Snake bite: What to do, what not to do and why

common krait
The common krait is mostly seen at night
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Jayanti and her classmate from school were playing in the garden on a hot summer evening in Cochin, Kerala. While picking up a ball from amongst the dried leaves on the ground, Jayanti felt a sudden pain on her hand, as though she had been stuck with a needle. Hearing a rustle in the leaves, she just caught the glimpse of a snake slithering away. She realised she had been bitten, and ran indoors to inform her parents. Her mother Laila was at home, talking with a doctor friend of hers who was visiting. Laila was panic-stricken and confused about what to do.

Renuka, the doctor, examined the child’s hand and found two tiny bite marks, confirming that she had been bitten. Jayanti was taken to the hospital, treated and discharged home in three days’ time.

This article illustrates the do’s and don’ts in such a situation. The first section is written as a conversation between Laila, the child’s mother, and Dr Renuka, who was experienced in treating snake bites. The second section provides important information about common venomous snakes and explains how to prevent snakebites.

Laila: “We are both so scared! What should I tell Jayanti, Dr Renuka?”

Doctor: “Keep calm and please act calm, reassure her that it is nothing serious and that she will be all right. Please do not scare her by asking what the snake looked like, whether it was a cobra or a viper and so on. If the patient gets panicky, the increase in circulation will spread the venom faster throughout the body. It is important to keep the patient as calm as possible.”

Laila: “I can hardly see the bite marks on her hand! They are so tiny!”

Doctor: “Yes, the bite marks are often so small, they may escape notice. Let us use a red marker and draw a circle around it for reference.”

Laila: “Shall I tie a tight tourniquet (rope) on her hand so that the poison will not spread to the rest of her body?”

Doctor: “That is not recommended anymore; it can be dangerous when it is too tight. I have heard of amputations becoming necessary due to improperly applied tourniquets choking blood supply to the limb.”

Laila: “But how can we prevent the venom from spreading?”

Doctor: “Venom spreads slowly through her lymphatics and small blood vessels. The best thing is to keep the hand below the level of the heart. Let her lie down on her side with the hand dangling down. We can use the power of gravity to reduce the spread of the venom.

Instead of tying a tourniquet, we can apply an elastic crepe bandage, about 4 inches in width, over the bitten limb. Let me help you do that.”

Laila: “Oh dear! I don’t have a crepe bandage at home. What can I do?”

Doctor: “A long strip of cloth of four-inch width can be used instead of a crepe bandage. Our aim is to slow the flow of lymph, and not to cut off the blood supply. Such bandages may be used in cobra and krait bites. Starting from the bitten finger, we can gently cover the entire limb.”

Laila: “Thanks. But how do I make sure it is not too tight?”

Doctor: “A useful rule of thumb for the amount of tightness of the crepe bandage is to have enough room to slide our finger underneath the bandage.”

Laila: “Is she allowed to move her hand?”

Doctor: “It is better to keep the hand as still as possible to reduce the spread of venom. A splint can be used along with the crepe bandage to keep the hand immoblilised, just like the case of a fractured limb.

Likewise, those who got bit on the leg should be advised to sit still and not to run, while other means of transport are being arranged to go to hospital. Walking and running will make the venom spread faster through blood circulation.”

Laila: “Should she be sitting up or lying down?”

Doctor: “It is best for her to lie down quietly on her side while we get her to hospital. It is called recovery position. This position will protect her lungs in case of vomiting.”

Laila: “Shall I suck on the wound and draw the venom out?”

Doctor: “No. That is of no use. Venom will not come out by applying suction.”

Laila: “Shall I make a few cuts near the wound with a blade so that the venom will drip out?”

Doctor: “No. That will not only be useless, but will increase her chance of having an infection and severe bleeding. Applying ice, electric shock, ‘snake-stone’, potassium permanganate or inducing burns on the wound are wrong practices, too.”

Laila: “What should I do with Jayanti’s watch and bangles?”

Doctor: “Let us remove them now, before the swelling sets in. Once the area is swollen, we will not be able to remove the ring, watch or her bangles, and it can become dangerous for her circulation”

Laila: “I heard there is a traditional healer in the village nearby. Shall I take her there?”

Doctor: “What will save Jayanti’s life is immediate diagnosis, supportive care and prompt injection of antivenin. Wasting time with a traditional healer is not advisable and could cost her life.”

Laila: “But Dr Renuka, I heard that this healer has healed many snake bite victims. The villagers have a blind trust in her ability.”

Doctor: “Many of their so-called success stories are from non-venomous snake bites. Besides, many venomous snake bites occur without envenomation, that is, even though the snake bites, it may fail to inject its venom at that moment. We call them dry bites. In fact, about half of Russell’s viper bites and a third of cobra bites are dry. Such cases recover without any medication, and the healer gets the credit.”

Laila: “Wow, I did not know that non-venomous snakes bit people.”

Doctor: “Yes. In a recent study from Calicut Medical College, one out of every four bites were from non-venomous snakes.”

Laila: “Are you saying that traditional treatments are fake?”

Doctor: “That is not what I meant. In fact, snakes have lived on the planet longer than man, and therefore snake bites have caught medical attention for thousands of years. Several herbal treatments have been tried all over the world by traditional medical practitioners, but unfortunately none of them have been proven yet by currently accepted scientific methods.

For a life-threatening condition, it is unwise to try something that is unproven, based on hearsay alone. As of now, the W.H.O. does not endorse any other treatment for snake bite than antivenin, also called ASV. The introduction of ASV has reduced the death rate from venomous snake bites from 50% to 5%.”

Finishing up with the child’s bandage, Laila asked: “Should we go outside to the garden and try to catch the snake that bit Jayanti, so that we can take it to the hospital?”

Doctor: “It is good to be able to identify the snake, but attempting to catch a venomous snake can become dangerous without the help of a professional snake rescuer. Besides, snakes do not stay in one place; and we don’t have time to lose.”

Laila: “But if we don’t catch the snake, how will the doctors know what medicine to give?”

Doctor: “Polyvalent antivenin is an injection that is able to neutralise the venom of the most common snakes in India. The same antivenin is given to all snake bite victims, and is effective against the bite of cobra, krait, Russel’s viper and saw-scaled viper, the so-called big four. Thus, doctors do not necessarily require to see the snake to be able to administer antivenin.

However, identifying the snake can help them tailor the supportive treatment accordingly. Besides, they can also avoid giving ASV in specific cases that they know it won’t work, such as the hump-nosed pit viper (HNPV)”

Laila: “Have you treated HNPV bite? Is it common in Kerala?”

Doctor: “They are seen along the hilly sections of Kerala, in forests and rubber plantations. I remember a case referred from the western ghats after the patient received ASV for a suspected viper bite. The snake could not be found, and ASV was given assuming it was Russel’s or saw-scaled viper bite as usual. However, even massive doses of ASV produced no improvement in the deranged blood clotting parameters.

That case turned out to be a hump nosed viper bite, for which only supportive treatment is available in India at this time. Unfortunately, that patient developed complications from ASV that were worse than the effects of the snake bite. If only they had identified the snake as HNPV, they could have avoided giving ASV and the outcome might have been better.”

Laila: “Is there anything else we can do to help identify the snake?”

Doctor: “Taking a photo of the snake using a mobile phone might help identify the species.”

Laila: “Why not go to the doctor’s private clinic on the next street? I heard he is a very good doctor and has lots of patients.”

Doctor: “The doctor might be excellent. But to treat an emergency, any doctor is only as good as the equipment and facility he or she gets to work with. The OP clinic is a place where a doctor consults on non-emergency patients. It is not equipped to treat emergencies like snake bite, chest pain, or asthma attack. Such cases must only be treated in the casualty where there is resuscitation equipment and trained staff available to help the doctor.”

Laila: “But how do we decide which hospital to go to?”

Doctor: “It is better to go to the nearest hospital, but we must make sure that they have antivenin in stock. We can call the hospital on the way and talk with the doctor at casualty to confirm they do have antivenin in stock.”

Laila: “Why do we have to rush? Why don’t we at least try the traditional medicine first and then go to hospital if there is no improvement?”

Doctor: “The best chance of survival Jayanti has is to get to hospital at the earliest, and receive antivenin injection. We need to do it before venom spreads to all parts of her body. Waiting is not an option.”

Within ten minutes, they were on their way to hospital in Dr Renuka’s van with Jayanti lying down in the backseat with her grandmother comforting her. Dr Renuka put on some of Jayanti’s favourite music to distract her. On the way, Laila quietly asked: “I hate to ask you this, but is there a chance my child could die?”

Doctor: “Don’t worry, she will be perfectly fine, as we are already on our way to hospital. I recall a recent study from Kannur Medical college of fifty children with venomous snakebites. No deaths occurred as most of the children were brought promptly to hospital, and antivenin was given by protocol.”

Laila: “But when I searched Google, I read that antivenin has side effects?”

Doctor: “A few patients can have an allergic reaction, which can be treated promptly if they occur. Antivenin (ASV) is the only life-saving treatment available. The chance of a minor injection allergy can’t even be compared to the chance of death from envenomation. Therefore, we should not be reluctant to take antivenin if the doctor recommends it after examining her.”

Laila: “Should she get a test dose first, as in the case of a penicillin shot?”

Doctor: “No. A test dose is not necessary in the case of antivenin”

Laila: “How much ASV will she need? She is only a child, maybe they will give her a paediatric dose?”

Doctor: “She will need 8-10 units initially, which is the same dose as an adult. The dose of the ASV is determined by the amount of poison injected by the snake, not by the patient’s age or body weight.”

Laila: “When will they decide to give her antivenin?”

Doctor: “Not all cases of snake bite need antivenin. They will monitor Jayanti carefully for any signs of envenomation. If any signs appear, they will administer ASV.”

Laila: “What are some of the effects of envenomation or spread of venom throughout the body?”

Doctor: “Vomiting is an early symptom of envenomation. Neurotoxic venoms from kraits and cobras cause blurring of vision, drooping of eyelids, weakness of the neck and limb muscles. Without antivenin, the patient can deteriorate to complete paralysis and die from inability to breathe. In severe cases, symptoms appear sooner, that is within three hours of the bite.

For hemotoxic venoms such as viper bite, blood in the urine, bleeding from the gums or nose can occur, along with severe pain and swelling of the affected limb. When treatment gets delayed, bleeding can occur in the brain and lungs. Heart rhythm problems and kidney shut down can occur too. Most snake venoms contain a mixture of various toxins.”

Laila: “That sounds so scary! I hope Jayanti will not develop any of these complications.”

Doctor: “There is no need to worry, Laila. Remember, these complications occur mainly among those who do not go to the hospital early enough. I am glad that Jayanti realised she was bitten and immediately informed us, so there was no delay. Since she is already being taken to hospital, everything will be just fine.”

Laila: “Why would someone with a snakebite not seek treatment immediately?”

Doctor: “That is a good question. We might wonder why people who suffer a snakebite do not rush to hospital every time. But in the real world, there are times when the person fails to notice the bite. This is a common problem among those who are doing manual labour in the field, collecting firewood in the forest and in the case of children who are busy at play. The snake might not get noticed each time. Children might not feel the bite in the excitement of playing. Labourers might ignore it thinking that it is only a scratch while collecting firewood. In fact, krait bites are known to kill people in their sleep.

I have seen several cases where people are brought to casualty with loss of consciousness or other complications without a reported history of snakebite. The diagnosis in such cases is made only later, after we perform investigations. On the flip side, many cases of alleged snakebite turn out not to be the case too.

In remote rural areas, delays can occur because of lack of availability of modern medical facilities, inadequate means of transport, insufficient stock of antivenin, cultural factors that give preference to indigenous treatment methods, and financial limitation to avail medical care.”

Laila: “If antivenin injection cures snakebite, then why not give it in a local clinic? What is the need to hospitalise her?”

Doctor: “Antivenin will only neutralise the snake’s venom in the body. However, plenty of supportive treatment is necessary to repair the damage caused by the venom in various organs of the body. For example, when muscles are paralysed and the patient can’t breathe, antivenin alone will not save the patient. ICU care and ventilator support will be required till the muscles recover from the neurotoxin and the patent is able to breathe again.

If the kidneys are damaged, dialysis will be needed till they recover. When blood clotting is deranged, transfusion and other specialised treatments might become necessary. Some patients develop severe infection and tissue damage at the bite site, requiring prolonged treatment and surgery. These can only be done in well-equipped hospitals.”

Laila: “How long should we stay in the hospital?”

Doctor: “A minimum of 24 hours observation is needed even if there are no initial signs of envenomation. The stay may be longer as the case might be.”

snake-pattern-01
Sajeeth Kumar et al, Int J Gen Med 2018

Snakebite: a preventable cause of death

Snakebite is an important preventable cause of death, disability and economic distress. Most of the snake bite victims in developing nations come from rural areas, and are the chief wage-earners of the family. Death rates remain high in areas without access to modern medical care. Several of those who survive snakebites have limb loss or deformity, chronic kidney disease, residual effects of stroke, hormonal deficiency, chronic pain, fatigue, depression, headaches and other ailments.

Fortunately, the majority of snakes are non-venomous. Of the 100 species of snakes found in Kerala, only four are common enough to pose significant danger to human life when they bite. These include the Russel’s viper, saw-scaled viper, common krait and cobra—all of which are frequently found near areas of human habitation. Also called the Big Four, they are responsible for over 90% of the 45,000 snake-bite deaths that occur in India every year.

The king cobra is venomous too, but as it is a shy snake that mostly lives in dense forests, human encounters are uncommon—and deaths are relatively rare in India. The hump-nosed pit viper is another venomous snake found in Kerala. A few others such as the grass snake are mildly venomous, only causing local skin irritation.

Failure to take basic precautions is the reason for the majority of snake bites. The most important cause of death is delay in reaching the hospital, a common problem in rural areas.

Understanding snake behaviour

Snakes are found in undisturbed wooded areas, underneath piles of firewood, bricks and rocks. They are also seen near paddy fields and other places where rodents are found. Snakes may venture into the garden and even indoors in search of food and cooler resting places. While indoors, snakes prefer dark corners, including the inside of shelves, cupboards and shoes.

Snakes are shy animals. They are able to feel vibrations on the ground and generally move away as they hear human footsteps approaching. They hunt for prey using their sense of smell. Vipers have the ability to detect heat from the prey and bite accurately even in complete darkness. For the most part, snakes only bite in self-defence—most commonly when people step on them by accident.

While many would assume that all venomous snakes attack when stepped upon, studies have in fact shown that they do not attempt to bite every time they are provoked. In some cases, they may simply try to escape when stepped upon.

When threatened from a distance, the Russel’s viper first lets out a warning hiss, while the saw-scaled viper makes a rasping noise by rubbing its scales. They strike only when they continue to be harassed. In addition to their dramatic hood display when threatened, cobras are also known to try and scare away the offender by occasionally delivering a closed-mouth strike—that is without attempting to injure or kill.

A significant number of open-mouth strikes involve a dry bite, when the snake does not inject venom through its fangs. Venom metering or the ability of snakes to regulate the amount of venom in each bite is a matter of much study. Contrary to common belief, dry bites do not occur because the snake recently had a meal.

Doubtless, these surprisingly benign traits of venomous snakes help reduce the overall number of human deaths that follow snake encounters.

The big four’.

snake-pattern-02
1. Russel’s viper (anali, chenathandan)

1. Russel’s viper (anali, chenathandan) is a large snake, about 4 feet in length. The head is large and triangular. It is brown in colour with three rows of solid or hollow oval black spots arranged in a chain-like pattern along its body. This colour pattern is mimicked by non-venomous snakes such as common sand boa and Indian rock python. Due their excellent camouflage, vipers can be difficult to spot while lying motionless in their natural habitat, among dried leaves in open, grassy or bushy areas.

Russel’s vipers are active at night, searching for rodents and frogs. When threatened, it gives out a loud hiss not unlike that of a pressure cooker. Armed with sharp fangs and a lightning-fast accurate strike, they account for the majority of snakebite deaths in India. More bites occur during the months of May to August, when large numbers of baby snakes are born.

snake-pattern-03
Saw-scaled viper and its characteristic coil

2. The saw-scaled viper (chruttamamdali) is a small snake of light brown colour with pale white or yellow spots on its body, giving it near-perfect camouflage against dry ground with fallen leaves. It is seen predominantly in hilly areas. When provoked, it launches into a continuous coiling motion, making a noise by rubbing its scales together, holding its distinct triangular head in strike-ready position. Being only a foot in average length, it is often mistaken for a harmless species by unsuspecting passers-by.

common krait
Common krait (shankuvarayan)

3. The common krait (shankuvarayan) is black with narrow white rings on its body. Kraits are also known to visit homes at night in search of prey such as lizards and mice. When a person who is sleeping on the floor accidentally rolls over on to the snake, bites can occur. Such bites may be painless or go completely unnoticed, and the person may wake up later in a state of paralysis. In such instances, although wide awake, the profound muscle paralysis might unfortunately create the impression that the victim died while sleeping. The harmless wolf snake copies the krait’s design, in a classic example of Batesian mimicry.

snake-pattern-05
Cobras (moorkhan)

4. Cobras (moorkhan) come in different colours: brown, black, tan, and have a black spectacle-shaped mark on the back of their hood. They feed on rats, mice, poultry and frogs, and therefore can be seen around where humans live. They are also seen on paddy fields, with more bites occurring during harvest season.

Significant others:

In addition to the big four above, two snakes deserve special mention in this context. One is the venomous hump nosed pit viper and the other is the harmless rat snake. Details of other snakes are available in the further reading section.

The hump-nosed pit viper (churutta) is not part of the big four. Commonly misidentified as the saw-scaled viper, this small snake is seen in the plantations of Kerala and Sri Lanka. It sits motionless among rocks and dry leaves with its head pointed upward. Unfortunately, its venom is not covered by the ASV available in India. Initially thought to be relatively less toxic, its bite is now known to cause kidney failure (10%) and blood clotting abnormalities (39%). Death can rarely occur (1.7%).

The rat snake (chera) is a common non-venomous snake that is sometimes mistaken for the cobra by lay people. Rat snakes are 6-8 feet long and come out mainly during daytime to feed on rats and frogs. They help keep rodent population under control. They can be identified from their slender head and big round eyes. Large scales with thick black borders are found on the head, which produce distinctive vertical black lines above and below their white lips.

How to prevent snake bites:

  1. Avoid all contact with snakes; leave them alone.

  2. Use a torchlight while walking at night along trails near wooded areas.

  3. Clear walking paths of dried leaves and twigs at regular intervals.

  4. Use protective footwear while walking along snake-infested areas.

  5. Be extra careful while walking in the dark after a rain, when snakes tend to come out more.

  6. Children must be specifically trained not to pick up snakes out of curiosity.

  7. Do not reach blindly beneath rocks, piled up bricks, coconut shells or firewood.

  8. Do not poke inside dense bushes with bare hands; use a stick instead.

  9. Avoid collecting firewood after dark.

  10. If a baby snake is sighted, remember to check for other snakes in the area.

  11. Workers in rubber and cashew plantations and paddy fields must take special care.

  12. Dispose garbage properly so that rats do not infest the area, attracting snakes.

  13. Do not raise poultry inside or near the home as they attract snakes.

Further reading:

» Details of snakes found in India: http://indiansnakes.org/

» WHO guidelines for snakebite management: http://apps.searo.who.int/PDS_DOCS/B4508.pdf

» Studies from Calicut Medical College: https://jemds.com/data_pdf/Snake%20bite%20Edited%20Latest.docx, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5993036/

» Long-term complications of snake bite,file:///D:/Downloads/toxins-11-00193.pdf

» Early admission to hospital prevents death in snake bite: https://www.ijpediatrics.com/index.php/ijcp/article/view/1359

» Mechanism of dry bites by venomous snakes: https://static1.squarespace.com/static/54694fa6e4b0eaec4530f99d/t/59ca860c12abd9e9dab524e9/1506444813088/%E2%80%9CDry+bite%E2%80%9D+in+venomous+snakes-+A+review.pdf

» Snake-stone treatments in Kerala, a shadow of the past: https://www.thehindu.com/news/national/kerala/a-vanishing-breed-of-snakebite-healers-in-kerala/article5338801.ece

» Snake sightings in Kerala: https://www.thehindu.com/sci-tech/energy-and-environment/close-encounters-of-the-slithery-kind/article24300695.ece

» Hump-nosed pit viper, the snake which is not covered by the polyvalent ASV in India: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4062887/

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