Communicable Disease, Emergency Preparedness and Response
Botulism is a rare but serious illness caused by a toxin (botulinum toxin) produced by the bacteria Clostridium botulinum. There are four naturally occurring forms of botulism: foodborne, wound, infant and adult intestinal colonization botulism. Spores produced by Clostridium botulinum exist widely in the environment, and do not cause illness when ingested. However, under anaerobic conditions (i.e., in the absence of oxygen), the bacteria or spores germinate and produce toxins that cause illness.
Foodborne botulism is caused by eating food where botulinum toxin is present. Home preserved or home canned food can be a source of botulism. Outbreaks have occurred as a result of consumption of uneviscerated smoked or salted fish, baked potatoes wrapped in foil, carrot juice, improperly handled potpies and minced garlic in oil. Symptoms of foodborne botulism generally appear within 12 to 36 hours of eating a contaminated food. Symptoms include: blurred or double vision, drooping eyelids, slurred speech, difficulty swallowing, and descending paralysis. If left untreated, infection may lead to respiratory arrest and even death.
Wound botulism is caused by botulinum toxins produced from a wound infected with C. botulinum. People who use illicit injection drugs are at higher risk for wound botulism. The botulism spores get into an open wound, germinate and produce toxin in an anaerobic environment.
Infant botulism is caused by ingestion of C. botulinum spores, which grow in the intestine and produce botulinum toxin. It affects children under one year of age with most cases occurring in children between 6 weeks and 6 months of age. Honey, which can be a source of the spores, should not be fed to infants. Symptoms include constipation, weakness, loss of appetite, an altered cry and a striking loss of head control.
Adult intestinal colonization botulism also occurs from ingestion of C. botulinum spores and the formation of the toxin in the intestine. This form of botulism is very rare and occurs in adults with bowel abnormalities such as inflammatory bowel disease or patients on long-term antimicrobial therapy.
The treatment for botulism is an antitoxin that neutralizes circulating toxin but not toxin that has become bound to nerve terminals. Therefore, it is important for botulism to be treated promptly, so health care should be sought immediately if symptoms are suspected. Healthcare professionals should refer to Botulism Guide for Health Care Professionals (March 2017) on how to order botulism antitoxin.