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What is botulism?

Botulism is a rare, but serious muscle-paralyzing illness caused by a nerve toxin (botulinum toxin) produced by the common bacterium, Clostridium botulinum. This type of bacteria is found in soil and normally exists as a dormant spore.  In low oxygen environments (e.g., canned foods, deep wounds, and intestinal tracts) the spore can germinate into active bacteria, which produce the botulinum toxin. This toxin can be colorless, odorless, and tasteless when put in a liquid solution. Botulinum toxin is some of the most lethal, naturally occurring substances known to man and can lead to death if not treated.

How can people become exposed to botulinum toxin?

There are three main forms of naturally occurring botulism:

  • Foodborne botulism occurs when a person ingests pre-formed botulinum toxins from food products (e.g., improperly canned foods).
  • Infant botulism occurs when ingested C. botulinum bacteria produce the toxin in the intestinal tract. It’s for this reason doctors advise against feeding honey to infants. Honey can contain botulism spores that grow and produce the toxin in the digestive tract of infants.
  • Wound botulism occurs when a deep wound is infected with the bacteria and the toxin produced is absorbed into the blood stream.

A fourth type of botulism, inhalation botulism, is a disease that is acquired from breathing aerosolized botulinum toxin. This can only result from an intentional aerosol release or laboratory accident.  Botulism is not spread from person to person. 

What are the symptoms of botulism?

The symptoms of botulism are caused by toxins that the bacteria produce. The symptoms are similar for all types of botulism, but the severity and time it takes for them to appear can vary. Symptoms of foodborne botulism usually begin within 12 to 36 hours, but up to 10 days after eating contaminated food. Symptoms include double and/or blurred vision, drooping eyelids, slurred and/or disturbed speech, difficulty swallowing solid food, dry mouth, and muscle weakness. Infants with botulism appear lethargic, feed poorly, are constipated, and have a weak cry and poor muscle tone.  If left untreated, botulism symptoms may progress to paralysis of the arms, legs, trunk, and respiratory muscles and, eventually, death from respiratory failure.

Could botulinum toxin be used as a weapon?

If used as a biological weapon, botulism toxins would pose a major threat. They are extremely potent and lethal, some toxins are easy to produce, and people with botulism require prolonged intensive hospital care. A deliberate release of botulinum toxin could involve an aerosolized release or contamination of the food or water supply. There have been prior attempts to use an aerosolized form of the botulinum toxin as a weapon by the Japanese cult Aum Shinrikyo, although these attempts failed. The only known example of human inhalational botulism occurred when three German laboratory scientists were accidentally exposed during an animal experiment.

How is botulism treated? 

Treatment with a specific anti-toxin can help destroy any botulinum toxins circulating in the blood. This antitoxin is effective in reducing the severity of symptoms only if it is administered early in the course of the disease. Good supportive care in a hospital is the mainstay of therapy for all forms of botulism. The respiratory failure and paralysis that occurs with severe botulism may require a patient to be on a breathing machine (ventilator) for weeks, plus intensive medical and nursing care. Most patients eventually recover after weeks to months of care if anti-toxin is administered early. 

How can I minimize and/or prevent exposure to botulinum toxins? 

Foodborne botulism is usually caused by eating home-canned foods with low acid content, such as asparagus, green beans, beets, and corn. However, outbreaks of botulism can result from more unusual sources such as chopped garlic in oil, chili peppers, tomatoes, improperly handled baked potatoes wrapped in aluminum foil, and home-canned or fermented fish. Furthermore, since honey can contain spores of C. botulinum and has been a source of infection for infants, children less than 12 months old should not be fed honey. Wounds should be immediately washed with soap and water. Wound botulism can be prevented by promptly seeking medical care for infected wounds and by not sharing hypodermic needles. 

What should I do if I am exposed to botulinum toxins? 

If someone is showing symptoms of botulism, they should seek medical treatment immediately. Botulism can be fatal and is considered a medical emergency. In the extremely unlikely event that you think you have been exposed to an aerosol containing botulinum toxins, you can protect yourself by immediately and thoroughly washing clothing and skin with soap and water. Objects and/or surfaces contaminated by a botulinum aerosol can be washed with household bleach for 10 minutes to destroy remaining toxins. Seek medical care as soon as possible as signs and symptoms may not show up for a few days and careful medical monitoring may be required. Report suspected cases of botulism or suspected intentional release of botulinum toxin to your local health department and/or local law enforcement agency. 

Where can I get more information on botulism?

  • Visit the Centers for Disease Control and Prevention (CDC) Botulism webpage at
  • Call the Michigan Department of Community Health Communicable Disease Division (517-335-8165)