Botulism is an illness caused by a neurotoxin produced primarily by Clostridium botulinum. Five types of disease can occur: Foodborne botulism, wound botulism, infant intestinal botulism, adult enteric botulism (similar to infant botulism), and inhalational botulism.¹ Of note, inhalational botulism is exceedingly rare, but could occur as a result of bioterrorism.²

Clostridium botulinum food poisoning

Botulinum toxin food poisoning

Wound botulism

Infantile botulism

• Symptoms usually begin 12 to 36 h following ingestion of the toxin.
• Severity of illness is related to the quantity of toxin ingested.
• Significant findings:
  1. Acute, bilateral cranial nerve palsies, with ocular and bulbar manifestations being most frequent (diplopia, ophthalmoplegia, ptosis, dysphagia, dysarthria, fixed and dilated pupils, and dry mouth)
  2. Bilateral motor nerve involvement that may progress to a descending flaccid paralysis
  3. No sensory deficits aside from possible blurred vision
  4. GI symptoms (dry mouth, nausea, vomiting, diarrhea, or cramps)
  5. Normal heart rate, blood pressure, and temperature
  6. Normal mental status
• Wound botulism:
  1. Occurs primarily in injection drug users (subcutaneous “black tar” heroin injection-“skin popping”) or with traumatic injury.²
  2. Presentation is similar to that of foodborne disease, except for a longer incubation period (4 to 14 days) and absence of GI symptoms.
  3. Fever is uncommon and if present may be due to wound infection, which is not always apparent.

• Botulism is caused by one of several neurotoxins (usually A, B, E, or F) produced by C. botulinum, an anaerobic, gram-positive bacillus.^1,4 Spore production guarantees survival of the organism in extreme conditions; it is found worldwide. Botulinum toxin blocks acetylcholine-mediated neurotransmission and is the most powerful neurotoxin known.
• Disease results from absorption of toxin into the circulation from a mucosal surface or wound. Botulinum toxin does not penetrate intact skin.
• In foodborne botulism, disease is caused by ingestion of preformed toxin. Although rapidly inactivated by heat, the toxin can survive the proteolytic environment of the stomach.
• In wound botulism, toxin is elaborated by organisms that contaminate a wound.
• In infant botulism (and probably adult botulism of unknown etiology), toxin is produced by organisms in the GI tract. Antibiotic use and achlorhydria can predispose to colonization by C. botulinum and elaboration of toxin.
• Inhalational botulism has been demonstrated experimentally in primates. Rare case reports of inhalational botulism from snorting contaminated cocaine have been reported, and there is concern for the potential use of manufactured aerosolized toxin as a bioterrorism agent.

• Myasthenia gravis, Lambert-Eaton myasthenic syndrome (Table E1)
• Guillain-Barré syndrome or other acute inflammatory demyelinating polyneuropathy
• Tick paralysis
• Stroke
• Polio
• Acute flaccid myelitis
• Heavy metal intoxication
• Shellfish poisoning

Diagnosis of botulism depends on high clinical suspicion and a thorough neurologic examination.^2,3

• Treatment should start before laboratory confirmation in suspected cases, as laboratory testing may take several days.^1,3-5
• Serum, food, and/or stool should be sent for anaerobic cultures and toxin assay.
  1. Public health laboratories may perform mouse bioassay testing, which confirms toxin type in 75% of cases. Immunoassays and PCRs are under investigation for rapid source tracking.
  2. Specimens for botulism laboratory confirmation and testing parameters are summarized in Table E2.

• Supportive care with intubation if respiratory failure occurs; ventilation may need to continue for some time, as pharmacologic therapy halts only short-term disease progression
• Débridement of the wound in wound botulism

The only specific therapy for botulism is botulinum antitoxin. The standard adult dose is one vial administered by intravenous infusion. The pediatric dose is based on weight.^4-6

• For noninfants: Give equine heptavalent botulinum antitoxin (HBAT), which contains antibodies for seven known botulism types (A through G), as early as possible. Antitoxin should be administered before laboratory confirmation if botulism is suspected.
  1. The antitoxin (BAT, Cangene Corporation) is available from the Centers for Disease Control and Prevention (24 h/day, 7 days/wk at 770-488-7100); it is derived from horse serum, so there is a significant incidence of serum sickness.
  2. Skin testing (conjunctival instillation and observation for 15 min), and possible desensitization, is recommended before treatment. Reported hypersensitivity rates range from 9% to 20%.
• Give wound botulism patients penicillin 3 million U intravenous (IV) q4h after antitoxin has been administered. Use metronidazole 500 mg IV q8h as an alternative for penicillin-allergic patients. Avoid aminoglycosides and tetracyclines, as they are ineffective and can worsen neuromuscular blockade.³
• For infants: Give human botulinum immunoglobulin (BabyBIG) IV as a single dose as early as possible. Immunoglobin should be administered before laboratory confirmation if botulism is suspected. Call 510-231-7600 to begin the process of drug acquisition and for administration instructions.⁴ Do not use equine antitoxin. Babies with infantile intestinal botulism may benefit from a cathartic to mechanically clear the number of C. botulinum vegetative forms and spores residing in the gastrointestinal tract. Avoid antibiotics in infant botulism because antimicrobials may lyse C. botulinum in the gut and increase toxin load.

• Highest mortality in the first cases in an outbreak, with subsequent cases receiving rapid treatment.
• Complete recovery for most individuals (may take up to 1 yr).

• Routine cooking inactivates the toxin, but spores are resistant to environmental factors. At room temperature, spores can germinate and produce toxin. Pressure cooking can kill spores.
• Most outbreaks are associated with home-canned foods, including fruits, vegetables, and fish. Botulinum spores can be found in honey and corn syrup, and thus children under 12 mo of age should not eat honey or foods with honey in them.
• Patients must be closely monitored for progression to respiratory failure.
• Notify public health authorities immedia-tely to alert other health care services of possible additional cases and to initiate investigation into cause and scope of outbreak.
• Immunity to botulism does not occur after toxin exposure/infection, and repeated botulism can occur.
• Treat patients with suspected, symptomatic botulism with botulinum antitoxin on the basis of clinical findings; do not await laboratory confirmation because results might take several days, and they can be negative in patients who have botulism.⁷

Botulism (Patient Information)