DISEASES : Botulism

Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium Clostridium botulinum.

There are three main kinds of botulism. Food-borne botulism is caused by eating foods that contain the botulism toxin. Wound botulism is caused by toxin produced from a wound infected with Clostridium botulinum. Intestinal (infant and adult) botulism is caused by consuming the spores of the botulinum bacteria, which then grow in the intestines and release toxin. All forms of botulism can be fatal and are considered medical emergencies. Food-borne botulism can be especially dangerous because many people can be poisoned by eating contaminated food from the same source.

The symptoms of botulism include double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness. Infants with botulism appear lethargic, feed poorly, are constipated have a weak cry and poor muscle tone. These are all symptoms of the muscle paralysis caused by the bacterial toxin. If untreated, these symptoms may progress to cause paralysis of the head, neck, arms, respiratory muscles, torso and legs. In food-borne botulism, symptoms generally begin 12 to 36 hours after eating a contaminated food, but they can occur as early as six hours or as late as 10 days. Vomiting and constipation or diarrhea may be present initially.

Physicians may consider the diagnosis if the patient's history and physical examination suggest botulism. However, these clues are usually not enough to allow a diagnosis of botulism. Other diseases and conditions such as Guillain-Barré syndrome, stroke, and myasthenia gravis can appear similar to botulism, and special tests may be needed to exclude these other possibilities.

The respiratory failure and paralysis that occur with severe botulism may require a patient to be on a breathing machine (ventilator) for weeks, plus intensive medical and nursing care. After several weeks, the paralysis slowly improves.

If diagnosed early, food-borne and wound botulism can be treated with an antitoxin that blocks the action of toxin circulating in the blood. The antitoxin can prevent a patient's condition from becoming worse, but recovery may still take many weeks. Physicians may try to remove contaminated food still in the patient by inducing vomiting or by using enemas. Wounds should be treated, usually surgically, to remove the source of the toxin-producing bacteria. Good supportive care in a hospital is the mainstay of therapy for all forms of botulism.

Botulism can result in death due to respiratory failure. However, the proportion of patients with botulism who die has fallen in the last 50 years to 8% from 50%.

A patient with severe botulism may require a breathing machine as well as intensive medical and nursing care for several months. Patients who survive an episode of botulism poisoning may have fatigue and shortness of breath for years and long-term therapy may be needed to aid recovery.

Anyone with concerns or questions about botulism : please contact your physician or the staff of your local public health unit.

References

The information provided is subject to change. The information was collated from the following three sources :

1. Chin, J. "Control of Communicable Diseases Manual". 17th Edition. 2000. American Public Health Association: Washington D.C.
2. Health Canada website
3. Centers for Disease Control and Prevention website

*Advice on the most up-to-date treatment should be sought from a clinical expert.

January 2003