The identification of contaminated honey as a source of spores has lead to the recommendation that honey should not be given to infants younger than 1 year. Susceptibility decreases with age as the normal intestinal flora develops. The major systemic features of botulism involve motor weakness or paralysis. Paralysis begins with cranial nerve involvement and progresses caudally to involve extremities. A generally symmetric descending paralysis occurs, with involvement of neck, arms, thorax, and legs.
Respiratory difficulties occur with intercostal and diaphragmatic weakness.
Autonomic features are to be expected, reflecting cholinergic neurotransmission disruption, with impairment of salivary secretion, paralytic ileus, constipation, and urinary retention. Postural hypotension may be present. The gag reflex may be suppressed. Typically, patients are afebrile. Ophthalmic manifestations may reflect the anticholinergic effects of the neurotoxins.