2. SNAKES
• Poisonous :
• Cobra, Russell viper, saw
scaled viper, pit viper and
Krait
• Non poisonous:
• Rat snake, vine snake,
sand boa and mud snake
3. SNAKE BITES
• Around 30-40 thousand death per year
• More prevalent in rural than urban areas, commonly seen in summers, mostly
at night
• Most of the bites
• in tropical countries: lower extremities since
• non-tropical countries: on fingers and hands due to deliberate handling of snakes
5. SNAKE VENOM
• Poisonous secretion (saliva)
• Faint transparent yellow and viscous, when fresh
• Proteinous in nature, which are glycopolypeptides that are enzymatic in action
• Contents:
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11. VENOMOUS SNAKEBITE
(OPHITOXAEMIA/ ENVENOMATION)
• Incidence:
• Usually accidental. Rarely, homicidal or suicidal
• Entry:
• Inoculation
• Spitting
• Degree of toxicity
• Toxic principle in venom
• Quantity
• Types of fang
• Channeled (viperine): complete transfer
• Grooved (elapid): less transfer
12. SIGNS AND SYMPTOMS
• Most common symptom is fear
- semi consciousness, cold clammy skin, hypotension, rapid breathing
• Shock
• Local signs: fang marks, pain, bleeding, inflammation
13. NEUROTOXIC
• Local action:
• Severe burning at bite site, rapid edema and inflammatory changes followed by
oozing of serum
• Systemic action:
• Within 15-30 minutes or 2 hours of bite
• Neurotoxic effect: giddiness, weakness, lethargy, etc.
14. HEMOTOXIC
• Local actions:
• Severe pain at bite site followed by swelling, ecchymosis, cellulitis and severe
hemorrhage
• Systemic action:
• Due to hemolytic effect
• If the patient survives,
• suppuration, sloughing with infection at the bite site,
• hemorrhage from mucosa of rectum, other natural orifice, etc.
• Gangrene of the parts involved
16. SIGNS AND SYMPTOMS
-COBRA
• One or two puncture marks
• Local symptoms start within 6–8 minutes (min)
• Reddish wheal at site of bite, tender bite site
• Early symptoms:
• vomiting, heaviness of eyelids, blurring of vision, parasthesia around mouth,
hypersalivation
• Soft tissue swelling (progressive)
• Alteration of mental status
• Ptosis
• Progressive paralysis
• Chest pain and tightness
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17. SIGNS AND SYMPTOMS
-KRAIT
• Similar to cobra, but less rapid
• Abdominal pain, ptosis, dysarthria, dysphagia, chest pain, respiratory paralysis and
death may occur.
• No nausea and froth, but drowsiness is more.
• Common krait hunt nocturnally and are quick to bite people sleeping on the floor
• Often without waking their victims since the venom is painless.
• Victims wake up later, paralyzed or die in their sleep.
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18. SIGNS AND SYMPTOMS
-VIPER
• One or two fang marks
• More local reaction is seen along with pain and oozing.
• Serous and serosanginous blisters sometimes appear
• Progressive tissue swelling
• Extensive local necrosis leading to gangrene
• Bilateral parotid swelling (viper head), conjunctival edema and subconjunctival
hemorrhage
• Bleeding from bite site and rectum, Petechial hemorrhages, epistaxis, gum
bleeding, hemoptysis, hemetemesis, hematuria,
• Death: d/t circulatory failure and hemorrhagic complications
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19. SIGNS AND SYMPTOMS
-SEA SNAKE
• Painless bite, minimal or no local swelling
• Headache, sweating, thirst
• Generalized rhabdomyolysis
• Myoglobinuria may be seen within 3 hours after the bite
20. SNAKE VENOM OPHTHALMIA
• If the spat venom enters the eyes -
- immediate and intense burning
- stinging pain
- profuse watering of eyes
- production of whitish discharge
- congested conjunctiva
- swollen eyelids
21. DIAGNOSIS
• History
• time elapsed since the bite is important to determine if the process is confined locally or if
systemic signs have developed.
• Description of the snake to determine its species.
• Examination (including neurologic examination)
• Urinary venom may be detected even after treatment with anti-venom
• Radioimmunoassay: most sensitive and specific
• Enzyme immunoassay
• ELISA
• 20 min whole blood clotting test (WBCT)
• A normal 20 WBCT and clot lysis would exclude viperidae species.
23. PRINCIPLE
• To reduce the anxiety and fear
• Prevention of the spread of venom (first aid measures)
• Anti-venom treatment
• General measures
24. FIRST AID
• Reassurance of the victim
• Do not tamper bite wound
• Clean the wound with soap and water , or iodine
• Apply firm pressure over the area (delay absorption of venom)
• Pressure immobilization
• Immobilize the limb
• Avoid local incision, suction (bleeding and nerve injury) and cryotherapy
• Avoid tourniquets
• Make the patient lie on one side in recovery position
• Transport to medical facility immediately
25. PRESSURE IMMOBILIZATION
• Recommended for bites by neurotoxic elapid snakes, including sea snakes
• Should NOT be used for viper bites because of the danger of increasing the local effects of the
necrotic venom.
Broad firm bandage (Sutherland wrap) applied around limb; pressure of 50-70 mm Hg maintained,
enough to occlude superficial venous and lymphatic return
26. AT HOSPITAL
• Primary survey
• Release of a tight tourniquet or compression bandage may result in the
dramatic development of severe systemic envenoming
Ideally, compression bandages should not be released until the patient is in
hospital, resuscitation facilities are available and anti-venom treatment has been
started
27.
28. ANTI-VENOM TREATMENT
• Two types:
• Monovalent/ monospecific anti-snake venom
• specific antibody to neutralize that venom
• Polyvalent/ polyspecific anti-snake venom (PAV)
• Neutralizes venoms of several species; effective against common poisonous snakes
• Useful when given within 4 hours of bite
• Each vial neutralize about 6-8 mg of venom
• Half life: about 90 hours
• Patients should be observed for at least 1 hour after starting antivenom
29. ANTI-VENOM TREATMENT
• Administration
• IV 5ml/minute, or dilute in isotonic fluid, infused over 30 to 60 minutes
• Minimal symptoms: local swelling without systemic reactions, 5 vials
• Moderate symptoms: progressing beyond bite site with systemic reaction, 10 vials
• Severe symptoms: marked local reactions, severe symptoms, 10 to 15 vials
• Children require the same dose as in adults
30. ANTI-VENOM REACTIONS
• Early reactions (Anaphylactic):
• itching, urticaria, glottic edema, wheezing, cough,palpitation, nausea, vomiting
• Adrenaline (0.5 to 1 ml of 0.1% solution, SC; children: 0.01 mg/kg), antihistamines
• Pyrogenic reactions:
• In 1-2 hours; chills, shivering, sweating, vomiting, etc.
• Hypothermia blanket, sponging and antipyretic drugs
• Late reactions:
• About 7 days after treatment
• Antihistamines
• Steroids in more severe cases
31. SUPPORTIVE TREATMENT
• Antibiotics: if wound infection
• Tetanus injection
• Paracetamol for pain
• If clotting abnormalities, Heparin
• Ventilatory support for respiratory failure
• Surgical debridement of blebs, vesicles and superficial necrosis
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32. POSTMORTEM FINDING
• Clothing may show amber-colored fluid which
becomes yellowish on drying
• Venom over skin: present as yellow crystals
• Venomous : Two or occasionally one fang marks
with marks of smaller teeth
• Non-poisonous snakes: leave a set of semicircular
teeth marks
• Bite marks
• 1-1.5 cm deep in colubrine
• 2.5 cm deep in viperine bites.
33. POSTMORTEM FINDING
• Cobra/Krait bite: bite site contains fluid and hemolysed blood causing staining
of vessels
• Viper bite: discoloration, swelling and cellulitis around the mark and
hemorrhage
• Hemorrhage into bowel and lungs
• Purpuric spots on pericardium
• Inflamed kidneys with tubular necrosis, interstitial nephritis, congestion,
subcapsular pinpoint hemorrhage
• Regional lymph nodes: swollen and hemorrhagic
34. MEDICO-LEGAL ASPECTS
• Poisoning is mostly accidental
• Occasionally, murder by throwing a poisonous snake on to someone
• Very rarely used for suicide
• Cattle poisoning
35. REFERENCES
• The Essentials of Forensic Medicine and Toxicology, Reddy, 34th edition
• Textbook of Forensic Medicine and Toxicology, Rao, 2nd edition
• Review of Forensic Medicine and Toxicology, Biswas 3rd edition
