Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium Clostridium botulinum. There are three main kinds of botulism. Foodborne botulism is caused by eating foods that contain the botulism toxin. Wound botulism is caused by toxin produced from a wound infected with Clostridium botulinum. Infant botulism is caused by consuming the spores of the botulinum bacteria, which then grow in the intestines and release toxin. All forms of botulism can be fatal and are considered medical emergencies. Foodborne botulism can be especially dangerous because many people can be poisoned by eating a contaminated food.
Causes
A very small amount of the botulism toxin can cause illness. People come in contact with this toxin in one of three ways:
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Eating food contaminated with the bacteria and its toxin. It is the toxin produced by C. botulinum—not C botulinum itself—that causes botulism in humans. Foods that may be contaminated with the toxin include:
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If an infant swallows C botulinum spores, they will grow in the baby's body and produce the toxin. Unlike adults and older children, infants become sick from toxin produced by bacteria growing in their own intestines. Honey is a prime source of infant botulism. Other sources include soil and dust.
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A wound becomes infected with the bacteria (rare in the US). The toxin then travels to other parts of the body through the bloodstream.
In some cases, the source of the bacteria is unknown. Botulism toxin is also a potential bioterrorism agent.
Risk Factors
A risk factor is something that increases your chance of getting a disease or condition.
Risk factors for botulism include:
Symptoms
The classic symptoms of botulism include 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. These are all symptoms of the muscle paralysis caused by the bacterial toxin. If untreated, these symptoms may progress to cause paralysis of the arms, legs, trunk and respiratory muscles. In foodborne botulism, symptoms generally begin 18 to 36 hours after eating a contaminated food, but they can occur as early as 6 hours or as late as 10 days.
Diagnosis
The doctor will ask about your symptoms and medical history, and perform a physical exam. Blood, stool, and stomach contents will be tested for the toxin. In infants, stool will also be tested for C botulinum. If available, samples of questionable food may also be tested for the toxin and bacteria. A wound culture will be done if wound botulism is suspected.
Tests to rule out other medical conditions may include:
Treatment
The respiratory failure and paralysis that occur with severe botulism may require a patient to be on a breathing machine (ventilator) for weeks, plus intensive medical and nursing care. After several weeks, the paralysis slowly improves. If diagnosed early, foodborne and wound botulism can be treated with an antitoxin which blocks the action of toxin circulating in the blood. This can prevent patients from worsening, but recovery still takes many weeks. Physicians may try to remove contaminated food still in the gut by inducing vomiting or by using enemas. Wounds should be treated, usually surgically, to remove the source of the toxin-producing bacteria. Good supportive care in a hospital is the mainstay of therapy for all forms of botulism. Currently, antitoxin is not routinely given for treatment of infant botulism.
Prevention
High temperatures can destroy the botulism toxin. Strategies to prevent botulism include:
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Do not feed honey to children less than one year old.
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Refrigerate oils that contain garlic or herbs.
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Bake potatoes without foil. If potatoes are wrapped in foil, keep them hot until served or refrigerate them.
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Do not taste foods that appear spoiled.
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Do not eat food from a can that is bulging.
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Boil home-canned foods for 10-20 minutes before eating.
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Practice good hygiene when canning. Follow government recommendations.
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Seek medical care for wounds. Return to the doctor if a wound looks infected (redness, warmth, pus, tenderness).
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Do not inject illicit drugs.
RESOURCES:
Centers for Disease Control and Prevention
http://www.cdc.gov
Center for Food Safety and Applied Nutrition
http://www.cfsan.fda.gov
References:
AAP 2000 Red Book: Report of the Committee on Infectious Diseases, 25th ed. American Academy of Pediatrics; 2000.
Cecil Textbook of Medicine, 21st ed. WB Saunders Company; 2000.
Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov.
Nelson Textbook of Pediatrics, 16th ed. WB Saunders Company; 2000.
Principles and Practice of Infectious Diseases, 5th ed. Churchill Livingstone, Inc.; 2000.
CDC
