Botulism
(Clostridium Botulinum Toxin · Botulin Toxin)
In this condition factsheet:
The Facts on Botulism
Most people know that botulism is dangerous, but many are confused about whether it's an infection or a case of poisoning. In fact, it can be both. Clostridium botulinum is a worldwide bacterium that inhabits rivers, soil, and the guts of mammals, fish, and shellfish. It's not an organism that normally makes its living by attacking humans. We most often encounter C. botulinum by accident.
C. botulinum secretes a neurotoxin (nerve poison) that can weaken or paralyze muscles and can even cause death. This is botulin toxin, one of the most dangerous substances known. Botulism is the condition of having been poisoned with C. botulinum toxin.
Causes of Botulism
Botulism is rare, but there are still cases every year.
There are 6 ways to get botulism:
- Foodborne botulism occurs when food contaminated with the toxin is eaten. The bacteria are dead or gone by the time you eat the food, but the toxin remains. Most foodborne botulism is attributed to home-canned foods, but outbreaks occasionally occur in commercially-prepared foods.
- Infant botulism occurs when infants under 12 months of age eat bacterial spores rather than the toxins. Spores of C. botulinum then grow in the infant's intestines, where they produce toxins. Honey can contain spores of C. botulinum and is associated with infant botulism and should not be given to children under 12 months old. Infant botulism is rare.
- Adult intestinal colonization botulism occurs when C. botulinum spores are ingested. The spores grow and eventually produce toxins in the digestive system. People with altered gastrointestinal systems and local microbes (due to surgery, presence of inflammatory bowel disease, or exposure to antibiotics) are most often affected.
- Wound botulism occurs when live bacteria infect an open cut and the toxin is carried through the body by the blood.
- Bioterrorism-associated botulism is a possible terrorist threat. It would be delivered by aerosol or foodborne means.
- Iatrogenic botulism caused by cosmetic use of botulin toxin occurs when people receive botulinum toxin injections (e.g., Botox®) for a variety of health reasons or cosmetic purposes. If injected improperly or at the wrong dose, this could cause botulism.
Rarely, toxins can be inhaled or absorbed through the eyes.
Botulism can cause death due to paralysis of muscles used in breathing. However, advancements in supportive care have greatly reduced the death rate, and now less than 10% of people who get botulism die from the condition.
Symptoms and Complications of Botulism
C. botulinum toxin attacks nerve endings, damaging them and then stopping muscle function. It can't cross the barrier that protects the brain. The heart has its own wiring system and also isn't affected. However, botulin can affect all the other nerves of the body, including the nerves of the muscles that operate the lungs. Botulin toxin kills by shutting down breathing.
Symptoms usually appear quickly in foodborne botulism, within 12 to 36 hours, but a few people feel no symptoms for as many as 8 days after eating the poison. Dry mouth, vomiting, nausea, diarrhea, and abdominal cramps are the first signals.
Then the neurological symptoms begin to appear – the muscles slowly shut down, starting with the temple and forehead and proceeding slowly down both sides of the body. The face goes slack and expressionless, the eyelids droop, and the victim may drool. Vertigo and double vision are common. The arms slowly get weaker, then the legs. Diarrhea is replaced by constipation. By this time there's also difficulty in talking, swallowing, and breathing. Temperature and pulse remain normal.
The first sign of infant botulism is constipation. The neurological symptoms are the same as in foodborne botulism but develop less rapidly. This is because the spores produce toxin slowly and the child absorbs it bit by bit instead of all at once as in foodborne botulism. The baby may also suck milk weakly, have difficulty crying loudly, lose head control, and lack facial expression.
People with wound botulism do not have digestive symptoms.
