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Botulism

Botulism is a rare but serious illness caused by a toxin that affects the nervous system and can cause paralysis. The bacterium Clostridium botulinum, which is found commonly in nature, produces this toxin. There are several types of botulism, including foodborne botulism, which is caused by eating foods that contain the botulinum toxin.

Botulism is a serious illness that should be treated as a medical emergency.

Causes

What causes foodborne botulism?

Foodborne botulism is caused by eating or drinking food or beverages contaminated with the Clostridium botulinum toxin.

The following foods have been associated with botulism:

  • improperly prepared home-canned, low-acid foods (for example, corn, green beans, peas, asparagus, beets, mushrooms, spaghetti sauce, salmon);
  • improperly stored low acid fruit juices (for example, carrot juice);
  • leftover baked potatoes stored in aluminium foil; and
  • honey, which has been linked to cases of infantile botulism and should not be fed to infants under one year of age.

Outbreaks of botulism have occurred in Canada's Inuit populations when people have eaten improperly prepared raw or partially cooked traditional food, including seal meat, fermented whale blubber, smoked salmon and fermented salmon eggs.

Symptoms

What are the symptoms of botulism?

Symptoms of botulism can include

  • fatigue, weakness and dizziness;
  • blurred or double vision;
  • dryness in the mouth, throat and nose and difficulty in swallowing and speaking;
  • headache;
  • nausea, vomiting, abdominal pain and, less commonly, diarrhea; and
  • paralysis that starts in the shoulders and arms and moves down the body.

Severe cases of botulism can lead to paralysis of the breathing muscles, respiratory or heart failure and death.

Symptoms of foodborne botulism generally begin 12 to 36 hours after ingesting contaminated food; however, onset can begin as soon as 6 hours after exposure, or as long as 10 days later.

How long do the symptoms last?

Symptoms can last for several weeks and then slowly go away over several months.

Risks

Are there certain foods that increase the risk of getting botulism?

Botulism is a serious illness that should be treated as a medical emergency.

Severe cases of botulism can lead to paralysis of the breathing muscles, respiratory or heart failure and death.

If not diagnosed and treated, death from respiratory failure can occur within 1 to 10 days.

Anyone with the signs, symptoms or history of botulism should be hospitalized immediately.

Are there certain foods that increase the risk of getting botulism?

The following foods have been associated with botulism:

  • improperly prepared home-canned, low-acid foods (for example, corn, green beans, peas, asparagus, beets, mushrooms, spaghetti sauce, salmon);
  • improperly stored low acid fruit juices (for example, carrot juice);
  • leftover baked potatoes stored in aluminium foil; and
  • honey, which has been linked to cases of infantile botulism and should not be fed to infants under one year of age.

Outbreaks of botulism have occurred in Canada's Inuit populations when people have eaten improperly prepared raw or partially cooked traditional food, including seal meat, fermented whale blubber, smoked salmon and fermented salmon eggs.

Why are young children at risk of getting botulism from honey?

Don’t feed honey (even pasteurised honey) to children under one year old. The bacteria that cause botulism cannot grow or make toxins in the honey, but they can grow and make toxins in a baby's body.

Treatment

How is botulism diagnosed and what is the treatment?

A diagnosis is made through a combination of clinical assessment by a physician and specialized tests to eliminate other illnesses or conditions such as a stroke, myasthenia gravis and Guillain-Barré syndrome, which may appear similar to botulism. Possible tests include a brain scan, an examination of spinal fluid or testing the electrical activity produced by muscles. The diagnosis can also be confirmed by blood or stool tests.

Foodborne botulism is treated with botulism antitoxin, which can prevent the illness from getting worse and reduce the chances of complications. In addition, a physician may try to remove undigested food from the patient’s gut by inducing vomiting or using an enema.

For severe cases that lead to paralysis and respiratory failure, intensive medical and nursing care in a hospital are required, and the patient may be put on a respirator. This therapy can last up to several weeks or months depending on the severity of disease.

If not diagnosed and treated, death from respiratory failure can occur within 1 to 10 days.

Anyone with the signs, symptoms or history of botulism should be hospitalized immediately.

Prevention

How can botulism infections be prevented?

Proper hygiene and safe food handling and preparation practices are key to preventing the spread of all foodborne illnesses, including botulism.

There are a number of precautions you can take to reduce the risk of becoming infected with botulism:

  • Never eat food from cans that are dented, leaking or have bulging ends. The food may not look or smell spoiled, but it may still contain the toxin.
  • When canning foods at home, be sure to process all low-acid products (for example, vegetables, mushrooms and seafood) in a pressure canner and follow the manufacturer's instructions closely.
  • Take precautions with home-prepared foods stored in oil (for example, vegetables, herbs and spices). If these products are prepared using fresh ingredients, they must be kept refrigerated and for no more than 10 days.
  • If you purchase the products described above at fairs, farmer's markets or roadside stands, or if you receive them as a gift, check when they were prepared and discard them if they are more than a week old.
  • Don’t use aluminium foil to wrap potatoes or other vegetables for baking unless the vegetables will be cooked and eaten right away or unwrapped and refrigerated right after they’re cooked.
  • Don’t feed honey (even pasteurised honey) to children under one year old. The bacteria that cause botulism cannot grow or make toxins in the honey, but they can grow and make toxins in the baby's body.
  • Date and label preserves and canned goods, and strictly follow proper canning requirements.
  • Keep all work surfaces, food, utensils, equipment and hands clean during all stages of the canning process.
  • Refrigerate all foods labelled "keep refrigerated."
  • If you experience symptoms of botulism, seek medical attention immediately.

How long are people infectious?

Botulism is not spread from person to person.

Surveillance

Does the Public Health Agency of Canada keep track of botulism cases across the country?

Yes, the Public Health Agency of Canada works with the provinces and territories to track the number of botulism cases across the country. If a foodborne botulism case is identified by a province or territory, the Public Health Agency of Canada is informed to assist in the investigation of a potential food source. The Public Health Agency of Canada collaborates with Health Canada’s National Botulism Reference Laboratory to identify cases of botulism in the Canadian population.

Are botulism outbreaks common in Canada?

While outbreaks of food-borne illnesses in Canada are relatively common, botulism outbreaks are quite rare. In recent years, about two cases per year have been reported in Canada.

Typically, a case refers to illness in one person and an outbreak refers to two or more cases of illness that are linked by a common exposure within a specific time frame. However, because botulism is both a rare and severe illness, a single case is usually treated with the same attention as an outbreak of another more common type of food-borne illness.

A national outbreak occurs when illness is linked in two or more provinces or territories.

Protect yourself against food-borne illness by following safe food handling practices. For even more information about food safety, go to www.foodsafety.gc.caExternal Link.