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Botulism Clostridium Botulinum Toxin · Botulin Toxin The Facts Most people know that botulism is bad, 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 bacterium that inhabits rivers, soil, and the guts of mammals, fish, and shellfish worldwide. It's not an organism that normally makes its living by attacking humans. When we meet C. botulinum, it's by accident. Unfortunately, these bacteria secrete a neurotoxin (nerve poison) so deadly that a few billionths of a gram could kill you. This is botulin toxin, one of the most dangerous substances known. Botulism is the condition of having been poisoned with botulin toxin. Causes There are three ways to get botulism: foodborne botulism is the commonest type, with hundreds of outbreaks worldwide each year. The bacteria are dead or gone by the time you eat the food, but the poison remains. Most foodborne botulism is attributed to home-canned foods. Infant botulism was only discovered 25 years ago. More cases are reported each year. Children under one year old either eat bacterial spores, or inhale them. Spores of C. botulinum can be blown around when it's dusty and windy. If inhaled, they can end up in the lungs rather than the intestines. They settle there and begin producing toxin. Adults' stomachs are usually protected by other species of bacteria already living there. Spores in food can also cause infant botulism. This is different from foodborne botulism, where only the poison is in the food. Honey and corn syrup are especially associated with infant botulism and should not be given to children under one year old. Wound botulism is the rarest type. Live bacteria infect an open cut, and poison is carried through the body by the blood. The U.S. centers for Disease Control (CDC), which tracks deadly infections, expects to add a fourth type soon. They now believe airborne live bacteria can infect certain adult intestines. All the adults affected so far either had previous intestinal surgery or had recently taken antibiotics. Antibiotics have the side effect of clearing the "good" bacteria out of the intestines. With the "good" bacteria gone, C. botulinum had no rivals and moved in. Ironically, the way most people get botulism nowadays is from their doctor - and intentionally. Tiny amounts of toxin are injected into twitching and spasmodic muscles to calm them. It's a very successful treatment. Very small amounts of botulinum toxin are also marketed for the cosmetic purpose of removing "crow's feet" around the eyes. This product requires a prescription and should be administered by a physician skilled in the technique. Symptoms and Complications Botulin toxin attacks nerve endings, permanently damaging them. 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 18 to 36 hours, but a few people feel no symptoms for as many as eight days after eating the poison. Vomiting, diarrhea, and abdominal cramps are the first signal. 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 expresionless, the eyelids droop, and the victim may drool. Vertigo and double vision are common. Slowly the arms 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. It might take three weeks for clear neurological symptoms to appear. The baby will suck milk weakly and have difficulty crying loudly. Making the Diagnosis There is a test for botulin toxin, but it's only available in certain clinics. It involves injecting the suspected botulin toxin into a mouse that's received a toxoid, a sort of vaccine against poison. In the U.S., tissue and stool samples are often flown to Atlanta for inspection by the Centers for Disease Control (CDC), who take botulism very seriously. Treatment and Prevention Luckily, the CDC has also developed an antitoxin that neutralizes botulin. However, the antitoxin needs to be administered as soon as possible after diagnosis. The medication can't repair nerve endings already damaged. This means that while you may survive, you will be left in the state you were in at the time the medication was administered. That may mean paralysis, sometimes to the point of being unable to talk or even swallow. The good news is that you'll recover because new nerves grow to replace those killed. It may take up to a year before you're fully yourself again, but a few months is typical. The antitoxin is made from horse serum and isn't used in infants for fear of a deadly reaction. This doesn't mean they die. Children who have ingested botulism bacteria are given medications that cause vomiting or treatments like enemas that are able to remove undigested food from the digestive system. So long as the lungs can be kept in working order, botulism won't kill you. With mechanical ventilators and intubation, 95% of North American victims now survive. Preventing botulism is sometimes impossible, but if you prepare and store a lot of your own food, you may be creating unnecessary risk. The C. botulinum bacteria is anaerobic, meaning it likes airless environments. This is why you can get foodborne botulism out of a can. Very few cases of botulism arise from commercially canned food. Most occur when individuals can their own products. Botulin toxin has been found in North America in these foods:
Only highly acidic foods are safe from C. botulinum. Freezing will shut down poison production, but a fridge isn't cold enough. The following food-handling procedures can help you to prevent foodborne botulism:
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