This presentation basically talks about classification, identification, nature & composition of snake venom, snake poisoning management(treatment i.e., both ASV & supportive, don'ts in case of snake envenomation) and forensic significance.

1. P R ES ENT AT I ON B Y : -
M R . M A NI S H K U M A R M I S H RA
A S S T . P R O F .
P G D E PA R T MENT O F F O R ENS I C S C I ENC E,
J A I N(DEEMED T O B E ) U N I VER SI T Y,
B E NGAL URU- 2 7
Snake Envenomation-
Fundamentals

2. Statistics

3. General Classification
 Kingdom: - Animalia
 Phylum: - Chordata
 Subphylum: - Vertebrata
 Class: - Reptilia
 Order: - Squamata
 Family: - Four families are there;
a) Elapidae (e.g.: - Cobra, Krait)
b) Viperidae (e.g.: - Russell’s Viper, Pit Viper)
c) Colubridae (e.g.: - Tree snake, Asian rat snake)
d) Hydrophidae ( e.g. :- Sea snakes)

4. Classification based on nature of Venom
S.No. Family Type of Venom COD
1 Elapidae Neurotoxic Respiratory failure
2 Viperidae Hemo/ Vasculotoxic Renal failure or
Haemorrhage
3 Hydrophidae Myotoxic Respiratory failure

5. Big four in India
1. Naja naja : - Kobra,
2. Bungarus caeruleus: - Common Krait,
3. Vipera russelli: - Russel Viper,
4. Echis carinatus: - Saw Scaled Viper
Other common venomous snakes are: -
1. Ophiophagus hannah: - King Kobra,
2. Bungarus fasciatus: - Banded Krait.

6. Who am I ?

7. Who am I ?

8. Fatal dose & Fatal period of few snakes
S.No. Snake Fatal dose (Dried venom) Fatal period
1 King Kobra 12 mg 30 minutes- 1 day
2 Kobra 15 mg 30 minutes- 1 day
3 Saw Scaled Viper 8 mg 2-4 days
4 Russell’s Viper 20 mg 2-4 days

9. Clinical manifestation
 Any form of snake bite has two types of clinical
manifestation: -
a) Local,
b) Systemic
Note: - I ) Both manifestation can be equally potent
or otherwise is possible,
II ) 20 % of snake bites are dry bites,
III ) 3/4th of snake bites are non-venomous
and do not need any specific treatment.

10. Venom
 Toxic saliva secreted by modified parotid gland of
venomous snake.
 Delivered through fang.
 Constituents: -
a) Agglutinin, f) Haemolysin
b) Proteolysin g) Thromboplastin
c) Fibrinolysin h) Cardio toxin
d) Neurotoxin i) Hyaluronidase
e) Cholinesterase j) Lecithinase

11. Venomous Non-venomous
 Head scale- Large
(Kobra, Krait), Small
(Viper)
 Belly scale- Large
(Covers entire breadth)
 Caudal scales- Divided
 Fang:- Short (Kobra,
Krait), Long (Viper)
 Habitat- Mostly
nocturnal
 Head scale- Large
 Belly scale- Small
(Do not cover entire
breadth)
 Caudal scales- Not
divided
 Fang- None
 Habitat – Diurnal or
nocturnal
Comparison between Venomous & Non-venomous
snake

13. Diagrammatic representation of Venomous & Non-
venomous snake bite marks

14. Snake Bite Management & Treatment
 Management; -
a) Identification of snake species is important,
b) Management varies based on the clinical
manifestation following the snake bite and severity
of envenomation.
 Immediate care or first aid: -
a) Reassurance to relieve fear is important,
b) Immobilization of the patient especially the
affected part.

15. Say No to following
 No incision or suction of wound (can lead to
secondary infection & necrosis),
 No tourniquet ( inappropriate application can lead to
gangrene),
 No cryotherapy ( causes ischemia & increased
possibility of tissue necrosis),
 No application of herbs etc.

16. Treatement
 Antisnake venom(ASV) therapy is the specific antidote
of choice for snake envenomation,
 The antisnake venom(ASV) should be administered by
slow intravenous (IV) injection,
 Dose: - Recommended average initial dose is 10-20 vials
for common Krait & Kobra , 10 vials for Russell’s Viper &
5 vials for Saw Scaled Viper,
 Each vial of ASV is capable of neutralizing 6 mg of Kobra
& Russell’s Viper venom & 4.5 mg of Saw Scaled Viper &
Common Krait
 ASV can be Monovalent of Polyvalent (Only polyvalent
ASV is used in India),
 The dose of ASV is similar in children & adults.

17. Cross reactions
 Indiscriminate use of ASV is discouraged because of
life threatening immune reactions like Type I
hypersensitivity (within few hours), Type III
hypersensitivity (delayed).
 In case of Type I hypersensitivity ASV therapy
should be transiently discontinued and adrenaline
should be given urgently.
 In case of Type III hypersensitivity antihistamines &
corticosteroids are given.

18. Supportive treatment
 Clear the airways & start artificial ventilation to treat
respiratory failure,
 Transfusion of fresh blood in case of Viper bites,
 Treatment of hypotension & shock by Atropine
administration,
 Dialysis in case of Acute Renal Failure(ARF),
 Anticholinesterase [e.g. Neostigmine (IM) ] along
with atropine is administered with neurotoxic
symptoms.

19. Medico-legal importance
1. Homicide – Rare,
2. Suicide – Very rare,
3. Occupational hazard – Very common,
Autopsy :- At autopsy, skin & underlying tissues
around the alleged site of bite marks and the
control sample from another healthy site is
dissected out, and preserved in saturated saline
solution along with blood preserved in Sodium
fluoride.

20. References
1. Aggrawal,A.(2016). Textbook of Forensic Medicine &
Toxicology for MBBS, Avichal Publishing Company.
2. Bhuyan, A(2021, February 18). Despite being undercounted,
India has the most snakebite deaths in the world. Scroll.in.
https://scroll.in/article/987003/despite-being-undercounted-
india-has-the-most-snakebite-deaths-in-the-world.
3. Kanchan,T.(2018). Rapid review of TOXICOLOGY, Jaypee
Brothers Medical Publishers (P) Ltd.

21. Thank you