A toxin produced by the bacteria, Clostridium botulinum, can result in a disease called botulism. This toxin is called a neurotoxin because it affects the nervous system. Symptoms appear 12 to 48 hours after eating a food which contains the toxin. The symptoms include double vision, droopy eyelids, trouble with speaking and swallowing and difficulty with breathing. Without treatment death may result from suffocation because the nerves can no longer stimulate breathing. Antitoxins have been used to reduce the fatality rate of the disease but persons may recover slowly and suffer from nerve damage.

The bacteria, Clostridium botulinum, is anaerobic i.e. it only grows where there is little or no oxygen. This bacteria can exist as a vegetative cell or a spore. The spore is the dormant state of the cell and can exist under conditions where the vegetative cell cannot. When the conditions are right, the spore will grow into the vegetative cell. When the vegetative cells grow to high numbers, this bacteria produces the toxin. The vegetative cells of this bacteria are destroyed by heat but the spore is very resistant to heat. The bacteria and the spore also are inhibited from growing in acid environments (pH 4.6 or below).

Improperly canned low-acid foods (vegetables, meat, poultry, fish) are usually the cause of a botulism foodborne illness.

Control

Never taste food from leaking, bulging, or damaged cans; from cracked jars or with loose or bulging lids; from containers that spurt liquid when opened; or any canned food that has an abnormal odour or appearance.