Snake venom

“ When envenoming does occur, it can be rapidly life-threatening. Snake venom is a complex mixture of toxins and enzymes, each of which may be responsible for one or more distinct toxic actions. In bites by South Asian viperid snakes, envenoming results in local pain and tissue damage, characterised by swelling, blistering, bleeding, and necrosis at the bite site, sometimes extending to the whole limb [40] . Viperid venoms can also induce coagulopathy and platelet dysfunction, leading to spontaneous systemic haemorrhages and persistent bleeding from fang marks, wounds, or gums (Figure 1) . ”

“ First, it may be as well to impressively repeat what has been already constantly affirmed by all our scientific experimentalists on snake venoms, that ‘as yet no antidote to them has been found.’ Remedies there are in abundance; and it is just as great an error to believe that all snake venom is incurable—i.e. that a bitten person must necessarily die—as that there are countless ‘antidotes,’ as persons broadly and loosely call the various means of cure. ”

“ And assuredly the remedies are generally so severe as to be in themselves sufficiently terrifying. ‘No time for reflection;’ ‘no mercy must be shown,’ declares Sir Joseph Fayrer, in describing the incredible rapidity with which the venom inoculates the blood ‘in a moment of time.’ Where a deep wound has been inflicted by a highly venomous snake on a small animal, death has been known to occur in a few seconds, especially if the bite were on a large vein or an artery. Therefore if the bite be on a limb, to tie a ligature is the first thing to be done. ”

“ It is very difficult to specify, even within broad limits, the dose of venom necessary to kill a human being. The quantity of poison introduced by the bite of a venomous snake depends, as has already been stated, upon a large number of factors, and, very fortunately, this quantity is not always sufficient to cause death. Thus in India, that is to say in the region in which snakes are most numerous and most dangerous, the mean mortality seems scarcely to exceed 35 to 40 per cent., so far as it is possible to judge from official statistics. ”

“ The venom contains digestive enzymes that start digesting the prey from the inside.
Snakes grow rapidly till they mature and then continue to grow very slowly till their death. As they grow, they outgrow their skin so they moult the old one after a new skin has formed under it. The snake splits the old skin at the nose and literally crawls out of the old skin. During moulting, the snake stops eating but becomes aggressive.
A bite from a poisonous snake affects either the nervous system (neurotoxic) or the blood vessels (hemotoxic) of human beings. ”

“ The power of a strike imbeds the fangs into the skin of the victim, and muscles force venom from the glands through the duct and hollow fang and out of the opening at the tip. The venom causes a breakdown of the red blood corpuscles and walls of blood vessels. It also has an effect upon the nervous system. Some snakes have venom which is much more destructive to the nervous system. The pit vipers have venom which is more hemotoxic (destructive to blood) , whereas the coral snake, which belongs to the cobra group, has a venom which is neurotoxic (destructive to nerves) . ”

“ The supply may be readily exhausted; for a time the bite would then be harmless. Contrary to the general impression, snake-venom when swallowed is a deadly poison, as proved by the experiments of Fayrer, Mitchell, and Reichert. Death is most likely caused by paralysis of the vital centers through the circulation. In this country the wounds invariably are on the extremities, while in India the cobra sometimes strikes on the shoulder or neck.
If called on to describe accurately the symptoms of snake-venom poisoning, few medical men could respond correctly. ”

“ In hot countries, on the other hand, they attain large dimensions, their venom is much more active, and, although they hardly ever attack man, and in most cases avoid him, they cause a considerable number of fatal accidents.
It is sometimes a rather difficult matter to recognise from the mere appearance of a snake whether it is poisonous or not. Naturalists themselves are occasionally deceived. It is therefore useful to learn to distinguish the most dangerous species by their external characters, and to know in what countries there is a risk of their being encountered. ”

“ On making an autopsy of an animal which has succumbed to intoxication by snake-venom, we find that the blood in the heart and large vessels is sometimes coagulated into a mass, sometimes entirely fluid, and that, in certain cases, it is as black as prune-juice, while in others it is of a fine transparent red colour. ”

“ In its slow, stealthy movements there is the same striking contrast between the Heloderm and most other lizards, that there is between the deadly vipers and the active colubrine snakes; and the inquiry suggests itself, Can the venom elaborated in their system so act upon themselves as to produce this habitual lethargy? Drowsiness and coma are almost invariable effects of snake venom in the blood, and why is it that the deadly serpents are so constitutionally different from others? ”

“ Clinical Features of Snake Bite Envenoming
A widespread belief is that snake bites inevitably result in envenoming. However, bites by nonvenomous snakes are common and bites by venomous species are not always accompanied by the injection of venom (dry bites) . A large survey conducted in ten hospitals of southern Nepal revealed that envenoming occurred in only 10% of the victims [10] . In Kerala, India, only 219 out of 635 patients (34%) with proven snake bite developed signs of systemic envenoming [18] . ”

“ One of the most important yet undeterminable factors of the gravity of snakebite is the amount of venom injected into the victim. Since this volume varies considerably in every bite, attempts have been made to determine the amount and toxicity of venom produced by each species of poisonous snake. Individual yield is so variable that a large number of snakes must be milked in order to determine the average yield. ”

“ The abundant saliva must be a powerful agent in the process, because mastication takes no share in the work. This has become more than mere conjecture, since recent experiments have shown that snake venom possesses strong peptic qualities; that, like pancreatic juice, it will even dissolve raw meat and albuminous substances. Recent experiments have also shown that the salivary gland is the laboratory in which the poison of venomous serpents is elaborated; that ordinary saliva is there intensified, concentrated, and endowed with its toxic properties. ”

“ SNAKE-CHARMERS.
In all the countries of the globe where poisonous snakes are formidable to man, there are certain individuals who profess to be secure from all ill-effects from the bites of these reptiles, whether because they are immune to venom, or because they possess secrets which enable them to cure themselves when they happen to have been bitten. Not unnaturally these secrets are sometimes turned to profitable account, and the possessors of them generally enjoy considerable popular influence, and are very highly venerated. ”

“ I have never met a native who knew that a venomous snake could be distinguished by its fangs, except a few doctors and educated men who have imbibed western science. In fact they do not think of the venom as a material substance situated in the mouth. It is an effluence from the entire animal, which may be projected at a man in various ways, by biting him, or spitting at him, or giving him a flick with the tail.
The Government of India spends a large sum of money every year in rewards for the destruction of snakes. ”

“ When the quantity of venom introduced into the organism is insufficient to cause death, the phenomena that precede and accompany recovery differ very greatly according as the snake from which the venom was derived belongs to the Colubridæ or Viperidæ.
After a non-lethal bite from a Cobra or Krait, for example, convalescence usually takes place very rapidly, and, apart from the local œdema of the subcutaneous tissue surrounding the wound, which in very many cases leads to the formation of a suppurating abscess, no lasting injury to health is observed. ”

“ The venom is related to snake poison, but is neither crotaline nor elapine. From animal experiments it is thought that it might be fatal to man under unfavorable conditions. There are no fangs proper. The poison gland is in the lower jaw, instead of in the upper, as in snakes, and its product is projected through small ducts which open in the gums outside the teeth. The Gila monster has the grip of a bulldog. Torture will not loosen its hold, once fastened on. It is through this intimate contact that the venom works into the wounds. ”

“ Fishes succumb rapidly to snake-venom, 172. “ venomous, 288. ““ poison-apparatus of, 289. Flexner and Noguchi, on action of snake-serum on red corpuscles, 219. ““ cytolytic action of venoms, 206. ““ investigations on toxicity of snakes’ organs, 220. Food, abstinence from, by snakes, 149. Fowls killed by causing them to ingest venom, 180. Fox, W. A., bite from Sepedon hæmachates, 337. France, mortality from snake-bite in, 3. Fraser, on destructive action of bile on cobra-venom, 215. 383 Frog-serum, antidote to poison of pedicellariæ, 274. Frogs succumb slowly to snake-poisoning, 172. ”

“ Poison Apparatus.—The grooved or furrowed teeth in the Proteroglypha and the canaliculate teeth in the Solenoglypha are arranged, not for the purpose of seizing 9 prey, but in order to deal it a mortal blow by injecting the venom into its flesh.
In the normal position they lie almost horizontally, and exhibit no mobility of their own. But, when the animal prepares to bite, their erection is effected by the snake throwing its jaw back; and this movement, which is always very sudden, enables it at the same time to compress its poison-glands, by the aid of special constrictor muscles. ”

“ When inoculated into frogs it produces œdema and hæmorrhage; if injected into warm-blooded animals it causes necrosis. In sufficiently strong doses it kills by arresting respiration. Its effects strongly resemble those produced by Viperine venoms. This venom, if attenuated by being heated at 50° C. and injected into mammals, vaccinates them and leads to the formation in their blood of antitoxic substances, which are capable of preventing intoxication by salamander-venom, and, curiously enough, also confer immunity against viper-venom and the serum of the common snake. ”

“ At the Pondicherry Hospital venom is collected in the following manner;168 The snake is brought by the snake-charmer in a chatty, a kind of earthern pot, covered with a rag, or half a calabash. Ensconced at the bottom of this receptacle, the reptile has a difficulty in making up its mind to emerge, which it does only after having been stirred up several times. Once it is outside the charmer forces the cobra to uncoil, and, while the animal is moving slowly along, fastens it to the ground by placing the end of a bamboo on its neck, quite close to the head. ”

“ During my stay at the snake park I was bitten on several occasions by a variety of non-poisonous (but hot-tempered) snakes and when I left after 3 weeks I had at least about 15-20 bites on my arms. Some of the bites were quite painful and one was so bad that my wrist had swelled up and I couldn't wear my watch for quite sometime. However when you remember that the snake gets damaged much more than you-it loses quite a few of its teeth in the bite-then you don't feel too bad. At any rate there was no question of using anti-venom as the snakes were all non-poisonous. ”

“ The ringhals, when excited, exudes a quantity of venom, which drips down the fangs and lodges behind the abrupt, horny, lower lip. Upon this the angry snake directs a blast of air through its extensible windpipe, with the effect that a jet of fine venom spray is emitted toward an enemy. This jet may reach a height of six feet. That the eyes are aimed at I have proved by experiment. If the poison reaches them blindness, which may be permanent, results. The bite of the ringhals is highly venomous, but the snake appears to prefer disabling its enemy by means of the spray of venom. ”

“ This we can understand from the indiscriminate use of such vernaculars as ‘adder,’ ‘jararaca,’ ‘cobra,’ as explained in previous chapters. Or, if undoubtedly a bite has been given by an undoubtedly venomous kind, it does not follow that a full charge of venom accompanied the bite. The glands may have been previously exhausted, the snake may have been feeble, or it might not have expended its poison. For among other marvels we are led to believe that vipers, perhaps also the elapidæ, have a control over their store of venom, and do not involuntarily expend it, that is, when forced to bite. ”

“ Facial bones, special arrangements of, characteristic of poisonous snakes, 6. Fasting, prolonged, snake-venom shows greatest activity after, 176. Faust, S., salamandrine prepared by, 316. Fayrer, Sir J., fatal results of experimental ingestion of venoms, 180. ““ on the daboia (Vipera russellii) , 47. ““ habits of the krait (Bungarus candidus) , 33. ““ harmless ingestion of venom exceeding lethal dose, 214. ““ Naja bungarus, 39. Feeding, artificial, in laboratories for collection of venom, 157. ““ of poisonous snakes, 17, 18. Fer-de-lance (Lachesis lanceolatus) , 112, 113, 114. ”