Can you get botulism from canned foods? Signs and symptoms

Canned foods are made by the process of canning, which preserves and extends the shelf life of many foods, including meats, fish, vegetables, and fruits. You can buy canned food at any grocery store, but in some cultures home canning is a popular practice.
However, many people are concerned about the health and safety of certain canned foods, including their ability to harbor dangerous diseases like botulism, a serious and life-threatening illness. This article explains everything you need to know about botulism and the risks associated with canned foods.

What is botulism?

Botulism is a serious disease caused by toxins produced mainly by the bacteria Clostridium botulinum, but also by strains of the bacteria Clostridium baratii and Clostridium butyricum. These toxins are called botulinum neurotoxins (BoNT) because they damage the nervous system, often resulting in various forms of paralysis.

Therefore, although this disease is rare, with approximately 475 cases reported each year in the United States, Canada and Europe, it is a public health problem to watch and potentially fatal.

There are several types of botulism:

Foodborne botulism: infection caused by eating food contaminated with botulinum neurotoxins.

Intestinal colonization: Bacteria enter the body and produce neurotoxins while living in the intestine.

Wound botulism: A wound or damaged or cracked skin becomes infected with the bacteria that produces botulinum neurotoxins.

Iatrogenic botulism: infections caused by high concentrations of toxins injected for cosmetic or therapeutic purposes, for example botox injections.

Inhalation botulism: inhalation of botulinum toxins during accidental release or biological warfare.

Foodborne botulism (or food poisoning) is the most common cause of botulism and will be the focus of this article.
The strains of bacteria responsible for the production of botulinum toxins ideally grow in anaerobic (low oxygen) environments, with low acidity, low salt and water, and a storage temperature between 3 and 37 degrees C.

Thus, canned foods provide an ideal environment for bacterial growth.

Signs and Symptoms of Botulism

The signs and symptoms of botulism develop over a few hours to a few days, depending on the amount of toxin consumed from the contaminated food. For example, a study of 35 years of botulism cases in Turkey determined that symptoms developed 26.9 hours after patients were first exposed to the toxin. Other research shows that symptoms usually develop after 12 to 48 hours, but in some rare cases they do not appear until 10 to 15 days after exposure to the toxin. This delay in the onset of symptoms, along with the mild symptoms that are often present in other foodborne illnesses, makes it difficult to diagnose botulism.

Botulinum neurotoxins disrupt the nervous system, which is responsible for many of the symptoms developed. Symptoms of botulism can be mild but progress in severity if left untreated and can cause gastrointestinal and visual symptoms as well as forms of paralysis, including:

– dry mouth (xerostomia)
– nausea or vomiting
– constipation or diarrhea
– abdominal pain
– double vision or blurred vision
– droopy eyelids
– headache
– facial paralysis
– slurred speech
– dysphagia (difficulty swallowing) and choking
– urinary retention
– limb paralysis
– respiratory failure
The combination of these severe symptoms can lead to coma and death.

Treatment may involve intubation and support in an intensive care unit (ICU) if necessary, as well as the administration of an antitoxin, which has been shown to be effective up to 24 hours after the onset of symptoms.

Most botulism risk comes from home-canned foods

In general, about 80% of foodborne botulism cases can be attributed to home-canned foods. For example, of the 466 cases of botulism that occurred in Italy between the years 1986 and 2015, 90% (421 cases) were caused by foodborne botulism, with most linked to improperly canned food at home. .

Similarly, almost all of the 8,614 cases of botulism recorded in Ukraine between 1955 and 2018 were caused by artisanal canning, with few cases attributed to commercial canning.

Common home-canned foods that have been linked to cases of botulism in several countries include:

– vegetables canned in oil and brine/water (mushrooms, olives, turnip greens, leafy vegetables, peppers)
– canned and salted fish, smoked fish (tuna)
– homemade salted meat (ham, pork sausage, salami/sausages)
– tofu and seitan

Less frequently, certain commercial canned products, including green olives, canned fish, vegetables and fruits, have been associated with cases of botulism. Commercial unpasteurized dairy products are also high risk foods for botulism.

Summary

Most cases of botulism from canned foods are associated with homemade canned or bottled vegetables, meats, and fish. Commercial canned olives, fish and fruit are associated with fewer cases of botulism.

Canned food safety

In some cultures, home canning is a common practice to preserve food access during the off-season. For example, many people can vegetables in the summer for use in the winter, when food prices may be higher.

Practice safe home canning:

Blanch vegetables before canning, or add boiling water to vegetables in jar before sealing.

Do not add salt, vinegar or uncooked vegetables when canning.

Adding garlic has been shown to reduce the risk of botulism.

Use home-canned foods within six months.

Frequently Asked Questions

Here are some questions people often ask about canned food and botulism.

Can cooking kill botulism?

Unfortunately, bacterial spores capable of growing in canned food produce toxins that survive standard cooking methods, where food is not heated above 100°C.

Therefore, standard cooking does not simply kill the bacterial spores that cause botulism, but botulism can be prevented by pressure cooking, sterilizing your cooking and canning equipment, and using safe food hygiene practices. . Commercially, ionizing radiation deactivates bacterial spores.

Can botulism be detected in canned foods?

Canned foods, whether homemade or store-bought, can be inspected for contamination.

Throw away the canned food if any of the following conditions exist:

– the can is leaking, swollen or has bulges
– the box appears damaged or cracked
– liquid or foam squirts out of the box when opened
– the food in the box is mouldy, smells bad or is discoloured.

Can you get botulism by smelling or touching contaminated food?

Botulism toxins cannot be absorbed through intact skin or the simple smell of food. However, if you touch contaminated food and then touch your face, the toxin can be absorbed through the mucous membranes of the eyes or nose. The toxin can also infect open wounds or cracks in the skin.

Hand hygiene, including frequent hand washing, is therefore important.

Inhalation botulism is rare and is usually only reported in cases where the toxin is sprayed into the air or in the case of a young man who has inhaled cocaine.
Also, botulism is not considered contagious, but a person can become infected if they come into contact with the bodily fluids of a person with botulism through the eyes, nose, mouth, or skin wound. .

In summary

Botulism is a rare but serious disease caused by neurotoxins produced by strains of Clostridium bacteria. Foodborne botulism is the most common cause of botulism and causes mild to severe symptoms, depending on the amount of exposure to the toxin. Difficulty swallowing, headaches, abdominal pain, respiratory failure and even death can occur if the disease is not treated. Most cases of foodborne botulism are caused by home-canned or bottled vegetables, meat, and fish. Few cases are linked to commercially canned olives, fish and fruit.

Canned food safety reduces the risk of botulism. Throw away canned foods that show signs of contamination, can them safely at home, cook canned foods at high temperatures, sterilize cooking equipment, and wash your hands regularly.