Snake venom is a highly toxicsaliva[1] containingzootoxins that facilitates in the immobilization and digestion ofprey. This also provides defense against threats. Snake venom is usually injected by uniquefangs during abite, though some species are also able to spitvenom.[2]
Thevenom glands that secrete zootoxins are a modification of theparotid salivary glands found in othervertebrates and are usually located on each side of the head, below and behind the eye, and enclosed in a muscular sheath. The venom is stored in large glands calledalveoli before being conveyed by a duct to the base of channeled or tubular fangs through which it is ejected.[3][4]
Venom contains more than 20 different compounds, which are mostly proteins andpolypeptides.[3][5] The complex mixture of proteins, enzymes, and various other substances has toxic and lethal properties.[2] Venom serves to immobilize prey.[6]Enzymes in venom play an important role in the digestion of prey,[4] and various other substances are responsible for important but non-lethal biological effects.[2] Some of the proteins in snake venom have very specific effects on various biological functions, including blood coagulation, blood pressure regulation, and transmission of nerve or muscle impulses. These venoms have been studied and developed for use as pharmacological or diagnostic tools, and even drugs.[2][5]
Proteins constitute 90-95% of venom's dry weight and are responsible for almost all of its biological effects.[5][7] The hundreds, even thousands, of proteins found in venom include toxins,neurotoxins in particular, as well as nontoxic proteins (which also have pharmacological properties), and many enzymes, especiallyhydrolytic ones.[2] Enzymes (molecular weight 13-150 KDa) make up 80-90% ofviperid and 25-70% ofelapid venoms, including digestivehydrolases,L-amino-acid oxidase,phospholipases,thrombin-like pro-coagulant, andkallikrein-likeserine proteases andmetalloproteinases (hemorrhagins), which damage vascularendothelium. Polypeptide toxins (molecular weight 5-10 KDa) includecytotoxins,cardiotoxins, andpostsynaptic neurotoxins (such asα-bungarotoxin andα-Cobratoxin), which bind toacetylcholine receptors at neuromuscular junctions. Compounds with low molecular weight (up to 1.5 KDa) include metals, peptides, lipids,nucleosides, carbohydrates, amines, andoligopeptides, which inhibitangiotensin-converting enzyme (ACE) and potentiate bradykinin (BPP). Inter- and intra-species variation in venom chemical composition is geographical and ontogenic.[3]Phosphodiesterases interfere with the prey's cardiac system, mainly to lower theblood pressure.Phospholipase A2 causeshemolysis by lysing thephospholipidcell membranes ofred blood cells.[8] Amino acidoxidases andproteases are used for digestion. Amino acid oxidase also triggers some other enzymes and is responsible for the yellow colour of the venom of some species.Hyaluronidase increases tissue permeability to accelerate the absorption of other enzymes into tissues. Some snake venoms carryfasciculins, like themambas (Dendroaspis), which inhibitcholinesterase to make the prey lose muscle control.[9]
| Type | Name | Origin |
|---|---|---|
| Oxidoreductases | lactate dehydrogenase | Elapidae |
| L-amino-acid oxidase | All species | |
| Catalase | All species | |
| Transferases | Alanine amino transferase | |
| Hydrolases | Phospholipase A2 | All species |
| Lysophospholipase | Elapidae, Viperidae | |
| Acetylcholinesterase | Elapidae | |
| Alkaline phosphatase | Bothrops atrox | |
| Acid phosphatase | Deinagkistrodon acutus | |
| 5'-nucleotidase | All species | |
| Phosphodiesterase | All species | |
| Deoxyribonuclease | All species | |
| Ribonuclease 1 | All species | |
| Adenosine triphosphatase | All species | |
| Amylase | All species | |
| Hyaluronidase | All species | |
| NAD-Nucleotidase | All species | |
| Kininogenase | Viperidae | |
| Factor X activator | Viperidae, Crotalinae | |
| Heparinase | Crotalinae | |
| α-Fibrinogenase | Viperidae, Crotalinae | |
| β-Fibrinogenase | Viperidae, Crotalinae | |
| α-β-Fibrinogenase | Bitis gabonica | |
| Fibrinolytic enzyme | Crotalinae | |
| Prothrombin activator | Crotalinae | |
| Collagenase | Viperidae | |
| Elastase | Viperidae | |
| Lyases | Glucosaminate ammonia-lyase |
Snake toxins vary greatly in their functions. The two broad classes of toxins found in snake venoms areneurotoxins (mostly found in elapids) andhemotoxins (mostly found in viperids). However, exceptions occur – the venom of theblack-necked spitting cobra (Naja nigricollis), an elapid, consists mainly ofcytotoxins, while that of theMojave rattlesnake (Crotalus scutulatus), a viperid, is primarily neurotoxic. Both elapids and viperids may carry numerous other types of toxins.
| α-neurotoxins | α-Bungarotoxin, α-toxin,erabutoxin,cobratoxin |
|---|---|
| β-neurotoxins (PLA2) | β-Bungarotoxin, Notexin,ammodytoxin,crotoxin,taipoxin |
| κ-neurotoxins | Kappa-bungarotoxin |
| Dendrotoxins (Kunitz) | Dendrotoxin, toxins I and K; possiblyβ-Bungarotoxin chain B |
| Cardiotoxins | Naja nigricollis y-toxin,cardiotoxin III (aka cytotoxins) |
| Myotoxins | Myotoxin-a,crotamine |
| Sarafotoxins | Sarafotoxins a, b, and c |
| Hemorrhagins (metalloprotease) | Mucrolysin,Atrolysins,Acutolysins, etc.[11] |
| Hemotoxins (serine protease) | Venombin A |
 | This sectionis missing information about how evolutionary/structural classifications correspond to functional classifications. Please expand the section to include this information. Further details may exist on thetalk page.(August 2021) |
The beginning of a new neural impulse goes as follows:
Myotoxins are small, basicpeptides found inrattlesnake[16][17] andlizard (e.g.Mexican beaded lizard)[18] venoms. This involves a non-enzymatic mechanism that leads to severeskeletal musclenecrosis. These peptides act very quickly, causing instantaneousparalysis to preventprey from escaping and eventually death due todiaphragmatic paralysis.
The first myotoxin to be identified and isolated wascrotamine, discovered in the 1950s byBrazilianscientistJosé Moura Gonçalves from the venom of tropical South American rattlesnakeCrotalus durissus terrificus. Its biological actions,molecular structure andgene responsible for its synthesis were all elucidated in the last two decades.
| This sectionis missing information about why albumin dilution works better. Please expand the section to include this information. Further details may exist on thetalk page.(August 2021) |
Snake venom toxicity is assessed by a toxicological test called themedian lethal dose, lethal dose 50% (abbreviated as LD50), which determines the concentration of a toxin required to kill half the members of a tested population. The potency of wild snake venom varies considerably because of assorted influences such asbiophysical environment, physiological status,ecological variables, genetic variation (eitheradaptive or incidental), and other molecular and ecological evolutionary factors.[citation needed] This is true even for members of one species. Such variation is smaller in captive populations in laboratory settings, though it cannot be eliminated. However, studies to determine snake venom potency must be designed to minimize variability.
Several techniques have been designed to this end. One approach is to use 0.1% bovine serum albumin (also known as "fraction V" inCohn process) as a diluent in determining LD50 values. It results in more accurate and consistent LD50 determinations than using 0.1% saline as a diluent. For example, fraction V produces about 95% purified albumin (dried crude venom). Saline as a diluent consistently produces widely varying LD50 results for nearly all venomous snakes. It produces unpredictable variation in precipitate purity (35-60%).[19] Fraction V is structurally stable because it has seventeendisulfide bonds; it's unique in that it has the highest solubility and lowestisoelectric point of major plasma proteins. This makes it the final fraction to be precipitated from its solution.Bovine serum albumin is located in fraction V. The precipitation of albumin is done by reducing the pH to 4.8, near the pH of the proteins, and maintaining the ethanol concentration at 40%, with a protein concentration of 1%. Thus, only 1% of the original plasma remains in the fifth fraction.[20]
When the ultimate goal of plasma processing is a purified plasma component forinjection ortransfusion, the plasma component must be highly pure. The first practical large-scale method of blood plasma fractionation was developed byEdwin J. Cohn duringWorld War II. it's known as theCohn process (or Cohn method). This process is also known as cold ethanol fractionation, as it involves gradually increasing theconcentration ofethanol in thesolution at 5 °C and 3 °C.[21] The Cohn Process exploits differences in plasma proteins properties, specifically, the highsolubility and lowpI of albumin. As the ethanol concentration is increased in stages from 0 to 40%, the pH declines from neutral (pH ~ 7) to about 4.8, which is near the pI of albumin.[21] At each stage, proteins areprecipitated out of the solution and removed. The finalprecipitate is purified albumin. Several variations to this process exist, including an adapted method by Nitschmann and Kistler that uses fewer steps, and replacescentrifugation and bulk freezing withfiltration and diafiltration.[21][22] Some newer methods of albumin purification add additional purification steps to the Cohn process and its variations. Chromatographic albumin processing emerged in the 1980s, however, it was not widely adopted until later due to the scarity of large-scalechromatography equipment. Methods incorporating chromatography generally begin with cryo-depleted plasma undergoing buffer exchange via eitherdiafiltration or buffer exchange chromatography, to prepare the plasma for followingion exchange chromatography steps. After ion exchange, generally purification steps and buffer exchange occur.[21]
However, chromatographic methods began to be adopted in the 1980s.[citation needed] Developments were ongoing between when Cohn fractionation started emerge in 1946, and whenchromatography emerged, in 1983. In 1962, the Kistler and Nistchmann process was created as a spin-off of the Cohn process. In the 1990s, the Zenalb and the CSL Albumex processes were created, which incorporated chromatography with variations. The general approach to using chromatography for plasma fractionation for albumin is: recovery of supernatant I, delipidation,anion exchange chromatography, cation exchange chromatography, and gel filtration chromatography. The recovered purified material is formulated with combinations of sodium octanoate and sodium N-acetyl tryptophanate and then subjected to viral inactivation procedures, including pasteurization at 60 °C. This is a more efficient alternative than the Cohn process because:
Compared with the Cohn process, albumin purity increased from about 95% to 98% using chromatography, and the yield increased from about 65% to 85%. Small percentage increases make a difference in regard to sensitive measurements such as purity. The big drawback has to do with the economics. Although the method offered efficient, acquiring the necessary equipment was difficult. Large machinery is necessary, and for a long time, the lack of equipment availability limited its widespread use.[citation needed]
Venom evolved just once among allToxicofera about 170 million years ago, and then diversified into the huge venom diversity seen today.[23] The original toxicoferan venom was a very simple set of proteins that were assembled in a pair of glands. Subsequently, this set of proteins evolved independently in the various lineages of toxicoferans, includingSerpentes,Anguimorpha, andIguania.[24] Several snake lineages have since lost the ability to produce venom, often due to a change in diet or a change in predatory tactics.[23] In addition to this, venom strength and composition has changed due to changes in the prey of certain snake species. For example, the venom of the marbled sea snake (Aipysurus eydouxii) became significantly less toxic after the diet of this species changed from fish to strictly fish eggs.[23] The evolution of venom is thought to be responsible for the enormous expansion of snakes across the globe.[23][25]
The mechanism of evolution in most cases has beengene duplication in tissues unrelated to the venom.[24] Pre-existing salivary proteins are the likely ancestors of most venom toxin genes.[26] Expression of the new protein in the venom gland followed duplication.[24] Then proceedednatural selection foradaptive traits following the birth-and-death model, where duplication is followed by functional diversification, resulting in the creation of structurally related proteins that have slightly different functions.[23][24][27] The study of venom evolution has been a high priority for scientists in terms of scientific research, due to the medical relevance of snake venom, in terms of making antivenom and cancer research. Knowing more about the composition of venom and the ways it can potentially evolve is very beneficial. Three main factors that affect venom evolution have been closely studied: predators of the snake that are resistant to snake venom, prey that are in anevolutionary arms race with snakes, and the specific diets that affect the intraspecific evolution of venom.[23][28] Venoms continue to evolve as specific toxins and are modified to target a specific prey, and toxins are found to vary according to diet in some species.[29][30]
Rapid venom evolution can also be explained by the arms race between venom-targeted molecules in resistant predators, such as theopossum, and the snake venom that targets the molecules. Scientists performed experiments on the opossums and found that multiple trials showed replacement to silent substitutions in the von Willebrand factor (vWf) gene that encodes for a venom-targeted hemostatic blood protein. These substitutions are thought to weaken the connection between vWf and a toxic snake venom ligand (botrocetin), which changes the net charge and hydrophobicity. These results are significant to the venom evolution because it's the first citation of rapid evolution in a venom-targeted molecule. This shows that an evolutionary arms race may be occurring in terms of defensive purposes. Alternative hypotheses suggest that venom evolution is due to trophic adaption, whereas these scientists believe, in this case, that selection would occur on traits that help with prey survival in terms of venom evolution instead of predation success. Several other predators of the pit viper (mongooses and hedgehogs) show the same type of relationship between snakes, which helps to support the hypothesis that venom has a very strong defensive role along with a trophic role. Which in turn supports the idea that predation on the snakes can be the arms race that produces snake venom evolution.[31]
Some of the various adaptations produced by this process include venom more toxic to specific prey in several lineages,[30][32][33] proteins that pre-digest prey,[34] as well as a method to track down prey after a bite.[35] Though venom function has evolved to be specific to prey class (e.g. particular coagulatory effects),[36] the evolution of broad toxicological effects (e.g.neurotoxicity or coagulotoxicity) does not appear to be broadly affected by prey type.[37] The presence ofdigestive enzymes in snake venom was once believed to be an adaptation to assist digestion. However, studies of thewestern diamondback rattlesnake (Crotalus atrox), a snake with highlyproteolytic venom, show that venom has no impact on the time required for food to pass through thegut.[38] These various adaptations of venom have also led to considerable debate about the definition of venom and venomous snakes.[23]
Invipers, which have the most highly developed venom-delivery apparatus, the venom gland is very large and is surrounded by themasseter ortemporal muscle, which consists of two bands, the superior arising from behind the eye, the inferior extending from the gland to the mandible. A duct carries venom from the gland to the fang. In vipers and elapids, this groove is completely closed, forming a hypodermic needle-like tube. In other species, the grooves are not covered, or only partially covered. From the anterior extremity of the gland, the duct passes below the eye and above themaxillary bone, to the basal orifice of the venom fang, which is ensheathed in a thick fold ofmucous membrane. By means of the movable maxillary bone hinged to the prefrontal bone and connected with the transverse bone, which is pushed forward by muscles set in action by the opening of the mouth, the fang is erected and the venom discharged through the distal orifice. When the snake bites, the jaws close and the muscles surrounding the gland contract, causing venom to be ejected via the fangs.
In theproteroglyphouselapids, the fangs are tubular, but are short and do not possess the mobility seen in vipers.
Opisthoglyphouscolubrids have enlarged, grooved teeth situated at the posterior extremity of themaxilla, where a small posterior portion of the upper labial or salivary gland produces venom.
Several genera, includingAsian coral snakes (Calliophis),burrowing asps (Atractaspis), andnight adders (Causus), are remarkable for having exceptionally long venom glands, extending along each side of the body, in some cases extending posterially as far as the heart. Instead of the muscles of the temporal region serving to press out the venom into the duct, this action is performed by those of the side of the body.
Considerable variability in biting behavior is seen among snakes. When biting, viperid snakes often strike quickly, discharging venom as the fangs penetrate the skin, and then immediately release. Alternatively, as in the case of a feeding response, some viperids (e.g.Lachesis) bite and hold. Aproteroglyph oropisthoglyph may close its jaws and bite or chew firmly for a considerable time.
Differences in fang length between the various venomous snakes are likely due to the evolution of different striking strategies.[39] Additionally, it has been shown that the fangs of different species of venomous snakes have different sizes and shapes depending on the biomechanical properties of the snake's prey.[40]
Spitting cobras of the generaNaja andHemachatus, when irritated or threatened, may eject streams or a spray of venom a distance of 1.2 metres (4 ft) to 2.4 metres (8 ft). These snakes' fangs have been modified for the purposes of spitting; inside the fangs, the channel makes a 90° bend to the lower front of the fang. Spitters may spit repeatedly and still be able to deliver a fatal bite.
Spitting is a defensive reaction only. The snakes tend to aim for the eyes of a perceived threat. A direct hit can cause temporary shock and blindness through severeinflammation of thecornea andconjunctiva. Although usually no serious symptoms result if the venom is washed away immediately with plenty of water, blindness can become permanent if left untreated. Brief contact with the skin is not immediately dangerous, but open wounds may be vectors for envenomation.
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The four distinct types of venom act on the body differently:
The effect of the venom ofproteroglyphous snakes (sea snakes,kraits,mambas,black snakes,tiger snakes, anddeath adders) is mainly on thenervous system, respiratoryparalysis being quickly produced by bringing the venom into contact with the central nervous mechanism that controls respiration; the pain and local swelling that follow a bite are not usually severe. The bite of all the proteroglyphous elapids, even of the smallest and gentlest, such as thecoral snakes, is, so far as known, deadly to humans. However, some mildly venomous elapids remain, such as the hooded snakes (Parasuta), bandy-bandies (Vermicella), etc.
Viper venom (Russell's viper,saw-scaled vipers,bushmasters, andrattlesnakes) acts more on the vascular system, bringing about coagulation of the blood and clotting of the pulmonary arteries; its action on the nervous system is not great, no individual group ofnerve-cells appears to be picked out, and the effect upon respiration is not so direct; the influence upon the circulation explains the great depression, which is a symptom of viperine envenomation. The pain of the wound is severe and is rapidly followed by swelling and discoloration. The symptoms produced by the bite of the European vipers are thus described by Martin and Lamb:[41]
The bite is immediately followed by the local pain of a burning character; the limb soon swells and becomes discolored, and within one to three hours great prostration, accompanied byvomiting, and oftendiarrhea, sets in. Cold, clammy perspiration is usual. The pulse becomes extremely feeble, and slightdyspnoea and restlessness may be seen. In severe cases, which occur mostly in children, the pulse may become imperceptible and the extremities cold; the patient may pass intocoma. In from twelve to twenty-four hours these severe constitutional symptoms usually pass off; but in the meantime, the swelling and discoloration have spread enormously. The limb becomes phlegmonous and occasionally suppurates. Within a few days recovery usually occurs somewhat suddenly, butdeath may result from the severe depression or from the secondary effects ofsuppuration. That cases of death, in adults as well as in children, are not infrequent in some parts of the Continent is mentioned in the last chapter of this Introduction.
The Viperidae differ much among themselves in the toxicity of their venoms. Some, such as the Indian Russell's viper (Daboia russelli) and saw-scaled viper (E. carinatus); the American rattlesnakes (Crotalus spp.), bushmasters (Lachesis spp.), andlanceheads (Bothrops spp.); and theAfrican adders (Bitis spp.),night adders (Causus spp.), andhorned vipers (Cerastes spp.), cause fatal results unless a remedy is speedily applied. The bite of the larger European vipers may be very dangerous, and followed by fatal results, especially in children, at least in the hotter parts of the Continent; whilst the smallmeadow viper (Vipera ursinii), which hardly ever bites unless roughly handled, does not seem to be possessed of a very virulent venom, and although very common in some parts ofAustria andHungary, is not known to have ever caused a serious accident.
Biologists had long known that some snakes had rear fangs, 'inferior' venom injection mechanisms that might immobilize prey; although a few fatalities were on record, until 1957, the possibility that such snakes were deadly to humans seemed at most remote. The deaths of two prominent herpetologists,Robert Mertens andKarl Schmidt, from African colubrid bites, changed that assessment, and recent events reveal that several other species of rear-fanged snakes have venoms that are potentially lethal to large vertebrates.
Boomslang (Dispholidus typus) andtwig snake (Thelotornis spp.) venoms are toxic to blood cells and thin the blood (hemotoxic, hemorrhagic). Early symptoms include headaches, nausea, diarrhea, lethargy, mental disorientation, bruising, and bleeding at the site and all body openings.Exsanguination is the main cause of death from such a bite.
The boomslang's venom is the most potent of all rear-fanged snakes in the world based on LD50. Although its venom may be more potent than some vipers and elapids, it causes fewer fatalities owing to various factors (for example, the fangs' effectiveness is not high compared with many other snakes, the venom dose delivered is low, and boomslangs are generally less aggressive in comparison to other venomous snakes such as cobras and mambas). Symptoms of a bite from these snakes include nausea and internal bleeding, and one could die from abrain hemorrhage andrespiratory collapse.
Experiments made with the secretion of theparotid gland ofRhabdophis andZamenis have shown that evenaglyphous snakes are not entirely devoid of venom, and point to the conclusion that the physiological difference between so-called harmless and venomous snakes is only one of degree, just as various steps exist in the transformation of an ordinary parotid gland into a venom gland or of a solid tooth into a tubular or grooved fang.
Given that snake venom contains many biologically active ingredients, some may be useful to treat disease.[42]
For instance,phospholipases type A2 (PLA2s) from the Tunisian vipersCerastes cerastes andMacrovipera lebetina have been found to have antitumor activity.[43] Anticancer activity has been also reported for other compounds in snake venom.[44][45] PLA2s hydrolyze phospholipids, thus could act on bacterial cell surfaces, providing novel antimicrobial (antibiotic) activities.[46]
Theanalgesic (pain-killing) activity of many snake venom proteins has been long known.[47][48] The main challenge, however, is how to deliver protein to the nerve cells: proteins usually are not applicable as pills.
The question whether individual snakes are immune to their own venom has not yet been definitively settled, though an example is known of a cobra that self-envenomated, resulting in a largeabscess requiring surgical intervention, but showing none of the other effects that would have proven rapidly lethal in prey species or humans.[49] Furthermore, certain harmless species, such as theNorth Americancommon kingsnake (Lampropeltis getula) and theCentral andSouth Americanmussurana (Clelia spp.), are proof against the venom of thecrotalines, which frequent the same districts, and which they are able to overpower and feed upon. Thechicken snake (Spilotes pullatus) is the enemy of thefer-de-lance (Bothrops caribbaeus) in St. Lucia, and in their encounters, the chicken snake is invariably the victor. Repeated experiments have shown the Europeangrass snake (Natrix natrix) not to be affected by the bite of theEuropean adder (Vipera berus) and theEuropean asp (Vipera aspis), this being due to the presence, in the blood of the harmless snake, of toxic principles secreted by the parotid and labial glands, and analogous to those of the venom of these vipers. Several North American species of rat snakes, as well as king snakes, have proven to be immune or highly resistant to the venom of rattlesnake species. The king cobra, which does prey on cobras, is said to be immune to their venom.
Thehedgehog (Erinaceidae), themongoose (Herpestidae), thehoney badger (Mellivora capensis) and theopossum are known to be resistant to a dose of snake venom.[citation needed] Recently, the honey badger and domestic pig were found to have convergently evolved amino-acid replacements in their nicotinic acetylcholine receptor, which are known to confer resistance to alpha-neurotoxins in hedgehogs.[50] Whether thepig may be considered immune is still uncertain, though early studies show endogenous resistance in pigs tested against neurotoxins.[51] Though the pig'ssubcutaneous layer of fat may protect it against snake venom, most venoms pass easily through vascular fat layers, making this unlikely to contribute to its ability to resist venoms. Thegarden dormouse (Eliomys quercinus) has recently been added to the list of animals refractory to viper venom. Some populations ofCalifornia ground squirrel (Otospermophilus beecheyi) are at least partially immune to rattlesnake venom as adults.
The acquisition of human immunity against snake venom is ancient (from around 60 CE,Psylli tribe).[52] Research into development of vaccines that will lead to immunity is ongoing.Bill Haast, owner and director of the Miami Serpentarium, injected himself with snake venom during most of his adult life, in an effort to build up an immunity to a broad array of venomous snakes, in a practice known asmithridatism. Haast lived to age 100, and survived a reported 172 snake bites. He donated his blood to be used in treating snake-bite patients when a suitable antivenom was not available. More than 20 so-treated individuals recovered.[53][54][55] Amateur researcherTim Friede also lets venomous snakes bite him in the hopes of a vaccine against snake venom being developed, and has survived over 650 bites from different species as of May 2025. Researchers reported 856 documented self-immunizations by him over an 18 year period.[56] Scientists identified multiple antibodies in Friede's blood that are capable of neutralizing venom from multiple snake species, and are hopeful that these may be used to produce a universal antivenom.[57]
TheWorld Health Organization estimates that 80% of the world's population depends on traditional medicine for their primary health-care needs.[58] Methods of traditional treatments of snakebites, although of questionable efficacy and perhaps even harmful, are nonetheless relevant.
Plants used to treat snakebites in Trinidad and Tobago are made into tinctures with alcohol or olive oil and kept in rum flasks called snake bottles, which contain several different plants and/or insects. The plants used include the vine called monkey ladder (Bauhinia cumanensis orBauhinia excisa, Fabaceae), which is pounded and put on the bite. Alternatively, a tincture is made with a piece of the vine and kept in a snake bottle. Other plants used include mat root (Aristolochia rugosa), cat's claw (Pithecellobim unguis-cati), tobacco (Nicotiana tabacum), snake bush (Barleria lupulina), obie seed (Cola nitida), and wild gri gri root (Acrocomia aculeata). Some snake bottles also contain the caterpillars (Battus polydamas, Papilionidae) that eat tree leaves (Aristolochia trilobata). Emergency snake medicines are obtained by chewing a three-inch piece of the root of bois canôt (Cecropia peltata) and administering this chewed-root solution to the bitten subject (usually a hunting dog). This is a common native plant of Latin America and the Caribbean, which makes it appropriate as an emergency remedy. Another native plant used is mardi gras (Renealmia alpinia) (berries), which are crushed together with the juice of wild cane (Costus scaber) and given to the bitten. Quick fixes have included applying chewed tobacco from cigarettes, cigars, or pipes.[59] Making cuts around the puncture or sucking out the venom had been thought helpful in the past, but this course of treatment is now strongly discouraged, due to the risk of self-envenomation through knife cuts or cuts in the mouth (suction cups from snake bite kits can be used, but suctioning seldom provides any measurable benefit).[60][61]
Serotherapy usingantivenom is a common current treatment and has been described back in 1913.[note 1] Both adaptive immunity and serotherapy are specific to the type of snake; venom with identical physiological action do not cross-neutralize. Boulenger 1913 describes the following cases:
A European in Australia who had become immune to the venom of the deadly Australiantiger snake (Notechis scutatus), manipulating these snakes with impunity, and was under the impression that his immunity extended also to other species, when bitten by alowland copperhead (Austrelaps superbus), an allied elapine, died the following day.
InIndia, the serum prepared with the venom ofmonocled cobraNaja kaouthia has been found to be without effect on the venom of two species ofkraits (Bungarus), Russell's viper (Daboia russelli), saw-scaled viper (Echis carinatus), andPope's pit viper (Trimeresurus popeiorum). Russell's viper serum is without effect on colubrine venoms, or those ofEchis andTrimeresurus.
InBrazil, serum prepared with the venom of lanceheads (Bothrops spp.) is without action on rattlesnake (Crotalus spp.) venom.
Antivenom snakebite treatment must be matched as the type of envenomation that has occurred. In the Americas, polyvalent antivenoms are available that are effective against the bites of most pit vipers.Crofab is the antivenom developed to treat the bite of North American pit vipers.[62] These are not effective againstcoral snake envenomation, which requires a specific antivenom to their neurotoxic venom. The situation is even more complex in countries such as India, with its rich mix of vipers (Viperidae) and highly neurotoxic cobras and kraits of the Elapidae.
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