India suffers over 58,000 snakebite deaths annually, almost 80% of global snakebite deaths. Of these, around 90% are caused by the Big Four: Common Krait, Spectacled Cobra, Russell’s Viper and Saw-Scaled Viper. Agricultural workers and children are the most affected and children with their smaller body mass often suffer more severe effects.
A venomous snakebite can result in loss of limbs, paralysis, and an extremely painful death. Even today, many snakebite victims go to a ‘baba’ whose outright dangerous treatments sometimes work only because the snake was non-venomous or the bite was dry; i.e. no venom was injected. Fortunately, today we have a fairly reliable treatment.
Early days
In 1895, French scientist Albert Calmette began production of the first snake antivenom created by inoculating horses with the venom of Naja naja (Spectacled Cobra) at the Pasteur Institute in Lille, France. A small amount of venom injected into a horse or sheep causes an immune system response and release of antibodies. At certain intervals, the animal’s blood is collected and neutralising antibodies purified to produce an antivenom for the treatment of envenomation.
Though basic processes have remained the same, there has been significant improvement. Many technological advances and purification processes have been introduced to achieve a higher quality product and reduce side effects. Rapid tests to identify the injected venom have been established and first-aid strategies have also evolved. Additionally, antivenom administered into the vein (intravenous) as opposed to the earlier subcutaneous (under the skin) or intra-muscular has helped decrease severe reactions.
Two kinds
Antivenoms are broadly of two types: monovalent and polyvalent. Monovalent AV is when venom from a single species is injected into the animal. This can treat bites only of that species. So, Calmette created a monovalent antivenom for the Spectacled Cobra. Polyvalent AV contains neutralising antibodies raised against two or more species. In India, we use a polyvalent antivenom that covers the big four: Saw-scaled Viper, Russell’s Viper, Spectacled Cobra, Common Krait.
Venom being extracted at the Irula Snake Cooperative. | Photo Credit: KARUNAKARAN M
Despite the progress, the biggest challenges are availability and access. Two eternal questions remain: was it truly a deadly serpent and did it inject enough venom to kill? Some doctors wait and see if a bite victim shows symptoms of envenomation before administering antivenom. However, the effectiveness of treatment can be compromised by waiting. AV can prevent venom-induced damage to a body but is less able to reverse damage already caused. Thus, it is important that antivenom treatment start as quickly as possible. Depending on the amount and toxicity, a victim may need many injections of antivenom to sufficiently neutralise the venom.
Are you wondering where the snake venom to create antivenom comes from? Well, Irula tribe, who are specialised snake catchers, who capture the Big Four, hold them in earthen pots, and extract venom before releasing the snakes back into the wild. Through their Irula Snake Cooperative, they collect about 80% of the country’s venom!
