Clostridium botulinum

The bacterium Clostridium botulinum produces a potent neurotoxin, a poison which attacks the nervous system. Although cases of botulism are rare, between 10 and 30 outbreaks per year in the US, they should be taken seriously and treated immediately, because the risk of death is high.

Onset of symptoms usually occurs 18 to 36 hours after eating the affected foods, although onset occasionally occurs as much as 4-8 days later. First signs and symptoms include:

• Fatigue
• Muscle weakness
• Blurred vision
• Constipation
• Difficulty swallowing

All of these symptoms are the early signs of a progressive muscle paralysis. A person showing these signs should seek immediate medical evaluation. Infants and small children are particularly vulnerable to botulin toxin.

If the paralysis is not treated, it progresses to the arms and legs, and eventually to the diaphragm and other muscles that regulate breathing. Untreated, the paralysis interferes with breathing, and the victim dies of asphyxiation.

Spores of Clostridium botulinum are found in soil, both where crops are cultivated and in the wild. They are also found in many streams and lakes, in the gills of shellfish and crabs, and in the digestive tracts of many fish and animals, including those raised for human consumption. The bacterium grows easily in non-acidic environments, in any pH above 4.6. Infections have been found in ripe olives, green beans, smoked fish, salted fish, ham, sausage, beets, mushrooms, spinach and asparagus. Any can or container which is bulging is suspect, and should be thrown away.

Many outbreaks have been traced to home canned foods in which the food was not heated to the proper temperature. Botulin toxin is relatively easy to denature. For safe processing, food should be brought to a minimum temperature of 80° Centigrade, 176° Fahrenheit, and held at that temperature for ten minutes.