Botulism is a rare, life-threatening paralytic illness caused by neurotoxins produced by an anaerobic, gram-positive, spore-forming bacterium, Clostridium botulinum. Unlike Clostridium perfringens, which requires the ingestion of large numbers of viable cells to cause symptoms, the symptoms of botulism are caused by the ingestion of highly toxic, soluble exotoxins produced by C. botulinum while growing in foods.
These rod-shaped bacteria grow best under anaerobic (or, low oxygen), low-salt, and low-acid conditions. Bacterial growth is inhibited by refrigeration below 4° C., heating above 121° C, and high water-activity or acidity. And although the toxin is destroyed by heating to 85° C. for at least five minutes, the spores formed by the bacteria are not inactivated unless the food is heated under high pressure to 121° C. for at least twenty minutes.
The incidence of foodborne botulism is extremely low. Nonetheless, the extreme danger posed by the bacteria has required that “intensive surveillance is maintained for botulism cases in the United States, and every case is treated as a public health emergency.” This danger includes a mortality rate of up to 65% when victims are not treated immediately and properly. Most of the botulism events that are reported annually in the United States are associated with home-canned foods that have not been safely processed. Very occasionally, however, commercially- processed foods are implicated as the source of a botulism events, including sausages, beef stew, canned vegetables, and seafood products.