TLDR: The Big Four refers to the four venomous snake species in India that are responsible for the most snakebite cases. They are the Russell's viper, common krait, Indian cobra, and Indian saw-scaled viper.

The Big Four are a group of venomous snakes found in India that are known for causing a significant number of snakebite cases. These snakes are the Russell's viper, common krait, Indian cobra, and Indian saw-scaled viper. They are called the Big Four because they are responsible for the majority of medically significant snakebite cases in India.

The Russell's viper is the most common snake responsible for snakebites in India, accounting for 43% of cases. It is followed by the common krait (18%), Indian cobra (12%), hump nose viper (4%), saw-scaled viper (1.7%), and water snake (0.3%). The remaining cases (21%) were caused by unidentified snake species.

Snakebites can be dangerous and require medical treatment. In India, a polyvalent serum is widely available to neutralize the venom of the Big Four snakes. This serum is frequently administered to save lives.

If you want to learn more about the Big Four snakes in India, you can check out the following links:

• Russell's viper
• Common krait
• Indian cobra
• Indian saw-scaled viper

And if you're interested in snakebites and their impact in India, you can read more here:

• Snakebites in India
• Snake antivenom

Remember, it's important to stay safe and be aware of your surroundings when in areas where venomous snakes are present.