Botulism - The Details

Reviewed by Wendy Marcason, RDN
botulism bacterium

Botulism is a rare, yet serious illness that can be caused by eating foods contaminated with the bacteria Clostridium botulinum. This bacteria is commonly found in soil and produces a toxin that affects the nervous system. It is rare but if contracted requires immediate medical attention.

What causes foodborne botulism?

Foodborne botulism comes from eating foods contaminated with the toxin. The mains sources are home-canned foods with a low-acid content, improperly canned commercial foods, home-canned or fermented fish, herb-infused oils, baked potatoes in aluminum foil, cheese sauce, bottled garlic, foods held warm for extended periods of time and honey for infants.

Home-canned vegetables are the most common cause of botulism outbreaks in the United States. From 1996 to 2008, there were 116 outbreaks of foodborne botulism reported to the Centers for Disease Control and Prevention. Forty-eight of those outbreaks were caused by home-prepared foods, and 18 outbreaks, or 38 percent, were from home-canned vegetables. These outbreaks often occur because home canners did not follow canning instructions, did not use pressure cookers, ignored signs of food spoilage or were unaware of the risk of botulism from improperly preserving vegetables. If you can foods at home, be careful and follow approved canning methods.

What are botulism's symptoms?

Double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness. Infants with botulism appear lethargic, feed poorly, are constipated and have a weak cry and poor muscle tone.

How do I prevent botulism?

Look for warning signs on cans including swollen, dented or leaking cans, cracked jars, loose lids, cans that spurt when opened and clear liquids turned milky.

Always use approved home canning methods:

  • Use a pressure canner or cooker.
  • Be sure the gauge of the pressure canner or cooker is accurate.
  • Use up-to-date process times and pressures for the kind of food, the size of jar and the method of packing food in the jar.

Do not let babies (under 1 year) eat honey because it can contain the bacteria that causes infant botulism. This bacteria is harmless for adults and older children. If you have symptoms, contact your doctor immediately.

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