Different Snake Bite: Signs and Symptoms

A snakebite is an injury caused by a bite from a snake, often resulting in puncture wounds inflicted by the animal's fangs and sometimes resulting in envenomation. Although the majority of snake species are non-venomous and typically kill their prey with constriction rather thanvenom, venomous snakes can be found on every continent except Antarctica. Snakes often bite their prey as a method of hunting, but also for defensive purposes against predators. Since the physical appearance of snakes may differ, there is often no practical way to identify a species and professional medical attention should be sought.


The outcome of snake bites depends on numerous factors, including the species of snake, the area of the body bitten, the amount of venom injected, and the health conditions of the victim. Feelings of terror and panic are common after a snakebite and can produce a characteristic set of symptoms mediated by the autonomic nervous system, such as a racing heart and nausea. Bites from non-venomous snakes can also cause injury, often due to lacerations caused by the snake's teeth, or from a resulting infection. A bite may also trigger an anaphylactic reaction, which is potentially fatal. First aid recommendations for bites depend on the snakes inhabiting the region, as effective treatments for bites inflicted by some species can be ineffective for others.


The most common symptoms of all snakebites are overwhelming fear, panic, and emotional instability, which may cause symptoms such asnausea and vomiting, diarrhea, vertigo, fainting, tachycardia, and cold, clammy skin. Television, literature, and folklore are in part responsible for the hype surrounding snakebites, and a victim may have unwarranted thoughts of imminent death.

A.COBRA BITE:

With the exception of the king cobra (Ophiophagus hannah) Asiatic cobras belong to a single genus: Naja. Four species are found in India: Naja naja(common Indian cobra, spectacled cobra) is seen throughout the country,Naja kaouthia in the east and the north east regions, Naja oxiana in the extreme north-west region, and Naja sagittifera in the Andaman islands. Most adult cobras measure 100-150 cm, though specimens measuring up to 220 cm have been reported. 

Cobras are found in a variety of habitats, but are especially common in agricultural fields: sugarcane, paddy, soybean or jawar. Many cobra bites occur among farmers and their families living in mud houses near such fields; the snake may be encountered among rubble in the attic, or among firewood, etc. Many a time, the snake enters the cages of hens often located near the corner of a hut. Since rats flourish in and around grain bags stored in these houses, and especially in granaries, cobras are often seen in such places, and many accidental bites occur among humans handling these bags. Jawar (sorghum) breads or chapattis are often kept in baskets near windows in mud walled huts, and rats invade the basket leading snakes to follow them. Bites occur when the housewife blindly puts in her hand to take out the chapattis.

SNAKE VENOM: In simple terms is highly modified saliva with a mixture of different kinds of proteins, toxins and enzymes capable of digesting the entire prey. The cobra venom is Neurotoxin in nature and acts on the nervous system and brain. It can lead to respiratory paralysis and cardiac failure.

The venom glands of baby cobras (Hatchling) are as poisonous as a fully grown cobra. Their venom glands are fully functional. A large yolk sac remains in the hatchlings stomach which provides for nourishment up to two weeks, before it needs to find food on its own.

The maximum quantity of venom injected by a cobra is up to 211 mgs. However, a mere 16 mg of venom is sufficient to kill an adult human being.

SYMPTOMS OF COBRA BITE: Convulsions, drowsiness, headache, blurring of vision, slurred speech, limb paralysis, loss of consciousness, nausea, vomiting, intense abdominal pain and severe pain around the bite wound. Increased blood pressure and abnormal heart beats. Good chances of respiratory failure.

TREATMENT: The first snake Antivenom discovered in 1895 by Albert Calmette was due to the significant number of fatalities resulting from the bite from the spectacled Indian cobra.

FIRST AID:

• Reassure the patient to be calm. Explain that 90 % of cobra bites are dry bites and are harmless.
• Do not use tight tourniquets
• Do not allow the patient to exert or walk.
• Raise the leg and cover with blanket.
• In case of vomiting, turn the patient to one side to avoid choking.
• Take the patient to the nearest hospital-Anti venom serum.

RESEARCH ON COBRA VENOM: Research conducted at the Tata Memorial Cancer Institute at Bombay on various fractions of cobra venom has shown promise in treating certain cancer cells in mice. At present, the American pharmaceutical companies have successfully brought out pain killers made from cobra venom-COBROXIN, and NYLOXIN.

B. VIPER BITE:

Russell’s viper

Russell’s viper (Daboia russelii: previously Vipera russelii) is commonly seen in many parts of India, and even neighbouring coutries such as Pakistan, Sri Lanka, Bangladesh, and Myanmar. It is generally 90-150 cm long, with a stout and rough-scaled body. The head is triangular and much broader than the neck. Nostrils are relatively large, and the eyes have vertical pupils. The colour of this snake is generally brown or yellowish brown. There are three rows of large brown or black, oval or round spots along the entire back. The spots may have pointed ends, to form a chain like pattern, or the margins may be rimmed with white or cream colour. The head usually has a narrow, inverted ‘V’ shaped mark.

This snake is nocturnal. It is often encountered in grassy areas, forest edges, rocky hillocks, and dense scrub vegetation. Most of the bites are reported during harvest time.

Saw scaled viper

The saw scaled viper (Echis carinatus) is a small snake, growing up to 30-90 cm in length. The head appears more rounded than triangular, while the rest of the body is cylindrical, short, and stout. It has large eyes with vertical pupils. The tail is very short. The entire body is covered with rough, serrated scales. This snake is usually pale brown in colour, with dark brown, brick red, or gray zigzag patterns on the back. An arrowhead-like or bird foot-like mark is present on the head.

The saw scaled viper is mainly nocturnal. It frequents open dry, sandy, or rocky plains and hills. It often rests under rocks, or at the base of shrubs or trees during the day. The quickness with which it bites on smallest provocation, with an extremely rapid strike makes it one of the most dangerous snakes. 

Pit vipers

Various kinds of pit vipers are found in hilly areas, or forests in most parts of the country. The Western Ghats and the Malabar region of Kerala abound in these snakes. Often they are encountered near low bushes, or stream edges. 

Viperid venoms typically contain an abundance of protein-degrading enzymes, called proteases, that produce symptoms such as pain, strong local swelling and necrosis, blood loss from cardiovascular damage complicated by coagulopathy, and disruption of the blood clotting system. Death is usually caused by collapse in blood pressure. This is in contrast to elapidvenoms that generally contain neurotoxins that disable muscle contraction and cause paralysis. Death from elapid bites usually results from asphyxiation because the diaphragm can no longer contract. However, this rule does not always apply: some elapid bites include proteolytic symptoms typical of viperid bites, while some viperid bites produce neurotoxic symptoms.

Proteolytic venom is also dual-purpose: firstly, it is used for defense and to immobilize prey, as with neurotoxic venoms; secondly, many of the venom's enzymes have a digestive function, breaking down molecules in prey items, such as lipids, nucleic acids, and proteins. This is an important adaptation, as many vipers have inefficient digestive systems.

Due to the nature of proteolytic venom, a viperid bite is often a very painful experience and should always be taken seriously, even though it may not necessarily prove fatal. Even with prompt and proper treatment, a bite can still result in a permanent scar, and in the worst cases, the affected limb may even have to be amputated. A victim's fate is impossible to predict as this depends on many factors, including (but not limited to) the species and size of the snake involved, how much venom was injected (if any), and the size and condition of the patient before being bitten. Viper bite victims may also be allergic to the venom and/or the antivenom.

C. KRAIT BITE:

The common krait or Indian krait (Bungarus caeruleus) is said to be the most venomous of all the species of snakes seen in India. The common krait is a relatively small snake (30-120 cm) with the head slightly broader than the neck; eyes have round pupils. The color of the snake is usually glossy black, bluish gray or brownish black with narrow (often paired) white bands all across the back that continue to the tip of the short tail. These bands may be absent proximally, where they are replaced by white vertebral spots. The non-venomous wolfsnake, which resembles the krait, on the other hand has bands right from the beginning of the head, but may be absent towards the narrow long tail.

Kraits are mostly nocturnal. During the daytime they may rest in termite mounds, rodent burrows, piles of brick, heaped coconuts or firewood, cowdung, and sometimes within the house underneath beddings or pillows. Kraits are known to enter human dwellings quite commonly in search of prey. Even in proper concrete houses, kraits can enter via the drains of the bathroom if these are not closed with grating.

The maximum incidence of krait bite is said to be during the monsoon months, probably because due to heavy rain, the holes where rats and other rodents dwell get filled with water. Also due to the cold and wet weather, the snakes may enter human dwellings to take advantage of the shelter and warmth. Majority of the bites occur between 11 PM and 5 AM. Since there is not much pain associated with a krait bite, the sleeping person may not even realize he was bitten by a snake when he wakes up in the morning. The ensuing neurological symptoms and signs may in fact be mistaken for a cerebral stroke.

The Indian krait's venom consists mostly of powerful neurotoxins which induce muscle paralysis. Clinically, its venom contains pre-synaptic and post-synaptic neurotoxins. These neurotoxins generally affect the nerve endings near the synaptic cleft of the brain.

In mice, the LD₅₀ values of its venom are 0.365 mg/kg SC, 0.169 mg/kg IV and 0.089 mg/kg IP.^[2][3] while the average venom yield is 8—20 mg.

Kraits are nocturnal and seldom encounter humans during daylight hours, so incidents are rare. There is frequently little or no pain from a krait bite and this can provide false reassurance to the victim. Typically, victims complain of severe abdominal cramps, accompanied by progressive paralysis. Once bitten, the absorption of the venom into the victim can be considerably delayed by applying a pressure bandage to the bite site (using about the same tension as one uses for a sprained ankle) and immobilising the area. This allow for gentle transport to medical facilities, where the venom can be treated when the bandage is removed. As there are no local symptoms, a patient should be carefully observed for signs of paralysis (e.g., the onset of ptosis) and treated urgently with antivenom. It is also possible to support bite victims via mechanical ventilation, using equipment of the type generally available at hospitals. Such support should be provided until the venom is metabolised and the victim can breathe unaided. If death occurs it takes place approximately 6–8 hours after the krait bite. Cause of death is general respiratory failure, i.e. suffocation.

Often in rainy season the snakes come out of their hiding places and find refuge on dry places inside a house. If bitten by it in sleep the victim seldom comes to know as the bite feels more like an ant bite or a mosquito bite. The victim may be dead before he even wakes up.

One such case was recently reported in Indore, where Mr Rajan Jadhav, a various accent instructor of English language was bitten by it inside his house, and was declared dead on arrival at the hospital.

Prof Krishna Shrivastava has made this as reference that Mr. Mohsin Khan, student SSBT's College of Engineering Jalgaon, bitten by Krait on 24/8/11 in morning at 4 AM, after giving 79 Anti Venom,survived.

A clinical toxicology study gives an untreated mortality rate of 70–80%.

D. KING COBRA BITE:

Recoverd snake bite:

The venom of the king cobra consists primarily of neurotoxins, but it also contains cardiotoxic and some other compounds.Toxic constituents are mainly proteins and polypeptides.

During a bite, venom is forced through the snake's 1.25 to 1.5 centimeters (0.49 to 0.59 in) fangs into the wound, and the toxins begin to attack the victim's central nervous system. Symptoms may include severe pain, blurred vision, vertigo, drowsiness, and paralysis. Envenomation progresses to cardiovascular collapse, and the victim falls into a coma. Death soon follows due to respiratory failure. Moreover, king cobra envenomation is clinically known to cause renal failure.

King cobra skull, lateral view, showing fangs

A 1990 book makes a passing statement of a LD₅₀ of 0.34 mg/kg for this species, however this value is inconsistent with most toxicological studies. For example, a recent study lists the LD₅₀ of the king cobra venom as 1.6 mg/kg – 1.8 mg/kg, making its venom one of the least potent among the elapids. This value is further backed up by another toxicological study which lists the IV LD₅₀ of the king cobra at 1.7 mg/kg. A similar mean LD₅₀ value of 1.93 mg/kg was obtained from the venom of five wild caught king cobras in Southeast Asia (Meier et al 1995). Engelmann listed the IV LD₅₀ at 0.9 mg/kg.

This species is capable of delivering a large quantity of venom, injecting a dose anywhere from 200-500 milligrams on average and can up to 7ml. Engelmann and Obst (1981) list the average venom yield at 420 mg (dry weight). Though the venom is weak compared to most other elapids based upon the LD50 in mice, it can still deliver a bite which can potentially kill a human due to the massive amount of venom it delivers in a single bite. Mortality can vary sharply with amount of venom involved, most bites involve nonfatal amounts. According to a research report from the University of Adelaide Department of Toxinology, an untreated bite has a mortality rate of 50-60%  Depending on many factors, especially in cases of very severe envenomation, death can occur as early as 30 minutes after being bitten by this species but this is exceptionally rare as most untreated bite victims in Asia live through their bites, usually because the vast majority of bites involve non-fatal amounts of venom.

There are two types of antivenom made specifically to treat king cobra envenomations. The Red Cross in Thailand manufactures one, and the Central Research Institute in India manufactures the other; however, both are made in small quantities and are not widely available.Ohanin, a protein component of the venom, causes hypolocomotion and hyperalgesia in mammals. Other components have cardiotoxic, cytotoxic and neurotoxic effects. In Thailand, a concoction of alcohol and the ground root of turmeric is ingested, which has been clinically shown to create a strong resilience against the venom of the king cobra, and other snakes with neurotoxic venom.

The haditoxin in the king cobra venom was discovered by Singaporean scientists to be structurally unique and can have unique pharmacological properties. Biochemical studies confirmed that it existed as a non-covalent dimer species in solution. Its structural similarity to short-chain α-neurotoxins and κ-neurotoxins notwithstanding, haditoxin exhibited unique blockade of α7-nAChRs (IC50 180 nM), which is recognized by neither short-chain α-neurotoxins nor κ-neurotoxins.

OVERVIEW

India had the largest number of reported venomous bites, about 80,000 a year with 11,000 deaths. Sri Lanka ranked second in bites, with about 33,000 a year.

"The fact that snakebite varies geographically and seasonally, that it is mainly a rural tropical phenomenon where reporting and record keeping is poor and that health-seeking behavior is diverse with traditional treatments being sometimes preferred to Western medicine, all contribute to the difficulties faced when studying its epidemiology," the report said.

About 600 of the 3,000 snake species are venomous enough to be dangerous to humans.

There are about 216 species of snakes in India, of which 52 are known to be venomous. The major families of venomous snakes in India comprise elapids (cobra, king cobra and kraits) viperids (Russell’s viper, saw scaled viper or carpet viper, and pit vipers), and hydropids (sea snakes).

Snake Venom

Different species of snakes inject different volumes of venom when they bite, and the toxicity of the venom produced by each species can vary a great deal. Antivenom dosing recommendations are based on the quantity of a particular venom [in milligrams (mg), dry weight] that can be neutralized by each milliliter (ml) of antivenom. The half life of Indian ASV is said to be 26-95 hours. In India, each milliliter of a polyvalent antivenom is supposed to neutralize:

• 0.6 mg of Indian cobra (Naja naja) venom;
• 0.6 mg of Russell’s viper (Daboia russelii) venom;
• 0.45 mg of Common krait (Bungarus caeruleus) venom; and
• 0.45 mg of Saw scaled viper (Echis carinatus) venom.

The average venom yield of these species are:

• 200 mg for Indian cobra (Naja naja);
• 150 mg for Russell’s viper (Daboia russelii);
• 22 mg of Common krait (Bungarus caeruleus) venom; and
• 4.6 mg of Saw scaled viper (Echis carinatus) venom.

The amount of venom that may be fatal to humans varies from one species to another. Literature reports suggest that the lethal doses of these four species are about:

• 120 mg for Indian cobra (Naja naja);
• 150 mg for Russell’s viper (Daboia russelii);
• 60 mg of Common krait (Bungarus caeruleus) venom; and
• 80 mg of Saw scaled viper (Echis carinatus) venom.

High incidence of snakebite is reported during the summer and the rainy season.

By Hemant Sachan