Facts about Botulism - Centers for Disease Control and Prevention

Frequently Asked Questions

What is botulism?

Botulism is a serious illness caused by a nerve toxin (poison), produced by the bacterium Clostridium botulinum. These bacteria are found naturally in soil throughout the world, and are harmless when oxygen is present. When they are in an environment that contains no oxygen, they produce the toxin. Botulism usually occurs in three forms:

Foodborne botulism is caused by eating foods that are contaminated with botulinum toxin. A common cause of this type of illness is improperly processed home-canned foods with low-acid content, such as green beans and corn, and lightly preserved foods such as salted or smoked fish.

Intestinal botulism is rare, but is more often seen in children younger than a year old, rather than older children or adults. It previously was referred to as infant botulism. This type occurs when an infant consumes something that is contaminated with the C. botulinum spores, which then grow in the baby’s intestines and produce toxins. In most cases, the source of spores is not identified, and these may be airborne from soil or dust. Intestinal botulism has been associated with consumption of honey that has not been certified to be free of C. botulinum spores.

Wound (skin) botulism is a rare disease occurring when C. botulinum spores contaminate a wound, grow within the wound and produce toxin that is absorbed into the bloodstream. This type of botulism has been associated with gross trauma, crush injuries and injection with black tar heroin from Mexico.

A person can be exposed by breathing in the toxin if it is intentionally released into the air. This does not occur naturally.

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What are the symptoms of botulism?

Foodborne and intestinal botulism produce symptoms that affect the nervous system. The classic symptoms include double or blurred vision, drooping eyelids, slurred speech, difficulty swallowing, and dry mouth. Muscle weakness descends through the body: it begins at the shoulders and moves down to the upper arms, lower arms, thighs, calves and feet. If untreated, these symptoms may progress to paralysis. Infants with botulism appear lethargic, feed poorly, are constipated and have a weak cry and poor muscle tone.

How soon after exposure do symptoms occur?

Generally, symptoms begin 12-36 hours after eating contaminated food, but may occur as early as a few hours and as late as 10 days. The incubation period for intestinal (infant) botulism is unknown, though estimated at 3 to 30 days from the time of exposure. For wound botulism, the incubation period is 4 to 14 days from the time of the injury until the onset of symptoms.

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What is the treatment for botulism?

The symptoms of botulism make hospitalization necessary. If diagnosed early, foodborne and wound botulism can be treated with an antitoxin that is maintained by the Centers for Disease Control. The antitoxin reduces the progression of paralysis and may reduce the severity and duration of symptoms.

Most patients eventually recover after weeks to months of supportive care. An investigational human derived botulinal immune globulin is available from the California Department of Health for the treatment of intestinal (infant) botulism. Antibiotics are of little use to treat the symptoms caused by the toxin, and should be avoided in intestinal botulism because lysis of the bacteria could increase the amount of toxin available for absorption.

If left untreated, a patient may need to be on a ventilator for weeks and would require intensive medical and nursing care. The annual fatality rate for cases in the United States is 5-10 percent.

How is botulism diagnosed?

Because botulism occurs rarely, and the symptoms are similar to other neurological diseases, diagnosis is difficult and the disease may be misdiagnosed. The laboratory test used to confirm a diagnosis of botulism is sensitive and specific but can take several days to complete

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Can botulism be prevented?

Yes. Follow proper home canning techniques (required time, pressure and temperature) to destroy spores.
Do not eat food from damaged cans (food cans with slits, holes, dents or bulges). Do not feed honey or honey-water to infants younger than 12 months of age.

Can botulism be used as a bioterrorism threat?

Botulinum toxin has been a concern as a potential biological warfare agent since World War II. The extreme toxicity of the toxin, the ease of production, transport and delivery make this an agent of bioterrorism concern. Individuals intentionally exposed to the toxin, breathing it in or ingesting it in contaminated food or water could develop botulism. It is unknown what the effects of inhaling the toxin are, but they may be similar to the foodborne type of the disease.

For more information about botulism, call the Vermont Department of Health, Epidemiology Field Unit, at 1-800-640-4374 (in VT only), or 1-802-863-7240.

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