Botulism is a toxi-infection due to a mighty bacterial neurotoxin called botulinum toxin. It is a group of seven toxins produced by the Clostridium botulinum, the spores of which are present in soil and the organism of some animals (fish included). When spores sprout, they generate vegetative bacteria that produce toxin. Botulism affects humans and animals. It is a rare disease: 0.001 case/100,000 inhabitants per year in Belgium (but it is an underestimation). It is present everywhere in the world.
Botulism and botulinum toxin are not contagious. Transmission from one person to another is thus impossible. Infected persons do not represent any menace for the others and do not have to be placed in quarantine. However, if it was intentionally modified to produce botulinum toxin, the bacilli could be contagious. After diffusion of toxin by aerosol, there is no risk of contamination from person to person.
Botulism can naturally show under the three following forms:
The incubation period in case of food contamination ranges, most of the time, from 12 to 36 hours but can sometimes be of up to several days. The stronger the infection dose is, the shorter the incubation period.
The most typical symptoms are the sudden neurological symptoms, starting most of the time with an effect on cranial vessels (drop of visual acuity, diplopia, dysphagia, dysphonia and mouth dryness), followed by a slow and descending symmetric paralysis. Vomiting is frequent due to paralytic ileus. Diarrhoea rapidly gives way to constipation. In general there are no fever or disorders of consciousness.
Recovery can take months.
All forms of botulism show the same symptoms but the seriousness of the disease can considerably vary. In case of contamination by inhalation, gastro-intestinal symptoms do not precede neurological symptoms. Infant botulism provokes constipation and general hypotony that can cause respiratory failure and finally death.
Mortality by foodborne botulism is of the order of 5 to 10 % in the United States. Mortality in newborn children hospitalized for botulism is inferior to 1 %.
The diagnosis is clinical.
Clinical signs here above described along with a careful anamnestic interview will be most of the time enough to establish a diagnosis. An electromyography can reveal useful in some cases. Cerebrospinal liquid remains unchanged in case of botulism. A microbiological diagnosis and a post mortem diagnosis can also be carried out.
Treatment of botulism is symptomatic and surveillance implies hospitalization, sometimes in a reanimation unit, due to the risk linked to deglutition disorders and/or to heart rhythm disorders than can occur even in moderate forms. Assisted ventilation (artificial breathing) can be necessary and justified during several weeks.
Botulism remains a disease provoking serious clinical complications. It can sometimes be avoided thanks to an adequate preparation of food. It relies upon simple hygiene rules in home canned-food (industrial production is generally safe from intoxication). Preservation processes must be scrupulously respected. Control of temperature, saline concentration and PH is essential. Foods preserved under vacuum always have to be sufficiently cooked.
Federal Public Service (FPS) Health, Food Chain Safety and Environment
Place Victor Horta, 40 box 10
Contact Center: +32 (0)2 524.97.97
Published on 14/10/2008 – Page last updated on 14/10/2008