As per the WHO figures, a million people are bitten by snakes in India per year and fifty thousand out of them die. The main victims are the young farmers, the breadwinners of the cultivator family. Others who are at risk are the construction workers, trekkers and campers. In conversation with Dr Vijay Muralidhar Sonar who has been treating the victims of snakebite for the past fifteen years in the city of Ahmednagar. He is an MBBS and MD, anesthesia from BJ Medical College Pune, India. He has been practicing general and emergency medicine. He treats about 150 snakebite victims a year.
In India, how many types of snakes do we have?
We have 250 species of snakes in India, fifty from those are venomous and five are very dangerous for humans. Four of them are responsible for most of the killer bites – common cobra (called naga), saw scaled viper, common krait (manyar) and Russell’s viper. The concept of the Big Four is slowly becoming a thing of the past. Humpnosed pit viper, also called hypnale was considered as harmless to humans but is capable of causing uncontrolled bleeding and sudden kidney failure leading to death. The current anti-venom serum (AVS) does not give protection against the bite of this viper. Sea snakes are also poisonous to humans.
Which of those five dangerous ones is the most dangerous?
If you ask me it is the common krait, for its bite has hardly any local symptoms – no swelling, no bleeding and no pain. It is a very peculiar snake, in the villages it comes out in the dead of the night to explore for food (rats) and bites people who sleep on the floor. This can happen to people camping outdoors. The problem with Krait bite is that sometimes one cannot even ‘see’ the wound and in many cases people, especially the children are unaware that they are even bitten. The bite of krait is deceptive, while the local symptoms are minimum it has severe degree of venomation (injection of venom into human body). In most of the cases the victim gets severe stomach pain and vomiting and even if he/she is taken to a doctor, the victim is treated for the stomach pain. By morning the neurotoxin spreads in the body and the victim dies of respiratory failure. We always advise people to sleep on a cot, or while camping outdoors use mosquito nets to keep the reptiles away. Russell Viper is also very dangerous for it injects maximum venom in its victim and has less number of dry-bites.
So the venom of a snake attacks the nerves?
Venom of a snake has 26 components, out of which 14 are common in all. The venom of a snake is meant to kill its prey before it swallows it, and humans are just a collateral damage. The venom of a common krait and a cobra are neuro-toxic, means the venom attacks the central nervous system (brain and nerves in the spinal cord), and the symptoms like dropping eyelids, difficulty in swallowing and breathing difficulties appear after a few hours. The venom from the viper family is more hemolytic, meaning it causes massive internal bleeding. Some of its components also cause certain degree of neuro-toxicity.
How do you access the victims?
The most important is to first find out if the bite is from a poisonous snake. Before we start AVS treatment we try to understand that if it is from a poisonous snake we hope for a dry bite or at least for a less degree of venomation (how much venom has been injected by the snake into the victim’s body). The next is to find out which snake? Here we take what is called a syndromic- approach (symptoms caused by a neurotoxin like breathing difficulty means a Krait or a cobra).
In any case, the bites on the hands have less venomation (since we tend to jerk our hand as a reflex action to get rid of the snake) but if the bite is on the lower legs because someone has accidently strode on a snake, it usually causes severe degree of venomation. Another aspect is the time between the snake bite and the victim reaching the hospital. First eight hours are crucial, we observe the victims of venomous snakes for 24 hours and watch for the systemic signs like breathing difficulty, and paralysis.
Does that mean without AVS you are helpless?
No, for a Krait and Cobra bites patient can be saved if artificial-ventilatory-support is available. It will not let the victim’s respiratory system collapse. After a few hours the victim’s body will neutralize the venom and the victim will live on. That is why we want all the villages, and town to have ventilator-support in civil and government hospitals. AVS helps a far quicker recovery though.
Are babies of these venomous snakes harmless?
Far from it. The venom of a baby snake is far more potent than the adult ones.
In other facts you want to share with our readers?
About 25% develop reactions to the anti-venom serum (AVS) ranging from mild to fatal anaphylaxis. Anyone treating snakebite with AVS must have antidote against this reaction ready-at-hand. Also, if a person has survived snakebite (poisonous, non-poisonous) earlier in his/her life, his body contains antigens. In such cases a second bite can produce a huge reaction and this victim may need a more aggressive treatment with AVS.