Clostridium botulinum

Clostridium botulinum

Changed on: 25.08.2021

Animal disease categories:


Botulism ("sausage poisoning") is a poisoning caused by the bacterium Clostridium botulinum: the neurotoxins produced by this bacterium are among the most potent poisons known.


Worldwide in the soil and in coastal waters.

Pathogen reservoir

Clostridium botulinum is an environmental pathogen that can be found in soil, sea and river beds, dust, water and in the digestive tract of humans and animals. Foodstuffs that come into contact with these materials, e.g. soil or water, may therefore be contaminated with it.

Route of infection

Botulism occurs in humans in three forms: Foodborne botulism, infant botulism, and wound botulism, depending on the portal of entry of the toxin produced by the bacterium. The bacterium grows only in oxygen-free conditions. It forms heat-resistant spores that are only killed at temperatures above 100 °C.

Incubation period

12 to 36 hours


The toxins formed by the bacteria are extremely toxic: as little as 10 nanogrammes (ten billionths of a gramme) are considered a lethal dose for humans. The toxins damage nerve tissue, causing "flaccid paralysis". After twelve to 36 hours, nausea, diarrhoea or constipation occur. Typical symptoms are visual disturbances (double vision, blurred vision, photophobia), dysphagia and a rapidly progressing flaccid paralysis which also affects the respiratory muscles.


Patients with botulism symptoms should receive medical treatment immediately. Since the introduction of artificial respiration, no laboratory-confirmed death from botulism has been documented in Austria.


Foodstuffs do not show whether they contain germs, spores or toxins of Clostridium botulinum. However, an indication can be given by so-called "bombages", i.e. canned foods that have been bloated by gas-forming Clostridia. If you have such bloated tins at home, they should not be opened under any circumstances, but disposed of or handed over to the official food control for examination.

As the botulinum toxins are heat-sensitive, they are inactivated in a few seconds during cooking after reaching an internal temperature of 100 °C in the food.

In the past, it often happened that spores of Clostridium botulinum survived the "preservation" of canned food and sprouted during storage. Today, therefore, the so-called "botulinum cook" is carried out on critical products during sterilisation in industrial food production: This involves heating the food at 121 °C for three minutes. This reliably kills all spores.

Caution is advised when preserving fruit or vegetables yourself in preserving jars at home: Without special technology, a temperature of 100 °C (boiling water) cannot be exceeded for physical reasons. When preserving fruit and vegetables, the food should therefore be heated to 100 °C twice - at least 24 hours apart - in order to kill any spores that may have sprouted.

Since bee honey can also contain spores of Clostridium botulinum, it is not recommended in some countries to give honey to infants (for example, to make the pacifier or the mother's breast more palatable to them if they are unable to suck): The infant's intestine does not yet have a stable intestinal flora, the spores can germinate in the infant's intestine, form toxins and lead to the so-called "infant botulism".

Situation in Austria

Botulism diseases are very rare: Since 2000, 36 cases have been reported in Austria.

The bacteria only become critical when they multiply and produce toxins. Foodstuffs that are stored under oxygen-free conditions and whose environment is only slightly acidic or neutral are primarily at risk, e.g. home-pickled vegetables/fruit or home-made preserves. In western industrialized countries, exposure of food to botulinum toxins is extremely rare.

Figure 1: Reported cases of botulism, Austria, 2000-2020


    Contact, Forms

    National Reference Centre for BotulismBeethovenstraße6 8010 Graz Dr. Christian KornschoberTel: +43 50 555-61201E-Mail:

    Since 1.1.2008 the National Reference Centre for Botulism exists at the Institute of Medical Microbiology and Hygiene Graz. Toxin detection and in some cases cultural detection of Clostridium botulinum is carried out on human samples (e.g. serum, blood, stool, wound material or vomit) and food samples using mouse bioassays.


      Nationale Referenzzentrale für Botulismus - Jahresbericht 2020 (296 K)
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      Nationale Referenzzentrale für Botulismus (352 K)
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      Botulismus Antitoxin Fachinformation (50 K)
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