The etiologic agent of botulism is Clostridium botulinum. This Gram-positive, anaerobic rod-shaped bacillus is found in soil, sources of running and standing water, and the animal’s intestinal tract. The bacteria can exist in a vegetative state or as a spore. The spore is the dormant form of the cell and can exist under conditions where the vegetative cell cannot.

When the vegetative cells grow in high numbers, the bacteria produces a toxin. Under ideal conditions the bacteria form spores which allow the bacteria to survive in its dormant state until exposed to conditions that can support their growth, i.e., increasing temperature and alkaline pH, depending on the subtype.

There are seven types of botulium toxin designated by the letters A through G. The most common types found in cattle and poultry are C and D.  However, types A, B, E and F can cause illness in humans.