Forensic Medicine & Toxicology
High-yield MBBS Forensic Medicine & Toxicology question bank — medical jurisprudence, identification, thanatology, injuries, asphyxia, forensic sexology and toxicology, at Reddy’s / Parikh depth.
12chapters144questions77High-Yield
Definition
Organophosphates are insecticides that cause poisoning by irreversible inhibition of acetylcholinesterase, leading to accumulation of acetylcholine.
Clinical Features
- Muscarinic (DUMBELS) — Diarrhoea, Urination, Miosis (pinpoint pupils), Bronchorrhoea and bronchospasm, Emesis, Lacrimation, Salivation; bradycardia
- Nicotinic — muscle fasciculations, weakness, tremor, respiratory muscle paralysis, tachycardia, hypertension
- Central — anxiety, confusion, convulsions, coma, respiratory centre depression
- Characteristic garlic-like (kerosene) odour of breath and vomit
- Death from respiratory failure — bronchorrhoea, bronchospasm and muscle paralysis combined
- Intermediate syndrome at 24–96 hours; delayed peripheral neuropathy after 2–3 weeks
Diagnosis, Treatment & Medicolegal
- Diagnosis: history, pinpoint pupils with garlicky odour, low plasma and red-cell cholinesterase levels
- Atropine — blocks muscarinic effects; give repeatedly until atropinisation (dry secretions, clear chest, heart rate above 80)
- Pralidoxime (2-PAM) — reactivates cholinesterase; effective only before ‘ageing’ of the enzyme, so must be given early; helps nicotinic features
- Decontamination — remove clothing, wash skin; gastric lavage if early; attendants must wear gloves
- Ventilatory support; avoid morphine and aminophylline
- Manner — commonly suicidal in India (agricultural availability); also accidental and occupational
- Autopsy: non-specific; garlicky smell, pulmonary oedema; preserve viscera and blood for cholinesterase
Pralidoxime must be given before the enzyme ages irreversibly. Effect Feature Drug Muscarinic DUMBELS Atropine Nicotinic Fasciculations Pralidoxime Central Convulsions, coma Supportive Applied
- Pinpoint pupils with garlicky odour is the classic bedside diagnosis
- There is no maximum dose of atropine — titrate to effect
🔑KEY POINTS TO REMEMBER- Organophosphates irreversibly inhibit acetylcholinesterase.
- Muscarinic (DUMBELS), nicotinic and central features; death from respiratory failure.
- Atropine plus early pralidoxime; commonest suicidal poisoning in India.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Ethyl alcohol (ethanol) is a CNS depressant of major medicolegal importance; methyl alcohol (methanol) is a far more toxic industrial alcohol.
Ethyl Alcohol
- CNS depressant, not a stimulant; metabolised by alcohol dehydrogenase at a fixed rate (about 15 mg/dL per hour) — zero-order kinetics
- Stages by blood level: 50–100 mg/dL euphoria; 100–200 incoordination and slurred speech; 200–300 confusion, vomiting; >300 stupor; >400 mg/dL coma and death
- Legal limit for driving in India: 30 mg/100 mL blood (Motor Vehicles Act)
- Drunkenness examination — gait, speech, pupils, breath odour, coordination; blood sample preserved in sodium fluoride and potassium oxalate
- Chronic: cirrhosis, Wernicke-Korsakoff, cardiomyopathy, delirium tremens on withdrawal
Methyl Alcohol
- Found in illicit (hooch) liquor, varnish and antifreeze — cause of mass hooch tragedies
- Metabolised by alcohol dehydrogenase to formaldehyde then formic acid — the toxic metabolites
- Latent period of 12–24 hours, then severe high anion-gap metabolic acidosis
- Blindness — optic atrophy from formic acid damage to the retina and optic nerve; dilated non-reactive pupils
- Abdominal pain, vomiting, hyperventilation (Kussmaul), coma
- Treatment — ethanol or fomepizole (compete for alcohol dehydrogenase), sodium bicarbonate for acidosis, haemodialysis, folinic acid
It is methanol's metabolites, not methanol itself, that cause the damage. Feature Ethanol Methanol Toxic agent Itself Formic acid Onset Rapid 12–24 h delay Eye Normal Blindness Applied
- Ethanol is the antidote to methanol — it competes for the same enzyme
- Never use rectified spirit as viscera preservative when alcohol is suspected
🔑KEY POINTS TO REMEMBER- Ethanol is a CNS depressant metabolised at 15 mg/dL per hour; legal driving limit 30 mg/100 mL.
- Methanol is converted to formic acid causing acidosis and blindness after 12–24 hours.
- Treat methanol with ethanol or fomepizole, bicarbonate and haemodialysis.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Opioids and barbiturates are CNS depressants causing coma and respiratory depression in overdose.
Opioids
- Include morphine, heroin, codeine, pethidine, methadone, tramadol; act on μ receptors
- Classical triad: coma, pinpoint (pin-point) pupils and respiratory depression
- Also: hypotension, hypothermia, non-cardiogenic pulmonary oedema, absent bowel sounds
- Autopsy: fresh and old needle (injection) marks and track scars, froth at mouth, pulmonary oedema, visceral congestion
- Antidote: naloxone — dramatic response; short-acting, so repeated doses or infusion are needed
- Withdrawal is unpleasant but rarely fatal; covered by the NDPS Act
Barbiturates
- Classified by duration: ultra-short (thiopentone), short, intermediate, long-acting (phenobarbitone)
- Features: drowsiness, ataxia, slurred speech, coma with depressed reflexes, respiratory depression, hypotension, hypothermia
- Pupils are usually normal or slightly constricted (dilate terminally) — helps distinguish from opioids
- Barbiturate blisters (bullae) over pressure points — characteristic but not specific
- No specific antidote — supportive care, ventilation, forced alkaline diuresis and haemodialysis for long-acting agents
- Withdrawal can be fatal (seizures) — unlike opioid withdrawal
Pupil size and response to naloxone separate the two at the bedside. Feature Opioid Barbiturate Pupils Pinpoint Normal/dilated Antidote Naloxone None Skin Needle marks Bullae Applied
- A therapeutic trial of naloxone is both diagnostic and therapeutic in coma of unknown cause
- Barbiturate withdrawal can kill — taper, never stop abruptly
🔑KEY POINTS TO REMEMBER- Opioid triad: coma, pinpoint pupils, respiratory depression; naloxone is the antidote.
- Barbiturates cause coma with bullae over pressure points and have no antidote.
- Opioid withdrawal is rarely fatal; barbiturate withdrawal can be.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Plant poisons of major medicolegal importance in India include dhatura, aconite, oleander and nux vomica.
Dhatura and Aconite
- Dhatura (Datura stramonium) — contains atropine, hyoscine and hyoscyamine; anticholinergic syndrome
- ‘Hot as a hare, blind as a bat, dry as a bone, red as a beet, mad as a hatter’ — hyperthermia, dilated non-reactive pupils, dry mouth, flushed skin, delirium
- Known as the ‘poison of road-side robbers’ — used to stupefy travellers; seeds resemble chilli seeds
- Antidote: physostigmine; supportive care and sedation
- Aconite (Aconitum, monkshood, ‘bish’) — the ‘king of poisons’; contains aconitine
- Tingling and numbness of tongue and mouth, then generalised paraesthesia, cardiac arrhythmia and death; no specific antidote
Oleander and Nux Vomica
- Yellow oleander (Thevetia peruviana) and white oleander (Nerium) — contain cardiac glycosides (thevetin, oleandrin)
- Act like digitalis — vomiting, hyperkalaemia, bradycardia, heart block, arrhythmia; treated with atropine, correction of potassium, digoxin-specific antibody
- Common suicidal poison in South India and Sri Lanka
- Nux vomica (Strychnos nux-vomica) — contains strychnine, which blocks glycine (inhibitory) at spinal cord level
- Violent symmetrical convulsions with the body arched (opisthotonus), risus sardonicus, consciousness fully retained — the key distinguishing feature; triggered by any stimulus
- Death from asphyxia during spasm; treatment: diazepam, dark quiet room, ventilation; rigor mortis appears early
Each plant produces a syndrome recognisable at the bedside. Plant Toxin Hallmark Dhatura Atropine Dilated pupils, delirium Aconite Aconitine Tingling tongue Oleander Glycosides Hyperkalaemia, block Nux vomica Strychnine Convulsions, conscious Applied
- Strychnine convulsions with retained consciousness distinguish it from tetanus and epilepsy
- Preserve seeds and plant fragments found in the stomach for botanical identification
🔑KEY POINTS TO REMEMBER- Dhatura causes an anticholinergic syndrome; antidote is physostigmine.
- Aconite causes tingling of the tongue and arrhythmia; oleander acts like digitalis.
- Strychnine causes convulsions with fully retained consciousness.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Snake bite is envenomation by a venomous snake, a major cause of preventable death in rural India.
Types of Venomous Snakes & Effects
- Big four in India: cobra, krait, Russell’s viper, saw-scaled viper
- Elapidae (cobra, krait) — neurotoxic: ptosis (earliest sign), ophthalmoplegia, dysphagia, descending flaccid paralysis, respiratory failure; local signs minimal
- Krait bites often occur during sleep, are painless, with abdominal pain and no local swelling — easily missed
- Viperidae — vasculotoxic (haemotoxic): severe local pain, swelling, blistering, necrosis, bleeding from gums and injection sites, coagulopathy, acute kidney injury, shock
- Sea snakes — myotoxic: muscle pain, myoglobinuria, kidney injury
- Fang marks — two punctures in venomous bites; non-venomous show a row of small marks
Management & Medicolegal Aspects
- First aid — reassure, immobilise the limb in a neutral position, pressure immobilisation bandage, transport urgently
- Avoid tourniquets, incision, suction, ice and traditional remedies — all harmful
- 20-minute whole blood clotting test — simple bedside test for viper coagulopathy
- Polyvalent anti-snake venom (ASV) — the definitive treatment; given only if signs of envenomation are present; watch for anaphylaxis
- Neostigmine with atropine for neurotoxic (cobra) bites; ventilation for respiratory failure
- Manner — usually accidental; rarely homicidal or suicidal; autopsy shows fang marks, local oedema and haemorrhages
Anti-snake venom is given only when envenomation is actually present. Snake Venom Key sign Cobra Neurotoxic Ptosis Krait Neurotoxic Painless, at night Viper Vasculotoxic Bleeding, swelling Applied
- Ptosis is the earliest sign of neurotoxic envenomation
- Never apply a tourniquet — it worsens local necrosis
🔑KEY POINTS TO REMEMBER- Big four: cobra, krait, Russell’s viper, saw-scaled viper.
- Elapids are neurotoxic (ptosis, paralysis); vipers are vasculotoxic (bleeding, AKI).
- Polyvalent ASV is definitive; avoid tourniquets, incision and suction.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Carbon monoxide is a colourless, odourless, non-irritant gas that causes asphyxia by forming carboxyhaemoglobin.
Mechanism & Features
- Affinity of carbon monoxide for haemoglobin is about 200–300 times that of oxygen
- Forms carboxyhaemoglobin (COHb), reducing oxygen-carrying capacity and shifting the dissociation curve to the left
- Sources: incomplete combustion — charcoal braziers (angithi) in closed rooms, vehicle exhaust, gas geysers, house fires
- COHb 10–20% headache; 30–40% giddiness, nausea, weakness; 50–60% confusion, collapse; >60–70% coma and death
- Cherry-red discoloration of skin, lividity, blood and viscera — the classic autopsy finding
- Survivors may develop delayed neuropsychiatric sequelae after 2–4 weeks
Diagnosis, Treatment & Medicolegal
- Diagnosis: estimation of COHb by CO-oximetry (pulse oximetry is falsely normal)
- Treatment: 100% oxygen by tight-fitting mask — reduces half-life from about 4 hours to under 1 hour; hyperbaric oxygen in severe cases and pregnancy
- Autopsy: cherry-red lividity, congestion; preserve blood in a fully filled sealed container
- Presence of COHb in a fire victim proves the person was alive and breathing during the fire
- Manner — mostly accidental (winter heating in closed rooms); also suicidal
- Whole families may be affected together — a diagnostic clue
Pulse oximetry reads falsely normal, so COHb must be measured directly. COHb Effect 10–20% Headache 30–40% Giddiness, weakness >60% Coma, death Applied
- Cherry-red lividity is also seen in cyanide poisoning and cold exposure
- Raised COHb in a burnt body proves antemortem burning
🔑KEY POINTS TO REMEMBER- CO binds haemoglobin 200–300 times more avidly than oxygen.
- Cherry-red lividity is classical; pulse oximetry is falsely normal.
- Treat with 100% or hyperbaric oxygen; COHb proves life during a fire.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Cyanide is one of the most rapidly acting poisons, causing histotoxic (cellular) asphyxia by blocking cellular respiration.
Mechanism & Features
- Inhibits cytochrome c oxidase in the mitochondria → cells cannot utilise oxygen despite adequate supply
- Sources: industrial (electroplating, gold and silver extraction), fumigants, burning plastics and synthetic fabrics in fires, seeds of bitter almond, apricot and cassava
- Extremely rapid — collapse within seconds to minutes; death in minutes
- Bitter almond odour in breath and at autopsy — detectable by only about 40–60% of people (genetically determined)
- Giddiness, headache, dyspnoea, convulsions, coma; severe metabolic acidosis with high lactate
- Venous blood appears bright red (arterialised) — oxygen is not extracted; lividity pink or cherry-red
Treatment & Medicolegal
- Sodium nitrite → induces methaemoglobin, which binds cyanide as cyanmethaemoglobin
- Sodium thiosulphate → provides sulphur for rhodanese to convert cyanide to thiocyanate, excreted in urine
- Hydroxocobalamin — safest and preferred; forms cyanocobalamin
- Amyl nitrite by inhalation as immediate first aid; 100% oxygen
- Autopsy: bitter almond smell on opening the body, pink lividity, congestion, corrosion of gastric mucosa (with the salt)
- Manner — suicidal (industrial workers with access), accidental (fires); classically described as an ideal but readily detectable poison
Tissues are oxygen-rich but unable to use it — hence bright red venous blood. Antidote Action Sodium nitrite Forms methaemoglobin Sodium thiosulphate Forms thiocyanate Hydroxocobalamin Forms cyanocobalamin Applied
- Suspect cyanide in fire victims with acidosis not explained by carbon monoxide
- Hydroxocobalamin is preferred in fire victims (nitrites worsen CO poisoning)
🔑KEY POINTS TO REMEMBER- Cyanide blocks cytochrome oxidase, causing histotoxic asphyxia.
- Bitter almond odour and bright red venous blood are characteristic.
- Antidotes: sodium nitrite plus thiosulphate, or hydroxocobalamin.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Aluminium phosphide is a grain fumigant marketed as Celphos, Quickphos or ‘rice tablet’, and a leading cause of fatal poisoning in North India.
Mechanism & Features
- On contact with moisture or gastric acid it liberates phosphine gas (PH₃) — the toxic agent
- Phosphine inhibits cytochrome c oxidase and causes massive oxidative damage
- Garlicky or decaying-fish odour of breath and vomit — characteristic
- Refractory hypotension and circulatory collapse — the hallmark and usual cause of death
- Severe metabolic acidosis, arrhythmias, myocarditis, ARDS, hepatic and renal failure
- Very high mortality (60–80%); death usually within 12–24 hours
Treatment, Autopsy & Medicolegal
- There is NO specific antidote — management is entirely supportive
- Gastric lavage with potassium permanganate (oxidises phosphine) or coconut oil, which retards the release of gas
- Aggressive fluids, vasopressors, correction of acidosis with bicarbonate, magnesium sulphate, intensive care
- Attendants must be protected — phosphine liberated from vomit can affect staff; ventilate the room
- Autopsy: garlicky odour on opening the body, congested and haemorrhagic viscera, pulmonary and gastric mucosal haemorrhages
- Manner — overwhelmingly suicidal; freely available in agricultural areas; a major public health problem
- Silver nitrate paper test on breath or gastric aspirate turns black — simple confirmatory test
The absence of an antidote makes early intensive support the only option. Feature Detail Toxic agent Phosphine gas Hallmark Refractory hypotension Antidote None Applied
- Mortality is very high even with intensive care
- Protect staff from phosphine released by the patient’s vomit
🔑KEY POINTS TO REMEMBER- Aluminium phosphide releases phosphine gas on contact with gastric acid.
- Garlicky odour with refractory hypotension and severe acidosis; mortality 60–80%.
- No antidote — lavage with potassium permanganate and intensive supportive care.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Cannabis (Cannabis sativa, Indian hemp) is a deliriant plant drug; its active principle is tetrahydrocannabinol (THC).
Preparations & Effects
- Bhang — dried leaves; weakest; taken as a drink
- Ganja — flowering tops of the female plant; stronger
- Charas (hashish) — resin; the most potent
- Acute effects: euphoria, talkativeness, distorted perception of time and space, conjunctival congestion (red eyes), dry mouth, increased appetite, tachycardia
- Higher doses: hallucinations, anxiety, acute paranoid psychosis (‘cannabis psychosis’)
- Death from cannabis alone is extremely rare
Chronic Use & Medicolegal Importance
- Amotivational syndrome — apathy, loss of drive, poor concentration
- Chronic bronchitis; impaired memory; precipitation of schizophrenia in susceptible people
- Psychological dependence; mild withdrawal (irritability, insomnia)
- ‘Run amok’ — sudden outburst of violent, indiscriminate homicidal behaviour, classically described with cannabis
- Regulated under the NDPS Act, 1985 — possession and trafficking are offences (bhang is exempted in some states)
- Detected in urine for days to weeks in chronic users; relevant to criminal responsibility and driving
Voluntary intoxication is generally not a defence to a criminal charge. Preparation Part Potency Bhang Leaves Weakest Ganja Flowering tops Moderate Charas Resin Strongest Applied
- Run amok is the classic medicolegal association
- Long urinary detection window complicates interpretation of positive tests
🔑KEY POINTS TO REMEMBER- Bhang (leaves), ganja (flowering tops) and charas (resin, strongest).
- THC causes euphoria, distorted time perception, red eyes and possible psychosis.
- Regulated under the NDPS Act; classically associated with running amok.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Kerosene is a petroleum distillate and one of the commonest causes of accidental poisoning in children in India.
Mechanism & Features
- Danger is chiefly from aspiration, not from absorption — due to low viscosity and low surface tension
- Even a small amount aspirated causes chemical (aspiration) pneumonitis
- Local: burning of mouth and throat, vomiting, characteristic kerosene odour of breath and vomit
- Respiratory: cough, choking, tachypnoea, cyanosis; X-ray changes appear within a few hours
- CNS: drowsiness, restlessness, convulsions, coma
- Commonly stored in soft-drink bottles — the usual reason for accidental ingestion by children
Treatment, Autopsy & Medicolegal
- Gastric lavage and induced emesis are CONTRAINDICATED — they greatly increase the risk of aspiration
- Lavage only with a cuffed endotracheal tube in place, and only for very large ingestions
- Oxygen, bronchodilators, ventilation; treat pneumonitis; steroids and prophylactic antibiotics are not routinely recommended
- Observe for at least 6 hours; chest X-ray
- Autopsy: kerosene odour on opening the body, congested haemorrhagic lungs with patchy consolidation
- Manner — almost always accidental in children; occasionally suicidal; prevention by proper storage and labelling
The lungs, not the gut, are the organ at risk. Aspect Detail Main danger Aspiration pneumonitis Lavage Contraindicated Manner Accidental, children Applied
- Never induce vomiting in kerosene ingestion
- Store kerosene in clearly labelled, child-resistant containers, never soft-drink bottles
🔑KEY POINTS TO REMEMBER- Kerosene’s danger is aspiration causing chemical pneumonitis, not absorption.
- Gastric lavage and induced emesis are contraindicated.
- Almost always accidental in children; treat with oxygen and supportive care.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Abrus precatorius (jequirity, rati, gunchi, crab’s eye) is a plant whose seeds contain the highly toxic protein abrin.
Features
- Seeds are scarlet red with a black spot at one end — easily recognised; used as beads and formerly as jewellers’ weights (1 rati)
- Abrin is a toxalbumin that inhibits protein synthesis, similar in action to ricin
- Intact swallowed seeds are relatively harmless because of the hard impervious seed coat; toxicity arises only if the seed coat is broken
- Ingestion: severe gastroenteritis, vomiting, bloody diarrhoea, dehydration, convulsions, circulatory collapse
- Parenteral entry: local oedema and necrosis, haemolysis, kidney and liver failure
- Delayed onset of several hours to days
Medicolegal Importance & Treatment
- Historically used for cattle poisoning in India, to claim hides and insurance
- The characteristic implement was the ‘sui’ or ‘sutari’ — a needle-like spike; its use is described in forensic texts so that the puncture wound is recognised at postmortem
- Human poisoning is rare and usually accidental (children eating seeds) or occupational
- Autopsy — look for a small puncture mark with surrounding oedema and necrosis; congested haemorrhagic viscera
- No specific antidote — supportive care, fluids, electrolytes, dialysis if needed
- Preserve viscera and any recovered seeds for botanical and chemical identification
The hard seed coat is why intact swallowed seeds rarely cause harm. Feature Detail Toxin Abrin (toxalbumin) Seed Red with black spot Antidote None Applied
- Search for a puncture wound in suspected cases, especially in cattle
- Recovered seeds should be sent for botanical identification
🔑KEY POINTS TO REMEMBER- Abrus seeds contain abrin, a toxalbumin inhibiting protein synthesis.
- Intact swallowed seeds are relatively harmless due to the hard seed coat.
- Historically used for cattle poisoning; no antidote — supportive care only.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Food poisoning is illness from contaminated food; botulism is the most severe form, caused by the neurotoxin of Clostridium botulinum.
Types of Food Poisoning
- Bacterial infective — Salmonella, Campylobacter, E. coli; incubation 12–36 hours
- Bacterial toxin — Staphylococcus aureus (rapid, 2–6 hours, profuse vomiting), Clostridium perfringens, Bacillus cereus (fried rice)
- Botulism — Clostridium botulinum toxin
- Chemical — metals, pesticides; plant/fungal — mushrooms, lathyrism (khesari dal), epidemic dropsy (argemone oil in mustard oil), aflatoxin
- Medicolegal: mass outbreaks require investigation; may raise questions of negligence or adulteration under the Food Safety and Standards Act
Botulism
- Caused by a preformed neurotoxin — the most potent biological toxin known
- Associated with improperly processed canned, bottled and preserved foods; the organism is anaerobic
- Toxin blocks release of acetylcholine at the neuromuscular junction
- Incubation 12–36 hours; descending symmetrical flaccid paralysis
- Bulbar signs first — diplopia, ptosis, blurred vision, dysarthria, dysphagia, dry mouth; no fever, consciousness retained
- Death from respiratory paralysis; treatment: trivalent antitoxin, mechanical ventilation, supportive care; toxin destroyed by boiling
Descending paralysis with clear consciousness and no fever is characteristic. Cause Incubation Feature Staphylococcal 2–6 h Vomiting Salmonella 12–36 h Fever, diarrhoea Botulism 12–36 h Descending paralysis Applied
- Botulinum toxin is destroyed by boiling — proper cooking prevents it
- Suspect botulism in descending paralysis after eating preserved food
🔑KEY POINTS TO REMEMBER- Food poisoning may be bacterial infective, toxin-mediated, chemical or plant-related.
- Botulism results from a preformed toxin blocking acetylcholine release.
- Descending flaccid paralysis without fever; treat with antitoxin and ventilation.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.