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Botulism is caused by botulinum toxins, neurotoxins produced by Clostridium botulinum and a few other species of Clostridium. By binding to nerve endings, these toxins cause progressive flaccid paralysis in humans and animals. Many untreated cases end in death from paralysis of the respiratory muscles. C. botulinum spores are common in the environment, but they can germinate and grow only in anaerobic environments under specific conditions. Foodborne botulism results from the ingestion of the preformed toxin after the organism has grown in food.

Botulinumproducing organisms may also grow in the immature gastrointestinal tracts of human infants and foals, in human gastrointestinal tracts with certain abnormalities, and in anaerobic wounds. In addition, these toxins are a concern in bioterrorism.

Sporadic cases and outbreaks of botulism occur in both humans and animals. This disease is an important cause of death in unvaccinated ranched mink, and it can cause large outbreaks among wild birds such as waterfowl and gulls. Livestock may be accidentally fed the toxin in contaminated feed. Botulism seems to be increasing in cattle, possibly due to the increased use of plastic-packaged grass silage, and these outbreaks can cause significant economic losses. Cattle in areas with phosphorusdeficient soils may also chew on toxin-contaminated bones and scraps of flesh in the environment to satisfy the deficiency. In Senegal, which has such soils, botulism is thought to cause more deaths than any other cattle disease. In addition, botulinum has been reported in a variety of other species including poultry, dogs, cats, foxes, captive lions and sea lions, turtles, farmed fish and wild bighorn sheep. Botulism can be treated successfully, but patients may require weeks or months of intensive care, sometimes including mechanical ventilation, while the nerve endings regenerate. Treatment may be impractical in adult livestock unless the case is mild.

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Iowa State University



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