a compound in snake venom that disrupts endothelial cells, which line the inner surface of blood vessels. "It causes the cells to separate from one another, which kills them," Woods said. "When that happens, the function of the blood vessel is inhibited, preventing or at least interfering with blood flow to the tumor [effectively starving it of nutrients]."

Woods will not specify which snake venoms his team is studying, because the compounds have not yet been patented.

The Cure That Doesn't Kill

The advantage of these venom-derived toxins is that they seem to act only on certain types of cells.

Chemotherapy and many other drug treatments do not distinguish between tumor cells and other healthy cells, causing debilitating side effects. But natural toxins have evolved to impact very specific targets.

"We believe the cells that line blood vessels in tumors are different in subtle ways from similar cells elsewhere in the body, because they are exposed to different stimulation and chemicals," Woods said. That means toxins inhibiting tumor blood vessels may not effect surrounding healthy cells, which would theoretically leave patients using these toxins feeling better than those who go through chemotherapy.

Woods anticipates that he will begin testing the venom-derived toxin in animals within the year. Those results will reveal whether the drug is suitable for human clinical trials.

"I don't actually like snakes, they scare me to death, but I'm fascinated by their venom," Woods said. "So long as it's provided to me in nice plastic tubes, I'm very comfortable with handling it."

The snake man of India

Romulus Whitaker talks about his mission to get the King Cobra recognised as the king of the jungle.

HE IS more at home with snakes and crocodiles than fellow human beings. He caught his first snake when he was just five and studying in Kodaikanal. He has many films on reptiles and other crawlers to his credit. He is one of the better-known environmentalists in the country. He is Romulus Whitaker, the snake man of India.

In Thiruvananthapuram to promote an exhibition on snakes, Whitaker said his new mission was to make the King Cobra the symbol of Western Ghats just as the Tiger was the symbol of conservation in India.

"I caught my first snake when I was five and ever since I have been smitten by them," Whitaker recounts.

His passion for reptiles took him to Wyoming University in the United States to do a course in Wildlife Management. In 1963, he joined as an assistant manager with the Miami Serpentarium, Florida, and in 1967, he returned to India as manager of the Venom Production Laboratory in Mumbai. In India, he continued to actively pursue his interest in snakes.

Whitaker's 53-minute-long film, `King Cobra', was awarded the Emmy Award for Outstanding News and Documentary Programme Achievement in 1998. The film was shot extensively in the rainforests of Kerala and took two years of intensive research.

Although he was bitten thrice by snakes ("It was quite bad", he says), Whitaker does not hold it against them. "I am more scared of human beings than snakes," he says.

Other than the `King Cobra', `Rat Wars', `Spunky Monkey', `Croc Man' and `Thunder Dragons' are the other documentaries he has shot for various channels.

He is a member of many important committees connected with wildlife and environment such as the Palni Conservative Council and Society for the Study of Amphibians and Reptiles, U.S. Whitaker has won awards and acclaim such as the Rolex Award for Enterprise (Switzerland) and the Order of the Golden Ark (Netherlands) for his work. He has travelled extensively. Recently, the King of Bhutan, Jigme Singye Wangchuck, a well-known conservationist, consulted with him on why the crocodiles in Bhutan were not breeding. "I found that there was no male and told the King to get a couple of males for the company of the female crocs."

Although Whitaker is for harvesting crocs for their skin, the environmental laws of the country are against it. "The people who protect the crocs should have some stake in it," he says.

Today, Whitaker is the vice-chairman of Crocodile Specialist Group IUCN/Species Survival Commission and lives in Chegalpatu near Chennai.

"I want the King Cobra to be recognised as the real king of the jungle," he says. And that is a tough task in this country where the King Cobra has to compete with another living being that is bent on destroying its habitat - Man.

King Cobra - the snake that would be King

Its size, deadliness, intelligence and ability to rear up and look a human straight in the eye have earned it a name that is more like a title: the King Cobra. The world's longest venomous snake, with a bite potent enough to kill an elephant. And no one knows that better than Romulus Whitaker, the Founder-Director of the Madras Snake Park who has spent most of his life in India wandering around the jungles of Western Ghats, Kerala and Tamil Nadu in his quest for King Cobras.

Whitaker's Emmy award winning film on the real King of the Jungle explores the relationship between the charismatic cobra and creatures such as the forest tortoise, vine snakes, cow elephants, and giant squirrels. The film shot mainly in the rainforests of Kerala is a result of two years of intensive research in which Whitaker and his team travelled the length and breadth of Western Ghats, Orissa and contacted every zoo that breeds the King Cobra to know its habits.

" We also set up a breeding programme in captivity to get the best shots of the female cobra laying eggs and then hatching them," says Whitaker. But the filming wasn't without its perils. The team's cameraman escaped narrowly when the King Cobra struck him on the head when he was trying to get a close shot of the snake without using the remote. Even Whitaker had a miraculous escape. When they were filming a fight between two King Cobras Whitaker got too close and one of the cobras pounced upon his back and hit him on his behind. " Luckily," says Whitaker, " It missed biting me. Though the venom of the King Cobra is less toxic than the common cobra, its massive glands have been known to yield over seven ccs of venom in a single extraction which is enough to wipe out an elephant."

One of the most exciting phases of the production came when the cameraman captured a long footage of a male and female cobra mating. " It was a unique sight to watch the male courting the female," says Whitaker. The King Cobra has a number of unique characteristics not found in any other snake. It has a higher level of intelligence, awareness and alertness as compared to other animals. The male is very conscious about his territory. If another snake ventures into his territory, he chases the intruder out.

The female cobra is the only snake that makes a nest and her presence on the pile of leaves over the eggs deters predators like wildboar, monitor lizards and the deadly mongoose. The King Cobra often feeds on other snakes. Its double hinged jaw and elastic throat permits it to consume prey much larger than itself. It is the largest venomous snake in the world, sometimes growing to over five meters in length.

Whitaker is the world's best known authority on King Cobra. A naturalised Indian, his association with country began in 1951 as a 7-year-old child. Following his schooling at Kodaikanal, he did a course on Wildlife Management in Wyoming, USA. In 1963, he joined as an Assistant Manager with Miami Serpentarium, Florida and in 1967 he returned to India as manager of the Venom Production Laboratory in Mumbai. In India, he has continued to actively pursue his pet passion - snakes!

Whitaker has produced many stunning documentary films including The King Cobra, Rat Wars, Spunky Monkey, Croc Man and Thunder Dragons. King Cobra, was awarded the Emmy Award for Outstanding News and Documentary Programme Achievement in 1998.

Snakes have been a passion with him and he says, " My mother used to tell me jokingly that I started collecting snakes even before I started to walk. But seriously I caught my first snake when I was a student at Kodaikanal." And from then on its been a long crawly journey into the realm of the slithering creatures which has made Whitaker the most celebrated snake man of the world.

King, the Snake

The King Cobra is the largest venomous snake. The solitary King Cobra lives in rainforests, tropical deciduous forests, tropical scrub forests, and tropical grasslands of India, southern China, and southeast Asia. Several of people die from the bite of the King Cobra each year. A King Cobra can even kill an elephant.The King Cobra can slither on land, climb on trees, and swim on water; it often lives near water. It has a life span of about 20 years.The Hood: When the King Cobra is threatened or on the attack, it will hiss, rear up, and flatten its neck ribs into a hood. There are false eyespots on the hood, which can scare some predators.Anatomy: King Cobras have been found up to 18 feet (5.5 m) long, but average about 13 ft (4 m) long. Its hollow fangs are up to 1/2 inch (1.25 cm) long. Poison is forced through the fangs when the cobra bites. The scaly skin glistens but is dry to the touch. Adults are yellow, green, brown, or black; the throat is light yellow or cream-colored. Juveniles are black with yellow or white bars crossing the body. The King Cobra smells using its forked tongue. Although it is deaf to sounds, it can feel vibrations (like footsteps).Like all snakes, King Cobras are cold-blooded; they are the same temperature as the environment. They continue to grow all their lives, getting bigger and bigger each year.Hunting and Diet: The King Cobra is a carnivore (meat-eater). King Cobras are venomous; one bite can paralyze and kill their prey within minutes. The victim dies from suffocation, as the lungs and heart stop.Like all snakes, they swallow the prey whole, head first. The top and bottom jaws are attached to each other with stretchy ligaments, which let the snake swallow animals wider that itself. Snakes can't chew their prey; food is digested by very strong acids in the snake's stomach.The King Cobra eats mostly cold-blooded animals, including snakes (like the rat snake) and lizards. After swallowing a large animal (which can take hours), the King Cobra can go without food for months.Reproduction: Female King Cobras build a leafy nest early in spring; they lay up to 20 to 50 white, leathery eggs, which have an incubation period of 60 to 70 days. Nesting females are very dangerous.Classification: Class Reptilia (reptiles), Order Squamata (lizards and snakes), Suborder Serpentes, Family Elapidae, Genus Ophiophagus, Species hannah.

CNS and anticonvulsant activity of a non-protein toxin (KC-MMTx) isolated from King Cobra (Ophiophagus hannah) venom

A Saha , A Gomes , A K Chakravarty , A K Biswas , B Giri , S C Dasgupta

In the present study, King Cobra (Ophiophagus hannah) venom was subjected to TLC followed by column chromatography/HPLC to isolate and purify a non-protein toxin designated as KC-MMTx. (1)H NMR, IR and EIMS studies showed KC-MMTx likely to be a 282 D unsaturated aliphatic acid having molecular formula C(18)H(34)O(2). The minimum lethal dose of KC-MMTx was 200mug/kg (i.v.) and 350mug/kg (i.p.) in Swiss albino male mice. It significantly increased pentobarbitone induced sleeping time and significantly decreased the body temperature of male albino mice. It provided protection against amphetamine aggregate toxicity in mice but failed to protect amphetamine stereotypy in male albino rats. KC-MMTx provided significant protection against drug (strychnine, pentylenetetrazole, yohimbine) induced convulsions in male albino mice. It increased serum Na(+) and decreased serum Ca(2+) significantly in male mice. MAO activity and brain neurotransmitter levels in male mice were altered significantly. Further detailed study is warranted on the CNS, anticonvulsant potential of KC-MMTx, which may lead to the development of newer therapeutic tools in the near future.

Role of snake venom in medical and biological research

Snake venom is a highly modified saliva that contains many different powerful toxins. There are at least 2.500 species of snakes living at the present time of which over 600 are known to produce venom. Unlike most other predators, all snakes swallow prey whole, so are especially vulnerable to injury if their prey animals are active. Most snake venoms contain specific proteins that (1) paralyze the prey so that it no longer moves (2) interfere with normal blood clotting mechanisms so that the animal goes into shock and (3) begin the process of digestion by breaking down the tissues of the prey animal. Venom also helps deter predators, and is an important defense mechanism for the snake.
The process of introducing venom into a victim is called "envenoming". Envenoming by snakes is most often through their bite, but some species, like the 'spitting cobra', use additional methods such as squirting venom onto the mucous membranes of prey animals (eyes, nose, and mouth). Venoms differ from snake species to snake species, and seem to be specialized to dispatch the particular kinds of animals that make up that snake's preferred diet. The great majority of the many biological toxins in snake venom are proteins: some haveenzymatic activity, some can block nerve or muscle cell receptors, and some have activity in the protein cascades for coagulation, complement fixation or inflammation. Effects of snake venom in the tissues envenomated by the bite are called local effects. Other actions arise from toxins transported through the blood vessels or through lymph vessels, and are called systemic effects.

With advances in molecular biology, a general schema for the expression of such proteins by genes in the specialized salivary gland cells that secrete venom has become apparent. The components of the venom may even change over the course of a snake's life, in species (for example, certain rattlesnakes of the genus Crotalus) that rely on one set of prey animals as juveniles (cold-blooded lizards and other small exotherms), and a different set of prey animals as adults (warm-blooded rodents).[1]
Toxicity: LD50
Toxicity of venoms is usually expressed by the LD50: the lowest dose that kills 50% of a group of experimental animals (most often rodents). That dose varies not just between the venoms tested, but also depends on which species of prey animals receive the venom. Generally, the most toxic venom is the one with the lowest LD50. However, some snakes have venoms that are quite specialized for certain types of prey. Few studies have used the natural prey of a snake species, which would involve capturing a number of wild animals. Instead, most research has used inbred strains of laboratory animals. Human susceptibility to a snake venom is generally estimated from the LD50 for rodents. The next factor in assessing the danger of a particular species of snake is the dose of venom that is actually introduced into the tissues. Some types of snakes have an extremely efficient mechanism of injecting venom with a single strike, others have poor success in doing so. The amount of venom produced by snakes that is available for secretion with a bite also varies between kinds of snakes, and between individuals (usually by size) of any one species.

[edit]Venom characteristics and delivery of venom according to snake family
The venomous snakes are represented in only four families. There are variations in the methods of envenomation according to family.

[edit]Atractaspididae (atractaspidids)
(common names of well-known members: burrowing asps, mole vipers, 'stilleto snakes')

[edit]Colubridae (colubrids)
(common names of well-known members: boomslang)

This family of snakes contains about 2/3 of all living species. A minority have somewhat enlarged grooved teeth at the back of the upper jaw for delivering venom under low pressure. This unsophisticated system for venom delivery makes it more difficult for scientists to collect colubrid venom for chemical studies than the venom from vipers and most elapids, which inject venom through front fangs under higher pressure. Often, couloubrid venoms were collected only in relatively small quanitites and with impurites from other mouth contents from the snake. As more recent collection methods have been devised that overcome some of these problems, researchers have discovered that earlier assumptions about the venom contents were sometimes mistaken. For example, Phospholipase A2 (PLA2),which had been thought to be lacking in venoms in this family has now been detected in at least two species

"Some venoms show high toxicity toward mice, and others are toxic to birds and/or frogs only. Because many colubrids feed on non-mammalian prey, lethal toxicity toward mice is probably only relevant as a measure of risk posed to humans. At least five species (Dispholidus typus, Thelotornis capensis, Rhabdophis tigrinus, Philodryas olfersii and Tachymenis peruviana) have caused human fatalities."[2]

[edit]Elapidae (elapids)
(common names of well-known members: cobras , kraits, coral snakes, mambas, sea snakes, sea kraits, Australian elapids)

The venom of elapid snakes is notorious for the potency of its neurotoxins. These snakes have similarities in their XXXXX. Venemous elapid snakes greatly range in size, aggressiveness, and in habitat. "The king cobra (Ophiophagus hannah) is the world’s longest venomous snake, growing up to 5.5 m (18.5 ft). The main constituent of king cobra venom is a postsynaptic neurotoxin, and a single bite can deliver up to 400–500 mg of venom, ...about fifteen thousand times the LD50 dose for mice. The world’s most venomous snake is the Australian elapid small-scaled snake (Oxyuranus microlepidotus), can deliver up to 100 mg of venom with an LD50 for mice of 0.01, giving up to 500 000 LD50 mice doses. [3].

Although sea snakes have some of the world's most potent venom, the numbers of human fatalities from snake bites is apparently limited by their marine environment and behavior (more coming with references).

For prey animals, and in cases of defensive behavior towards humans, "neuromuscular paralysis usually occurs with elapid (cobra, krait, and mamba) envenomation." [4], however, many elapid snakes have venoms that also include toxins that cause bleeding. For example, the venom of , all contain metalloproteinases that interfere with platelet aggregation.

Besides neurotoxins and metalloproteinases, there are additional types of bioactive proteins and polypeptides that are common in elapid venom. "A second group of toxins are cell membrane poisons that act in a general fashion, but their chief effect is on the heart, producing arrhythmias and impaired contractility. The third group of toxins contains enzymes that break down protein and connective tissue. These necrosis-producing toxins are typical of the venom from the spitting cobras (Naja spp.) of Africa, China, and Sumatra." [5]

[edit]Viperidae (viperids)
(common names of well-known members: pitless vipers, pit vipers)

Bites by snakes of the family Viperidae often induce local breakdown of muscle and tissues which may result in permanent deformity in the region of the bite (Myotoxic phospholipases).[6] Some types of vipers inject venom that travels though the bloodstream and breaks down muscle cells systemically, with relatively little reaction at the site of the bite, but enough muscle cells throughout the body release their contents into the victim's bloodstream to cause a condition known as rhabdomyolysis. In rhabdomyolysis (literally rhabdo=rod , myo=muscle cell, lysis= breaks apart) the large iron-containing protein myoglobin is released into the circulation (myoglobulinemia). When myoglobin reaches the kidney, the renal system attempts to filter it out of the blood. If the amount of myoglobin is very large, acute renal failure results, and the blood is no longer properly filtered of even normal body wastes by the kidneys.

The common names of vipers frequently fail to identify an actual species. For example, the name, Rock viper refers to two entirely different kinds of snakes.

[edit]Crotalinae (crotalines)
(common names of well-known members: pit vipers, including lanceheads, moccasins, rattlesnakes)

Pit viper venom characteristically contains a potent mix of enzymes that produce an emphatic degree of tissue destruction at the site of the bite. As with most venoms, there can be both local and systemic effects. However, unless a bite by a pit viper is "dry" (meaning no venom injected), there will ordinarily be marked inflammation at the site of the bite and possibly systemic effects.

Rattlesnakes range in size from small (pigmy rattlesnakes, Sistrurus) to large (many species of Crotalus, such as the Eastern diamondback, Crotalus adamanteus). Most pit vipers are potentially very active and aggressive snakes. The strike can be lightning quick, measured in one study as under 50ms [7].

[edit]Effects of Venom
Snake venoms contain molecules that are biologically active. The poison gland of snakes adds these molecules to saliva, which is the digestive juice produced by the mouth of most all land vertebrates. In nonvenemous snakes, and in other creatures, such as we humans, saliva moistens the food and initiates digestion with enzymes. In venemous snakes, the toxic molecules added to their specialized venom include some of the most powerful substances known in their effects on biological systems.

Some toxins take effect at the site of the bite, others are only active in certain tissues and cause their harmful effects once they reach these tissues through the blood stream. The effects of the snake venom on that victim are not always direct, sometimes the toxic substances trigger cascades of reactions, that, like a toppling row of dominoes, lead to many cumulative disruptions.

Hemorrhage and intravascular coagulation: disruption of the normal blood clotting pathways
Many components in snake venom disrupt normal blood flow and normal blood clotting (coagulation). Some common enzymes in snake venoms increase bleeding by preventing the formation of clots, and others by breaking down established clots. Both of these types of enzymes include metalloproteases. Other toxins increase 'bleeding time' by inhibiting the aggregation of platelets, the small odd-shaped blood cells that collect at the site of a tear in a blood vessel and form a plug to close it. Profound loss of blood can cause hemorrhagic shock, and disable a prey animal. When many tiny blood clots form in the bloodstream there is a pathological condition known as disseminated intravascular coagulation (DIC), which also causes shock. Some enzymes in snake venom set off DIC in the bloodstream of their envenomated prey by interfering with the activity of serine proteases involved in the regulation of hemostasis.

Infarction: Stroke and Heart Attack
Toxins that set off clotting within the blood vessels of envenomated animals can cause both stroke and heart attacks. Infarction is a medical term that means death to tissues because of a block in their blood supply, and clots within the arteries of the neck and brain, as well as the coronary arteries can deprive the blood supply enough to cause infarctions in these organs.

Some proteins secreted in snake venoms are toxins that affect nerves (neurotoxins) and the contractibilty of muscle. Most neurotoxins in snake venoms are too large to cross the blood-brain barrier, and so they usually exert their effects on the peripheral nervous system rather than directly on the brain and spinal cord. Many of these neurotoxins cause paralysis by blocking the neuromuscular junction. In fact, biologists first learned some of the details of how the neuromuscular junction normally functions by using purified snake venoms in physiology experiments.

[edit]The Neuromuscular Junction
The neuromuscular junction is the microscopic connection between a motor nerve fiber and a muscle fiber, and is a type of synapse. Muscle contractions are normally regulated by the electrical activity of large nerve cells in the spinal cord and brainstem, called motor neurons or motoneurons. These neurons have long axons ('nerve fibres') that end in contact usually with just a single muscle fibre. The axon endings make a specialized contact with the muscle fiber, that is very like the synapses 'synaptic contacts' between nerve cells in the brain. This contact zone is called the neuromuscular junction, and on both the muscle side and the nerve side of this junction there are specialized structures and specific proteins for regulating the passage of information from neuron to muscle fiber. The nerve ending is filled with small synaptic vesicles that contain neurotransmitters - chemical messengers. When the brain gives the command to move a muscle, electrical signals (action potentials) are propagated down the motoneuron axons to the endings. The endings are depolarized by these signals, and as a result voltage-sensitive calcium channels open in the nerve ending. This calcium entry causes some of the synaptic vesicles to fuse with the nerve cell membrane, causing them to release their chemical contents into the narrow cleft between nerve ending and muscle fiber. The most important of these messengers at the neuromuscular junction is acetylcholine. Across this tiny space between the nerve ending and the muscle cell, the acetylcholine molecules bind to other molecules - the acetylcholine receptor molecules (specifically, muscle-type nicotinic acetylcholine receptors). This receptor is a ligand-gated ion channel; when acetylcholine binds to it, the channel opens, allowing sodium to enter the muscle cell. The inflow of sodium ions causes the muscle fiber to become depolarized and as a result, voltage-sensitive calcium channels open, allowing calcium to enter. As calcium enters, it triggers further calcium release from stores inside the cell (in the sarcoplasmic reticulum), resulting in a 'wave' of calcium that spreads throughout the muscle fiber. The calcium interacts with filaments inside the muscle cell called myofibrils, causing them, and as a result the whole muscle fiber, to contract.

The effect of acetylcholine is normally very short lived, as it is rapidly destroyed by acetylcholinesterase, an enzyme produced both by the muscle fibres and by the motoneurons that very efficiently breaks down the acetylcholine. Without acetylcholinesterase, enough aceytlcholine would remain in the cleft between nerve fiber and muscle cell to keep reactivating the muscle contraction mechanism for a long time, producing a form of tetany.

Acethylcholine receptor blocked by cobra venomNeurotoxins in snake venom can block transmission of acetylcholine from nerve to muscle at the side of the nerve ending (pre-synaptic literally, before the synapse), or affect the activity of the muscle fiber past the synapse (post-synaptic literally after the synapse). Most commonly, the postsynaptic method of producing paralysis is an anti-cholinesterase toxin in venom that prevents acetylcholinesterase from degrading the acetylcholine. Most snake venoms contain toxins that cause paralysis by both methods: pre and postsynaptic interference. [8]. Presynaptic neurotoxins are commonly called ß-neurotoxins and have been isolated from venoms of snakes of families Elapidae and Viperidae. ß-Bungarotoxin was the first presynaptically active toxin to be isolated from Bungarus multicinctus (banded krait), which is an elapid. ß-bungarotoxin has a phospholipase subunit and a K+ channel binding subunit, and their combined effects are to destroy sensory and motor neurons [9] The banded krait venom also contains alpha-bungarotoxin, which binds to nicotinic acetylcholine receptors, thus preventing acetylcholine from doing so (i.e. it is a receptor antagonist), and kappa bungarotoxin, which is an antagonist of neuronal acetylcholine receptors.[10]

[edit]Relief of pain (analgesia) and feeling of well-being (euphoria)
One of the toxins of Crotalus durissus has been shown to act as a pain reliever in mice, apparently by a novel mechanism.

In a case report of a human bite by a king cobra, Ophiophagus hannah, in New York City, a 30 year old reptile importer was struck by a captive in the baggage department of Kennedy Airport. "The patient instantly felt a generalized "warm rush" soon followed by euphoria, "brightly colored visual hallucinations", a distorted perception of the passage of time and "razor-like pain" throughout the right arm." (reference for quote:Warren W. Wetzel and Nicholas P. Christy: A king cobra bite in New York City • SHORT COMMUNICATION, Toxicon, Volume 27, Issue 3, (1989) Pages 393-395)

[edit]Role of snake venom in medical and biological research
[edit]Basic research in physiology
[edit]Laboratory tests in medicine
Phospholipase A2 (which sets off the coagualtion of clotting factors in blood) makes up the majority of protein toxins in the venom of Russell's viper (Daboia russelii sp..). Dilute venom is sold commercially to medical laboratories. Russell's Viper Venom Clotting Time tests are routinely used to help diagnose certain kinds of abnormal antibodies. anticoagulants) in the serum of patients with the autoimmune disease, Lupus.

[edit]Therapeutic removal of thrombus
Fibrinolytic enzymes isolated from venom can directly break down a fibrin clot. Current medical research seeks to find such an enzyme to remove clots causing heart attacks and strokes.

[edit]Natural protection from venom: genes and antibodies
[edit]Among snakes
[edit]Among other animals
There are particular kinds of animals that have been noted to have some resistance to the effects of venom. Just as there seems to be a correlation between the toxic mix in snake venom and a prey animal, such that a given snake's venom is particularly toxic to that species preferred prey, some of the animals that have resistance to snake venom themselves prey on venomous snakes.

There are more than 30 species of mongoose, these small mammalian carnivores are found in Asia, Africa, the Caribbean, and southern Europe. Some species, particularly H. edwardsii, the Indian mongoose, eat snakes, including venemous snakes such as the cobra: Rudyard Kipling's story Rikki-Tikki-Tavi from The Jungle Book is about a young mongoose's fight with two cobras. The mongoose has been observed to survive envenomation by snakes, and was often thought to be somehow "immune" to the venom. Although the mongoose has no special immune powers against venom, there are some genetic traits that are protective.

In particular, the acetylcholine receptor in the mongoose has a slightly different protein sequence than that of animals who are easily paralyzed by (alpha)-bungarotoxin. In laboratory experiments, the reconstituted mongoose AChR alpha-subunit of the acetylcholine receptor did not bind (alpha)-bungarotoxin [11]. This is an example of natural resistance of the mongoose to a component of cobra venom, but it does not imply "immunity" in the sense of protection afforded the mongoose by its immune system.

Venom is milked from rear-fanged snake in Thailand.Antivenin is blood serum that is made by injecting partially denatured proteins from snake venom into large host animals, such as horses or sheep. These are given in low enough doses so that the animal is not harmed, but antibodies are produced to counter-act the active components of the venom. Early antivenins were problematic, because whole horse serum was used and many people suffered adverse reactions to the plasma. As refinements have been made in the purification of the antibody fractions of the serum, allergic and other reactions have been reduced.

As antivenins are specific antidotes that neutralize the particular active toxins of venoms, the type of antivenom must be properly matched to the snake responsible for the bite. Antivenins have revolutionized the treatment for the more deadly snake envenomations. For example, the first horse antivenin against against bites from Bungarus candidus in Vietnam changed the course of a group of patients from an 80% mortality to 100% recovery.[12]

[edit]Venomous snake bite
Not every snakebite involves venom. Not only are dry bites common among venomous snakes, but bites by nonvenomous snakes are commonly feared to have been inflicted by "the poisonous kind". Adding to the difficulty of accurately identifying a fleeing snake in the wild, is the fact that some snakes of both venomous and nonvenomous kinds are called by the exact same common name. For example, the name Puff adder is applied to entirely different kinds of snakes.

Even where there are laws against the keeping venomous snakes in captivity, enforcement is not strict enough to prevent this entirely. Additionally, though rarely, snakes can be introduced into distant locations through importation of goods. Therefore, a bite by a venomous snake that is not native to a particular geographic region is possible. However, statistically, the number and type of snake bites in the general population occurs in a geographic distribution that reflects the native habitat of these snakes, and, sometimes, occupations and recreational practices by residents and travellers that are at higher risk for snake bite.

Most envenomations from snakes occur in tropical countries. In areas where antivenom is available, along with technologically sophisticated medical care, mortality from venomous snake bite is very low. The World Health Organization has indicated that treatment for venomous snake bite is a health issue for the developing world.

Most snakebites in North America that require medical intervention are from pit vipers. "Eastern and western diamondback rattlesnakes (Crotalus adamanteus and C. atrox, respectively) are responsible for most snakebite deaths in the United States. However,the mortality rate is <1% for victims receiving antivenom". [13] Elapid envenomations do occur in the USA and Mexico from coral snakes. North American coral snakes include the eastern coral snake (Micrurus fulvius), the Texas coral snake (M. tener), and the Arizona (Sonoran) coral snake (Micruroides euryxanthus).
Central America
South America

Despite the paucity of native venomous snakes in Europe, there are reports of venomous snakebite. In 1970–77, 17 people in the UK were victims of 32 bites by foreign venomous snakes.
In North Africa and the Middle East, the desert horned vipers (genus Cerastes) is a distinctive snake of the desert sands, implicated in cases of snake bite reported in Dharan, Saudi Arabia. This snake is not uncommonly kept as a pet, and some cases reported by physicians have been due to the snake biting its captor during handling and occurred in places like Switzerland. [14]
Pit vipers exclusive to China include the large and spectacular Mt. Mang Viper (Trimeresurus mangshanensis) of the Hunan province. Many of the widespread elapid snakes, such as the King Cobra (Ophiophagus hannah), in southern China , are also native to Southeast Asia, including India and the Phillipines.
In Southern Asia, cobras are large snakes with potent venom that adapt to living in areas of human habitation. Although it is estimated that up to 45% of their bites are dry, in Burma and India, an annual mortality incidence of between 3 and 10 per 100,000 has been reported (but as most snake bites occur in areas without consistent medical reporting, estimates are very imprecise).
Every species of snake native to Australia is venomous. These include tiger snakes (Notechis), brown snakes (Pseudonaja).