The knowledge regarding snakes and the effects produced by their venoms date back to the remotest past. The symptoms produced by snake venom and the different remedies applied to relieve its effects have formed the subject of study by the ancient peoples. Folk tales about the peculiar symptoms produced by snake venom in man and the wonderful after effects of sub- lethal doses are many, and venoms have been regarded as a panacea for many incurable diseases by even those practising the healing art. In fact, the snake has become an ideal of the art of healing, magic and authority in Greek mythology.
The emblematic figures of Asklepios, an an old man reclining on a staff with snakes coiling around it and his sister Hygeia as a woman holding a snake in one hand and a bowl in the other are well known. The Roman mark of healing “Caudeceus is represented by flying wings attached to a staff with a pair of snakes coiling round it. According to Hindu ideas Seshanaga holds his hood of a thousand heads over the head of Sri Bhagawan, the Lord of the universe. Siva, who revealed the Ayurveda to the world, has been shown with coils of snake round His neck. Basuki, the lord of the snakes, holds this earth on his head. The mark on the head of the cobra, resembling somewhat the Greek letter “Omega” is considered holy by many in India.
It was only during the last thirty years that attempts have been made, by the Allopathic school of medicine, to study the therapeutic effects of snake poisons in various diseases and to give a scientific explanation of how they are produced. While the first trituration and first dilution in alcohol of the snake poison. Trigonocephalus Lachesis was made by Constantine Hering on July 28, 1828, the first cases were published in the Archives in 1835. In 1837 this remedy was introduced into our Materia Medica (Wirkungen des Schlangengiftes) by Constantine Hering.
There are about 15,000 species of snakes in the world and about 110 varieties exist in India. Out of these, 69 species (40 land and 29 seas snakes) are poisonous. Excluding the poisonous sea snake it is apparent that one is exposed, taking India as a whole, to the bites of 81 species, out of which only 40 (50 percent) are poisonous. The commonest poisonous snakes are the cobra, krait, daboia, echis and pit vipers.
Of the persons bitten by poisonous snakes, about half may not receive a fatal dose; the bite may have been through thick clothes, the fangs may have simply grazed the skin or the attack has been unsuccessful and the venom has only been spilled on the surface of the intact skin and so does not find its way into the tissues and get absorbed. The fangs may have hit a bony portion of the limb or the biter may be on fingers or toes from which absorption into the general circulation takes place slowly. Under these circumstances the usual procedure of incision, ligature, suction, cauterization, etc. may be effective.
Therefore, even of the 50 percent of cases bitten by poisonous snakes, only half the number (20 to 25 percent) are in reality in a serious condition and need immediate attention and prompt treatment in order to save their lives. In 1928 Clark reported on 46 cases of snake bite. In half the cases the snakes were not identified or caught and 10 percent were fatal and these were from the bites of L. Atrox and L. Mutans (Bushmaster).
The bites recorded there were on hands and fingers in 20 cases, wrists and forearm in 6, shoulder in 1, foot or toes in 10, leg in 1 thigh in 1. The above figures show that hardly 25 percent of all persons bitten are in real danger of losing their lives and if adequate and prompt measures are taken we may be able to save a good number of these lives also.
In persons who are badly bitten, where the venom has found a direct passage into a large vessel, and if more than half an hour has elapsed between the bite and the proper medical aid, so much harm has probably been done that there is not much chance of saving life. Frequently such cases occur in out of the way places and jungles where medical aid and antivenene are not available.
ACTON and KNOWLES have reported that almost all the poisonous snakes, when giving a good and satisfactory bite, inject a dose ranging from two to fifteen times the minimum lethal dose for man. Fitzsimons observed that two drops of venom usually comprise a fatal dose for a strong healthy adult man. An adult cobra is capable of discharging as much as 8 to 10 drops of venom at a bite. On the average, an adult cobra inject about 5 to 6 drops of venom is a single bite. It is obvious therefore that there is little hope of recovery for a person who is bitten by an adult cobra when the latter has given a successful bite.
In such cases the the victims rarely survive over six hours unless specific treatment is given immediately. This being the case the mortality is very high in certain parts of India where cobras, kraits and Russel vipers are abundant. Where ever there is a case of snake bite, the fear of death becomes so great in the mind of the victim that he almost gives himself up for lost immediately after the infliction of the bite, and gets into a state of collapse or in a moribund condition, even though they may not have been bitten by a poisonous snake.
We have already said that of all the cases that come for medical aid as many as 80 percent have not received a fatal dose of the venom, do not require specific treatment and need only be treated for shock and collapse from which they are suffering. In the majority of cases, therefore, much may be done if the victim is assured of the fact that there is only a 20 and 25 percent chance of his being fatally bitten and thus given mental and moral assurance of considerable chance of recovery. After giving him this assurance start with symptomatic treatment immediately. The specific treatment, if available, should also be given in every case immediately.
It may be a piece of interesting reading to know some of the methods adopted by the other school for the treatment of snake bites. These are given in bare outlines. In addition to the specific remedies, such as polyvalent antivenene, the use of other measures such as ligature, incision, venesection, local use of Potassium Permanganate, Gold Chloride etc., the patient may be saved if the other serious complications that occur after the bite, can be treated.
In case of Cobra-bites the venom affects the respiratory centre particularly, in addition to its effects on the other centres of the brain. Cardiazol, Ephedrine and Veritol have been reported to be useful in counteracting the respiratory failure and have a stimulating effect in narcotic poisoning. Artificial respiration and inhalation of CO2 should also be employed to stimulate the respiratory centre. In the case of viper poisoning there is fall of blood pressure from acute dilatation and later paralysis of blood vessels, particularly of the splanchnic area.
Drugs such as Pituitrin and Veritol have been shown to contract such organs as the spleen, liver, intestines and push the blood into the general circulation. Veritol has the advantage as it pushes out the blood and, unlike Adrenaline, it does not constrict the blood vessels and in this way increases the peripheral resistance.
These drugs, along with perfusion of physiological saline with Gum Acacia and Glucose, have been experimentally shown to revive animals in a condition of collapse and may be useful in human beings as well. For subsequent haemorrhages intravenous injections of Calcium Chloride, Congo Red, Normal Horse Serum, Coagulin and Vitamin C. are worth trying.
We shall now discuss about the Pharmacological action of snake venoms. The poisonous glands of snakes are situated in the back portion of the upper jaw. The ducts are connected with a perforation in the fangs. The poison is squeezed out when the snake closes the jaw tightly in the act of biting or swallowing. The venom is a digestive secretion. Everytime the snake swallows food, the poison swallowed with it and helps in digestion, particularly that of proteins. It is well known that the reptile dies if the venom is milked and a bolus of meat is introduced into the stomach. The action may be of the nature of a kinase.
Venom when fresh is a transparent and clear fluid. It is faintly acid in reaction and its consistency varies from that of water to the thickness of the white of an egg. Cobra venom is a transparent, amber coloured or almost colourless fluid having a specific gravity of 1110. It is acid in reaction and slightly disagreeable in taste. Crotalus venom varies from a pale to an emerald green and orange or straw colour. It has no taste and its specific gravity varies from 1030 to 1044. The venom rapidly becomes alkaline in reaction on account of the disappearance of a volatile acid during decomposition.
When dried under a bell-jar on concentrated Sulphuric Acid or in the sun, it loses about 50 to 70 per cent of water and is converted into a yellowish scaly mass and can be easily powdered. If kept in hermetically sealed ampoules and in cool dark place it keeps its potency for a long time. The toxic principles of the venom reside in albumins which are thermostabile and a coagulable proteid which is thermolabile. The former is in excess in the cobra and is called “neurotoxin” and the latter is in excess in viper venoms and is called “haemorrhagin”. The Viperine venom contains another substance called “thrombose”, which causes intravascular clotting. The specific action of venoms, in short, appears to depend upon the ferments and the lysins they contain.
