Botulism
Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management
Definition
Botulism is a rare but life threatening neuroparalytic disorder caused by the neurotoxins of Clostridium botulinum, leading to flaccid paralysis and autonomic dysfunction.
Aetiology
- Caused by Clostridium botulinum, a spore-forming, Gram-positive anaerobic bacterium.
- Botulinum toxin blocks acetylcholine release at neuromuscular junctions, leading to paralysis.
- Three main types:
- Foodborne botulism: ingestion of preformed toxin in contaminated food (home-canned or fermented foods).
- Infant botulism: ingestion of spores, which germinate and produce toxin in the immature gut.
- Wound botulism: bacterial growth in contaminated wounds, often linked to IV drug use.
Pathophysiology
- Botulinum toxin irreversibly inhibits acetylcholine release at presynaptic terminals.
- Leads to descending flaccid paralysis with autonomic dysfunction.
- Recovery requires regeneration of nerve terminals, which may take weeks to months.
Risk Factors
- Consumption of improperly preserved or home-canned foods.
- Infants under 12 months ingesting honey (risk of infant botulism).
- Injection drug use (wound botulism).
- Soil exposure in traumatic wounds.
Signs and Symptoms
- Foodborne botulism:
- Acute onset of bilateral, descending weakness.
- Cranial nerve palsies (diplopia, ptosis, dysphagia, dysarthria).
- Symmetric flaccid paralysis progressing to respiratory failure.
- Autonomic dysfunction (dry mouth, constipation, urinary retention).
- Infant botulism:
- Floppy baby syndrome (generalised hypotonia, weak cry, poor feeding).
- Constipation (often the first symptom).
- Wound botulism: similar to foodborne but without gastrointestinal symptoms.
Investigations
- Clinical diagnosis: based on characteristic neurological symptoms and history.
- Stool or serum toxin assay: detects botulinum toxin.
- Electromyography (EMG): shows characteristic findings (decreased compound muscle action potential with incremental response to repetitive nerve stimulation).
- Wound culture: for suspected wound botulism.
Management
1. Supportive Care:
- Admission to intensive care for respiratory monitoring.
- Mechanical ventilation if respiratory failure occurs.
- Nasogastric feeding if swallowing is impaired.
2. Antitoxin Therapy:
- Botulinum antitoxin (equine derived) for adults.
- Human derived botulism immune globulin (BIG-IV) for infant botulism.
3. Antibiotics:
- Not indicated for foodborne or infant botulism.
- For wound botulism: penicillin or metronidazole after antitoxin administration.
4. Prevention:
- Proper food preservation and storage.
- Avoid giving honey to infants under 12 months.
- Wound care and harm reduction strategies for IV drug users.
5. Referral:
- Infectious diseases: for diagnosis and toxin management.
- Intensive care: for respiratory support.
- Neurology: for electrophysiological studies if diagnosis is unclear.