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Information for Health Professionals

Clinical Features

Botulism is a neuroparalytic illness characterized by symmetric, descending flaccid paralysis of motor and autonomic nerves, always beginning with the cranial nerves.

Botulism Case Consultation

If you suspect your patient may have botulism, call your state public health department immediately. If there is no answer, contact CDC 24/7 at 770-488-7100.

  • For non-infant cases: State public health officials can reach the CDC clinical emergency botulism service for consultation and antitoxin 24/7 at 770-488-7100. If administered early in the course of illness, antitoxin can prevent progression of illness and shorten its duration.
  • For infant botulism: The Infant Botulism Treatment and Prevention Program at the California Department of Public Health provides consultation 24/7 and can be reached at 510-231-7600.

If clinical consultation with state public health departments and CDC supports botulism, request antitoxin immediately and begin treatment as soon as it is available. Do not wait for laboratory confirmation.

Signs and symptoms in an adult may include:

  • Diplopia (double vision)
  • Blurred vision
  • Ptosis (drooping eyelids)
  • Slurred speech
  • Dysphagia (difficulty swallowing)
  • Dry mouth
  • Muscle weakness

Possible signs and symptoms in foodborne illness may also include:

  • Abdominal pain
  • Nausea
  • Vomiting
  • Diarrhea

Signs and symptoms in an infant may include:

  • Poor feeding
  • Diminished suckling and crying ability
  • Neck and peripheral weakness (“floppy baby”)
  • Constipation
  • Respiratory failure

If untreated, illness might progress to cause descending paralysis of respiratory muscles, arms, and legs.

Etiology and Transmission

Botulism is caused by a potent neurotoxin produced from Clostridium botulinum, and rare strains of C. butyricum and C. baratii, which are anaerobic, spore-forming bacteria.

Transmission differs by type of botulism:

  • Foodborne botulism occurs when a person ingests botulinum toxin, which leads to illness within a few hours to days. Outbreaks of foodborne botulism have potential to be a public health emergency because the contaminated food may be eaten by other people. A frequent source is home-canned foods prepared in an unsafe manner.
  • Infant botulism occurs each year in a small number of susceptible infants who harbor C. botulinum in their intestinal tract. It occurs when an infant ingests spores of C. botulinum, which in turn colonize the intestinal tract and produce toxin.
  • Wound botulism is a rare disease that occurs when wounds infected with C. botulinum secrete the toxin. It occurs more frequently among persons who inject drugs, but has also been seen in cases of traumatic injury, such as motorcycle crashes, and surgeries.
  • Adult intestinal colonization (also called adult intestinal toxemia) is an even rarer type of botulism. It involves intestinal colonization in a person older than one year of age. In the small number of these cases, most patients had a history of gastrointestinal surgery or illness, such as inflammatory bowel disease, which might have predisposed them to enteric colonization. No other specific risk factors have been identified.
  • Iatrogenic botulism occurs after an overdose of injected botulinum toxin for cosmetic or medical purposes.


Botulism differs from other flaccid paralyses in that it always manifests initially with prominent cranial nerve palsies. It also differs in its invariable descending progression, in its symmetry, and in its absence of sensory nerve dysfunction.

Botulism is frequently misdiagnosed, most often as a polyradiculoneuropathy (Guillain-Barré or Miller-Fisher syndrome), myasthenia gravis, or other diseases of the central nervous system.

Clinical diagnosis of botulism is confirmed by specialized laboratory testing that often requires days to complete. Routine laboratory test results are usually unremarkable.

Differential Diagnosis for Adults may include:

Differential Diagnosis for Adults May Include:

  • Guillain-Barré syndrome
  • Myasthenia gravis
  • Cerebrovascular accident (CVA)
  • Bacterial or chemical food poisoning
  • Tick paralysis
  • Chemical intoxication (for example, carbon monoxide, opioid intoxication)
  • Mushroom poisoning
  • Poliomyelitis
  • Psychiatric illness

Differential Diagnosis for Infants may include:

Differential Diagnosis for Infants May Include:

  • Sepsis
  • Meningitis
  • Electrolyte-mineral imbalance
  • Reye’s syndrome
  • Congenital myopathy
  • Werdnig-Hoffman disease
  • Leigh disease

Tests and Laboratory Studies

Initial diagnosis is based on clinical symptoms. Do not wait for laboratory confirmation to begin treatment.

Laboratory confirmation is done by demonstrating the presence of botulinum toxin in serum, stool, or food, or by culturing C. botulinum, C. butyricum, or C. baratii from stool, a wound, or food.

Other tests and laboratory studies to help with clinical diagnosis include:

  • Routine lab tests (CBC, electrolytes, LFTs, urinalysis): Generally not helpful in diagnosis as these tests show no characteristic abnormalities.
  • Cerebrospinal fluid (CSF) studies: Essentially normal, although occasionally a borderline elevation in protein level may be seen.
  • Tensilon test: A normal test helps to differentiate botulism from myasthenia gravis; borderline positive tests can occur in botulism.
  • CTs and MRIs: Normal CTs and MRIs help to rule out cerebrovascular accident (CVA).


Administer botulinum antitoxin or BabyBIG as soon as possible. Antitoxin does not reverse paralysis but arrests its progression. Recovery follows the regeneration of new neuromuscular connections.

Exercise meticulous intensive care, including monitoring of respiratory function and, when required, mechanical ventilation. In more severe cases, ventilator support may be required for weeks to months.

Treatment for wound botulism may also include wound debridement to remove the source of toxin‑producing bacteria and antibiotic therapy.

Infection Control

Medical personnel caring for patients with suspected botulism should use standard precautions [PDF – 226 pages]. Botulism is not transmitted person-to-person.

Patients with botulism do not need to be isolated.


Death can result from respiratory failure or the consequences of extended paralysis. About 5% of patients die. Recovery takes weeks to months. Those who survive may have fatigue and shortness of breath for years.


In 2015, there were 199 cases of laboratory-confirmed botulism reported to the CDC. Of these, 39 were foodborne, 141 were infant botulism, 15 were cases of wound botulism, and 4 cases were of unknown etiology. Get additional information and annual tabulations of cases >

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