NDSU Extension Service - Ramsey County


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What is Botulism and Why are We Concerned?

What Is Botulism and Why Are We Concerned?


            Foodborne botulism is a rare but serious illness caused by eating foods that contain neurotoxins produced by the bacteria Clostridium botulinum. After botulinum toxins are ingested, the symptoms generally start with nausea, vomiting and dizziness. They can progress to a series of neurological symptoms such as double vision, blurred vision, difficulty speaking and swallowing, muscle weakness and difficulty in breathing, which may lead to asphyxia and cause death.

            In the United States, an average of 21 cases of foodborne botulism are reported each year. Most of them are associated with home-processed and home-canned foods, especially low-acid foods such as vegetables, seafood, meats and poultry.

            C. botulinum is found in soil and marine sediments worldwide, most commonly existing as bacterial spores. C. botulinum form spores when they are stressed in poor survival conditions. C. botulinum spores are found everywhere, including the surfaces of fruits, vegetables and seafood.

C. botulinum has been linked to a variety of foods, including home-canned foods, unrefrigerated homemade salsa, baked potatoes sealed in aluminum foil, garlic or spices infused oil and traditionally prepared fermented fish.

            C. botulinum is a particular food safety challenge as:

            - C. botulinum can live and grow in low-oxygen conditions. Canned foods, garlic or spices infused oil or foil wrapped baked potatoes provide suitable conditions for C. botulinum to grow.

- When it is stressed under adverse conditions, C. botulinum forms spores. Spores are a form of dormant bacteria that wrap themselves with protective membranes and a hard coating. The spores are extremely resistant even under tough environmental conditions.

- C. botulinum spores can be found widely and can survive for years. When the conditions allow, spores can germinate to become C. botulinum.

            Foodborne botulism is caused by a three-stage reaction starting with the germination of spores, then the growth of C. botulinum and the production of botulinum toxin. To prevent foodborne botulism we need to target one or more of these stages. Temperature and pH (acidity of foods) are critical tools to prevent illness.

  • Low-acid foods must be canned using pressure canner. Tomatoes can be canned in a boiling water canner if extra acid is added to ensure safety. Otherwise, tomatoes also should be pressure canned.
  • Follow the U.S. Department of Agriculture or Cooperative Extension Service guidelines for home canning, especially for tomatoes and low-acid foods such as vegetables, meats, poultry and seafood.
  • Keep hot food hot and cold food cold. If you leave the food in the temperature danger zone (40-140 degrees Fahrenheit) for two hours, consume or further process the food immediately. If more than four hours, discard the food.
  • Keep homemade salsa or other foods containing low-acid ingredients in the refrigerator. Keep your refrigerator temperature at 40 degrees Fahrenheit or lower.
  • When in doubt, throw it out. When you open the container, inspect the product. Do not use products with abnormal color, smell or texture. Do not taste the product to determine if it is safe. If Clostridium botulinum bacteria survive and grow inside a sealed jar of food, they can produce a poisonous toxin. Even a taste of food containing this toxin can be fatal

  • If it is related to the safety of meat, poultry or egg products, call the USDA’s Meat and Poultry Hotline (1-888-674-6854) for further instructions.


            As of July 2013 the Centers for Disease Control and Prevention (CDC) recommendation is to discard any home canned food that might contain botulism toxin.    

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