Key facts
- Clostridium botulinum is a bacterium that generates dangerous toxins (botulinum toxins) in low-oxygen conditions.
- Botulinum toxin is one of the most deadly substances known.
- Botulinum toxins impair nervous functions and can cause respiratory and muscle paralysis.
- Human botulism may refer to foodborne botulism, infantile botulism, wound botulism, inhalation botulism, or other forms of poisoning.
- Foodborne botulism, caused by the consumption of improperly prepared food, is rare but potentially fatal if not quickly diagnosed and treated with an antivenom.
- Homemade canned, preserved or fermented foods are a common source of foodborne botulism and their preparation requires extra caution.
Overview
Foodborne botulism is a severe disease that can be fatal, but is relatively rare. It is a poisoning condition that usually results from the ingestion of potent neurotoxins, i.e. botulinum toxins, which are formed in contaminated foods. Botulism is not transmitted from one person to another.
The spores produced by C. botulinum resist heat and spread widely in the environment. They arise, grow, and then secrete toxins in the absence of oxygen. There are 7 distinct types of botulism, from type A to type G. Four of these types (i.e., types A, B, E, and, in rare cases, type F) cause human botulism. Types C, D, and E cause diseases in other mammals, birds, and fish.
Botulinum toxins are ingested through food that is not properly prepared in which the germs or spores survive and then grow and generate toxins. Human botulism is primarily foodborne but can also occur as a result of intestinal infection with C. botulinum in infants, injury, and inhalation.
Symptoms of foodborne botulism
Botulinum toxins cause neurotoxicity and thus affect the nervous system. Foodborne botulism is characterized by descending flaccid paralysis that can cause respiratory failure. Initial symptoms include pronounced fatigue, weakness, and dizziness, usually followed by blurred vision, dry mouth, and dysphagia and dysarthria. Symptoms of vomiting, diarrhea, constipation, and abdominal swelling may also appear. The disease can develop to lead to a feeling of weakness in the neck and arms and then affect the respiratory muscles and muscles of the lower body. He does not develop a fever or lose consciousness.
Symptoms do not appear as a result of the germ itself, but rather as a result of the toxin it generates. They usually appear within a period ranging between 12 and 36 hours (taking a period ranging from a minimum of four hours to a maximum of eight days) after exposure. The incidence of botulism is low, but the resulting mortality rate is high if the disease is not diagnosed quickly and not treated appropriately and immediately (by giving antitoxin early and providing intensive respiratory care). The disease can be fatal in a percentage of cases ranging between 5 and 10 percent.
Exposure to disease and its transmission
Foodborne botulism
Clostridium botulinum is an anaerobic bacterium, which means it can only grow in the absence of oxygen. Foodborne botulism occurs when Clostridium botulinum grows and produces toxins in food before it is consumed. C. botulinum generates spores that spread widely in the environment, including in soil, river water, and seas.
Bacteria grow and toxins form in products with low oxygen content and in some combinations of storage and preservation temperature parameters. This occurs most often in foods that are lightly preserved and foods that are improperly prepared or canned at home.
C. botulinum will not grow in acidic conditions (pH below 4.6) and therefore toxins will not form in acidic foods (however, a low pH will not break down any previously formed toxins). Combinations of low storage temperatures, salt contents and/or pH are also used to prevent bacterial growth or toxin formation.
Botulinum toxins have been found in various foods, especially in low-acid preserved vegetables such as green beans, spinach, mushrooms, and beets. Fish, including canned tuna and fermented, salted and smoked fish; And meat products such as salt pork and sausage. The foods involved vary between countries and reflect local dietary habits and food preservation procedures. Commercially prepared foods are sometimes involved.
C. botulinum spores are resistant to heat, but spore toxins generated by spores under anaerobic conditions are destroyed by boiling (if the internal temperature is above 85°C for 5 minutes or more, for example). Therefore, ready-to-consume foods kept in containers with low oxygen content cause foodborne botulism more often.
Food samples associated with suspected cases should be obtained immediately, stored in properly sealed containers, and sent to laboratories to determine the cause and prevent further cases.
Infantile botulism
Infantile botulism primarily affects infants younger than 6 months. Unlike foodborne botulism, which is caused by the ingestion of pre-formed toxins in foods, infantile botulism occurs when infants ingest C. botulinum spores, which develop into spores that invade the intestines and spread the toxins. This type of poisoning does not affect most adults and children over the age of about 6 months due to the presence of natural defenses in the intestines that develop over time and protect against the formation and growth of the bacteria.
Clostridium botulinum, which infects infants, causes constipation, loss of appetite, weakness, altered crying sound, and significant loss of head movement control. Although there are multiple possible sources of infection with infantile botulism, honey contaminated with spores has been linked to a number of cases. Therefore, parents and caregivers are warned against feeding honey to infants before they reach one year of age.
Botulism caused by wounds
Wound botulism is rare and occurs when spores enter the body from an open wound and are able to reproduce in an anaerobic environment. Its symptoms are similar to those of foodborne botulism, but it may take up to two weeks to appear. This form of the disease has been associated with the use of addictive substances, especially injection of black tar heroin.
Inhalation botulism
Inhalation botulism is rare and does not occur naturally, but may, for example, be associated with accidental or intentional events (eg bioterrorism) that result in the release of toxins in aerosols. Inhalation botulism has the same clinical effects as foodborne botulism. The estimated median lethal dose in humans is 2 nanograms of botulinum toxin per kilogram of body weight, three times the dose in foodborne cases.
After inhaling toxins, symptoms begin to appear within 1 to 3 days, and the period before symptoms appear is longer at low levels of poisoning. Symptoms develop in a manner similar to their development when botulinum toxin is swallowed, and culminate in muscle paralysis and respiratory failure.
If exposure to toxins through inhalation of droplets is suspected, the patient and other persons should be protected from further exposure. The patient's clothes must be removed and stored in plastic bags so that they can be washed well with soap and water. The patient should be washed and decontaminated immediately.
Other types of poisoning
Waterborne botulism can theoretically result from ingestion of pre-formed toxins. However, because standard water treatment processes (such as boiling or disinfection with a 0.1% bleach hypochlorite solution) destroy the toxins, the risks are limited.
As for botulism of unknown cause, it usually occurs in adults in which it is not possible to identify sources from food or wounds. These conditions can be compared to infantile botulism and may occur when the intestinal flora changes as a result of surgery or antibiotic treatment.
Adverse effects have been reported when patients use pure toxins for medical or cosmetic purposes, see heading “Botox” below.
"Botox"
C. botulinum is the same bacterium used in the production of Botox, a pharmaceutical product used primarily as injections for medical or cosmetic purposes. Botox treatment uses botulinum neurotoxin type A after it has been cleaned and greatly diluted. The treatment is given in medical care settings, is specifically designed according to the patient's needs, and is usually well tolerated by the patient, although some side effects have been observed.
Diagnosis and treatment
The diagnosis is usually based on clinical history and physical examination followed by laboratory confirmation, including demonstration of the presence of botulinum toxin in serum, stool, or food, or culture of C. botulinum from stool, wound, or food. Botulism is sometimes misdiagnosed and is often confused with Guillain-Barré syndrome or myasthenia gravis.
Antitoxin should be given as soon as possible after clinical diagnosis, as this is effective in reducing mortality. Severe cases of botulism require supportive treatment, especially mechanical ventilation, which may be required for weeks or even months. Antibiotics are not required (except in the case of botulism caused by wounds). There is a vaccine for botulism, but it is rarely used as its effectiveness has not been fully evaluated and it has proven negative side effects.
protection
Prevention of foodborne botulism is based on good food processing practices, especially during heating/sterilization, and hygiene. Foodborne botulism can be prevented by inactivating the bacteria and their spores in heat-sterilized (eg, by distillation) or canned products, or by preventing the growth of the bacteria and the generation of toxins in other products. Vegetative forms of spores can be destroyed by boiling, but spores can still survive after boiling, even if it continues for several hours. However, spores can be killed by treatment with extremely high temperatures such as those used in commercial canning.
Heat pasteurization used commercially (including vacuum-coated pasteurized products and heat-pasteurized products) may not be sufficient to kill all spores, so the safety of these products must be based on preventing spore growth and toxin generation. The temperature in the cooling devices and the salt and/or acid content prevent the growth of germs and the generation of toxins.
The Five Commandments for ensuring food safety issued by the World Health Organization form the basis of educational programs for training food handlers and educating consumers. These commandments are especially important in preventing food poisoning.
The five commandments are:
- Maintain cleanliness
- Separate raw foods from cooked foods
- Cook food well
- Maintaining food at safe temperatures
- Use safe water and raw materials