Snakebite Prevention & Treatment Guidelines in India 2023

Key points:-

• Around 50% of total deaths due to snakebites in the world are attributed to India¹⁰.
• Fang marks on the bitten area may be absent in krait bite (occult bite). krait are more active at night.
• Snake identified venomous but the patient having no signs or symptoms does not mean that ASV is to be given. it may be a dry bite. ASV is given once there is evidence of envenomation clinical or lab-based.
• When there is continuous bleeding from a bite site for more than 20 minutes (Hemotoxic venom), it is not advised to wait for 20WBCT results. we can directly give the ASV
• There is no need for a challenge test (sensitivity testing) before its administration (no reliability)
• Always a full dose of ASV is given, whenever indicated.
• Cold-chain should be maintained while storing ASV and should be used before the expiry date but in case of severe envenomation, recently expired ASV may be used if there is no alternative (WHO 2015)
• There are no absolute contraindications to ASV
• Administer Atropine followed by Neostigmine (‘AN’) in Cobra bite. for the practical purpose, all neuroparalysis patients are given AN, if there is no improvement after 3 doses. it is suggestive of a Kraite bite and AN is stopped, as ‘AN’ is not indicated in krait bite
• BIG FOUR: Are the four main venomous snakes in India that causes maximum number of bites. Includes – Russell’s viper, saw scaled viper, cobra and krait. Russell’s viper causes a maximum number of bites among all

Snakebite is a Medical Emergency, usually seen in the Rainy season following heavy rainfall and in humid climates. it is estimated that India had around 1 lakh 20 thousand snakebite deaths (Average 58,000/year) from 2000 to 2019¹¹. India accounts for almost 50% of the total number of annual snakebite deaths in the World¹⁰.

Venomous Snakes Around the World

There are more than 2000 species of snakes in the world. WHO has categorised venomous snakes into 2 categories found around the globe.²

Snakes in India

• There are around 300 species of snakes in India out of which 52 (around 18% only) are venomous.
• Venomous snakes in India belong to 3 families:
  1. Elapidae- India Cobra and Common Krait
  2. Viperidae- Russell’s Viper, Saw scaled Viper
  3. Hydrophinae- Sea snakes
• The BIG FOUR:- these are the four medically important snakes that cause most of the snakebite cases in the Indian subcontinent (mainly India). these big four are:-
  1. Russell’s Viper (Daboia russelii)-
  2. Indian Cobra (Naja naja)
  3. Common Krait (Bungarus )
  4. Indian Saw Scaled Viper ( Echis carinatus)

Indian States with High Prevalence of Snakebite Deaths:-

Of all 28 states in India, 13 states have a high prevalence of snakebite Deaths²:-

1. Andhra Pradesh
2. Madhya Pradesh
3. Orissa
4. Uttar Pradesh
5. Bihar
6. Jharkhand
7. Chhattisgarh
8. Karnataka
9. West Bengal
10. Tamil Nadu
11. Rajasthan
12. Maharashtra
13. Gujarat

Preventing Snake Bite

Raising awareness about the prevention of snakebites is the most effective strategy for reducing snakebite-related morbidity and mortality.

General Precautions

• Know about the snakes usually found in the locality, the weather and the time when they are active (for planning preparedness). for example in India 80% of snakebites occur in the rainy season (epidemic season³), Krait found in India is more active at night.
• Snakes prefer not to confront large animals such as humans, and therefore give them every opportunity to escape. Do not try to kill or handle a snake, as this can increase the risk of being bitten.
• Children are more vulnerable to snakebites and envenomation often leads to disability or death.⁵ sensitize children about the preventive measures.
• Be extra vigilant after heavy rains, during flooding, and during harvest time while walking to and from the fields before dawn and after dusk³.
• Be careful when handling dead or apparently dead snakes – even an accidental scratch from the fang of a snake’s severed head may inject venom
• Strict prohibition of open toileting¹. (in India, all villages have been declared as open defecation free and everyone has access to the Latrine.¹³)

At the Household Level

• Eradicate rats–
  • Snakes are carnivorous and enter houses for their prey (usually Rats)
  • Avoid setting cattle sheds near residential areas especially Chickens (serve as potential prey for larger snakes). cattle-sheds usually contain grains that attract rats and snakes shall follow to hunt the rats.
  • Store grains in the rodent-proof containers
• Avoid piling wreckage, rubble or firewood near residential areas. it may act as a hiding place for snakes. preferably store firewood well elevated off the ground.
• Avoid sleeping on the ground. In South Asia, almost all krait (Bungarus) bites are inflicted on people sleeping usually on the floor but sometimes even in beds and under pillows (e.g. in the Sundarbans)³.
  • if you can’t avoid sleeping on the ground, use insecticide-impregnated mosquito nets and tuck them well under the mattress or mat. it not only protects from snakes (snake bite when a person moves or rolls over the snake nearby) but also from misquotes and scorpions.
• Check for any potential portals of entry for snakes or rats in your house regularly and close or seal them properly. use the door seals to cover any gap at the bottom of doors (main door and any backdoor which opens outside)
• Don’t allow the branches of any tree to touch the house
• Don’t visit the snake charmer show, snakes are not under their control and snakes may develop fangs with time if removed initially.

In the Farm, Fields or Garden

• Keep grass short in the lawn or clear the ground around your house so that snakes cannot hide close to the house
• Wear high-sided Solid shoes or boots and long trousers are recommended especially during agricultural activities- snakes usually bite on lower legs, ankles and feet in people engaged in agricultural work in fields
• Water sources, reservoirs, and ponds may also attract prey animals (such as frogs and toads) and thus snakes.
• Observe the changed behaviour of animals and especially birds (birds mob the snake- group together and make noise on spotting snakes)

• Use a light when you step outside the house at night, use the latrine preferably, or relieve yourself in the open not in the bushes.
• Use a walking stick to prod or tap the ground in front of you to detect hidden snakes,  When walking at night, especially after heavy rains.
• Step onto rocks or logs rather than straight over them – snakes may be sunning themselves on the sides.
• Do not put your hands into holes or nests or any hidden places where snakes might be resting. Young boys often do this while hunting for rodents
• Be cautious:-
  • when stepping over fallen trees or large branches, as snakes may be hidden underneath.
  • when lifting rocks, logs, or other objects that could be snake hiding spots

On the Road

• Rain may wash snakes and debris into gutters at the edges of roads, and flush burrowing species out of their burrows, so be careful when walking on roads after heavy rain, especially after dark
• Never run over snakes on the road intentionally:-
  • The snake may not be instantly killed and may lie injured and pose a risk to pedestrians
  • The snake may also be injured and trapped under the vehicle, from where it will crawl out once the vehicle has stopped

In Rivers, Estuaries and the Sea

• Fishermen should avoid touching sea snakes caught in nets as their heads and tails are not easily distinguishable
• Sea snakes are airbreathing and therefore may survive on the beach if released there, which may pose the risk of snakebite to others.

Snakebite Management

Snakebite management can be divided into 1)First Aid measures, 2) confirming the venomous snakebite by a doctor and 3) Anti snake venom (ASV) therapy

First Aid Measures

first aid measures can be offered by anyone, no special skills are required. the only thing you should know is, what to do and what not to do⁸.

Important Do’s:-

• Reassure the patient as 70% of all snakebites are from non-venomous species⁸

• Immobilize the limb:- in the same way as a fractured limb for its entire length. use any straight, rigid object e.g.- a spade, piece of wood, sticks, or rolled-up newspaper.
• Shift the victim to the hospital using whatever means available- ambulance, boat, motorbike, bicycle, etc. While using a motorcycle third person must sit behind the victim.
• At and around the bitten area- Remove things that can act as a tourniquet (constrictor) if swelling appears. it may include- shoes, rings, a watch, jewellery or any tight clothing around.
• observe and tell the doctor about any drooping of eyelids, or the progress of swelling in the victim.

Important Don’ts

• Don’t tie the tourniquet- it may cut the crucial blood supply and develop gangrene in the limb. However, the crepe bandage may be rolled over the whole limb (preferably by a medical office or expert) if the referral facility is at more than 30 minutes and less than a 3-hour distance. please note that the crepe bandage should be loose enough to allow 2 fingers
• Don’t try to kill and never try to catch the snake alive. it provides no added advantage to the patient if you take the snake to the doctor. Moreover, the same snake can bite others trying to kill
• Don’t interfere with the bite wound- no incision, suction, or vigorous cleaning of the wound. it only harms the victim
• the victim should not run or drive a vehicle on his/her own.
• Don’t waste precious time in traditional healing– black stones, sacrification, herbal therapy etc. They have no role in treatment at all.
• Don’t give anything to eat, drink or put anything in the mouth of the victim as it may choking
• Don’t disturb blisters, if appear over the biting site

First Aid measure at Health care Facility

they are something that is expected from the health care provider who first receives the victim. it includes:-

• Admit and keep under observation– all suspected or confirmed snakebite victim
• Look and Observe for signs of envenomation (investigate the patient clinically and with laboratory tests)
• Secure IV line
• Start fluids if the patient is in shock (vitals not recordable)
• Start ASV therapy as soon as evidence of envenomation appears in the patient

Confirming Envenomation:-

Sign and Symptoms of Snakebite

All signs and symptoms can be grossly categorized into three categories:

1. Neuroparalytic- in Cobra and Krait bite
2. Vasculotoxic– in Viper bite (both saw-scaled and Russel’s viper)
3. Myotoxic- Flat-tailed sea snake

Neuroparalytic signs and symptoms

As we already learnt that Nuroparalytic signs and symptoms are found in the Cobra and Krait bites. patient presents with such symptoms within 30 minutes to 6 hours after the cobra bite and maybe even more delayed (6-12 hours) in the case of Krait. we can remember Neuroparalytic signs and symptoms with the mnemonic 2P-5D

• Ptosis– Dropping of eyelids. this is usually the first sign in order of appearance of signs and symptoms.

• Paralysis of skeletal and intercostal muscles is the last to occur. paralysis appears in descending manner (head to toe)
• Diplopia– double vision. the patient can tell that he/she is having double vision. it is usually the 2nd in order of appearance of signs and symptoms.
• Dysarthria– speech difficulty.
• Dysphonia– hoarse, rough, strained, weak, breathy voice
• Dyspnea– shortness of breath
• Dysphagia– inability to swallow

Bedside test to identify the impending respiratory failure:

• Single breath count- ask the patient to count numbers after having a deep breath in. Note the digits which the patient counted in a single breath. Normally a person can count more than 30 numbers in a single breath.
• Breath Holding time- Ask the patient to take a breath in and hold it. Normal breath-holding time is more than 45 seconds
• Note that if the patient is able to complete the one sentence in one breath or not. the normal person can complete one sentence in one breath.

if any of such sign-symptoms appear in a patient, administer the full dose of ASV and AN (Atropine and neostigmine) and refer the patient to a higher facility, as the patient may require breathing assistance (eg ventilators) owing to paralysis of the respiratory muscles.

Please note that Bilateral Dilated, poorly reacting or non-reacting pupil to light is not a sign of Brain Death in elapid (cobra, Krait) snakebite.

Vasculotoxic signs and symptoms

as we already learnt that vasculotoxic symptoms are seen in Viper bites. there can be local as well as system manifestations of vasculotoxic venom of vipers (saw-scaled and Russell’s viper)as we already learnt that vasculotoxic symptoms are seen in Viper bites. there can be local as well as system manifestations of vasculotoxic venom of vipers (saw-scaled and Russell’s viper)

Local- at bite site:-

• Swelling, Bleeding, blister formation and even necrosis. (severe swelling may cause compartment syndrome)
• Continued bleeding from the local (bitten)site may be there.
• Enlargement of lymph nodes which are painful to touch, draining the bitten area

Systemic manifestations- in the whole body internally

• Visible Systemic bleeding-
  • Gingival bleeding (bleeding from gums)
  • Epistaxis
  • Hemoptysis– blood containing sputum
  • Hematemesis– vomiting of blood
  • Bleeding per rectum
  • Sub-conjunctival haemorrhages
  • Bleeding from pre-existing conditions like freshly healed wounds, haemorrhoids, etc.
• Acute Abdominal Tenderness– suggests gastrointestinal bleeding (bleeding inside the abdomen)
• Some Neurological symptoms like Asymmetrical pupils may be indicative of intracranial bleeding (bleeding inside the head)

Myotoxic signs and symptoms:-

As we already learnt that myotoxic sign symptoms are seen in sea snakebites. A patient can present with:-

• Muscle pains, muscle swelling, involuntary contractions of muscles (fasciculations)
• Dark brown urine
• Complications like- compartment syndrome, cardiac arrhythmias (due to electrolyte imbalance- hyperkalemia), acute kidney injury (due to Myoglobinuria) etc.

Management of Snakebite as per Standard Guidelines in India

Investigations:-

• Check for vitals and stabilize the patient
• Closely monitor the patient for Neurological signs or symptoms and re-check all vitals every 1-2 hours.
• To check for Vasculotoxic envenomation do 20-WBCT⁸
  • Every 1 hour for the first 3 hours.
  • Every 4 to 6 hours for the next 24 hours
  • Precautions for 20WBCT:-
    • New clean and dry glass vessel/ tube
    • Glass tube washed with detergent– test will Not be valid
    • If in doubt about the glass tube take a control sample of a healthy person (usually an attendant) to fix the validity of the test (WHO)
  • Result interpretation:-
    • If blood is solid (clotted) at the end of 20 minutes, means it has passed the clotting test and ASV is not given to the patient. (the result should be read by gently tilting the glass tube, no vigorous shaking is allowed)
• While drawing the first sample for 20 WBCT also take the blood for other lab tests (for baseline)
  • Complete Haemogram:-
    • May show hemoconcentration due to a capillary leak. patients with capillary leaks may require higher doses of ASV. early recognition and infusion of fresh frozen plasma and thus reduction of hemoconcentration may play a key role in reducing mortality.¹⁴
    • May show Anaemia due to Hemolysis
    • May show Thrombocytopenia as in viper envenomation
    • Early Neutrophilic Leukocytosis may be a sign of envenomation (any species)
    • Serum may be Pinkish- in gross Haemoglobinemia or Myoglobinemia
  • RFTs
    • S. creatinine to know or rule out AKI (viper/ sea snake)
  • Electrolyte determinations: These tests are necessary for patients with respiratory paralysis
  • LFT (liver function tests)- ALP, AST, ALT
  • Urine examination for Proteinuria or RBC (red blood cells)
  • Serum CPK- S/o Muscle damage; Serum Amylase- S/o Pancreatitis
  • Prothrombin time (PT) and activated partial thromboplastin time (aPTT): Prolongation may be
  • Fibrinogen and fibrin degradation products (FDPs): Low fibrinogen with elevated FDP is present when venom interferes with the clotting mechanism
  • Other investigations like- ABG D-dimer, ECG, and EEG may be ordered at tertiary care centres, as and when required.

Administration of ASV (Anti-Snake Venom)

It is a specific treatment for snakebite envenomation and should be given as soon as it is indicated.

Indication:-

• Presence of signs and symptoms of Envenomation with or without evidence of Lab investigations.

Always Administer the full dose of ASV when indicated.

Important points to keep in mind while administering ASV:-

• For ASV administration use I/V (intra-venous) route only. Never give I/M or locally at the site of the bite.
• Keep watch on the patient during infusion and stop the infusion if develops any sign of ASV reaction. restart slowly after addressing the adverse event.
• 10 dissolved vials of ASV =100ml, (as each powdered vial is diluted with 10 ml of distilled water or normal saline, thus 10 vials make 100 ml solution). this 100 ml ASV solution is usually added to 400 ml of normal saline infusion BUT the total volume of infusion can be reduced (reducing Normal saline or using the infusion pump) depending upon the state of hydration of the patient, body size, age (ns for dilution = 5-10 ml/kg or 200ml in place of 400 ml NS) or other medical conditions (like anuria)
• A test dose of ASV is Not Recommended

Dose of ASV:-

Please note:- All patients of snakebite are given injection Tetanus Toxoid (TT) I/M in the deltoid region. (the injection may be delayed but not missed, in the patient with coagulopathy until hemostasis is achieved). Antibiotics may be added if required.

Complications of Snakebite

• AKI (Acute Kidney Injury- declining or No urine output, deteriorating RFTs. A patient may present with bilateral renal angle tenderness, albuminuria, hematuria, hemoglobinuria, and myoglobinuria followed by oliguria and anuria with AKI
• Hypotension-(due to hypovolemia, direct vasodilation or direct cardiotoxicity), refractory shock
• Parotid swelling, Conjunctival oedema, Sub-conjunctival haemorrhage, ARDS
• A long-term sequel like Pituitary insufficiency (Russell’s viper), Sheehan’s syndrome or Amenorrhea (females) among survivors may be seen.

FAQ