Infant Botulism

Infant botulism is a flaccid paralysis caused by toxin produced in the infant gut after ingestion of spores of Clostridium botulinum, and occasionally Clostridium butyricum or Clostridium baratii. It is the commonest form of botulism in children.

It occurs between 2 weeks and 12 months of age, with a peak at 2 to 4 months. Spores come from soil, dust and honey. Honey is a preventable source, and infants under 12 months should not be given it. Constipation is a precursor, and breastfed infants may present later, around weaning.

Illness ranges from mild hypotonia to respiratory failure. Mortality is under 2% with supportive care and specific treatment.

Pathophysiology.

The infant gut flora is immature, so spores germinate, colonise the colon and release toxin. Botulinum toxin enters cholinergic nerve endings and cleaves SNARE proteins, preventing acetylcholine release at the neuromuscular junction and in autonomic synapses.

Paralysis lasts until new nerve terminals sprout, over weeks.

• Constipation for several days, then poor feeding, weak suck, weak cry and drooling.
• Descending, symmetrical weakness: ptosis, ophthalmoplegia, facial weakness, loss of head control, hypotonia and reduced limb strength.
• Dilated, sluggish pupils, dry mouth, and respiratory weakness with hypoventilation and apnoea.
• Afebrile, alert at first, with preserved sensation.

Red flags.

• Respiratory insufficiency, weak cough, aspiration or inability to protect the airway.
• Rapid progression, or dehydration from poor feeding.
• Fever or altered consciousness, suggesting an alternative diagnosis.

• Clinical diagnosis, and treatment should not wait for confirmation.
• Stool (or enema) specimens for toxin assay and culture or PCR. Serum toxin is less often positive in infants.
• Electromyography with repetitive stimulation shows brief, small, abundant motor unit potentials and an incremental response at high rates.
• Lumbar puncture, metabolic tests, thyroid tests, and nerve conduction studies as needed to exclude alternatives.

Differential diagnosis. Sepsis, meningitis, spinal muscular atrophy, Guillain-Barre syndrome, myasthenia (congenital), hypothyroidism, metabolic disease, poliomyelitis and other enteroviral infection, tick paralysis, electrolyte disorders and toxic exposure.

Specific treatment.

• Human derived botulism immune globulin 50 mg/kg IV as a single infusion, given as early as possible once the diagnosis is suspected, without waiting for laboratory confirmation. It shortens hospital stay and the duration of ventilation.
• Equine antitoxin is not used in infants.

Supportive care.

• Admit to a unit able to provide intensive care, with close monitoring of respiratory function (vital capacity, oxygen saturation, secretions).
• Intubate for hypoventilation, inability to protect the airway or apnoea. Wean when strength returns.
• Nutrition by nasogastric tube with human milk or usual infant formula (continued breastfeeding is encouraged), and prevention of aspiration.
• Avoid aminoglycosides, clindamycin, magnesium and other drugs that potentiate neuromuscular blockade. Antibiotics are used only for intercurrent infection, choosing a non-aminoglycoside agent.
• Pressure area care, physiotherapy and bowel care.

Prevention. Avoid giving honey to infants under 12 months. Dust and soil exposure cannot be fully avoided.

Monitoring. Respiratory function, swallowing and weight daily. Recovery takes weeks, and relapse can occur around 2 to 3 weeks after treatment with high toxin load.

Referral and escalation. Notify public health authorities. Refer to a paediatric intensive care unit for any respiratory compromise.