What is Snake Antivenom?
The antibodies are raised against one or several species of venomous snakes and are used to treat venomous snakebites. When the antibodies are raised against a single species of venomous snake, it is called monovalent antivenom. If the antibodies are raised against several species of venomous snakes, it is called polyvalent antivenom.
Since snake antivenom is essential for saving lives, the World Health Organization (WHO) has included this in its List of Essential Medicines, which includes all medicines that are needed in the primary healthcare package.
What is Snake Antivenom Used For?Snake antivenom is used for treating patients bitten by a poisonous snake. Snake antivenom can reverse most of the symptoms produced by snake envenomation and significantly reduces the mortality and morbidity.
What Type of Snake Antivenom is Available in India?In India, polyvalent antivenom is available. Indian antivenom consists of antibodies against the venom of four species of venomous snakes, which are collectively responsible for the largest number of snakebite deaths in India. For this reason, these snakes are also called the “Big Four”. These include the Indian Cobra (Naja naja), Russell’s viper (Daboia russelii), Saw-scaled viper (Echis carinatus), and Common Krait (Bungarus caeruleus).
Indian polyvalent antivenom is a sterile preparation of equine (horse) immunoglobulin fragments F(ab’)2. Each milliliter of reconstituted antivenom has the potency to neutralize the venom of the following snakes:
- 0.6 mg of dried Indian cobra venom
- 0.6 mg of dried Russell’s viper venom
- 0.45 mg of dried saw-scaled viper venom
- 0.45 mg of dried common krait venom
How is Snake Antivenom Administered?Snake antivenom may be supplied in a liquid form or lyophilized (freeze-dried) form. The freeze-dried antivenom is reconstituted in 10 ml of sterile water for injection. The whole content of the freeze-dried antivenom dissolves into a clear colorless or light yellow solution.
If signs and symptoms of envenomation are evident, antivenom should be immediately administered without delay. It can be administered by slow intravenous (IV) injection (2 ml/min) or by infusion after dilution in isotonic saline or glucose over a period of 1 hour with close monitoring.
How is Snake Antivenom Manufactured?Manufacture of snake antivenom involves the following steps:
- Snake Venom Extraction: The snake is “milked” to extract the venom. To do this, the snake is securely held by hand just behind the head. The fangs are anchored to a collection vessel such as a Petri dish. The fingers are squeezed and the venom slowly drips from the fangs into the collection vessel.
- Lyophilization: The snake venom is freeze-dried (lyophilized) and reconstituted in sterile water at a particular concentration.
- Hyperimmunization: Large animals like horses are immunized with gradually increasing doses of venom. This process is called “hyperimmunization”, which elicits an immune response within the animal, generating large amounts of antibodies.
- Bleeding: After a few months, the horses are bled and the serum (containing the antibodies) is separated.
- Antibody Purification: The antibodies are treated with enzymes to cleave the F(ab’)2 fraction and then purified. The final product is either dissolved in sterile water (final product is a liquid) or freeze-dried (final product is a powder).
Does Snake Antivenom have any Side-Effects?Snake antivenom reactions are generally rare. However, they may occur in a few susceptible people. The most severe is anaphylaxis, which is a medical emergency that can be life-threatening. Anaphylaxis can be associated with one or more of the following signs and symptoms:
- Rashes and/or itching
- Fever, chills or rigor
- Nausea and vomiting
- Abdominal cramps and diarrhea
- Increased heart rate (tachycardia)
- Low blood pressure (hypotension)
- Spasm of the respiratory tract (bronchospasm)
- Puffy face and neck or other parts of the body (angioedema) resulting from accumulation of fluid under the skin
Know More about Snake Antivenom
How was Snake Antivenom Discovered?Snake antivenom was discovered over a century ago by Albert Calmette who was a renowned French physician, bacteriologist and immunologist. He demonstrated that it was possible to “hyperimmunize” an animal with increased regular dosage of snake venom. He further demonstrated that a second animal could be saved after snakebite by introducing the serum of the immunized animal. This discovery is still the basis of the production of modern antivenoms.
Snake Antivenom Manufacturers in IndiaSnake antivenom is manufactured by the following organizations:
- Haffkine Bio-Pharmaceutical Corporation Ltd., Mumbai
- Central Research Institute, Kasauli
- Bharat Serums and Vaccines Ltd., Mumbai
- Biological E Ltd., Hyderabad
- VINS Bioproducts Ltd., Hyderabad
- Serum Institute of India Ltd., Pune
- Kings Institute of Preventive Medicines, Chennai