snakes and snake bites

IN THE NAME OF

THE MOST BENEFICENT THE MOST MERCIFUL

SNAKE BITE

Irfan Ahmed

SNAKE BITES

Reptiles–Snakes

Arthropods–Scorpions–Spiders–Ticks–Insects

ARTHROPODS

• At least 750,000 species

• Three times number of all other animal species combined

• Scorpions, spiders, ticks, Insects etc.

ARTHROPODS

SNAKES A world free of snakes• Nearly a quarter of us would go

hungry• Are important elements in the food

chain to control the rodent population- Which destroy all major crops

The bottom line is we need snakes to survive

•Snakes belong to the order of animals called reptiles•This group also include crocodiles, lizards, and turtles•Snakes maintain a fairly steady body temperature by their behavior•Raise their temperature by lying in the sun or lower it by crawling into the shade

SNAKES

•Snakes have a long, legless, flexible body that is covered with dry scales•Snake's eyes are covered by clear scales rather than movable eyelids; therefore, their eyes are always open

SNAKES

•They repeatedly flick out their narrow, forked tongue, using it to bring odors to a special sense organ in the mouth

SNAKES

SNAKES – EVOLUTION• Early snakes killed their prey using surprise attacks and by suffocating them to death

• Snakes evolved a venom as new weapon about 60 million years ago

•3000 species of snakes in the world•375 are venomous (10 to 15 %)

SNAKES

WORLD DISTRIBUTION OF SNAKES

• Occur practically all over the world, apart from places like Greenland, Iceland, and Antarctica

• Most snakes are found in tropical regions

SNAKES – HABITAT• Long grass• Shrubs & hedges• Holes & burrows• Shady places like

under pre-fabricated construction

• Garbage pits

SNAKES – COLD BLOODED

• Do not have the ability of generating adequate amounts of heat in order to keep their body temperature at a constant level

• Dependent on the heat from their surroundings and the sun to control the temperature of their body

• Most snake species are found in the humid and warm climes of tropical regions

SNAKES – SIZE • Anaconda can

grow up to 38 feet in length

• Brahminy blind snake is just 2 inches long, making it the smallest snake

SNAKES – SENSE OF HEARING

• No external ears• Probably deaf to

most sounds• Hear by sensing

vibrations with their belly scales and lower jaw

SNAKES – SENSE OF SMELL

• Snakes use their forked tongue to smell

• Tongue gathers airborne particles

SNAKES – COLOUR• Dull to brilliant with

striking patterns• Dull for camouflage• Brightly coloured are

usually poisonous• Use bright colours to

warn predators• Some non-poisonous

snakes mimic the patterns and bright colors of poisonous snakes to fool predators

SNAKES – METABOLISM• Slow rate of metabolism

• King Cobra can go for months without food

SNAKES – MOLTING• We shed small

quantities of old skin continuously

• Snakes shed their old skins in a continuous sheet (a process called ecdysis)

SNAKES – MOLTING• Interval between

sheds depends on age, growth rate, environmental factors

• Young shed more frequently

• Adult snakes shed less often

SNAKES – CRAWLING• The type of

movement used depends largely on the terrain

Concertina Serpentine Side – winding Rectilinear

SNAKES – VENOM• Venom is the

toxic saliva produced by the parotid salivary glands of the poisonous snakes

•Snake venom is highly modified saliva, and is produced by modified saliva glands•Proteinaceous nature of snake venom was established by Napoleon Bonaparte's brother, Lucien in 1843

SNAKES – VENOM

•Proteins constitute the major portion of venom's dry weight–90% or more•Snake venom is a cocktail of hundreds, sometimes thousands, of different proteins and enzymes•Many of these proteins are harmless but a percentage of them are toxins•The makeup of these toxins varies widely from species to species•This complexity accounts for the widely differing effects of snakebite

SNAKES – VENOM

SNAKES – VENOM• Composition

Fibrinolysins Proteolysins Neurotoxins Cholinestarses Haemolysins Thromboplastin Agglutinins Cardiotoxins Hyaluronidase

POISON GLANDS AND VENOM EXTRACTION

POISON GLANDS AND VENOM EXTRACTION

•Venoms are rich in hydrolithic enzymes, a complex mix of polypeptides, nucleases, peptidases, etc., which help digest the snake's prey•Some of them also enhance or contribute to the toxic effect of the venom

SNAKES – VENOM

•Hemotoxin (blood toxin) Hemotoxic venom attacks the circulatory system

and muscle tissue causing excessive scarring, gangrene, and sometimes leads to amputation of the affected area

This venom basically destroys tissue and blood cells

In addition to killing the prey, part of the function of a hemotoxic venom for some animals is to aid digestion

The venom breaks down protein in the region of the bite, making prey easier to digest.ex : Vipers

SNAKES – VENOM

SNAKES – VENOM• Vasculotoxic

poison Enzymatic

destruction of cell membranes and coagulation disorders

Result in Destruction of

endothelial cells of blood vessels

Lyses of RBCs Failure of blood

clotting

•Neurotoxin (nerve toxin) Neurotoxic venom attacks the

victim's central nervous system and usually result in heart failure and/or breathing difficulties or even total respiratory paralysis. eg: Cobras, Kraits, Coral Snakes

SNAKES – VENOM

SNAKES – VENOM• Neuro Toxin

Acts on motor nerve Similar manner to tubocurarine poison Compete with acetylcholine at

nicotinic receptors Render acetylcholine inactive Leading to muscular weakness

SNAKES – VENOM• Krait- Pre-synaptic action

Beta-bungarotoxin- Phospholipases A2 Inhibiting the release of acetylcholine from

the presynaptic membrane Presynaptic nerve terminals exhibited

signs of irreversible physical damage and are devoid of synaptic vesicles

Antivenoms & anticholinesterases have no effect

Paralysis lasts several weeks and frequently requires prolonged MV. Recovery is dependent upon regeneration of the terminal axon

SNAKES – VENOM• Krait- Pre-synaptic action

1) Inhibiting the release of acetylcholine from the presynaptic membrane

2) Presynaptic nerve terminals exhibited signs of irreversible physical damage and are devoid of synaptic vesicles

3) Antivenoms & anticholinesterases have no effect

SNAKES – VENOM• Myotoxic poison

Muscular pains Myoglobinuria Respiratory

failure due to muscular weakness

CLASSIFICATION OF SNAKES

Five families

Clo

bri

dae

Boid

ae

• V

ipers

Vip

eri

da

e

• Cobra

s

Ela

psid

ae

• Wate

r sn

ake

s

Hyd

rop

hiid

ae

CLOBRIDAE• Most numerous

snake family • Two third of all

snakes in the world• Majority are

non-poisonous• Examples

— Corn snakes— Rat snakes

• Largest (size) snakes in the world

• Non-poisonous (Use their strength to constrict and kill prey)

• Three largest snakes— African rock

python— Reticulated

python— Anaconda

BOIDAE

VIPERIDAE• Poisonous

(Haemotoxic - Affects blood)

• Body characteristics— Typical triangle

shaped head— Folding fangs — Head covered with

small scales and nostrils are placed vertically

• Examples ─ Copperheads,

cottonmouths and rattlesnakes

ELAPSIDAE• Poisonous (Neurotoxic -

Affects nerves)• Body characteristics

— Hollow fixed fangs in the jaw below or in front of the eyes

— Do not have the triangle shaped head

— Head covered with large scales

— Lateral Nostrils• Examples

— Cobras, mambas, kraits and the coral snake

KING COBRA • 18 feet• Head as large as man’s

hand• Hood • Six feet tall

HYDROPHIIDAE• Sea snakes• Majority are poisonous

(Neurotoxic – Affects nerves)

• Examples— Banded sea snake— Yellow bellied sea

snake

COMPARISON OF POISONOUS & NON-POISONOUS SNAKES

COMPARISON OF POISONOUS & NON-POISONOUS SNAKES

Scale arrangement

Single row

Double row

COMPARISON OF POISONOUS & NON-POISONOUS SNAKES

POISON GLANDS AND VENOM EXTRACTION

COMPARISON OF POISONOUS & NON-POISONOUS SNAKES

WATER SNAKES

WATER SNAKES• If just the head is

showing, it is probably a harmless water snake

• Almost all venomous snakes swim with their lungs inflated, leaving the majority of their bodies afloat

Characteristic Poisonous Nonpoisonous

Shape of head Triangular RoundPit (+) (-)Pupils Elliptical RoundBite marks Fang marks 2 rows of teethCaudal plates Single row Double row

Color body Red ring next to yellow Alternating color

Swim in water Most of the body afloat

Often only head showing

POISONOUS / NON POISONOUS SNAKES

POISONOUS SNAKES IN PAKISTAN• Rat Snake

(Ptyas mucosus) Local Name: - Dhaman

• Indian Python (Python molurus) Local Name: - Azdaha

• Indian Cobra

(Naja naja) Local Name: - Cobra

• Leaf-nosed Viper ( Eristocophis macmahoni) Local Name: - Cobra

RISK TO HUMANS• Species and size of the

snake• Venom injected• Localization of the

bites• Weight & general

health of the victim• Sensitivity to the

venom• The availability of

health facility

SIGNS AND SYMPTOMS• Local effects

Fang mark at the site of injection

Intense local pain Swelling Oozing out of haemolyzed blood Blisters may appear

SIGNS AND SYMPTOMS• General effects

Haemoglobinuria Petechial haemorrhages Bleeding from gums, mucus

membranes such as rectum and body orifices

Haemoptysis Cold, clammy skin Death due to circulatory failure

SIGNS AND SYMPTOMS• Myotoxic

At the site of bite no pain and swelling

Muscle weakness Ptosis develops Generalized muscle paralysis Urine is brown in colour Respiratory muscle weakness leads to

death Hyperkalemia may result in cardiac

failure

SIGNS AND SYMPTOMS• Neurotoxic

Lethargy , giddiness , muscular weakness and spreading paralysis

Increased salivation and vomiting Ptosis and paralysis of extra ocular

muscles Breathing becomes slow and laboured Patient remains conscious but unable

to speak Finally respiratory paralysis

consequently death

WHAT TO DOOn seeing the Snake• Remain calm and

cautious• Get out of the way• Call for help• Use stick to kill the

snake by keeping a safe distance and striking the head

If you are the Victim

• Be calm• Try not to move the

effected part much• Call for help• Move away from

snake• Prevent further bite• Nearest health

facility

WHAT TO DO

If you are the helper of the Victim

• Remain calm• Reassure the victim• Call for help• Move the patient to safety• Evacuate the patient to

the nearest health facility• Try to kill the snake with

the help of others

WHAT TO DO

• There are two important aspects of snakebite treatment, one is the first-aid and then the treatment (antivenom serum)

TREATMENT – SNAKE BITE

FIRST AID•Reassure

•Evacuate

•Splintage

•Tourniquet

TREATMENT •Allaying anxiety and fright•Prevention of spread of venom•Shifting the victim to medical aid center•Use of antivenin

TREATMENT •Allaying anxiety and Fright To prevent the shock due to fright it is

desirable to reassure the victim by clarifying that

All snakes are not poisonous Even poisonous snakes are not fully

charged with poison all the time Even a snake with fully charged with poison

does not always inject it’s lethal dose

TREATMENT

•Prevention of spread of Venom Immobilization Application of tourniquet Cleaning the wound Local emetine injection Incision and suction at the site

TREATMENT

•Prevention of spread of Venom Immobilization Application of tourniquet Cleaning the wound Local emetine injection Incision and suction at the site

TREATMENT •Wash the bitten surface with plain water without rubbing•Polyvalent anti-venom should be given•Antibiotic & Tetanus prophylaxis

TREATMENT •Anti – Venom Types

Specific antivenin Polyvalent antivenin

Strength of polyvalent antivenin is 1ml will neutralize 0.6mg of dried cobra

venom, 0.45mg of dried krait venom, 0.6mg of dried russel’s viper venom and 0.45mg of dried saw-scaled viper venom

TREATMENT

•Neutralize Toxin at Tissue Level Neostigmine and atropine

administration in elapid snakebite Heparin and fibrinogen in viper

snakebite•Contraindications Morphine and alcohol as these

depresses respiratory center

TREATMENT •General measures Artificial respiration Blood Transfusion Steroids Antihistamines Antibiotics Stimulants are helpful in paralytic cases Aspirin short acting barbiturates

TREATMENT • Anti – Snake Venom (ASV)

Anti–venom is immunoglobulin (usually the enzyme refined F(ab)2 fragment of IgG) purified from the serum or plasma of a horse or sheep that has been immunized with the venoms of one or more species of snake

TREATMENT

5 vials(50ml)5-10 vials(50-100ml)

10-20 vials(100-200ml)

TREATMENT • Repeat dose of Anti – Snake

Venom (ASV) Continuing absorption- due to

improved blood supply following correction of shock, hypovolaemia etc,

After elimination of antivenom A redistribution of venom from the

tissues into the vascular space

TREATMENT • At the earliest sign of a reaction

Antivenom administration must be temporarily suspended

Adrenaline-0.1% solution, 1 in 1,000, 1 mg/ml is the effective

treatment for early anaphylactic reactions

IV hydrocortisone (adults 100 mg, children 2 mg/kg body

weight). The corticosteroid is unlikely to act for several hours,

but may prevent recurrent anaphylaxis

Increasing evidence for anti H2 antihistamines-Ranitidine –

adults 50 mg, children 1 mg/kg

Start fluids, inotropes along with IV adrenaline for circulatory

collapse-

5-day course of oral antihistamine/ Prednisolone.Chlorpheniramine: 2 mg six hourly Prednisolone: 5 mg six hourly

Serumsickness

DON'TS •Tight tourniquets (Tight band / rope)•Incisions at the site of snake•Local suction•Application of herbal medicines, cow dung, seeds, saliva etc•Unnecessary delaying

• Always remain cautious, snakes may silently harbour anywhere

• Ankle boots be used, with trousers tucked in the socks

• Boots should be shaken before use

• Remove bushes, shrubs etc lying close to the buildings

• Alter all sites that provide cool, damp, dark habitat

• A stick and torch, be used at night

PREVENTION OF SNAKE BITES

PREVENTION OF SNAKE BITES

• Never reach in to holes or crevices

• Bedding & clothing should be thoroughly shaken

• Mosquito nets• Two feet deep and two

feet wide trench with vertical sides

• The trench or the sleeping platform should be thoroughly inspected

• Watch your step; very few snakes bite unprovoked

WORLD DEADLIEST SNAKES

• Black Mamba Most deadly snake Located in Africa and is colored dark olive

or a dark brown color with black spotting along its back

Longest fangs Delivers quick multiple bites and flees Venom is a cardio toxin and a fully grown

Black Mamba can deliver 100mg to 120mg. A lethal dose of a cardio toxin to a human is

10mg to 15mg

WORLD DEADLIEST SNAKES

Black Mamba

• Common Krait Located mostly in Southeast Asia Normally black with yellow bands

around it Can go either on land or water Affects the nerves and produces a

nerve paralysis. Fangs are not very long so has to chew

on it’s pray to induce the venom into the blood stream

WORLD DEADLIEST SNAKES

Common Krait

• Russell’s Viper Located in South Asia Light brown with three rows of black

or brown spots bordered by yellow or white around

Responsible for the most fatalities Highly irritable, coils up before strike Damage to the blood cells and tissue

WORLD DEADLIEST SNAKES

Russell’s Viper

• Taipan Located in Australia Pale creamy color on the head Light brown, dark brown,

copper, or olive Usually stay away from humans Defend itself

WORLD DEADLIEST SNAKES

Taipan

• Cobra Located in South Asia Hood that pops up behind Symbol on the back, looks like

eyes Either spit venom or bite Spiting venom isn’t deadly Severe pain and damage to eyes

WORLD DEADLIEST SNAKES

Cobra

AQ&Q u e s t i o n s

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