Keeping Canadians safe from botulism

Have you ever heard of botulism? While this foodborne illness may be less well known than others, it can have serious consequences. Fortunately, botulism is very rare in Canada thanks to safe food practices and the work of devoted Health Canada scientists.

Botulism is caused by eating food and drinks contaminated with botulinum toxin, a potent toxin produced by bacteria called Clostridium botulinum. Symptoms typically include blurred and double vision, drooping eyelids, and difficulty swallowing and speaking. Paralysis may descend to the muscles that help us breathe, requiring the use of mechanical ventilation. In some instances, it can take months or years to recover. Tragically, approximately one in ten people with botulism die of the disease.

Health Canada Research Scientist, Dr. John Austin, and lab technicians, Dr. Richard Harris and Ryan Boone, analyse botulism samples and conduct research on the disease and the bacterium that causes it to find ways to better protect us from it.

Let’s take a closer look to see how their work helps keep Canadians safe.

Identifying the dangerous toxin

There are various types of botulism, but the main ones are foodborne botulism and infant botulism.

Foodborne botulism may occur in environments that have no oxygen, such as canned foods. This type of botulism can also be found in other foods such as garlic stored in oil, carrot juice, salted fish and traditionally prepared seal, whale and walrus meat.

Infant botulism happens when the C. botulinum bacteria (sometimes found in honey) grow inside a baby’s body and produce toxins. Because infants don’t yet have enough good bacteria in their body, C. botulinum bacteria are able to grow and produce botulinum toxin.

Working with the medical community

“Botulinum toxin is the most potent toxin known. The oral lethal dose for a person is estimated to be approximately 70 millionths of a gram or 0.00007 g, which is an extremely small amount,” explains Dr. Austin.

Because botulism is so dangerous, early intervention is key. As such, doctors prescribe antitoxins to patients they suspect may have botulism. They then send clinical samples to the Botulism Reference Service—run by Dr. Austin and his technicians—who determine if it’s actually botulism.

“Thanfully, most samples don’t test positive for botulism. But this is still helpful information for doctors, who can rule out botulism as the cause of illness, and in turn, improve their patient’s care. When it is a case of botulism, we work with provinces and local health units to determine the source of botulism so the food product can be recalled and prevent further cases.”

Helping food manufacturers and Indigenous communities improve their food safety practices

In addition to helping the medical and public health communities, Dr. Austin and his colleagues work hard to make our food safer.

“We’re always looking for ways to make food safer, so that botulism is even rarer. That’s why we continue to study new methods to eliminate the bacteria and its spores,” explains Dr. Austin.

One of these new methods is UV light used to pasteurize or kill C. botulinum in foods. If this new method is found to be both safe and effective, it could soon be used by manufacturers for commercial foods.

Certain traditional Indigenous foods, such as seal, are known to be sources of botulism. Recognizing this problem, Dr. Austin and his team worked with Dr. Daniel Leclair, then researcher at the Nunavik Research Centre, to find out why and to identify some mitigation strategies.

“Our research determined that the chances of contracting botulism would be significantly reduced if seal meat was kept at a controlled temperature of 3 or 4 °C, all while respecting the Indigenous peoples’ traditional ways of preserving food. Since submitting recommendations based on this work, there has been a reduction in cases from traditional Inuit foods. While 46% of Canadian cases of botulism from 2006 to 2021 occurred in Indigenous communities, this is down from the previous figure of 81% for the period of 1960 to 2005. This is some of the work that I am most proud of,” explains Dr. Austin.

While botulism is a serious and concerning food safety issue, we are lucky to have people like Dr. Richard Harris, Ryan Boone, and Dr. Austin helping to keep us safe from it.


You can keep you and your family safe by always following proper food practices. This includes never giving honey to a baby under one year of age and canning foods properly. You can find more tips on our website.