Stings and Bites in Forensic Medicine

1. SNAKE BITES

Epidemiology

• 3,500 species of snakes exist worldwide; only ~250 are venomous

• In India, ~216 species; 52 are venomous
• WHO estimates: >2.5 million venomous snake bites per year globally; >125,000 deaths
• Dangerously poisonous snakes in India (5): King cobra, common cobra, common krait, Russell's viper, saw-scaled viper
• Most common venomous snake in India: Common krait

Classification of Venomous Snakes

Identification: Venomous vs Non-Venomous Snakes

Individual Snakes

• Has a hood with a double spectacle mark on dorsal side
• Two black spots and three black bands on the underside of the hood
• Caudal scales are double
• Venom: Neurotoxic - acts on motor nerve end-plates (like curare), also has direct cardiotoxic and hemolytic action

• Central row of scales on back enlarged; undersurface of mouth has only 4 infralabials, the 4th being the largest
• Most common venomous snake in India
• Venom: Neurotoxic (pre- and post-synaptic blockade)

• Venom: White or yellow; hemotoxic/vasculotoxic - causes local necrosis, DIC, hemorrhage

• Causes the greatest mortality in India

Fang Marks and Forensic Recognition

• Venomous snake bites leave two fang marks (puncture wounds)
• Non-venomous snakes leave multiple row-marks (teeth marks)
• ~20% of venomous snake bites are "dry bites" (no venom injected) - seen in viper, elapid, and sea snake bites
• In sea snake bites, symptoms not produced in ~80% of bites
• Thin clothing can afford considerable protection
• Exact fang mark number can vary due to glancing blows, multiple strikes, or multiple fangs

Snake Venom - Composition

• Toxalbumins (neurotoxins, hemotoxins, cytotoxins)
• Enzymes: Phospholipase A2, hyaluronidase, L-amino acid oxidase, proteases
• Components cause both local and systemic effects
• Cobra venom: faint transparent yellow, slightly viscous
• Russell's viper venom: white or yellow

Clinical Features of Snake Bite

Postmortem/Forensic Findings

• Fang marks on the body
• Local edema, ecchymosis, necrosis
• Hemorrhages in viscera
• Renal cortical necrosis (viper)
• Pulmonary edema

Laboratory/Forensic Detection of Venom

1. Radioimmunoassay (RIA): Most sensitive and specific; detects venom at 0.4 μg/L - bitten skin should be preserved
2. Enzyme Immunoassay (EIA): Simple; detects 5 μg/L; commonly used
3. ELISA: Detects small amounts of venom antigens in body fluids; fang mark tissues should be sent to microbiology
4. Cholinesterase and thromboplastin detectable in bitten skin (by RIA) if no bacterial infection or putrefaction
5. Frog test: Swab from wound injected into a frog for evidence of toxicity

"Bitten area of skin should be preserved" - this is a key forensic instruction for medico-legal cases.

• The Essentials of Forensic Medicine and Toxicology, 36th ed.

First Aid and Treatment

1. Reassure the patient
2. Apply firm pressure over bitten area (delays venom absorption)
3. Pressure immobilization (Sutherland wrap): Recommended for elapid and sea-snake bites - NOT for viper bites (may cause local necrosis)
4. Immobilize the limb; avoid elevation (hastens systemic absorption)
5. Do NOT: incise and suck; cauterize (seals poison in tissues); apply tourniquet tightly

• Polyvalent antiserum (anti-snake venom, ASV) is the definitive treatment
• Neostigmine for neurotoxic bites (cobra)
• Tetanus toxoid
• Monitoring vital signs and oxygen saturation

2. SCORPION STINGS

• Scorpions have a crab-like appearance with a long, 5-segmented tail ending in a prominent hollow sting
• The sting communicates via a duct with venom-secreting glands
• Venom: Contains toxalbumins with neurotoxic and haemotoxic actions
• Red scorpion venom contains a potent cardiotoxin
• Toxicity of scorpion venom is greater than snakes, but only a small quantity is injected

Forensic Recognition

• The scorpion sting leaves only one hole in the center of the reddened area (distinguished from viper bite which has two holes)
• Edema, pain, and reddening at the extremity, lasting 1-2 hours

Clinical Features

• Local: Burning pain, redness radiating from site
• Systemic (neurotoxic venom): Similar to cobra bite - headache, giddiness, nausea, profuse perspiration, priapism, excessive salivation, ventricular premature contractions, dilated pupils, urticaria, muscular cramps, coma
• Duration: Usually 24-48 hours; neurologic manifestations can persist up to one week
• Children may succumb to pulmonary edema; mortality in adults is negligible
• Pathological findings in death: Widespread hemorrhages; myocardial damage in deaths from red scorpion stings

Diagnosis

• Confirmed by ELISA testing

Treatment

1. Immobilize the limb; apply tourniquet proximal to sting
2. Pack sting in ice; incise and suction; wash wound with ammonia, borax, or potassium permanganate
3. Local anesthetic (2% novocaine or 5% cocaine) at site for pain
4. Specific antivenin (available for most species)
5. Calcium gluconate IV (10 ml of 10% solution) - controls local swelling and muscular cramps
6. Barbiturates for excitement/convulsions - morphine is contraindicated
7. Atropine - prevents pulmonary edema

• The Essentials of Forensic Medicine and Toxicology, 36th ed.; Parikh's Textbook of Medical Jurisprudence Forensic Medicine and Toxicology

3. BEE AND WASP STINGS

Key Features

• Fire ants have well-developed abdominal stingers; commonly seen in mango trees

Venom Composition

• Bee venom: Dopamine, histamine, neurotoxin, enzymes, toxic peptides
• Wasp venom: Same as bee + serotonin
• Ant venom: Mainly alkaloids and proteins
• All venoms contain histamine

Clinical Features

• Reactions usually local (pain, redness, slight swelling at sting site)
• Stings of mouth, throat, face, neck can cause laryngeal edema - potentially fatal
• Severe systemic reactions (anaphylaxis) are uncommon but can be fatal

4. MARINE POISONING (Ichtchyism)

1. Ichtchyiosarcotoxic fish (toxic flesh)
2. Ichtchyiohaemotoxic fish (toxic blood)
3. Ichtchyootoxic fish (toxic eggs/roe)

• Scombroid poisoning: Histamine poisoning; tuna, mahi-mahi, bluefish - erythema, urticaria, dizziness, headache
• Ciguatera: Barracuda, parrot fish - ciguatoxin; commonest marine poisoning (up to 50% of cases)
• Tetrodotoxin (Fugu) poisoning: Puffer fish, toad fish - potent sodium channel blocker; ascending paralysis
• Shellfish poisoning: Oysters, clams, scallops - phycotoxin; paralysis

Medicolegal Importance of Stings and Bites

1. Death certification: Deaths from snake bite, scorpion sting, or bee sting must be certified after proper investigation; manner is usually accidental
2. Inquest/postmortem: Fang marks or sting marks should be documented carefully; tissues preserved for venom detection
3. Dry bites: Absence of symptoms does not rule out envenomation - forensically important
4. Homicide by snake: Rare but reported; needs careful investigation
5. Negligence cases: Delayed treatment or failure to administer antivenom can lead to medico-legal action
6. Postmortem decomposition: Can obliterate fang marks; early autopsy and tissue preservation (for RIA/ELISA) is essential

• The Essentials of Forensic Medicine and Toxicology, 36th ed. (2026)
• Parikh's Textbook of Medical Jurisprudence, Forensic Medicine and Toxicology
• P.C. Dikshit Textbook of Forensic Medicine and Toxicology