Botulism
☠️ Botulinum toxins are among the most toxic substances known-lethal at doses as low as 0.001 µg/kg.
They block acetylcholine release from presynaptic terminals → causing flaccid paralysis with autonomic dysfunction.
📖 About
- 🤒 Botulism results from exposure to one of eight neurotoxins (A–H).
- Causes paralysis by preventing acetylcholine release at neuromuscular junctions.
- Affects both skeletal and smooth muscles.
🧬 Aetiology
- Caused by exotoxins of Clostridium botulinum (anaerobic, gram-positive, spore-forming).
- 🌍 Found in soil and environmental reservoirs.
- 🧲 Toxin binds irreversibly to presynaptic nerve terminals.
- ✂️ Blocks ACh release by cleaving SNARE proteins involved in neuroexocytosis.
🔄 Methods of Contracting Botulism
- 🥫 Food-borne: ingestion of improperly canned/preserved food.
- 👶 Infant botulism: spores (e.g. honey) colonise immature gut → “floppy baby.”
- 💉 Wound botulism: spores in wounds (common in IV drug users).
- 👩⚕️ Adult intestinal botulism: rare, seen with GI surgery/abnormalities.
🩺 Clinical Features
- ⏱️ Onset 2–36h post-exposure.
- ⬇️ Descending weakness: cranial nerves → respiratory → limbs.
- 👀 Bulbar palsy: diplopia, dysarthria, dysphagia.
- ⚡ Autonomic dysfunction: dilated pupils, constipation, diarrhoea, nausea, hypotension.
- 👶 Infants: constipation, lethargy, weak cry → “floppy baby syndrome.”
🩺 Differential Diagnosis
- 🧠 Myasthenia gravis (pupils spared).
- 🦵 Guillain–Barré (with sensory loss).
- ⚡ Lambert–Eaton, diphtheria, Miller–Fisher, shellfish poisoning.
- ☣️ Organophosphate poisoning.
🔎 Investigations
- 🧪 Baseline labs: FBC, U&E, ABG, toxicology.
- 🧫 Detect toxin in stool, blood, food samples.
- ⚡ Nerve conduction: low CMAP amplitude; incremental response with repetitive stimulation.
⚕️ Management
- 💉 Immediate Botulinum antitoxin → mortality ↓ from ~46% → 10% if early.
- 🫁 Intubation/ventilation for respiratory compromise.
- 🏥 ICU supportive care; gastric lavage if recent ingestion.
- 🚽 Enemas (avoid magnesium-based).
- 💊 Antibiotics for wound botulism (penicillin, metronidazole).
📉 Prognosis
- 💀 Type A toxin → most severe course & highest mortality.
- ⏳ Recovery takes weeks–months as new NMJs regenerate.
- 🙂 Most patients ultimately recover fully with supportive therapy.
