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Poisoning with canned fish, meat and vegetables
Medical expert of the article
Due to the use of any substandard food products, food intoxication may develop, but poisoning with fish, meat and vegetable canned food, in which the body is affected by the bacterial toxin contained in them, is of particular danger. 
According to official CDC data from 1975 to 2009. In the United States, canned food poisoning was identified as botulism in 854 cases. A fatal outcome occurred in 7.1% of cases (61 patients died). In 2015-2016 CDC recorded 228 confirmed cases of botulism.
In the UK, between 1989 and 2005, 33 cases of botulinum toxin poisoning with three fatalities were identified. 
According to statistics from the European Center for Disease Prevention and Control, foodborne botulism in the EU does not exceed 200 cases per year and amounts to 0.03 cases per 100 thousand people. 
Causes of the canned food poisoning
In case of canning poisoning, the reasons lie in the ingestion of botulinum neurotoxin (botulinum toxin, BoNT), produced by the spores of the widespread sapronous obligate anaerobic bacteria Clostridium botulinum, which are present on raw vegetables, meat or fish before their preservation. 
The natural habitat of C. Botulinum is soil, and like many anaerobes, in the environment, including on raw products, this bacterium exists in the form of spores - dehydrated cells with a deactivated metabolism, protected from adverse conditions (in particular, air) by the membrane. 
The peculiarity of C. Botulinum spores is that they remain viable during heat treatment and sterilization if the duration of these processes or the temperature regime are violated. When this happens, in an anaerobic environment - with complete lack of air access in hermetically sealed canned food - spores, as microbiologists say, get out of a state of rest and even grow into a vegetative form with the restoration of metabolic processes. And the deadly toxin produced by them, having a protein origin, is a metabolic product of the microorganism.
The set of symptoms of poisoning of this etiology is called food botulism .
The key risk factors for canning poisoning - fish, meat, and vegetables - poor processing of raw materials and / or violation of their manufacturing technology with non-compliance with temperature conditions, insufficient pressure and sterilization time.
Most often, people are poisoned by the preservation of home cooking, which is due to insufficient decontamination of products, that is, incomplete neutralization of botulinum clostridia in the form of spores. It is considered the most heat-resistant pathogen: it is destroyed by heating under pressure to + 115-120 ° C for at least 15 minutes. Thus, home preservation during normal boiling cannot be considered protected from botulinum toxin. Insufficient acid level (pH ˂ 4.6) in canned food increases the potential risk of poisoning.
The toxin produced by spores of C. Botulinum belongs to the class of bacterial exotoxins of systemic selective action, inhibiting the release of endogenous neurotransmitters; in case of canned food poisoning, the body is affected by types BoNT A, B and E.
Due to its resistance to human gastrointestinal enzymes, toxins are easily absorbed in the stomach and small intestine, enter the bloodstream and spread through the systemic circulation.
The pathogenesis of the virulence of absorbed botulinum toxin lies in its effect on the human peripheral nervous system (autonomic and parasympathetic); Moreover, it not only causes a violation of neuromuscular transmission , but practically blocks it. 
The proteolytic enzyme toxin (endopeptidase containing zinc), after contact with the neuronal membrane, moves into the cytoplasm and breaks down cellular proteins that ensure the delivery of acetylcholine to the synapse in response to a nerve impulse.
Further, the toxin is transferred to peripheral cholinergic synapses, where it penetrates the structure of motor effector nerve endings, preventing the release of acetylcholine in the synaptic clefts of neuromuscular connections. This leads to muscle hypotension with the development of symmetric (bilateral) flaccid paralysis. 
Symptoms of the canned food poisoning
The first signs of poisoning by canned fish, meat or vegetables can most often occur 12-36 hours after the botulinum toxin enters the body (although the manifestation time can vary from 4-5 hours to 6-8 days).
Patients have symptoms in the form of general weakness and dizziness, dry mouth, decreased vision and diplopia (double vision). If the BoNT E serotype is affected, gastrointestinal symptoms (repeated vomiting, diarrhea, bloating and cramping) can occur at the initial stage.
Further distribution of neurotoxin leads to the development of:
- ptosis (prolapse of both upper eyelids), strabismus (squint) and anisocoria (asymmetric change in pupil size) due to bilateral paresis of the oculomotor muscles
- dysphagia (difficulty swallowing) and dysarthria (slurred speech);
- loss of mobility of facial muscles;
- difficulty breathing due to a decrease in the tone of the diaphragmatic and intercostal muscles.
In severe poisoning with neurotoxin C. Botulinum (ingestion of it in large quantities), there are observed: progressive descending paralysis of the lower extremities in the proximal-distal direction with loss of muscle function (leading to ataxia and loss of ability to move independently); reduction or disappearance of tendon reflexes; constipation - due to paralytic ileus; urinary retention or urinary incontinence (due to impaired detrusor muscle contraction).
Dysfunction of the respiratory muscles causes acute respiratory failure, fraught with a complete stop of breathing.
According to infectious disease specialists, foodborne botulism in case of canned food poisoning can vary from a mild form to a lightning lesion, which ends in death within 24 hours. Although a different combination of symptoms is possible, acute respiratory failure may occur before ophthalmopathy and other signs appear.
Complications and consequences
As clinical practice shows, the main complications and consequences during recovery after poisoning with canned botulinum toxin are manifested in the form of aspiration pneumonia.
If the duration of downward paralysis is from two weeks to two months, then pulmonary complications (shortness of breath during physical exertion), weakness and fatigue can occur for many years. In severe cases, full recovery may not occur, and the consequences will be permanent.
Diagnostics of the canned food poisoning
In cases of canned food poisoning, early diagnosis of foodborne botulism - based on the assessment of clinical symptoms and anamnesis - allows you to take the necessary measures in time.
Laboratory tests of blood and stool samples confirm the diagnosis to identify C. Botulinum toxin, as well as its detection in the gastric or intestinal contents and food consumed by the patient.
See details - Botulism –Diagnosis
It should be borne in mind that there is a possibility that it is impossible to detect botulinum toxin to confirm the clinical diagnosis. In some cases (up to 30%), this is due to an insufficient level of BoNT to detect it: three days after the onset of the disease, its level in blood serum and feces decreases by half from the initial one., 
Differential diagnosis is aimed at eliminating food poisoning associated with the bacteria Shigella dysenteriae , Salmonella enterica, Yersinia enterocolitica , etc., Guillain-Barré syndrome , viral encephalitis, poliomyelitis , Erba-Goldflam disease ( myasthenia gravis syndrome ), Myasthenia grafenitis, Myasthenia gravis syndrome, myasthenia grafenitis, and myasthenitis lambenierta .
Treatment of the canned food poisoning
First aid for canned food poisoning, as well as help with food poisoning of another etiology, consists in taking activated charcoal and emptying the stomach by washing it - provoking vomiting. But this measure gives results when a suspicion of eating was recent (within one hour). If neurological symptoms appear, flushing will not help
Emergency medical attention is called immediately!
The only specific treatment for foodborne botulism is the inactivation of the toxin in the patient’s body by intravenous administration of anti-botulinum serum, a trivalent (A, B and E) antitoxin that neutralizes free BoNT, which has not yet affected nerve endings. However, the antitoxin cannot repair damaged nerve endings.
Before the introduction of the full dose, a test for sensitivity to anti-botulinum serum is carried out by intradermal administration of 0.1 ml (diluted with saline) with observation of the reaction for a quarter of an hour.
The remaining drugs in a hospital setting are used for symptomatic intensive care in case of poisoning .
It is especially important to maintain the patient's respiratory function, for which artificial ventilation is used . Often, treatment requires a long stay in the intensive care unit - with the introduction of intravenous fluids and parenteral nutrition., 
See also - Botulism - Treatment
Foodborne botulism is not transmitted from one person to another, but is often found when consuming home-made canned foods containing BoNT. Therefore, it is imperative to diagnose food samples associated with suspicious cases - to prevent further poisoning.
Prevention consists in observing the preparation technology and the sterilization regime of canned food. 
The success of treatment and the general prognosis largely depend on early diagnosis and rapid administration of anti-botulinum serum.
The cause of death in the first poisonings by canned fish, meat and vegetables is respiratory failure due to the lack of adequate support for respiratory function. According to WHO, over the past 50 years, the proportion of deaths has declined from 60% to 5-10%. 
Neuromuscular transmission in the area of the affected synapses is restored over time, but this is a very slow process.