This article is from the Food Preserving FAQ, by Eric Decker ericnospam@getcomputing.com with numerous contributions by others.
Botulism is an intoxication of the bacteria clostridium botulinum.
This bacteria is anaerobic meaning that it requires an environment
relatively free of oxygen to multiply. It also requires a moist
environment and temperatures between 40 and 140F. The symptoms of
botulism are sore throat, vomiting, blurred vision, cramps, diarrhea,
difficulty breathing, and central nervous system damage (including
paralysis). Symptoms usually occur within 12 to 36 hours. The fatality
rate is up to 70%. [2
 
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