SNAKES OF INDIA

           Snakes are elongated, legless, carnivorous reptiles of the suborder Serpentes.Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Most species are nonvenomous and those that have venom use it primarily to kill and subdue prey rather than for self-defense. Some possess venom potent enough to cause painful injury or death to humans. Nonvenomous snakes either swallow prey alive or kill by constriction.

Venomous snakes are classified in two taxonomic families:

• Elapids – cobras including king cobras, kraits, mambas, Australian copperheads, sea snakes, and coral snakes.
• Viperids – vipers, rattlesnakes, copperheads/cottonmouths, and bushmasters.
  

There is a third family containing the opistoglyphous (rear-fanged) snakes (as well as the majority of other snake species):

Colubrids – boomslangs, tree snakes, vine snakes, mangrove snakes, although not all colubrids are venomous.

India has some 270 species of snakes, of which 60 are considered venomous and medically relevant, and with various levels of toxicity. 

The four venomous snake species responsible for causing the greatest number of medically significant human snake bite cases on the Indian Subcontinent (mostly in India) are sometimes collectively referred to as the Big Four. They are as follows:

1. Common krait, Bungarus caeruleus
2. Russell's viper, Daboia russelii
3. Indian saw-scaled viper, Echis carinatus
4. Indian cobra, Naja naja
   

COMMON KRAIT

  Venom : Presynaptic and postsynaptic neurotoxins.

RUSSELL'S VIPER

  Appearance :  The head is flattened, triangular, and distinct from the neck. The snout is blunt, rounded, and raised. The nostrils are large, each in the middle of a large, single nasal scale. The lower edge of the nasal scale touches the nasorostral scale. The supranasal scale has a strong crescent shape and separates the nasal from the nasorostral scale anteriorly. The rostral scale is as broad as it is high.

  Venom : The lethality varies with change in route of injection.

INDIAN SAW-SCALED VIPER

  Appearance : Head distinct from neck, snout very short and rounded. The nostril between three shields, and head covered with small keeled scales.The color-pattern consists of a pale buff, grayish, reddish, olive or pale brown ground color, overlaid middorsally with a series of variably colored, but mostly whitish spots, edged with dark brown, and separated by lighter interblotch patches. A series of white bows run dorsolaterally. The top of the head has a whitish cruciform or trident pattern and there is a faint stripe running from the eye to the angle of the jaw. The belly is whitish to pinkish, uniform in color or with brown dots that are either faint or distinct.  

  Venom :  Intravascular hemolysis and disseminated intravascular coagulation.

INDIAN COBRA  

 

  Appearance : The Indian cobra varies tremendously in colour and pattern throughout its range. The ventral scales or the underside colouration of this species can be grey, yellow, tan, brown, reddish or black. Dorsal scales of the Indian cobra may have a hood mark or colour patterns.

  Venom : Post-synaptic neurotoxin and cardiotoxin.

        Of the Big Four, the common krait is responsible for the most snake bites, followed by the Russell's viper, the saw-scaled viper, and the Indian cobra. 

TREATMENT

        A polyvalent serum that effectively neutralizes the venom of all of the Big Four snakes is widely available in India, and is frequently administered to save lives.