This document provides an overview of snake bites in India. It discusses the epidemiology of snake bites in India, which has the highest incidence in the world at 200,000 bites and 15,000 deaths per year. It also covers the classification, pathophysiology, mechanisms of action, symptoms, management, prevention and control of snake bites. Key points include the "Big 4" venomous snakes in India, the local and systemic effects of venom, treatment guidelines focusing on airway, breathing and circulation support, and use of antivenom when indicated.

1. SUBMITTED TO
DR. S. NAGARJUNA
HOD
DEPARTMENT OF PHARMACOLOGY
RIPER,INDIA-515721.
SUBMITTED BY
G . ARUN KUMAR
M.PHARM(PHARMACOLOGY)

2. TOPICS
INTRODUCTION
 EPIDEMIOLOGY
 CLASSIFICATION
 PATHOPHYSIOLOGY
 MECHANISM OF ACTION
 SYMPTOMS & SIGNS OF SNAKE-BITE
 MANAGEMENT OF SNAKE –BITES
 PREVENTION AND CONTROL


3. HISTORY
They live almost everywhere, in forests, oceans, streams
and lakes.
 They cannot survive in places where the ground stays
frozen the year around, so they are missing in the polar
regions or at high mountain elevations.
 Several islands, including Ireland and New Zealand, do
not have snakes.


4. Epidemiology
INDIA
 Records the highest annual incidence of total snake
bites as well as fatal snake bites in the world
 2,00,000 bites/year
 15,000 deaths/year
 Rural: urban ratio ---- 9:1
 Monsoon and post monsoon season, floods.
 Out of the 2700 known species of snake only 300 are
venomous.


Number of Indian snake species:
– 250 [ some say 272]
o Venomous species:
– 52

5. Classification of snakes

Colubridae

Most non venomous
snakes eg : grass snake

Elapidae


Viperidae

Cobras, krait, mambas,
coral snake
American rattlesnake,
Asian pitviper, Russels
viper, aders

Hydrophidae

Sea Snake

6. Commonest Indian venomous
snakes
The big 4 –
1.
Common cobra
– Naja Naja - neurotoxic venom
2. Common krait
– Bungarus Caeruleus - neurotoxic venom
3. Saw scaled viper (carpet viper)
– Echis carinatus - haemotoxic Venom
4. Russell’s viper
– Daboia russelli - haemotoxic Venom

7. Commonest Indian venomous snakes –
the big 4
Cobra
Krait
The venom is synthesized by the modified salivary glands and
injected through special channeled or grooved teeth called fangs
Russel’s viper
Saw-scaled viper

8. Poisonous
Non poisonous

Short and solid

Fangs : hollow like
hypodermic needles
Teeth : 2 long fangs

Several small teeth

Tail : compressed

Not much
compressed


9. Pathophysiology
The local effects of venom serve as a reminder of the
potential systemic disruption of organ system function.
 Local bleeding - coagulopathies are not uncommon with
severe envenomations.
 Local edema - increases capillary leak and interstitial fluid
in the lungs. Pulmonary mechanics may be altered
 Local cell death - increases lactic acid concentration
secondary to changes in volume status and requires
increased minute ventilation.
 The effects of neuromuscular blockade result in poor
diaphragmatic excursion.
 Cardiac failure can result from hypotension and acidosis.
 Myonecrosis raises concerns about myoglobinuria and renal
damage.


10. MECHANISM




Hemotoxin (blood toxin) : Hemotoxic venom attacks the
circulatory system and muscle tissue causing excessive
scarring,
This venom basically destroys tissue and blood cells.
The venom breaks down protein in the region of the bite,
making prey easier to digest.ex : Vipers
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.

11. Mechanism of Toxicity of Venom

The most common types of enzymes are proteolytic,
phospholipases and hyaluronidases
– Proteolytic Enzymes: digestive properties
– Phospholipases: degrade lipids
– Hyaluronidases: speed venom spread through the body

12. MECHANISM OF ACTION

It takes about 10 minutes for the venom to affect the
nervous system.

Most neurotoxins in snake venoms are too large to
cross the blood-brain barrier, and so they usually
exert their effects on the peripheral nervous system
rather than directly on the brain and spinal cord.

The neurotoxic effects are mainly at the
postsynaptic level of the neuromuscular junction
where the neurotoxins block acetylcholine
receptors, thereby producing muscular paralysis
and respiratory failure

13. Binding of neurotoxin to acetylcholine

14. NEUROTOXIN SYSTEMIC S&S
Neuromuscular junction blockade
Muscle paralysis which started from the group of small sized
muscles, larger and then generalized
 Ptosis
 respiratory paralysis
 generalized paralysis
 double vision (diplopia)
 sweating,
 excessive salivation,
 It takes about 10 minutes for the venom to affect the nervous
system.
 Mucular weakness sets in 1 hr ,lasts upto 10 days



Neurotoxic symptoms usually resolve in 2-3 days.

15. Management of

16. First Aid Methods — Not
Recommended






Traditional tight tourniquets.
Incisions at the site of snake of bite or any other
place.
Local suction either by mouth or by application of
chick.
Application of herbal medicines, stones, seeds,
saliva, potassium permanganate solution.
Ingestion of herbal products like oil, ghee, pepper to
induce vomiting.
Unnecessary delaying.

18. Laboratory lnvestigations(depending on
clinical features)







Coagulation tests - 20 min whole blood clotting test
ECG
Complete blood count
Blood urea
Urine R/E
Serum C P K(creatine phosphokinase)
Immuno diagnosis(by ELISA).

19. SUMMARY MANIFESTATIONS

20. FEATURE
Cobra Krait
Russels Saw
viper
scaled
viper
Hump
nosed
viper
YES
NO
YES
YES
YES
Ptosis/Neurologi YES
cal signs
YES
YES
NO
NO
Hemostatic abn
NO
NO
YES
YES
YES
Renal Comp
NO
NO
YES
NO
YES
Response to
Neostigmine
YES
NO?
NO?
NO
NO
Response to ASV YES
YES
YES
YES
NO
Local pain /
tissue damage

21. Neurotoxic
KRAIT
RV
Haemotoxic
S H
S N
V P
V
Local
reaction

22. CURRENT THERAPY GUIDELINES

23. Approach to diagnosis of snake bite
The history:
• Site of bite, circumstance of bite, time of bite
 Non-specific symptoms: headache, nausea, vomiting,
abdominal pain, loss of consciousness, difficulty in vision,
convulsions. '
 Neurological symptoms: Muscle paralysis, difficulty in
moving Jaw, tongue and eye, heaviness of eye lids (ptosis),
difficulty in swallowing, dribbling of saliva, nasal
regurgitation, nasal voice, difficulty in respiration, extreme
generalized weakness.
 Haematological symptoms: Spontaneous bleeding from
gum, vomiting of blood, haemoptysis, haematuria,
persistent bleeding from bite site and inflicted wound.
 Others: Severe muscle pain, dark colored urine, scanty
urine volume, collapse


24. Treatment protocol









Attend to AIRWAY , BREATHING, CIRCULATION
Tetanus toxoid
Routine antibiotic is not necessary
Identify the snake responsible
All patients should be kept under observation for a
min period of 24 hrs.
Determine the exact time of bite
Pain – give PARACETAMOL
Not Aspirin & NSAIDS
5o mg TRAMADOL can also be used

25. Pharmacotherapy
The goals of pharmacotherapy are to neutralize the toxin,
to reduce morbidity and to prevent complications
 Antibiotics
 Immunizations -- Snakes do not harbor Clostridium tetani
in their mouths, but bites may carry other bacteria,
especially gram-negative species.
 Tetanus prophylaxis recommended if patient not
immunized.
 Antivenin (At present only polyvalent antivenom is
available in our country


26. INDICATIONS / CRITERIA FOR
USING POLYVALENT ANTIVENOM
1. Neurotoxic signs: Ptosis, External ophthalmoplegia Broken
neck sign Nasal voice Respiratory difficulty
2. Rapid extension of local swelling (more than half of bitten
limb) not due to Green snake bite or tight touriquet.
3. Acute renal failure not due to sea snake bite.
4. Cardiovascular abnormalities.
5. Bleeding abnormalities.
6. Haemoglobinuria / Myoglobinuria not due to sea snakes.

27. ASV

28. AntiSnakevenoms available in
India



Polyvalent Snake Antivenom I.P
 4 Antivenoms effective against the Big 4, mixed together
Manufacturers:
1. VINS Bioproducts Ltd, AP
2. Serum Institute of India Ltd, Pune
3. Haffkine Institute, Mumbai
4. Bharat Serums of India, Mumbai
Owing to reports of significant bites by pit vipers, there is a
move to add a 5th antivenom!

29. Polyvalent antisnakevenom



Advantages
No need to waste time
or effort at identifying
the exact nature of
venomous snake
Less expensive
Easy distribution to all
parts of the country


Disadvantages
Decreased efficacy (?)
Increased incidence of
allergic reactions

30. ASV and children



Dose of antivenom
Snakes inject the same dose of venom into children
and adults.
Children must therefore be given exactly the same
dose of antivenom as adults.

31. PREVENTION AND CONTROL



Snakes love dark and cool places!
Never get into a dark bathroom; first switch on a light
and then see around you before you enter.
Drain mesh should be fixed with cement and not with
hinges. In case you need to clean the drain, just break
the cement; the cost of a little cement is not worth
bartering with your life. Mostly snakes make their way to
your bathrooms and toilets through drain system.

32. Summary
Snake bites may be by an non venomous snake or a
dry bite
 Not all snake bites require ASV
 ASV is the main stay in the treatment of snake bites
 ASV must be initiated if indicated at the earliest
 Respiratory paralysis can be because of different
reasons-Neurotoxicity, shock, sepsis, ARF…
 MV may be main stay of treatment or just
supportive depending on the cause of failure.


33. REFERENCES


WHO/SEARO GUIDELINES FOR THE CLINICAL
MANAGEMENT OF SNAKE BITE IN THE SOUTH
EAST ASIAN REGION by David A WarrellSupplement to The Southeast Asian Journal of
Tropical Medicine & Public Health
Visit website www.firstaid.co.in