Botulism

Botulism is a paralyzing and potentially fatal illness caused by one of the most poisonous toxins known. The toxin is produced by a bacteria called Clostridium botulinum and manifests in three main forms: infant botulism, foodborne botulism, and wound botulism. Foodborne and wound botulism cause weakness, dizziness, blurred or double vision, slurred speech, nausea, and difficulty swallowing and breathing. Symptoms usually appear 12 to 36 hours after the toxin enters the system but may appear as early as 2 hours or as late as 8days. While rare--only 34 cases were reported nationwide in 1994--foodborneand wound botulism require emergency medical attention and usually necessitates hospitalization to prevent respiratory failure. In the early stages, injection of an antitoxin produced from horse serum can reduce the severity of thesymptoms; however, allergic reaction to the antitoxin can pose a serious risk in itself.

C. botulinum bacteria are harmless, and their spores are found on fruit and vegetables, in seafood, and in soil and marine sediment worldwide. Thetoxin is produced when these bacteria grow. Growth occurs in the absence of oxygen and at temperatures ranging between 40 and 140° F (4.5-49°C). Home-canned or bottled fruit and vegetables and improperly cooked or reheatedfood are the most common causes of food botulism. Canned food should be heated to well above 212°F (100°C) for 10 minutes, and boiling food for 10minutes will kill toxins. Wound botulism, the least common type, occurs whenthe C. botulinum bacteria enters an infected wound.

When the botulism toxin enters the body, it binds to nerve endings where theyjoin the muscles and blocks signals which make the muscles contract. Onset of paralysis can be swift and severe and, before respirators, botulism killedmany more people than it does today. From 1910 to 1919, 70% of those infecteddied. In 1993, the death rate was less than 2%. However, even today, recovery is slow. In 1994, a 47-year-old man was hospitalized for 49 days and required a mechanical ventilator for 42 of those.

Infant botulism, although rare, is the most common form. From 1976, when it was first recognized, until 1993, only 1,206 cases were reported in the UnitedStates. About 75 to 100 cases are reported annually. Serious but seldom fatal, it develops when botulism spores are ingested and germinate in the intestinal tract before the baby's system can develop a complete range of beneficialbacteria. All infant cases affect children less than one year old and researchers believe one cause is ingestion of contaminated honey. While honey is perfectly safe for children older than one year, authorities recommend honey not be given to children less than 12 months old. Researchers also suspect a link between infant botulism and Sudden Infant Death Syndrome (SIDS).

Of growing concern is avian botulism, which kills millions of birds worldwideeach year. The botulism toxin develops in bodies of water with little or noflow and is ingested by the birds.

Purified botulism toxin is now being put to medical use. Its mechanism of action is the same as the poisonous toxin. Licensed by the FDA in 1989 for treatment of blepharospasm and strabismus--both caused by excessive muscle contractions of the eye--it is injected into specific muscles to control those contractions. Researchers are currently studying its use in other muscular disorders.

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