Poisoning from canned fish, meat and vegetables

Food poisoning can develop due to the consumption of any poor-quality food products, but poisoning from canned fish, meat and vegetables is especially dangerous, in which the body is affected by the bacterial toxin they contain.

Epidemiology

According to official CDC data, from 1975 to 2009, poisoning from canned food was identified as botulism in 854 cases in the United States. Fatalities followed in 7.1% of cases (61 patients died). In 2015-2016, the CDC registered 228 confirmed cases of botulism.

In the UK, between 1989 and 2005, there were 33 cases of botulinum toxin poisoning, with three deaths.[ 1 ]

According to statistics from the European Centre for Disease Prevention and Control, foodborne botulism rates in EU countries do not exceed 200 cases per year and amount to 0.03 cases per 100,000 people. [ 2 ]

Causes canned food poisoning

In cases of poisoning from canned food, the causes are rooted in the ingestion of botulinum neurotoxin (botulinum toxin, BoNT), produced by spores of the widespread sapronotic obligate anaerobic bacteria Clostridium botulinum, which are present on raw vegetables, meat or fish before they are canned.

The natural habitat of C. botulinum is soil, and like many anaerobes, in the environment, including on raw foods, this bacterium exists in the form of spores - dehydrated cells with an inactivated metabolism, protected from unfavorable conditions (in particular, air) by a membrane. [ 3 ]

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, then in an anaerobic environment - in the complete absence of air access in hermetically sealed canned goods - the spores, as microbiologists say, come out of a state of rest and even germinate into a vegetative form with the restoration of metabolic processes. And the deadly toxin they produce, which has a protein origin, is a product of the microorganism's metabolism. [ 4 ]

The combination of symptoms of poisoning of this etiology is called food botulism.

Risk factors

The key risk factors for poisoning from canned food – fish, meat, vegetables – are poor processing of the raw materials and/or violation of the technology for their production with non-compliance with the temperature regime, insufficient pressure and sterilization time.

Most often, people are poisoned by home-canned food, which is caused by insufficient decontamination of products, i.e. incomplete neutralization of Clostridium botulinum 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-canned food cannot be considered protected from botulinum toxin when boiled. The potential risk of poisoning is increased by insufficient acidity (pH ˂ 4.6) in canned food.

Pathogenesis

The toxin produced by C. botulinum spores belongs to the class of bacterial exotoxins of systemic selective action that inhibit the release of endogenous neurotransmitters; in cases of poisoning from canned food, the body is affected by BoNT types A, B and E.

Due to their resistance to human gastrointestinal enzymes, toxins are freely absorbed in the stomach and small intestine, enter the bloodstream and spread through systemic circulation.

The pathogenesis of the virulence of absorbed botulinum toxin lies in its effect on the human peripheral nervous system (autonomic and parasympathetic); in doing so, it not only causes a disruption of neuromuscular transmission, but practically blocks it. [ 5 ]

The toxin's proteolytic enzyme (zinc-containing endopeptidase) moves into the cytoplasm after contact with the neuronal membrane and breaks down cellular proteins that ensure the flow of acetylcholine into the synapse in response to a nerve impulse.

The toxin is then 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 junctions. This leads to muscle hypotonia with the development of symmetrical (bilateral) flaccid paralysis. [ 6 ]

Symptoms canned food poisoning

The first signs of poisoning from canned fish, meat or vegetables most often appear 12-36 hours after botulinum toxin enters the body (although the time of manifestation can vary from 4-5 hours to 6-8 days).

Patients experience symptoms such as general weakness and dizziness, dry mouth, blurred vision, and diplopia (double vision). In the case of BoNT serotype E, gastrointestinal symptoms (repeated vomiting, diarrhea, bloating, and cramping) may occur in the early stages. [ 7 ]

Further spread of the neurotoxin leads to the development of:

• ptosis (drooping 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;
• breathing difficulties due to decreased tone of the diaphragmatic and intercostal muscles.

In severe poisoning with the neurotoxin C. botulinum (if it enters the body in large quantities), the following 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 the ability to move independently); reduction or disappearance of tendon reflexes; constipation - due to paralytic ileus; urinary retention or urinary incontinence (due to impaired contraction of the detrusor muscles).

Dysfunction of the respiratory muscles causes acute respiratory failure, which can lead to complete respiratory arrest.

As infectious disease specialists note, food botulism from canned food poisoning can vary from a mild form to a lightning-fast lesion that ends in death within 24 hours. And although a different combination of symptoms is possible, acute respiratory failure can occur before the appearance of ophthalmopathy and other signs. [ 8 ]

Complications and consequences

As clinical practice shows, the main complications and consequences during recovery after poisoning with canned food containing botulinum toxin manifest themselves in the form of aspiration pneumonia.

If the duration of descending paralysis is from two weeks to two months, then pulmonary complications (shortness of breath during physical exertion), weakness and rapid fatigue can be observed for many years. In severe cases, complete recovery may not occur and the consequences will be permanent. [ 9 ]

Diagnostics canned food poisoning

In cases of poisoning from canned food, early diagnosis of foodborne botulism – based on an assessment of clinical symptoms and anamnesis – allows for timely action to be taken.

The diagnosis is confirmed by laboratory testing of blood and stool samples to identify the C. Botulinum toxin, as well as its detection in the patient's stomach or intestinal contents and food products consumed.

For more details see – 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 insufficient levels of BoNT for its detection: three days after the onset of the disease, its level in the blood serum and feces decreases by half from the initial level. [ 10 ], [ 11 ]

Differential diagnosis

Differential diagnosis is aimed at excluding food poisoning associated with bacteria Shigella dysenteriae, Salmonella enterica, Yersinia enterocolitica, etc., Guillain-Barré syndrome, viral encephalitis, poliomyelitis, Erb-Goldflam disease (myasthenia gravis), Lambert-Eaton myasthenic syndrome.

Treatment canned food poisoning

First aid for poisoning with canned food, as well as for food poisoning of other etiologies, consists of taking activated charcoal and emptying the stomach by rinsing it – inducing vomiting. But this measure gives results when the suspicion of food intake was recent (within one hour). If neurological symptoms appear, rinsing will not help

Call emergency medical assistance immediately!

The only specific treatment for foodborne botulism is to inactivate the toxin in the patient's body using intravenous antibotulinum serum, a trivalent (A, B, and E) antitoxin that neutralizes free BoNT that has not yet affected the nerve endings. However, the antitoxin cannot restore damaged nerve endings.

Before administering the full dose, a sensitivity test to antibotulinum serum is performed by intradermal administration of 0.1 ml (diluted with saline) and monitoring the reaction for a quarter of an hour.

The remaining medications are used in a medical facility for symptomatic intensive therapy in cases of poisoning.

It is especially important to support the patient's respiratory function, for which artificial ventilation is used. Treatment often requires a long stay in the intensive care unit - with the introduction of intravenous fluids and parenteral nutrition. [ 12 ], [ 13 ]

Read also – Botulism – Treatment

Prevention

Foodborne botulism is not spread from one person to another, but is often caused by eating home-canned foods that contain BoNT. Therefore, it is important to test food samples associated with suspected cases to prevent further cases of poisoning.[ 14 ]

Prevention consists of following the technology of preparation and sterilization of canned food. [ 15 ]

Forecast

The success of treatment and the overall prognosis largely depend on early diagnosis and prompt administration of antibotulinum serum.

The cause of death in the first cases of poisoning with canned fish, meat and vegetables is respiratory failure due to the lack of adequate support for the respiratory function. According to WHO, over the past 50 years the proportion of fatal outcomes has decreased from 60% to 5-10%. [ 16 ]

Neuromuscular transmission in the area of the affected synapses is restored over time, but this is a very slow process.