Condition Basics

What is botulism?

Food-borne botulism is a rare but serious type of foodborne illness that can result in paralysis. It is caused by the Clostridium botulinum (C. botulinum) bacterium. The bacteria produce a nerve toxin that can cause paralysis. Food-borne botulism can be fatal and is considered a medical emergency.

What causes it?

Food-borne botulism can be caused by eating contaminated home-canned foods that have a low acid content, such as asparagus, green beans, beets, and corn. But there have been cases of botulism from more unusual sources, such as chopped garlic in oil, chile peppers, tomatoes, improperly handled baked potatoes wrapped in aluminum foil, and home-canned or fermented fish.

In infants, botulism can result if a baby eats honey contaminated by C. botulinum spores. The spores multiply in the infant's intestine and produce toxins.

What are the symptoms?

The symptoms of foodborne botulism may include double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness. Infants with botulism appear to have little energy (lethargic), eat poorly, are constipated, and have a weak cry and poor muscle tone. These are all symptoms of the muscle paralysis caused by the nerve toxin. If botulism is not treated, advanced symptoms may cause paralysis of the arms, legs, and trunk and the muscles that help you breathe. In food-borne botulism, symptoms generally begin 18 to 36 hours after eating a contaminated food. But they can occur as early as 4 hours or as late as 10 days after eating the food.

How is it diagnosed?

Your doctor will do a medical history and physical examination and ask you questions about your symptoms and foods you have recently eaten. The best way to be sure of the diagnosis is for a doctor to inject your blood serum or stool into mice and look for signs of botulism. Other tests that may be done include a brain scan and a spinal fluid examination.

How is botulism treated?

If diagnosed early, food-borne botulism can be treated with an antitoxin that blocks the action of the botulism toxins. This can prevent the condition from getting worse, but recovery still takes many weeks. Your doctor may try to remove contaminated food in the digestive tract by inducing vomiting or by using enemas.

The paralysis that occurs with severe botulism may cause you to need a breathing machine (ventilator) for weeks, along with intensive medical and nursing care. After several weeks, the paralysis slowly improves.

Infants are usually not given antitoxin. But infants younger than 1 year old can be given a botulism immunoglobulin (BabyBIG) to treat botulism.

How can you prevent it?

Food-borne botulism often comes from home-canned foods. You can prevent botulism by following strict procedures when canning and by boiling home-canned food for 10 minutes before eating it. You can get instructions on safe home canning from Health Canada (https://www.canada.ca/en/health-canada/services/general-food-safety-tips/home-canning-safety.html) or your provincial ministry of health. In rare cases, people get botulism from commercially canned and processed foods.

Botulism from more unusual sources, such as chopped garlic in oil, chile peppers, tomatoes, improperly handled baked potatoes wrapped in aluminum foil, and home-canned or fermented fish, have occurred. To prevent this, refrigerate oils with garlic or herbs and serve baked potatoes while they are still hot.

Do not give honey to children younger than 12 months. It can contain spores of C. botulinum.