Botulism

Essentials of Diagnosis

• Recent ingestion of home-canned or smoked foods

• Recent injection drug use

• Recovery of toxin in serum or food

• Diplopia, dry mouth, dysphagia, dysphonia

• Muscle weakness leading to respiratory paralysis; normal sensory examination

• Pupils are usually fixed and dilated

General Considerations

• A paralytic disease caused by botulinum neurotoxin, which is produced by Clostridium botulinum, a ubiquitous, strictly anaerobic, spore-forming bacillus found in soil

• Four toxin types—A, B, E, and F—cause human disease

• Botulinum toxin inhibits release of acetylcholine at the neuromuscular junction

• Naturally occurring botulism exists in three forms

  • Food-borne botulism

  • Infant botulism

  • Wound botulism

• Food-borne botulism is caused by ingestion of preformed toxin present in canned, smoked, or vacuum-packed foods such as home-canned vegetables, smoked meats, and vacuum-packed fish

• Infant botulism

  • Associated with ingestion of honey

  • Honey consumption is safe for children 1 year of age or older

• Wound botulism

  • Often occurs in association with injection drug use

  • Results from organisms present in the gut or wound that secrete toxin

• Botulinum toxin

  • Extremely potent

  • Classified by the Centers for Disease Control and Prevention (CDC) as a high-priority agent because of its potential to be used a bioterrorism agent

Demographics

• Approximately 170 cases of botulism have been reported to the CDC over a year. Of these, 20% were food-borne and wound botulism and the remainder were infant botulism

Symptoms and Signs

• Visual disturbances, particularly diplopia and loss of accommodation, appear 12–36 h after ingestion of the toxin

• Characteristic signs

  • Ptosis

  • Cranial nerve palsies with impairment of extraocular muscles

  • Fixed dilated pupils

• Other symptoms

  • Dry mouth

  • Dysphagia

  • Dysphonia

• The sensory examination is normal

• The sensorium remains clear and the temperature normal

• Respiratory paralysis may lead to death unless mechanical assistance is provided

Differential Diagnosis

• Because the clinical presentation of botulism is so distinctive and the differential diagnosis limited, botulism once considered is not easily confused with the other diseases listed below

  • Poliomyelitis

  • Guillain-Barré syndrome

  • Myasthenia gravis

  • Brainstem infarct or vertebrobasilar insufficiency

  • Tick paralysis

  • Organophosphate poisoning

• Toxin in food and patients' serum may be shown by mouse inoculation and identified with specific antiserum

Medications

• If botulism is suspected

  • Contact the CDC for advice and help with procurement of equine serum heptavalent botulism antitoxin and for assistance in obtaining assays for toxin

  • Skin testing is recommended to exclude hypersensitivity to antitoxin preparation

  • Antitoxin should be given as early as possible, ideally within 24 h of onset of symptoms or signs, to arrest progression of disease

  • Do not delay administration of antitoxin to await laboratory confirmation of diagnosis

  • During off hours, the CDC provides assistance via a recorded message at 404-639-2206

Therapeutic Procedures

• Respiratory failure is managed with intubation and mechanical ventilation

Prevention

• Botulism toxin is destroyed by high temperatures; persons who eat home-canned foods should consider boiling the food for 10 min before eating it

Prognosis

• Early nervous system involvement leads to respiratory paralysis and death in untreated cases

When to Refer

• All cases should be reported to the public health authorities

• Obtain immediate consultation with infectious disease and neurology experts

When to Admit

• All suspected and proven cases because of the high fatality rate