Botulism is a potentially deadly illness that is caused by a toxin produced by a bacterium called Clostridium botulinum.

The bacteria are found in the soil and at the bottom of lakes, streams, and oceans. The intestinal tracts of fish, mammals, crabs, and other shellfish may contain C. botulinum and its spores. The bacterium's spores can survive in improperly prepared foods. A very small amount of the botulism toxin can cause illness. People are exposed to this toxin in one of three ways:

  • Food can be contaminated with the bacteria and its toxin. It is the toxin produced by C. botulinum—not C. botulinum itself—that causes botulism in humans. Food that may be contaminated with the toxin include:
    • Home-canned goods
    • Sausage
    • Meat products
    • Seafood
    • Canned vegetables
    • Honey
  • If an infant swallows C. botulinum spores, they will grow in the baby's body and produce the toxin. Unlike adults and older children, infants become sick from toxin produced by bacteria growing in their own intestines. Honey is a prime source of infant botulism. Other sources include soil and dust.
  • A wound can become infected with the bacteria, but this is rare in the United States. The toxin then travels to other parts of the body through the bloodstream.

In some cases, the source of the bacteria is unknown. Botulism toxin is also a potential bioterrorism agent.