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Epidemiology for public health - ISS

What is foodborne botulism?


Botulism is a neuroparalytic disease caused by botulinum toxins produced by some Clostridium bacteria. These microorganisms are ubiquitous in nature and can be found in several environments, such as soil, sea and fresh water sediments, dust and food, mainly as spores.


The spore form allows the microorganism to withstand adverse conditions by lying dormant for extended periods (even several decades). When environmental conditions are favourable again, spores transform back into vegetative cells.


Favourable conditions for the development of botulinum toxin-producing clostridia include:

  • Absence of oxygen
  • Low-acid substrates (pH> 4.6) containing large amounts of free water (i.e. the water that the microorganism can use to carry out its vital functions – this is also known as “water activity”, and a minimum value of 0.935 is needed to support the growth of botulinum toxins)
  • Substrates containing significant protein sources (since these microorganisms are unable to synthesize all amino acids). 

The best-known of the botulinum toxin-producing clostridia, Clostridium botulinum, was first described as the microorganism responsible for botulism by Emile van Ermengem in 1897, following a foodborne botulism outbreak after a funeral in the small Belgian town of Ellezelles. The disease was named after the Latin word for sausage (botulus) because its description was initially associated with the consumption of home-made sausages. However, at least in Italy, most cases of botulism are linked to the consumption of products of plant origin.


The disease can be classified into 5 categories:

  • Foodborne botulism: due to the presence of a preformed toxin in food
  • Wound botulism: caused by the growth of C. botulinum and subsequent production of toxins in infected wounds
  • Infant botulism: resulting from temporary intestinal colonization in infants under one year of age
  • Adult intestinal colonization: it occurs by the same route as infant botulism, among people over one year of age with a severe form of intestinal dysbiosis
  • Iatrogenic botulism: caused by incorrect injection of botulinum toxins for therapeutic or cosmetic reasons
  • Inhalation botulism: due to intentional or accidental release of botulinum toxins.

This section of EpiCentro mainly covers foodborne botulism. Each identified case of foodborne botulism may constitute a public health emergency, especially when a widely distributed food product is involved (e.g. industrially produced food). In order to protect public health, each food product potentially contaminated with botulinum toxins should be immediately withdrawn from the market and removed from household pantries and cupboards.

Publication date: 2 January 2021