Botulism
Key points
- In the United States, roughly 100 people become ill each year with botulism, a form of poisoning caused by exposure to Clostridium botulinum bacteria.
- All of the symptoms of botulism are the result of nerve paralysis during exposure to the toxin.
- If your doctor suspects botulism after asking you about your medical history and examining you, both blood and stool samples may be tested to check for the presence of botulinum toxin.
- Most paralysis symptoms of botulism last for several weeks and then slowly go away in the following months.
What Is It?
In the United States, roughly 100 people become ill each year with botulism, a form of poisoning caused by exposure to Clostridium botulinum bacteria. These bacteria manufacture a chemical poison known as botulinum toxin that interferes with muscle function in many areas of the body, causing paralysis of individual muscles or groups of muscles. Exposure to this toxin is life threatening, since one of the muscles it can paralyze is the diaphragm, the muscle that controls breathing.
You can be exposed to the bacteria causing botulism in several ways, the most familiar being by eating contaminated food. In most food-borne cases of botulism in adults, home-canned foods are responsible. The bacteria that cause botulism exist in dirt and dust as a spore, but this form is inactive and does not produce toxin. When a spore is moved into a low-oxygen environment, however, such as an enclosed jar or can, it can reproduce and produce its dangerous toxin.
Home-canned vegetables that are not highly acidic (asparagus, green beans, peppers, beets and corn) are good incubators for botulism bacteria unless they are heat-treated appropriately to kill the spores during the canning process and eaten quickly after opening. The bacteria can release large quantities of toxin into the canned food jar, causing botulism symptoms in people who sample the produce. Home-canned, smoked or fermented fish is also a risk.
More than two-thirds of botulism cases today occur in infants. Babies less than 1 year old, especially those that are breastfeeding, have a different intestinal system than adults. Spores swallowed by an adult with a mature digestive tract usually will remain in their hibernating, inactive state. But spores ingested by a young infant can reproduce and can form toxin that is absorbed into the bloodstream, causing botulism.
In one out of five cases of botulism in infants, the infant has eaten raw honey. More rarely, botulism spores are found in corn syrup. Since the majority of cases of infant botulism can't be traced to a food source, experts suspect that babies are exposed simply by swallowing small amounts of dust or dirt.
Rarely, botulism is the result of a contaminated wound. Most wound botulism today occurs in people who inject recreational drugs.
Symptoms
All of the symptoms of botulism are the result of nerve paralysis during exposure to the toxin. Symptoms usually begin within one to two days after eating contaminated food. Symptoms of infant botulism and wound botulism also appear suddenly.
The earliest symptoms involve the eyes and face, because nerves controlling their function are affected most quickly by the botulism toxin. Early or mild symptoms, which may resolve on their own, include:
Written and revised by
Gerald Hurowitz, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
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