Botulism is a medical emergency caused by a neurotoxin produced by a spore-forming bacteria called Clostridium botulinum. Home-canned foods are the most common sources. Cranial nerve palsies (diplopia, dysarthria, dysphonia, ptosis, and impaired gag reflex) are the first symptoms.

1,530 (US); 30,600 (Global)
Clostridium botulinum infection;
Foodborne: 12 hours to 1.5 days (range of 2 hours to 8 days); Infant: up to 30 days (estimated); Inhalation: similar to foodborne; Wound: 4-14 days; [CCDM, p. 73]
Symmetric cranial nerve palsies (diplopia, dysarthria, dysphonia, ptosis, impaired gag reflex) followed by symmetric descending flaccid paralysis in an alert patient without fever; Vomiting & abdominal pain may occur; [Harrisons, p. 492]
Standard; "Not transmitted from person to person." [CDC 2007 Guideline for Isolation Precautions]
The four types of botulism in nature are: foodborne, wound, infant, and adult intestinal. In the first type, poisoning results from exposure to preformed toxin. In the last three types, the toxin is produced by bacteria infecting the body. There are also two types of botulism that do not occur in nature: inhalational and iatrogenic (accidental injection of toxin into the systemic circulation). Foods associated with botulism include home-canned vegetables and fruits, seal meat, smoked salmon, fermented salmon eggs, and sausages. Most US cases occur among Alaskan natives who eat fermented fish and marine mammals. In cosmetic procedures, the dose of toxin in licensed products is too low to cause botulism. Wound botulism has been reported in drug abusers related to dermal abscesses (heroin injection) and sinusitis (cocaine abuse). Honey may contain C. botulinum spores and is one of the causes of intestinal botulism in infants (2-36 weeks old).

"Patients with botulism typically present with difficulty seeing, speaking, and/or swallowing." The impending paralysis may contribute to patient anxiety and hyperventilation. The classic triad of botulism is: 1.) bulbar palsies and descending paralysis; 2.) afebrile; and 3.) clear sensorium. Deep tendon reflexes are diminished or absent. In foodborne botulism, constipation, diarrhea, and/or vomiting may occur. In intestinal botulism, infants are weak, constipated, and "floppy" with loss of head control. Patients die from respiratory paralysis. Other symptoms after ingestion may include dry mouth, abdominal distention, urinary retention, postural hypotension, and paralysis of extraocular muscles. Symptoms progress over several days to respiratory paralysis. Less than 50% of patients have dilated or fixed pupils. Neurological deficits are symmetrical, and heart rate is normal. Respiratory distress results from airway obstruction due to a weakened glottis or from diaphragmatic paralysis. Dysphagia may cause aspiration pneumonia.

The toxin is destroyed by cooking (heating >185 degrees F for at least 5 minutes). In the USA, the average number of foodborne outbreaks is 9 per year, and the average size is 2.5 patients per outbreak. Most cases develop 2-3 days after eating home-canned food. Botulism antitoxin should be given as soon as the disease is suspected. Treatment should not be delayed while waiting for laboratory confirmation. [CCDM, p. 71-7; PPID, p. 2958; ABX Guide; Cecil, p. 1893-5] Toxoids are available for active immunization of workers handling C. botulinum toxins. [Merck Manual, p. 1466] Standard pasteurization does not eliminate spores, and outbreaks from dairy products have been reported. [PMID 20301016]

The differential diagnosis of suspected botulism includes myasthenia gravis, Eaton-Lambert, Guillain-Barre, stroke, and various poisons (organophosphate, tick paralysis, nerve gas, alcohol intoxication, heavy metals, and carbon monoxide). [ABX Guide] In Guillain-Barre syndrome, paralysis is ascending. In botulism, paralysis is descending. [Cecil, p. 1894] Botulism is strongly suggested by an outbreak of cranial nerve and descending paralysis because other illnesses that resemble botulism (including Guillain-Barre syndrome) do not cause outbreaks. [Harrison ID, 2nd Ed, p. 473]
Clinical; Detection of toxin in stool, serum, food, or wound material; [Harrisons, p. 493] "Clinical suspicion foremost." CSF: normal; MRI normal; EMG: nerve terminal disease; [ABX Guide]
  • >fatigue, weakness
  • E dysphagia
  • E pharyngitis
  • G abdominal pain
  • G constipation
  • G diarrhea
  • G nausea, vomiting
  • N muscle weakness
  • N paresthesia
  • R dyspnea
  • *cranial neuropathy
  • *paralysis
  • *pneumonia




Inhalation, Ingestion, Needle (Includes Drug Abuse), Scalpel or Transfusion, Skin or Mucous Membranes (Includes Conjunctiva)
Soil or Dust (Ingesting or Inhaling), Eating Contaminated Food, Eating Contaminated or Infected Meat, Eating Infected or Toxin-Containing Fish, Eating Unpasteurized Milk or Cheese, Eating Contaminated Produce
  • Consume unpasteurized milk/cheese
  • Eat undercooked meat or fish
  • Ingest toxins in food or water
  • Injection drug users
  • Victim--air release of toxins
  • Victim--water/food release
  • Work in a medical or research lab
Antitoxin stops progression, but does not reverse existing paralysis. [ABX Guide] CDC 24 hour #: is 404-329-2888; See
1. (US) Published in MMWR 2011 = 153; Use correction factor of 10 for reported diseases: 153 X 10 = 1,530;
2. (Global) Rare; [Fact sheets from WHO] Calculate: 20 X US rate = 30,600;