Botulinum toxin

Infectious agent:

Toxin produced by Clostridium botulinum, a spore forming obligate anaerobic bacillus. Three forms of botulims: 1) foodborne (the classic form), 2) wound, and 3) intestinal (infant and adult).

Incubation:

Neurologic symptoms of foodborne botulism appear within 12-36 hours, sometimes several days, after eating contaminated food. The shorter the incubation period, the more severe the disease and higher case-fatality rate.

Mode of transmission:

Ingestion of food with preformed toxin (foodborne botulism), ingestion of botulism spores which then germinate and produce toxin in the colon (intestinal botulism), contamination of wounds by soil or gravel (wound botulism)

Period of communicability:

Despite excretion of C. botulinum toxin and organisms at high levels in the feces of intestinal botulism patients for weeks to months after illness onset, no instance of secondary person to person transmission has been documented. Foodborne botulism patients typically excrete the toxin and organisms for shorter periods.

Clinical Symptoms:

Foodborne botulism: acute bilateral cranial nerve impairment and descending weakness or paralysis. Visual difficulty (blurred or double vision), dysphagia and dry mouth are often the first complaints. Symptoms may extend to a symmetrical flaccid paralysis in a paradoxically alert person. Vomiting and constipation or diarrhea may be present initially. Fever is absent unless a complicating infection occurs.

Wound botulism: the same clinical picture is seen after the causative organism contaminates a wound in which anaerobic conditions develop.

Intestinal (infant) botulism: illness begins with constipation, followed by lethargy, listlessness, poor feeding, ptosis, difficulty swallowing, loss of head control, hypotonia extending to generalized weakness (the "floppy baby") and, in some cases, respiratory insufficiency.

Pneumonic plague may be highly communicable under appropriate climatic conditions; overcrowding facilitates transmission.

Prophylaxis if exposed:

Trivalent (type A, B and E) and monovalent (type E) antitoxin available – contact local public health unit.

Diagnosis:

Clinical basis, no specific laboratory findings and limited diferential diagnosis. Intentional release suspected if number of co-located cases present.

Precautions:

Standard precautions are recommended.

Source:

Control of Communicable Diseases Manual, Chin 17^th edition, 2000, and Biological Agent Information Papers, United States Army Institute of Infectious Diseases.