Canada's food supply is one of the safest in the world. But sometimes the foods we eat may carry bacteria that can make us sick, like Clostridium botulinum, which causes botulism.
What is botulism?
The bacterial spores that cause botulism - Clostridium botulinum - are widespread in nature, commonly found in soil and dust. These bacterial spores rarely cause problems because they cannot grow if they are exposed to oxygen. Since the spores do not grow, they cannot produce the toxins that cause illness.
Botulism is a rare but serious paralytic illness caused by a nerve poison that is produced by the bacterium Clostridium botulinum (C. botulinum). Foodborne botulism is caused by eating foods that contain the botulism toxin. Infant botulism occurs when infants eat the spores of the bacteria, which then grow in their intestines and release toxin. You can also get botulism from an infected wound. All forms of botulism can cause paralysis and be fatal.
How do people get sick?
Botulism is rare in Canada. While C. botulinum bacteria can be found in soil and dust, they cannot grow in air, so they only tend to cause problems when certain foods are stored or prepared improperly.
The most common way of getting botulism is by eating or drinking contaminated foods and beverages, like:
- improperly prepared low-acid, home-canned foods (like asparagus, beets, green beans, mushrooms, peppers)
- improperly smoked fish
- improperly prepared raw marine mammal meat (like whale, walrus, seal)
- non-refrigerated storage of low-acid fruit juices (like carrot juice)
- baked potatoes stored in aluminium foil
C. botulinum bacteria are heat-resistant and can survive high temperatures. The bacteria can grow in a moist, oxygen-free environment, so home canning or bottling provides the perfect conditions for the bacteria to multiply and produce the toxin, unless the food is properly canned or heat processed.
Honey (which naturally contains C. botulinum) has been linked to infant botulism. While the bacteria can't grow or produce toxins in honey, they can grow and produce toxins in a baby's intestine.
What are the symptoms and treatment?
Anyone can get foodborne botulism. Most people with botulism develop the following symptoms 12 to 36 hours after eating or drinking food containing the toxin produced by C. botulinum bacteria:
- diarrhea (early)
- constipation (late)
- weakness and dizziness
- blurred or double vision
- dry mouth
- difficulty speaking and swallowing
- descending paralysis of the arms, legs, trunk and breathing muscles (starts in the arms and moves down)
With infant botulism, symptoms include constipation, weakness, a weak cry, a poor sucking reflex, irritability, lack of facial expression, and loss of head control. In some cases, the child may have trouble breathing because of paralysis of the diaphragm.
Most people recover if diagnosed and treated quickly. Treatment includes early doses of antitoxin and intensive respiratory care. Recovery can take several weeks to months. In some cases, it can take years and the person may never fully recover.
Severe botulism can require intensive medical and nursing care. It can also lead to paralysis and respiratory failure, which can require a person to be on a ventilator (breathing machine) to breathe. If not diagnosed and treated, botulism can lead to death from respiratory failure within three to ten days.
With proper treatment, the fatality rate of C. botulinum cases can be as low as five to ten per cent.
How do I avoid getting sick?
Foods contaminated with C. botulinum toxin might look, smell and taste normal. Unlike other bacteria, C. botulinum are not necessarily destroyed by cooking, so preventing the toxin from forming is key.
These tips will help protect you and your family from getting botulism:
- Keep all work surfaces, food, utensils, equipment, and hands clean during all stages of the canning process.
- Date and label all preserves and canned goods.
- Don't give honey (even pasteurized honey) to children under one year old. Healthy children over one year of age can safely eat honey because they have a very low risk of developing infant botulism.
- Never eat food from cans that are dented, bulging, or leaking.
- Don't use aluminium foil to wrap potatoes or other vegetables for baking, unless the vegetables will be cooked and eaten right away. If you want to store them after they've been cooked, unwrap and refrigerate them right away.
- Keep all low-acid juices (like carrot juice) and other products labelled "keep refrigerated" in the fridge.
Also, these safe food practices will reduce your risk of contracting botulism and other foodborne illnesses.