Diseases & Conditions
The most common type of the infectious disease known as “botulism” is a food-borne illness involving the toxin Clostridium botulinum, which is both rare and very deadly (two-thirds of those afﬂicted die). Another type is known as “infant botulism,” an uncommon illness that strikes infants under the age of one. Because botulism is technically an intoxication, not an infection, the patient cannot infect others even though the toxin and bacteria will be excreted in feces for months after the illness.
Botulism is more common in the United States than anywhere else in the world owing to the popularity of home canning; there are about 20 cases of food-borne botulism poisoning each year. Botulism got its name during the 1800s from botulus, the Latin word for “sausage,” because of a wave of poisoning from contaminated sausages.
Botulism toxins are a type of neurotoxin that attaches to the nerves, blocking the messages that are sent to the muscles. The C. botulinum spores (latent form of the bacteria) are found in air, water, and food; they are harmless until deprived of oxygen (such as inside a sealed can or jar). If conditions are favorable, the spores will start to generate and multiply, producing one of the most deadly toxins known—seven million times more deadly than cobra venom.
Cases of botulism from commercially canned food are rare because of strict health standards enforced by the U.S. Food and Drug Administration, although some people have gotten botulism from eating improperly handled commercial pot pies. In Canada cases have been reported from seal meat, smoked salmon, and fermented salmon eggs. Most cases occur during home canning.
Canned foods that are highly susceptible to contamination include green beans, beets, peppers, corn, and meat. Although the spores can survive boiling, the ideal temperature for their growth is between 78°F and 96°F. They can also survive freezing.
Even though botulism spores are invisible, it is possible to tell if food is spoiled by noticing if jars have lost their vacuum seal; when the spores grow, they give off gas that makes cans and jars lose the seal. Jars will burst or cans will swell. Any food that is spoiled or whose color or odor does not seem right inside a home-canned jar or can should be thrown away without tasting or even snifﬁng, since botulism can be fatal in extremely small amounts.
Botulism can also occur if the C. botulinum bacteria in the soil enters the body through an open wound, although this is extremely rare.
Onset of symptoms may be as soon as three hours or as late as 14 days after ingestion, although most symptoms usually appear between 12 and 26 hours. The ﬁrst sign is usually muscle weakness beginning with the head, often leading to double vision. This is followed by problems in swallowing or speaking, followed by the paralysis of the muscles needed to breathe. Other symptoms can include nausea, vomiting, diarrhea, and stomach cramps. The earlier the onset of symptoms, the more severe the reaction. Symptoms generally lasts between three to six days; death occurs in about 70 percent of untreated cases, usually from suffocation as a result of respiratory muscle paralysis. In infants, symptoms may go unrecognized by parents for some time until the poisoning has reached a critical stage.
Large commercial labs or state health labs can test for the toxin in food, blood, or stool; it is also possible to grow the bacteria from food or stool in a special culture.
Prompt administration of the antitoxin (type ABE botulinus) lowers the risk of death to 10 percent. Most untreated victims will die. The Centers for Disease Control is the only agency with the antitoxin, and it makes the decision to treat. Local health departments should be called ﬁrst for this information. While induced vomiting may help following ingestion of food known to contain botulism toxin, it may not eliminate the toxin completely. The disease can occur with only a small amount of toxin, thus botulism may still develop. Enemas may be necessary. Patients are usually put on a respirator to ease breathing.
Botulism is easy to prevent, since it is killed when canned food is boiled at 100°C for one minute, or if the food is ﬁrst sterilized by pressure cooking at 250°F for 30 minutes.
While the tightly ﬁtted lids of home-canned food will provide the anaerobic environment necessary for the growth of botulism toxins, the spores will not grow if the food is very acidic, sweet, or salty (such as canned fruit juice, jams and jellies, sauerkraut, tomatoes, and heavily salted hams).