Present in the form of spores in the soil and in the intestines of some animals, the bacterium responsible for botulism produces one of the most poisonous natural toxins. Here is everything you need to know about it.
What is botulinum and botulism
Botulinum (Clostridium botulinum) is a Gram + bacterium characterized by seven distinct strains, namely A, B, C, D, E, F, G. The most present in Europe is the type E which has a lower lethality than the type A , characteristic of the United States. The bacterium produces a highly neurotoxic protein – botulinum toxin – which is responsible for botulism. There are six different forms of botulism and the food one is only the best known. Among others there is the infantile one, in which the bacterium germinates in the intestine of children under one year old, the wound one and the iatrogenic one, induced by an incorrect use of the toxin for cosmetic and therapeutic purposes. The famous Botox used for the treatment of wrinkles is based precisely on the botulinum toxin.
Where you can find botulinum
Botulinum is an anaerobic microorganism, that is able to survive in the absence of oxygen, and in the form of spore it can be found practically everywhere, in the soil as well as in the dust and in the digestive tract of different animals.
How botulinum forms
If the spores find favorable conditions, that is absence of oxygen (anaerobiosis), water where they can proliferate, a pH included in a specific range and a temperature between 18 ° C and 25 ° C, they pass to the so-called vegetative state (sporulation), which is the one responsible for producing the toxin, one of the most dangerous natural poisons ever.
The danger of preserves
As is known, jams, preserves of various types and canned foods – such as tuna in oil or natural – can be exposed to the risk of botulinum contamination. Generally industrial products are safer because they undergo sterilization processes that drastically reduce the risks, while for those made at home the dangers are greater. It is no coincidence that most of the intoxications derive from foods (badly) packaged in the home. Basically acid preserves (such as tomato sauce) and those in which water is eliminated through the addition of sugar and salt, such as jams, if prepared properly are safer because there is an environment not suitable for the metabolism of the bacterium, while non-acid ones – such as the aforementioned tuna and pickled vegetables – can instead represent an ‘ideal' survival ground.
Boiling is not enough
Although botulinum toxin is thermolabile, that means it disintegrates itself at high temperatures, the simple homemade boiling is not sufficient to eliminate the botulinum spores. For this purpose, in fact, about ten hours are needed, and this would irreparably destroy the organoleptic properties of the foods you want to prepare. Not to mention that the process catalyzes the sporulation, furthermore, by eliminating the air, the useful condition is created for the production of the toxin.
A safe preparation
Safe preserves must be prepared by boiling the vegetables with a solution composed of water and wine vinegar in equal quantities, and after leaving them to dry, they should be put in jars completely covered with oil leaving a space of 2 centimeters between cap and surface, so as not to favor anaerobiosis. For the foods in brine the aqueous solution must contain at least 15 percent of salt, while as regards the jams, fruit and sugar must be used in equal quantities.
The appearance of contaminated foods
Based on the botulinum strain involved, it is possible that the food is not altered in terms of appearance and taste, making potential intoxication even more subtle. Unfortunately, the type E strain, the most common in Europe, does not cause putrefaction and the food may appear pleasant despite having high quantities of botulinum toxin; that's why proper preparation is essential. In other cases, the clues that may suggest to not consume a certain product are different: pack swelling, liquid spillage, rancid odor caused by the butyric acid produced by the bacterium, as well as color and consistency different from that which foods should have.
Symptoms of botulism
When you are intoxicated by botulinum, the symptoms normally appear between 24 and 72 hours after ingestion of the contaminated food. They are characteristic symptoms and doctors usually understand immediately that it is botulism, although it is always important to bring the packages of food suspected of intoxication into the hospital. Since the toxin inhibits the release of the neurotransmitter acetylcholine, the typical symptom is the so-called flaccid paralysis, which extends from the head muscles towards the rest of the body. Mortality is linked precisely to the blockage of the muscles of the respiratory apparatus system. Among the other characteristic symptoms there are split vision, dry mouth and dry pharynx, lowering of the upper eyelids (ptosis) and difficulty speaking. Dizziness, vomiting and nausea may also occur in some patients who however remain always conscious.
How to cure botulism
Botulinum intoxication is a medical emergency and it should be treated as such in the hospital. The rapidity of the health intervention is fundamental to increase the chances of survival, given that it is based on the administration of laxatives and an antitoxin that serve to eliminate that still present in the bloodstream. Although recovery may be rapid from the most severe symptoms, it can take months for a complete recovery.