Botulism – Causes, Symptoms, Diagnosis, Treatment and Ongoing care



  • Botulism is a muscle-paralyzing illness caused by a neurotoxin made by the bacterium Clostridium botulinum.
  • Characterized by acute onset of bilateral cranial nerve involvement (diplopia, difficulty swallowing or speaking) associated with symmetric descending weakness, intact mental state, no fever, and no sensory dysfunction
  • 7 types of C. botulinum (A–G) are distinguished by their antigenic characteristics. Types A, B, E, and, in rare cases, F, cause disease in humans.
  • Forms include:
    • Foodborne: Caused by ingestion of preform toxin
    • Infant botulism: Caused by ingestion of C. botulinum that produce toxin in the gastrointestinal (GI) tract
    • Wound: Caused by wound infection with C. botulinum that secretes the toxin
    • Aerosolized/inhalational botulinum: Bioterrorism attack potential because of high toxicity; <1 µg is lethal human dose
    • Injection related: Rare
    • Adult colonization botulism: Rare
  • System(s) affected: Neuromuscular; Respiratory; GI
  • Diagnosis is made through history and clinical exam.
  • Laboratory confirmation demonstrates presence of toxin in serum, stool, or wound; or culturing C. botulinum from stool, wound, or food
  • Treatment should not wait for laboratory confirmation.
  • Synonym(s): Sausage poisoning; Kerner disease
  • A purified and diluted form of Type A neurotoxin is used to produce Botox injections.



  • Average of 110 cases of botulism reported annually in US
  • ∼20% of cases are foodborne; 30–40% wound-related; 65% infant botulism
  • Wound botulism incidence increasing due to IV heroin use and cocaine abuse
  • Hidden or intestinal: More common in disorders of the GI tract, such as prior surgery, Crohn disease, or recent antibiotic use
  • Inhalation: Only a single incident involving 3 laboratory workers has been described.


  • Predominant age:
    • Foodborne: Mean age is 46 years; range of 3–78 years
    • Infantile: Mean age of onset 13 weeks, with range of 1–63 weeks
    • Wound: Median age is 41 years with a range of 23–58 years
  • Predominant gender:
    • Foodborne and infantile: Male = Female
    • Wound: Female > Male

Risk Factors

  • Foodborne: Ingestion of home-canned or prepared contaminated foods
  • Infantile: From ingestion of honey or corn syrup; breastfeeding (controversial)
  • Wound: IV drug use (black tar heroin; IM/SC) or “skin popping”

General Prevention

  • Foodborne: Proper handling, processing, preparation (heating), and storage of food; avoid eating food from bulging cans and food that smells/looks spoiled.
  • Infant: Avoid honey before 1 year of age.
  • Wound: Proper wound care
  • Health care providers: Standard precautions
  • If meningitis is suspected in patients with flaccid paralysis, medical personnel should use droplet precautions.
  • Heat potentially contaminated food or drink to an internal temperature of 85°C for at least 5 minutes.
  • After exposure to C. botulinum toxin, clothing and skin should be cleaned with soap and water.
  • Contaminated objects or surfaces should be cleaned with 0.1% bleach solution. All food suspected of contamination should be promptly removed from potential consumers.


  • Disease results from hematogenous spread of toxin from mucosal surface (stomach, small intestine) or from an infected wound.
  • The toxin prevents acetylcholine release at presynaptic membranes, blocking neuromuscular transmission in cholinergic nerve fibers.


  • Toxin produced by C. botulinum, an encapsulated, anaerobe, gram-positive, spore-forming, rod-shaped bacillus
  • Ingestion of C. botulinum neurotoxins (A, B, and E most common)
  • Foodborne, usually from home-canned vegetables, prepared foods, or foods incubated in anaerobic conditions
  • Infantile from ingestion of spores in environment or occasionally in honey
  • Wound due to contamination with toxin-producing C. botulinum
  • Inadvertent: IM injections of botulinum toxin

Botulism, Clostridium botulinum, Foodborne illness, Clostridium, Botox, cranial nerve involvement, bacterium clostridium botulinum, botox injections, cocaine abuse, sensory dysfunction, wound infection, neurotoxin, antibiotic use, bioterrorism,



  • Foodborne:
    • Incubation: Typically 12–36 hours after toxin ingestion. Rare case as late as 10 days after ingestion.
    • Wound and infant botulism: Incubation time cannot be ascertained.
    • Inhalational: Same as foodborne botulism
  • Adults: Acute onset of symmetric neuropathies. Difficulty in swallowing or speaking, dry mouth. Diplopia, blurred vision, dilated or nonrelated ptosis (drooping eyelids).
  • Symmetric descending, flaccid paralysis in oriented, afebrile patient
  • Respiratory dysfunction
  • Infant botulism: Disease presentation and severity variable:
    • Constipation, shortly followed by weakness, feeding difficulties, descending or global hypotonia, drooling, anorexia, irritability, and weak cry
  • Ask about diet, travel, drug use, and other persons with same symptoms.

Physical Exam

  • General appearance: Oriented, flaccid, may complain of malaise, dizziness, nausea, vomiting
  • Vital signs, afebrile (fever may occur in wound botulism due to secondary infection), normal blood pressure
  • Head, eyes, ears, nose, throat: Dry mouth
  • Chest/lungs: Respiratory muscle weakness, respiratory dysfunction, paralysis
  • Heart: Normal or slow rate
  • Abdomen: Distention, constipation (early sign in infant form); may be absent in wound form
  • Genitourinary: Urinary retention
  • Neurologic:
    • Symmetrical descending weakness beginning with the cranial nerves
    • Ptosis; extraocular muscle paresis; fixed, dilated pupils; dysphagia
    • Infant botulism: Poor muscle tone (loss of head control and facial expression), poor feeding (loss of suck), drooling, feeding difficulties, weak cry
    • Diminished or absent deep tendon reflexes

Diagnostic Tests & Interpretation


Initial lab tests

  • Laboratory confirmation is done by demonstrating the presence of toxin in serum or stool, or by culturing C. botulinum from stool, wounds, or food.
  • Mouse neutralization assay confirmation:
    • Standard method of diagnosis (1)[B]
    • Available from Centers for Disease Control and some state laboratories; takes ∼4 days for results
  • Routine tests (complete blood count, electrolytes, liver function tests, urinalysis) generally not helpful/show no characteristic abnormalities
  • Cerebrospinal fluid testing: Normal helps differentiate from Guillain-Barré syndrome. Occasionally a borderline elevation in protein is seen.
  • Toxin detected in gastric contents, serum, stool, and suspected food and containers:
    • PCR tests are also available for rapid detection of clostridia in food samples (2)[B].
  • A normal Tensilon test helps to differentiate botulism from myasthenia gravis; borderline can occur in botulism


CT or MRI to rule out neurologic pathology

Diagnostic Procedures/Surgery

Electrophysiology testing:

  • Presumptive evidence in patients with negative bioassay studies (3)[C]
  • Brief, small-amplitude motor potential with incremental response on repetitive nerve stimulation

Differential Diagnosis

  • Adult botulisms:
    • Guillain-Barré syndrome
    • Encephalitis, meningitis
    • Tick paralysis
    • Myasthenia gravis
    • Eaton Lambert myasthenic syndrome
    • Cerebrovascular accident: Basilar artery stroke
    • Congenital neuropathy or myopathy
    • Sepsis
    • Hypokalemic periodic paralysis
    • Poliomyelitis
    • Other poisonings (organophosphate, shellfish, Amanita mushrooms, atropine, and aminoglycosides)
    • Miller-Fisher variant of Guillain-Barré syndrome
    • Diphtheritic neuropathy
    • Carbon monoxide intoxication
    • Hypermagnesemia
  • Infant botulism:
    • Sepsis
    • Meningitis
    • Electrolyte–mineral imbalance
    • Reye syndrome
    • Congenital myopathy
    • Leigh disease
    • Werdnig-Hoffman disease



First Line

  • Antitoxin therapy with trivalent A-B-E antitoxin:
    • Call CDC Assistance (770) 488-7100
    • Initiating botulinum antitoxin therapy is primarily based on symptoms and physical examination findings that are consistent with botulism (4)[B].
    • Early administration is important (4)[B].
    • Horse serum derived: Up to 20% reaction incidence. Consider skin testing or pretreatment with steroids or antihistamines.
  • Infantile:
    • Treatment with human botulism immune globulin (BIG-IV or Baby BIG) for botulism types A and B (5)[B]
    • Available only through the California State Health Department (510) 540-2646 or (510) 231-7600
  • Wound:
    • Antitoxin therapy with trivalent A-B-E antitoxin, 1 vial IV and 1 vial IM, repeat in 2–4 hours if persistent symptoms
    • Antibiotics unproven by clinical trial, but widely used and recommended:
      • Penicillin G (3 million units IV q4h in adults)
      • Metronidazole (500 mg IV q8h) for penicillin-allergic patients
    • Vaccine: Pentavalent vaccine available:
      • Efficiency in terrorist attack is unknown
      • Newer vaccines being developed

Second Line

Supportive care, including mechanical ventilation (6)[C]

Pregnancy Considerations

Safety of botulism antitoxin during pregnancy and breastfeeding unknown or controversial (6)

Additional Treatment

Issues for Referral

  • Nutrition: For hyperalimentation and later, tube feeding
  • Physical/occupational therapy: Including swallow evaluation

Additional Therapies

  • Stress ulcer and deep vein thrombosis prophylaxis
  • Pulmonary and physical rehabilitation

Surgery/Other Procedures

Wound excision/debridement

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In-Patient Considerations

Initial Stabilization

Hospital admission with meticulous airway management

Admission Criteria

All suspected cases must be admitted.

IV Fluids

Keep patient well hydrated.


  • Prevent decubitus ulcer, IV line infections, other nosocomial infections
  • Before administration of antitoxin, skin testing should be performed for sensitivity.

Ongoing Care

Follow-Up Recommendations

Outpatient follow-up with physical/occupational therapy, nutrition specialist, and psychiatry as needed

Patient Monitoring

  • Pulmonary function testing
  • Cardiorespiratory monitoring


Nasogastric feedings, if needed

Patient Education

  • Spores destroyed by pressure cooking at 250°F (120°C) for 30 minutes
  • Toxin destroyed by boiling for 10 minutes or cooking at 175°F (80°C) for 30 minutes
  • Avoid honey in 1st year of life.
  • Avoid IV drug use.
  • Do not eat/sample foods that look and smell rotten or come from bulging cans.


  • Delay in administering antitoxin: Most important factor affecting clinical course and outcome (4)[B]
  • Mortality: Overall 7–10%; <5% if infection is treated, but approaches 60% if untreated (6)
  • Mortality for patients >60 years is twice that of younger patients
  • Full recovery may take months.
  • Significant health, functional, and social limitations several years after infection (7)[C]:
    • Recovery follows the regeneration of new neuromuscular connections.
    • 2–8 weeks of ventilator support may be required in more severe cases.
  • Dyspnea with severe ptosis and pupil abnormality has been shown to correlate with severe illness and respiratory failure (8)[C].
  • Increased incubation time has been shown to correlate with better outcomes (8)[C].


  • Nosocomial infections, including aspiration pneumonia and ventilator-associated pneumonia
  • Hypoxic tissue damage
  • Death


1. Lindström M, Korkeala H. Laboratory diagnostics of botulism. Clin Microbiol Rev. 2006;19:298–314.

2. Fach P, Micheau P, Mazuet C, et al. Development of real-time PCR tests for detecting botulinum neurotoxins A, B, E, F producing Clostridium botulinum, Clostridium baratii and Clostridium butyricum. J Appl Microbiol. 2009;107:465–73.

3. Bayrak A, et al. Electrophysiologic findings in a case of severe botulism. J Neurol Sci. 2006;23:49–53.

4. Dembek ZF, Smith LA, Rusnak JM. Botulism: cause, effects, diagnosis, clinical and laboratory identification, and treatment modalities. Disaster Med Public Health Prep. 2007;1:122–34.

5. Arnon SS, Schechter R, Maslanka SE, et al. Human botulism immune globulin for the treatment of infant botulism. N Engl J Med. 2006;354:462–71.

6. O’Brien KK, Higdon ML, Halverson JJ. Recognition and management of bioterrorism infections. Am Fam Physician. 2003;67:1927–34.

7. Gottlieb SL, Kretsinger K, Tarkhashvili N, et al. Long-term outcomes of 217 botulism cases in the Republic of Georgia. Clin Infect Dis. 2007;45:174–80.

8. Witoonpanich R, Vichayanrat E, Tantisiriwit K, et al. Survival analysis for respiratory failure in patients with food-borne botulism. Clin Toxicol (Phila). 2010;48:177–83.

9. Botulism Facts for Healthcare Providers. Accessed 5/30/2010 at

Additional Reading

See Also (Topic, Algorithm, Electronic Media Element)

Food Poisoning, Bacterial



  • 005.1 Botulism food poisoning
  • 040.42 Wound botulism


  • 398565003 Infection due to infection due to clostridium botulinum (disorder)
  • 398523009 Foodborne botulism (disorder)
  • 398530003 Wound botulism (disorder)

Clinical Pearls

  • Botulinum antitoxin should be administered as soon as possible; don’t wait for lab results.
  • Medical care providers who suspect botulism in a patient should immediately call their state health department’s emergency 24-hour telephone number.
  • A helpful mnemonic to recall progression of symptoms is the “dozen D’s”: Dry mouth, diplopia, dilated pupils, droopy eyes, droopy face, diminished gag reflex, dysphagia, dysarthria, dysphonia, difficulty lifting head, descending paralysis, and diaphragmatic paralysis (9)

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