Food poisoning: What is there to know?

Generality

What are food poisonings?

Food poisoning, commonly called "food diseases", are diseases caused by the consumption of food contaminated by toxic agents.

Note : intoxication and poisoning are problems with a different level of severity, so much so that, for example, in the classification of macromycete mushrooms (those in the shape of a mushroom, so to speak) the toxic species can be clearly distinguished from the poisonous ones.

The most common food poisonings are those caused by the metabolic action of certain microorganisms. However, in the strict sense of the term, these should NOT also include the presence of live and active infectious agents (bacteria, molds, yeasts, viruses). This last pathological form is more precisely defined as "food infection" (without toxins) or "food poisoning" (with the presence of toxins). Only in the case in which the microorganisms are absent or dead, leaving only the residues of their metabolism or part of them to act, should one speak of "food poisoning". Nevertheless, for reasons of convenience, we will generalize below and call food poisoning any foodborne illness of those described above.

Causes

Causes of food poisoning

Statistically, the most widespread food poisonings are those from microorganisms, in particular from bacteria and / or their toxins.

Pathological microorganisms or their toxins can contaminate food at any time during processing, production and storage (during which they can multiply exponentially):

1. Growth
2. Harvest / slaughter
3. processing
4. storage
5. Shipment
6. Preparation / regeneration.

Cross contamination

The so-called cross-contamination, or the transfer of live and harmful organisms from one surface to another, is the most frequent cause of food poisoning. This phenomenon mainly affects the transfer of pathogens from raw foods to those that are ready to eat, already cooked or even raw, left further in storage. By not undergoing any other heat treatment and having time to multiply, the micro-organisms thus reach the minimum concentration, or produce a sufficient quantity of toxins, to cause the disease. Note : as we will see later, some bacteria, being gram negative and therefore endowed with thermostable endotoxins, although destroyed through cooking can still give rise to intoxication.

Pathogens

The microorganisms and organisms responsible for food poisoning, in a general sense, are all those capable of generating, regardless of the system or mechanism, a foodborne illness.

Bacteria responsible for food diseases

They can generate food-related illnesses in different ways. First of all, some are able to interact directly with the mucous membranes of the digestive tract carrying out their pathological action. Note : some infections contracted with food, although harmless for normal subjects, as we have already said, can be very dangerous in pregnancy. Gram negative bacteria possess an external plasma membrane in which some toxins, usually thermostable (which do not degrade with cooking), which continue to exercise their toxic function even after cell death, are undermined. Some bacteria, both gram positive and gram negative, are capable of producing generally protein exotoxins which, if thermolabile, can be destroyed along with the bacterium by cooking. Note : some gram negative bacteria are capable of performing all three harmful functions.

Mycetes responsible for food diseases

The fungi (molds, yeasts, fungi) belong to a separate biological kingdom. Some molds that produce toxins are very dangerous and can cause, even not immediately, the death of those who take them. The same goes for the inedible macromycete mushrooms which however are classified according to their pathogenicity in non-edible properly called, toxic and poisonous, even lethal. Note: we remind you that there are a lot of false myths about mushrooms; for example, "those eaten by animals are not poisonous"; FALSE. Some animals, like snails, do not have liver. Since different species of fungi secrete hepatotoxic toxins, they have no effect on these invertebrates but are lethal to humans

Parasites responsible for food diseases

Protozoa and other parasites, especially amoebas and worms, contaminate the water, are hidden in the soil (for example Tenia solium ) or in the muscular tissues of other animals (for example the Anisakis in certain fish and the Trichinella for the pig). The following sources are therefore mainly responsible for amoeba and worm feeding diseases: non-potable water, unwashed vegetables and fruits, fish and raw meats. The cooking completely erodes them and does not produce toxins

Viruses responsible for food diseases

The virus mainly responsible for food poisoning is that of hepatitis A (HAV), which spreads mainly through water and sea molluscs reared in precarious hygienic conditions. Very sensitive to heat, they can easily be killed by cooking. Hepatitis A is almost always contracted by eating raw mussels, raw oysters, raw clams etc. Other frequent are norovirus and rotavirus.

Algae responsible for food diseases

Both of fresh and salt water, the algae are almost completely unknown to the Italian population. In other areas of the world, on the other hand, they are a real scourge. By contaminating the ecosystem with their toxins from the first link in the food chain, they accumulate in predatory fish and large marine mammals, sometimes killing them, and making them toxic to the man who consumes them. Cooking does not protect against the poisonous reactions of these toxins

Plants responsible for food diseases

All plants have natural defense mechanisms. For man some are totally harmless, others simply perform a marginal function (this is the case of anti-nutritional factors such as oxalates and phytates), a third category is toxic or poisonous. It is not rare that, almost exclusively during the wild harvest (for example the autumn colchicum or false saffron), people eat plants harmful to health. At best, misfortune resolves itself with a mild gastrointestinal symptomatology; in the worst case there can also be very serious consequences (especially for the younger ones). Cooking does not protect against many of the toxic molecules produced by plants

Animals responsible for food diseases

Almost totally absent in Italy, animals toxic to humans are mainly distributed in other oceans and other continents. Some fish, molluscs and crustaceans with a powerful toxin are particularly poisonous (see below). Theoretically foreign to the Mediterranean basin, some puffers have reached our seas through the Suez Strait. Poorly filleted (contaminating the meat with the toxins contained in the appropriate poison bags) they were subjected to food fraud with disastrous consequences for consumers. Some sea snails are classified as NOT edible or edible only when belonging to a specific sex; it is therefore advisable not to improvise fishermen and buy them from authorized dealers. The case of poisoning from land snails is very important, even if ambiguous. "Hypothetically" harmless to humans, these creatures have the characteristic of becoming real "reservoirs" of pollutants. Collecting snails on the roadside, especially at cultivated fields, greatly increases the risk of introducing harmful substances (toxic and carcinogenic) such as herbicides (glyphosate), fungicides, etc.

Most frequent pathogens

Below we offer a brief summary of the pathogens most often responsible for food poisoning:

Toxins

Mechanism of action of food toxins

The mechanisms of action of food toxins are as numerous as there are toxins present in nature. By generalizing very much these concepts that would otherwise require an entire biological text, we could define that food toxins may have the following mechanisms of action:

• They cause gastrointestinal disorders: they are exclusively gastrointestinal irritants
• Destruction of cells and tissues: it is called cytotoxic activity (a typical example is that of hepatotoxic toxins of some macromycete fungi)
• Impaired neurovegetative function: they interact with the nervous transmission system: it is called neurotoxic activity
• Promote the birth, growth and evolution of cancer: it is called carcinogenic activity
• They only cause problems in association with other molecules, such as ethyl alcohol (they are mainly mycotoxins).

Types of toxins responsible for food poisoning

Poisonous principles can be:

• Bacterial toxins:
• Exotoxins: by-products of bacterial microbiological metabolism (predominantly of a thermolabile protein type) of both gram-positive and gram-negative; some microorganisms that produce exotoxins are: Clostridium botulinum, Staphylococcus aureus, Vibrio cholerae, Shigella dysenteriae, Escherichia coli (strain O157) etc. They are mostly enterotoxic (cause diarrhea and vomiting), but that of Botox is neurotoxic
• Endotoxins: they are mainly components of the bacterial cytoplasmic membrane ONLY of the gram negative (substantially of the thermostable lipopolysaccharide type); some microorganisms that produce endotoxins are: Escherichia coli, Salmonella, etc.
• Mycotoxins:
• From macromycetes, such as amanitin and muscarine of the genus Amanita, or "properly so called"
• From micromycetes, such as aflatoxins, trichothecenes and fumonisins of molds belonging to the Aspergillus, Penicillium and Fusarium Genus
• Phytotoxins or plant toxins. They are the plant defense mechanisms. Some frankly toxic and widespread plants in the Italian vegetation are: oleander, ivy, badger, napon aconite, holly, belladonna, hemlock, dafne, morella, poisonous lettuce etc.
• Algal toxins:
• DSP (Diarrhetic Shellfish Poisoning) such as okadaic acid, dinophysitoxins,
• pectenotoxins and yessotoxins; they are produced by the dinoflagellate species ( Genus : Dinophysis, Prorocentrum, Protoceratium and Lingulodinium ). They basically produce a picture of gastroinestinal symptomatology
• PSP (Paralytic Shellfish Poisoning) such as saxitoxin (carbamate-, decarbamate- and sulfocarbamatoxins); they are produced by the dinoflagellate species ( Alexandrium, Gymnodinium and Peridinium ). They basically produce a picture of neuromuscular symptomatology
• Cyanotoxins: freshwater. They are subdivided into: hepatotoxins (microcystins), neurotoxins (anatoxin and saxitoxin) and cytotoxins; they are produced by cyanobacteria belonging to the genera Microcystis, Oscillatoria, Anabaena, Nostoc
• Animal toxins: the most famous that can be lethal also taken by mouth are the tetradotoxins, typical of some puffers (fugu, in Japan), porcupine fish, octopus (with blue rings) etc; other molluscs and crustaceans containing tetradotoxin are: Jania spp, Astropecten spp., Veremolpa scabra, Charonia sauilae, Rapana venosa, Demania toxica, Yongeichthys criniger and Hapalochlaena maculosa . Note: it is conceivable that tetradotoxin is not the result of animal metabolism, but rather of some specific bacteria that could colonize the venom sacs ( Pseudomonas and Vibrio ). In South America there are also amphibians able to secrete powerful toxins from the skin
• Residues of microbiological metabolism (for example, histamine in poorly preserved fish released by some bacteria, methanol in alcoholic fermentation freed from some yeasts etc.)
• Artificial chemical agents: for example herbicides, fungicides, insecticides, pesticides in general, rat poison, detergents, chlorine, ammonia and acids. They are mainly subject to contamination of foodstuffs, directly in the living organism as in the case of macromiceti mushrooms or land snails, or during cooking preparations.

Risk factors

Risk factors of food poisoning

The possibility of getting food poisoning depends mainly on:

• Immune system of the organism and subjectivity
• Age and general health status
• Amount of toxins or pathogens.

The people defined as having a high risk of food poisoning are:

• Elderly: as we age, the immune system, the liver and the kidneys may not respond effectively to organisms, infectious microorganisms and toxic agents
• Pregnant women: during pregnancy, changes in metabolism and circulation can increase the risk of food poisoning. Overall, during pregnancy the effects could also be more serious and affect the fruit of conception
• Infants and young children: their immune system is not yet fully developed, but reacts optimally to external stimuli and adapts extremely effectively
• People with chronic and immunodepressed diseases: having a severe chronic illness (type 2 diabetes mellitus, chronic viral hepatitis, AIDS, etc.) or undergoing chemotherapy or radiation therapy for cancer, drastically reduces the immune response.

Symptoms

What are the typical symptoms of food poisoning?

The most typical symptoms of food poisoning are: nausea, vomiting, diarrhea and abdominal cramps; high fever may also occur.

Signs and symptoms of food poisoning can start after a few hours after eating the contaminated food, or they can start days or even weeks later (for example, with some lethal fungi). The disease can last from a few hours to several days or weeks.

Due to their poor specificity and the severity, which is not always relevant, most food poisoning is treated at home; sometimes they are mistaken for viral flu.

Fortunately, cases of serious poisoning such as botulism, severe salmonellosis, cholera, fungal toxin carcinomas, fungal poisoning, severe poisoning from wild plants, neuromotor poisoning from algal toxins, death are rare. from tetradotoxin (puffer fish but not only), poisoning from chemical residues and pesticides etc.

Even in the most affluent countries diarrhea and vomiting are no longer a big problem thanks to the efficiency of the health system and pharmacological therapies, we recall that in third and fourth world countries (Africa, Middle East, South America, South East Asia) thousands of deaths continue to occur every day due to dehydration and malnutrition attributable to this kind of food-borne diseases. Only 40 years ago (1973), in Naples, there was a tremendous cholera epidemic that caused almost 1000 hospital admissions but no longer (they said) 12-24 deaths. Two centuries earlier, due to a similar epidemic, deaths amounted to several thousand.

Complications

Complications of food poisoning

The most frequent complication is dehydration, a serious loss of water and salts and minerals essential for the body's health. If you are healthy and drink enough to replace the fluids lost with vomiting and diarrhea, dehydration should not be a problem.

Infants, the elderly, and people with depressed immune systems or chronic illnesses can, on the other hand, worsen inexorably. In this case, it may be necessary to receive intravenous fluids (drip). In the most extreme cases, dehydration can be fatal.

Some types of food poisoning also have potentially serious complications, especially for some people:

• Listeriosis ( Listeria monocytogenes ): it is very dangerous for the pregnant woman's unborn child. At the beginning of pregnancy, listeria infection can lead to miscarriage; at the most advanced stage, it can lead to premature birth and a potentially fatal post-natal infection. Infants who survive a listeria infection may suffer neurological damage and developmental delays.
• Enterotoxicosis and coliform enteropathy ( Escherichia coli ): some strains of E. coli can cause a serious complication called "hemolytic uremic syndrome". This damages the lining of the tiny blood vessels in the kidneys, sometimes causing kidney failure. Older adults, children under the age of 5 and people with weakened immune systems are at greater risk of developing this problem.

Prevention

General prevention of food poisoning

To prevent food poisoning it is necessary:

• Procure only through professional, qualified and reliable suppliers
• Wash your hands often with soap and warm water, but also utensils and work surfaces in the kitchen
• Wash all fresh raw vegetable foods under running water and carefully evaluate the condition of the ingredients with visual and olfactory analysis
• Keep raw foods separate from ready-to-eat foods by preventing cross-contamination
• Keep raw food and cooked food tools separate, if not properly sanitized
• Cook the food at a suitable temperature. The best way to understand if the food is "really" cooked is to use a food thermometer, which is especially useful in the preparation of roasts
• Cook the minced meat at at least 72 ° C; single-cut steaks and roasts (not rolled) at least 63 ° C. Cook the poultry at 74 ° C. Make sure that fish and shellfish are well cooked, especially when they are not low in temperature
• Refrigerate or freeze perishable foods promptly (better by lowering the temperature); absolutely within two hours of purchase or preparation. If the ambient temperature is above 32 C °, do it within an hour
• Thaw food safely. Not at room temperature but in the refrigerator or microwave and then immediately cook it
• If in doubt, eliminate the food. Food left at room temperature for too long may contain bacteria or toxins that cannot be destroyed by cooking. Do not taste objectively poorly preserved food.

What and when to avoid?

Food poisoning is particularly serious and potentially dangerous for children, pregnant women and their fetuses, the elderly and people with compromised immune systems. These people should therefore take more precautions by avoiding the following foods:

• Raw meat or poultry
• Raw or undercooked shellfish, including oysters, clams, mussels, razor clams and scallops
• Raw or undercooked eggs or foods that can contain them, such as homemade ice cream, mascarpone cream, etc.
• Raw sprouts, such as alfalfa (alpha-alpha), beans, clover and radish sprouts
• Unpasteurized juices and ciders
• Milk and unpasteurized dairy products
• Soft cheeses like feta, brie and camembert, blue cheeses and overall unpasteurized cheeses
• Chilled pate and spreadable meat creams
• Hot dogs and raw meats.

Care

How to cure food poisoning?

The treatment of food poisoning cannot be unified for all circumstances. Since they are a set of pathologies that are also quite different from one another, they may require different treatments and different times or methods of healing. In some cases it is necessary to consult the doctor or go to the hospital; let us not forget that some poisonings are potentially lethal. In others, it may be sufficient for nature to take its course.

When to consult a doctor?

If you experience any of the following symptoms and / or clinical signs, especially knowingly that you have eaten unsafe products, you should consult your doctor.

If you experience any of the following signs or symptoms, consult a doctor.

• Frequent episodes of vomiting and inability to retain fluids in the stomach
• Bloody vomiting and / or diarrhea
• Diarrhea for more than three days
• Abdominal cramps or persistent severe pain
• Body temperature above 38 ° C
• Signs or symptoms of dehydration: excessive thirst, dry mouth, poor or no urination, severe weakness, dizziness or lightheadedness, sunken eyes, dry mucous membranes etc.
• Neurological symptoms: blurred vision, muscle weakness and tingling in the extremities of the limbs.