The clinical presentation, diagnosis, and treatment of infant botulism (IB) are reviewed by investigators at the University of California-San Francisco, CA. IB occurs between 2 weeks and 1 year of age (median 10 weeks). The incubation period is generally 3-30 days. Early signs of IB include constipation, weak cry and suck, decreased spontaneous movements, and hypotonia. Cholinergic blockade affecting the neuromuscular junction and autonomic nervous system causes a symmetric, descending motor weakness and flaccid paralysis with autonomic dysfunction that starts with the cranial nerves and progresses slowly to the trunk, extremities, and diaphragm. External ocular movements are paralyzed, pupils are fixed, corneal and gag reflexes absent or diminished, and deep tendon reflexes diminished or intact. Clinical signs vary with the severity of infection, the strain of Clostridium, and neurotoxin serotype. Contaminated honey is linked to IB in 20% of cases (59% of cases in Europe). Environmental exposure to dust and soil containing botulinum spores is the most common source. The clostridial species botulinum, baratii, and butyricum are all recognized as causative agents, and most cases of IB are caused by botulinum toxin types A and B, type A in the western US and type B in the eastern US. Electrodiagnostic findings include normal nerve conduction, and polyphasic motor units of small amplitude and short duration on electromyography, with an incremental increase of evoked potentials on rapid repetitive nerve stimulation. An absent response to edrophonium challenge helps to exclude myasthenia gravis. Identification of botulinum toxins or organisms in stool or serum confirms the diagnosis. Therapy with human botulism immune globulin (Baby-BIG), approved by the FDA in 2003, significantly reduces hospital stay, and duration of mechanical ventilation and tube feeding. Erythematous rash in 14% of cases is the most common adverse effect. Aminoglycoside antibiotics cause neuromuscular blockade and can exacerbate paralysis due to IB; they should be avoided in treatment of secondary infection in IB. Prognosis for full recovery is usually good, even with supportive therapy alone. Complications include aspiration, and death from diaphragmatic paralysis. IB has been associated with sudden infant death syndrome (SIDS), accounting for 3-20% of cases in some studies. 
COMMENT. Infantile botulism may mimic Guillain-Barre disease, congenital myasthenia gravis, and viral encephalitis, and unless suspected, can be difficult to diagnose. IB should be suspected, and an electromyogram ordered, in an afebrile infant who presents with feeding problems, bulbar symptoms, and paralysis. Early confirmation of the diagnosis by identification of botulinum toxin or organisms in the stool or serum, and treatment with human botulism immune globulin can decrease morbidity and the duration of hospitalization.