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Botulism: Background Information for Clinicians

  • Botulism is a public health emergency.
  • Prompt diagnosis and early treatment of botulism are essential to minimize the number of affected persons and the severity of illness.
  • Botulism is a neuroparalytic illness caused by a toxin made by the bacterium Clostridium botulinum. Van Ermengem described the toxin-producing microbe in 1897 after he investigated of a foodborne outbreak in Ellezelles, Belgium.
  • C. botulinumis a group of distinct organisms that are alike only in that they are clostridia and produce antigenically distinct neurotoxins with a similar pharmacologic action.
  • The C. botulinum organisms are straight to slightly curved, gram-positive, motile, anaerobic rods with oval, subterminal spores.
  • The seven types of C. botulinum (A-G) are distinguished by the antigenic characteristics of the neurotoxins they produce. Primate experiments suggest that humans may be susceptible to all types of C.botulinum.
    • Types A, B, E and, in rare cases, F cause disease in humans.
    • Types C and D cause disease in birds and mammals.
    • Type G, identified in 1970, has not yet been confirmed as a cause of illness in humans or animals.
  • The ability of C. botulinum to cause food poisoning in humans is directly related to the production of heat-resistant spores that survive preservation methods that kill nonsporulating organisms. The heat-resistance of spores varies from type to type and even from strain to strain within each type. Spores of many strains require temperatures above boiling to ensure destruction.

  • There are different kinds of botulism:
    • Foodborne botulism occurs when a person ingests toxin, which leads to illness within a few hours to days. Outbreaks of foodborne botulism have potential to be a public health emergency because the contaminated food may be eaten by other people.
    • Infant botulism occurs each year in a small number of susceptible infants who harbor C.botulinum in their intestinal tract. It occurs when an infant ingests spores of C.botulinum, which in turn colonize the intestinal tract and produce toxin.
    • Wound botulism is a rare disease that occurs when wounds infected with C. botulinum secrete the toxin.
    • Adult colonization botulism  is an even rarer type of intestinal colonization. It involves intestinal colonization in a person older than one year of age. In the small number of these cases, most patients had a history of gastrointestinal surgery or illness, such as inflammatory bowel disease, which might have predisposed them to enteric colonization. No other specific risk factors have been identified.
    • For more information visit: Botulism in the United States, 1899 - 1996.

  • Until the early 1960s nearly all recognized outbreaks of botulism in which toxin types were determined were caused by type A or B toxins and were usually associated with with ingesting home-canned vegetables, fruits and meat products.
  • Virtually all cases of botulism type E are from contaminated aquatic (i.e. originating either in sea or fresh water) products (fish or aquatic mammals) with several cases attributed to beavers. A limited number of outbreaks of type F botulism have been reported in this country with one outbreak traced to home-prepared venison jelly.
  • From 1950 through 1996  time period, 65% of botulism outbreaks have been traced to home-processed foods, while 7% have been linked to commercially processed foods, including foods served in restaurants.
  • Vegetables have been the most important vehicle for the botulism toxin in the US from 1950 through 1996. Beef, milk products, pork and poultry have caused fewer outbreaks.
  • Many of the initial recognized cases of botulism were caused by home-fermented sausage. Consequently, this new disease was dubbed “botulism,” which is derived from the Latin word botulus, meaning sausage. However illness can be caused by improperly preserved vegetables as well as animal products.
  • Page last reviewed October 06, 2006
  • Page last updated June 14, 2006
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