Botulism

Botulism is a bacterial infection that affects the nervous system. There are between 70 and 100 cases of botulism per year in the United States. The toxin formed by the bacteria is fatal at very low doses, and can therefore be used as a biological weapon. The causative organism of botulism is Clostridium botulinum, an anaerobic, spore forming, gram-positive bacteria. Bacterial spores are found in soil, dust, and marine sediment (both freshwater and saltwater). Many subtypes of the bacterium exist, but only A, B, E, or F can cause the botulism infection in humans. The bacterium produces a toxin that affects muscle contraction.

Infection occurs through ingestion of contaminated foods (which contain preformed toxin), through open wounds (e.g., through subcutaneous injections of heroin, also known as “skin popping”), and via bacterial colonization of the intestinal tract of infants. Honey should not be fed to infants under 12 months old, since it has been associated with intestinal botulism infections. Home canning is also associated with infection due to poor hygiene during the canning process. According to the Center for Disease Control and Prevention (CDC), of the 100 U.S. cases reported per year, over 70 percent are the infant form, while the rest are either foodborne or via wounds.

Symptoms of botulism arise one to six days after infection. The botulism toxin prevents muscles from contracting, causing relaxed paralyzed muscles, a condition known as “flaccid paralysis.” This effect is the opposite of that seen in the stiff muscles and “tetany” seen in tetanus infections. Severe infections are identified by a symmetric, descending (beginning at the head and spreading down to include the chest and leg muscles) paralysis, and cranial nerve (which affects hearing, smell, and facial and eye muscles) abnormalities. If the paralysis descends to include respiratory muscles, patients may need to be placed on a respirator for mechanical ventilation. Other symptoms include double vision, blurry vision, drooping eyelids, dry mouth, weakness, lethargy, constipation, and dilated or unreactive pupils. Infants often present with symptoms of weakness, floppy limbs, lethargy, and constipation. If the diagnosis of botulism infection is suspected, it can be confirmed with a laboratory blood test for the neurotoxin.

The disease is prevented via hygienic food storage, thorough cooking of food to kill spores prior to [Page 287]eating, and avoiding honey for infants. Botulism is treated with a botulism antitoxin that neutralizes the effects of the botulism toxin. Adult patients are also often treated with antibiotics. A vaccine is currently available for individuals with a known exposure to botulism and it may be useful in cases where botulism is used as a biological weapon.

Botulism toxin is also used as an injection for its paralytic effects to treat certain facial neuromuscular disorders and for cosmetic purposes.