Botulism

botulism (bŏch`əlĭz'əm), acute poisoning resulting from ingestion of food containing toxins produced by the bacillus Clostridium botulinum. The bacterium can grow only in an anaerobic atmosphere, such as that found in canned foods. Consequently, botulism is almost always caused by preserved foods that have been improperly processed, usually a product canned imperfectly at home. The toxins are destroyed by boiling canned food for 30 min at 176°F; (80°C;). Once the toxins (which are impervious to destruction by the enzymes of the gastrointestinal tract) have entered the body, they interfere with the transmission of nerve impulses, causing disturbances in vision, speech, and swallowing, and ultimately paralysis of the respiratory muscles, leading to suffocation. Symptoms of the disease appear about 18 to 36 hr after ingestion of toxins. Botulinus antiserum is given to persons who have been exposed to contaminated food before they develop symptoms of the disease and is given to diagnosed cases of the disease as soon as possible. Developments in early detection have reduced the mortality rate from 65% to 10%.

See food poisoning.

Medicinal Use of Botulin Toxin

In a technique pioneered by Alan B. Scott, an ophthalmologist, and Edward Schantz, a biochemist, in the late 1970s, botulin toxin has been purified and used in the treatment of debilitating muscle spasms caused by the excessive firing of certain nerves. The treatment utilizes the same process that paralyzes the muscles in botulism poisoning. Injected in tiny amounts into the affected tissue, the botulin blocks the release of acetylcholine, a neurotransmitter that controls muscle contraction, and temporarily relieves the spasms. Botulin was approved by the Food and Drug Administration in 1989 for treatment of blepharospasm (uncontrolled rapid blinking) and strabismus (crossed eyes); it is under study for use in other spasmodic conditions. The toxin is also injected to provide short-term (three to four months) cosmetic treatment of facial wrinkles.

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botulism

Poisoning by botulinum toxin, one of the most potent toxins known, produced by Clostridium botulinum bacteria. It usually results from improperly sterilized canned (mostly home-canned) foods. Heat-resistant spores of these anaerobic bacteria in fresh food may survive canning. The bacteria multiply and secrete toxin, which remains potent if the food is not well heated before it is eaten. Botulism can also result from wound infection. Botulinum toxin blocks nerve-impulse transmission. If botulism is recognized in time, administered antitoxins can neutralize it. The first symptoms of botulism are nausea and vomiting, which usually appear six hours or less after the contaminated food is eaten. Fatigue, blurry vision, and general weakness follow. Respiratory paralysis can cause death if not treated with emergency tracheotomy and respiratory aid. Most victims recover completely if they survive paralysis. The bacteria's intense toxicity makes it a potentially deadly biological warfare agent.

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Botulism

An illness produced by the exotoxin of Clostridium botulinum and occasionally other clostridia, and characterized by paralysis and other neurological abnormalities. There are seven principal toxin types involved (A–G); only types A, B, E, and F have been implicated in human disease. Types C and D produce illness in birds and mammals. Strains of C. barati and C. butyricum have been found to produce toxins E and F and have been implicated in infant botulism. See Virulence

The three clinical forms of botulism are classic botulism, infant botulism, and wound botulism. Classic botulism is typically due to ingestion of preformed toxin, infant botulism involves ingestion of C. botulinum spores with subsequent germination and toxin production in the gastrointestinal tract, and wound botulism involves production of toxin by the organism's infecting or colonizing a wound. The incubation period is from a few hours to more than a week (but usually 1–2 days), depending primarily on the amount of toxin ingested or absorbed.

There is classically acute onset of bilateral cranial nerve impairment and subsequent symmetrical descending paralysis or weakness. Commonly noted are dysphagia (difficulty in swallowing), dry mouth, diplopia (double vision), dysarthria (a neuromuscular disorder affecting speech), and blurred vision. Nausea, vomiting, and fatigue are common as well. Ileus (impaired intestinal motility) and constipation are much more typical than diarrhea; there may also be urinary retention and dry mucous membranes. Central nervous system function and sensation remain intact, and fever does not occur in the absence of complications. Fever may even be absent in wound botulism. See Toxin

In food-borne botulism, home-canned or home-processed foods (particularly vegetables) are commonly implicated, with commercially canned foods involved infrequently. Outbreaks usually involve only one or two people, but may affect dozens. In infant botulism, honey and corn syrup have been implicated as vehicles. Therapy involves measures to rid the body of unabsorbed toxin, neutralization of unfixed toxin by antitoxin, and adequate intensive care support. See Food poisoning