SNAKE (Ophidia)

 Important poisonous snakes of India are Cobra, king cobra, common krait, banded krait, common green pit viper, russell's viper and saw scaled viper. The poisonous snakes are further classified on the bases of poison secreted by them into three main types-
1. Elapids (secreting neurotoxic venom) 
2. Vipers (vasculotoxic venom)
3. Sea snake (myotoxic)

1. Elapids:-

 

 It consist of cobra, king cobra, common krait, banded krait and coral.

The head is nearly of the same width as that of neck, pupil are round, the fangs are situated anteriorly but being covered of fold of mucus membrane, tail is usually round. 

2. Viper:-

 

 This group consist of pit vipers and pitless viper, the head is triangular and wider than the neck and pupil is vertical. The fangs are long, movable and canalized with hypodermic needle. While bite of pit vipers seldom fatal to human beings, those of pitless viper are dangerous. The tail is tapering. The bamboo snake belong to the pit viper. Common green pit viper and russell, saw scale are pitless viper.

3. Sea snake:-

 They are found in the vicinity of sea coast. They have small heads and flat length tail to help in swimming.

Hall mark of a venomous snake bite:-

 The hall mark of attack by a venomous snake is the presence of fangmark. These are usually two but only one may be evident. If the bite is sideways. In contrast bite by not poisonous snake produce a U shape set of teeth marks. One can get an idea about the size of snake from the distance between the fang marks.

Sign and symptoms:-

 Poisoning may occur from bite or absorption of venom through cuts or scratch. In some cases instant death may occur due to fright.

Elapid snake-

A bite from ealpid snake is attended by mild local symptoms by mark neurotoxic effect.

i. There is a slight burning at the sight of the bite.

ii. It is followed by 15 min-2 hours by marked neurotoxic effects such as giddiness, lethargy, muscular weakness and paralysis.

iii. Salivation and even vomiting, weakness in the leg is manifested by staggering gait. Paralysis of the extraoccular muscle, ptosis may occur. After a couple of hours respiration ceases and heart stopped.

iv. The skin and cellular tissue surrounding the bite mark undergo necrosis.

Viper snakes-

A bite from a viper is attended by severe local symptoms and marked vasculotoxic effect. There is a intense local pain, swelling, ecchymosis and severe loosing of hemolytic blood. Blisters may appear, nausea and vomiting may occur. Bleeding from the gums, hemoptysis and bleeding from the mucus membrane of the rectum and orifice of the body. Collapse sets in with cold clammy skin, rapid feeble pulse and dilated pupil insensitive to light followed by coma or death.

Sea snakes-

A bite sea snake is felt as sharp pricking pain, become painless later. After 1 or 2 hour generalized musclar pain and stiffness developed starting in the neck and limb girdle. Myoglobin uria causes a characteristic brown discoloration of the urine. Respiratory failure may ensure. 

Fatal dose-

Cobra - 15mg

viper - 20mg

krait venom - 6mg

saw scale viper- 8 mg

A amount of cobra venom yielded in one bite is 200-350 mg. And viper bite is 150-200mg. Krait about 20mg and saw scaled viper 25mg.

Fatal period-

Death may occur from shock due to fright.

Death from cobra venom occur with in few minutes to an hour while that of viper venom in a few days. Sea snake bite is mostly non-fatal..

Treatment:-

The main principle of treatment include-

1. Allaying anxiety and fright

2. Prevention of the spread of venom

3. Uses of antivenin and antitoxic therapy 

4. General measures