Description

• An acute illness caused by neurotoxins produced by Clostridium botulinum or related neurotoxigenic species, which results in cranial nerve palsies and a symmetric, descending, flaccid paralysis
• The neurotoxin may be elaborated either in the large intestine of individuals temporarily colonized with the bacterium, or ingested, or absorbed from infected wounds.
• There are three main forms of the disease:
  • Infant botulism (IB) is the intestinal toxemia form in which swallowed spores germinate and colonize the infant’s colon and elaborate toxin in situ.
  • Foodborne botulism in children and adults occurs when preformed toxin is ingested with improperly prepared or stored foods.
  • Wound botulism occurs when spores of the bacterium contaminate the wound, germinate, and produce toxin that is then absorbed.

Epidemiology

• IB is the most common form of human botulism in the United States.
• IB occurs in the 1st year of life, with ~90% of cases reported in the first 6 months of life.
• IB affects infants of all racial backgrounds and socioeconomic groups.
• Male to female ratio is 1:1.
• Toxin types A and B represent 98.5% of cases in United States (1976 to 2015), with dual toxin types (e.g., Ba, Bf) and more rare type E and type F comprising the remaining 1.5%.
• IB has been recognized in all 50 states, with a greater proportion of toxin type B cases east of the Mississippi River and toxin type A cases west of the Mississippi.
• Recognized on five of the six inhabited continents, Africa being the exception.
• Often, a history of a recent change in feeding practice is found.
• Honey is an identified food reservoir of C. botulinum spores. Honey consumption in U.S. IB patients from 1976 to 2015 was only approximately 4.8%.
• For the majority of IB cases, spore acquisition likely occurs from the natural environment, that is, infants inhale and then swallow spores attached to airborne microscopic dust particles. Nearby soil disruption may play a role.
• Breastfed infants who acquire IB tend to be older at onset than are formula-fed infants.
• Foodborne cases are usually associated with home-processed, low acid foods—especially vegetables, fruits, and condiments. Restaurant-associated outbreaks have occurred. Recent outbreaks in U.S. prisons have been associated with fermented alcoholic beverage commonly referred to as pruno.
• Wound botulism has been associated with “black tar” heroin injection drug use and traumatic injuries in teenagers.

Risk Factors

• Infants who have <1 bowel movement per day may be at increased risk of developing IB.
• Honey is an identified, avoidable food source of C. botulinum spores.
• Ingestion of improperly canned or preserved low-acid foods may result in foodborne botulism.

General Prevention

• Do not feed honey or raw honey–containing products to infants.
• Botulinum toxin is heat-labile; 5 minutes of boiling will destroy the toxin.
• Spores are heat-resistant.
• Proper food preservation, storage, and preparation will prevent foodborne botulism.

Pathophysiology

• Neurotoxin is endocytosed at peripheral cholinergic nerve endings; it blocks release of acetylcholine at the neuromuscular junction.
• Cranial nerves are usually affected first and most severely, leading to ptosis, ophthalmoplegia, decreased facial expression, difficulty swallowing, and loss of airway-protective reflexes. Respiratory failure may ensue.
• Sensation and sensorium remain intact.
• Recovery occurs through regeneration of motor neuron axon terminals and the formation of new motor end plates.
• Infants are particularly prone to temporary colonic colonization by C. botulinum. When foods other than breast milk are introduced to breastfed infants, perturbation of the intestinal microbiome may predispose to illness.

Etiology

C. botulinum, the etiologic agent, is a gram-positive, spore-forming, obligate anaerobic bacterium that is found in dust, soil, and marine sediments worldwide. Rarely, neurotoxigenic Clostridium butyricum and Clostridium baratii may cause disease due to toxin type E and type F, respectively.