This disease is relatively uncommon, with only 171 cases reported in 2006 to the Centers for Disease Control and Prevention (CDC).¹ Because of its rarity, the disease is frequently confused with other neurologic and infectious diseases. It has such significant morbidity that most patients present initially to an emergency department for evaluation and management of their symptoms.

Pathophysiology

Botulism’s effect on nerve terminals is the same in all three varieties. After the toxin has entered the bloodstream, it is taken up at the presynaptic nerve terminals by endocytosis. Through a chain reaction of biochemical events, the toxin inhibits the release of acetylcholine from the presynaptic terminal. This action essentially limits motor and autonomic neuron function.^2,3 Because the effects of the toxin are irreversible, clinical recovery does not occur until new neuromuscular junctions are created.

Infantile (intestinal) botulism is the most common form of the disease and accounts for approximately two- thirds of all cases.¹ It is caused by the ingestion of botulism spores, which then germinate, colonize, and produce toxin in an infant’s colon.⁴ The disease is classically associated with feeding honey to infants, but only 15% of recent cases have been linked to honey.¹ The source of the remaining cases has not been identified, but the ingestion of environmental agents such as contaminated soil and vacuum cleaner dust is thought to be a likely cause.^3,5 This disease primarily affects infants, because their gastrointestinal tracts have yet to be colonized by the competitive flora that protect adults and older children.⁵

Food-borne botulism is caused by the ingestion of preformed toxin and is responsible for approximately 20% of cases.¹ Reports are clustered in the western states, particularly Alaska, where improper canning techniques and failure to cook home-canned food properly are blamed. Occasionally, commercially produced food products are responsible. In the summer of 2007, four cases of food-borne botulism were reported. All were connected to the ingestion of Castleberry’s Hot Dog Chili Sauce, and each of those cases presented to a different emergency department.⁶

Wound botulism is the rarest of the three entities.¹ It classically occurs when a wound becomes contaminated with Clostridia-laden soil. The bacteria then flourish and produce the toxin, which is systemically absorbed.² Clostridia-contaminated wounds usually do not appear as grossly infected as one might expect.

In the United States, cases of wound botulism are found almost exclusively in injection drug users, typically with subcutaneous rather than intravenous injection. Recently, a cluster of cases was associated with “black tar” heroin use.⁷