Food-borne botulism is a severe form of food poisoning. The bacterium, Clostridium botulinum, is normally found in soil and in the intestinal tract of domesticated animals. By itself, the bacterium is not harmful to humans and can be consumed without notice. However, when in unfavorable conditions, the bacterium produces spores to support itself. It is these spores, which produce the powerful neurotoxin that produces severe neurological illness in humans.

Neurotoxins attack nerve cells in the body, often resulting in paralysis. Botulinus toxins block the release of acetylcholine at neuromuscular junctions and throughout the autonomic nervous system, creating paralysis of both skeletal muscle (preventing movement, including swallowing) and smooth muscle (such as the heart, diaphragm and digestive tract, preventing autonomic functions such as breathing). Death from botulism is usually a direct result of asphyxiation, when the diaphragm can no longer contract sufficiently for respiration.

While the bacterium needs oxygen to survive, the spores and its toxin do not; the botulinum toxin thrives in anaerobic conditions (in the absence of oxygen) and in fact is inhibited by oxygen. The toxin can, however, be destroyed by extreme heat. This is why botulism occurs most often in home-canned goods; foods contaminated with Clostridium botulinum are not heated to the right temperature and are sealed shut, allowing the perfect conditions for the toxin to reproduce inside the sealed jar.

Botulism also occurs by two other modes of infection. These cases are called wound botulism and infant botulism. As mentioned, the Clostridum botulinum bacterium naturally occurs in soil and dirt. Wounds, which are not properly cleaned and dressed, can become infected with Clostridium botulinum. The neurotoxin is produced by the bacteria thriving in the open wound, and it permeates into the bloodstream and becomes systemic. Wounds are usually treated surgically to remove the toxin-producing bacteria. Wound botulism has increased with the rate of injectable drugs, such as black-tar Heroin, and consequently most incidences of wound botulism are associated with intravenous drug use.

You may have heard that you should never give a baby honey. The reason for this is the danger of botulism. In infant botulism, a baby’s natural intestinal flora (bacteria) have not yet established themselves if the child is less than twelve months old. The baby ingests Clostridium botulinum from unpasteurized honey, and the bacteria establish themselves in the place of normal intestinal bacteria and flourish, producing the neurotoxin. Symptoms of infant botulism include constipation, poor feeding, shallow breathing, weak crying, loss of head control and weak muscle tone.

The Centers for Disease Control and Prevention state, “in the United States an average of 110 cases of botulism are reported each year. Of these, approximately 25% are foodborne, 72% are infant botulism, and the rest are wound botulism.”1

Symptoms

Initial symptoms of food-borne botulism begin between 18 hours and 10 days of infection and include weakness, headache, dizziness, fatigue, blurry vision from lapsing eyes and drooping eyelids, dry mouth, slurred speech, and sore throat. Progressive cases present symptoms of dyspnea (labored, painful breathing), muscle weakness and paralysis of the extremities and eventually trunk.3

Treatment

Botulism, when diagnosed early, is treated by the administration of an antitoxin, not an antibiotic. The antitoxin is called trivalent antitoxin, and it is given immediately upon suspicion of infection, even if the laboratory test has not yet confirmed the infection.

The Centers for Disease Control and Prevention report that in the past 50 years the mortality rate of botulism has fallen from about 50% to 8%.1 A survivor of severe botulism may need machine-assisted breathing (a ventilator) for several months and suffer fatigue and shortness of breath for years afterward.

Prevention

Most cases of botulism are from home-canned foods with low acid content, such as green beans, corn, asparagus, beets and green beans. However, rare cases have resulted from more unusual sources such as chopped garlic in oil, chile peppers, tomatoes, foil-wrapped baked potatoes, and home-canned or fermented fish.1 If you bake potatoes in aluminum foil, keep them hot until they are served or refrigerate them. Vegetables prepared or stored in oil should be refrigerated. If you do any home-canning, refer to the US Department of Agriculture’s Home-Canning Guide.

In order to eliminate the risk of Clostridium botulinum contamination of home-canned foods, all low-acid foods must be canned at a 240°F or higher and under pressure in a pressure cooker or retort. A pressure of 10 lbs./sq.in. is required to reach 240°F.”2 Most foods are low-acid, with the exception of tomatoes, peaches, apples, pears, oranges and other citrus fruits. Pickled foods must be made acidic by either fermenting the food properly to an acid condition or adding vinegar before canning. The botulinum toxin cannot reproduce in an acidic environment. Any cans or jar lids that show unusual or extreme distension (bulging) should be discarded. If there is any evidence of frothing, foaming or bubbling at the seal or inside the jar, or any suspicious odor, it should also be discarded. NEVER taste-test a suspicious jar or can. The appearance of contamination should be enough to throw it away, and just a taste is enough to infect you with the potentially fatal neurotoxin.