Childhood diseases - how the child's immunity is formed. The development of the immune system and the formation of immunity in children When the child's immunity matures

To the barrier

The innate immunity meets the "troublemakers" first. It begins to work as soon as the baby appears in the white light, but does not turn on at full power immediately. Congenital immunity is considered a non-specific system of protection against infections, it is the same in almost all people, and its main task is to prevent the development of most bacterial infections - for example, bronchitis, otitis media, tonsillitis.

Physiological barriers - the skin and mucous membranes - are the first to stand in the way of the "stranger". They have a special acidic environment (pH level), which is detrimental to "pests", and are inhabited by microflora - protective bacteria. The mucous membranes also produce bactericidal agents. Both barriers trap most of the aggressive microorganisms.

"Outsiders" who overcome such obstacles meet with the cellular link of innate immunity, that is, with specialized cells - phagocytes, which are located in the skin, mucous membranes and blood cells. They act in cooperation with special types of proteins and protein complexes, for example, the well-known interferons, which have a bactericidal or antiviral effect. Thanks to their joint efforts, only 0.1% of the “aggressors” remain “alive”.

Special forces team

Specific (or acquired) immunity is not formed immediately, but only after the birth of the baby, and in several stages. Such protection is based on a more subtle mechanism of separating “us” from “aliens” and immunological memory, that is, recognizing the “alien” with whom one has already come into contact. If the enemy is unfamiliar, then the specific immunity will not react to him in any way. Such protection is formed when two very closely related factors interact - cellular (T- and B-lymphocytes) and humoral (immunoglobulin system). Both T- and B-lymphocytes remember a foreign substance (virus, microbe, allergen) and when they meet again, they immediately destroy it - this is how immunological memory is manifested. In this case, re-infection does not occur at all or the disease proceeds for more mild form... But if T-cells always act independently, then B-lymphocytes, in order to get rid of the enemy, synthesize special antibodies - immunoglobulins (Ig). The latter are of 5 types (IgA, IgM, IgG, IgD, IgE). Immunoglobulins in the baby's body are formed gradually, reaching "adult" values \u200b\u200bonly by a certain age.

A huge role in the development of acquired immunity is played by vaccinations made in the early stages, as well as the natural encounters of a child with bacteria and viruses in the first 5 years of life. The richer the "memory" for infections, the better the baby will be protected in the future.

Ready for battle

The beginning of the way

If adults have antibodies to hundreds of "pests", babies have yet to develop them. So at different stages of development, the child's immune system has different capabilities. It depends on what and at what age he is sick and how he reacts to contacts with the outside world.

The formation of the immune system begins during pregnancy. At 3-8 weeks, the liver is formed, B-lymphocytes appear in it. At 5-12 weeks, the thymus forms, where, after the birth of the baby, T-lymphocytes begin to mature. At the same time, the spleen and lymph nodes are formed. At the 21st week of pregnancy, the spleen also begins to produce lymphocytes. The lymph nodes must trap bacteria and other foreign particles and not let them go further inside. But they begin to perform this barrier function only by the age of 7–8. If in the I-II trimesters future mom will undergo an infectious disease, will eat unbalanced, there will be a risk of incorrect formation of these organs. During these periods, a woman should, if possible, avoid contact with patients with influenza and ARVI, hypothermia.

Between the 10th and 12th weeks of gestation future child begins to produce its own immunoglobulins, primarily of class G. He also receives a certain amount of the latter through the mother's blood and the placenta almost immediately after conception. But until the 6th month of pregnancy, maternal immunoglobulins are present in the blood of the unborn child only in very small quantities. For this reason, very premature babies have a very high risk of infection.

After the 32nd week of pregnancy, antibodies begin to form intensively, which will protect the baby from diseases in the first months of life.

There is a contact!

The moment of birth marks the first critical period in the development of the child's immune system. Within a month, your own immune defense will be suppressed, but it cannot be otherwise. After all, already passing through the birth canal, the baby meets bacteria that are new to him, and in the external environment where he gets after birth, there are billions of microorganisms unfamiliar to him. And if the immunity was as strong as in adults, the baby simply would not withstand the body's reaction to "strangers." For this reason, the mechanisms of innate immunity in a healthy newborn operate at about 40-50% of the adult level, and the synthesis of immunoglobulins - by 10-15%. The baby is very susceptible to viruses and microbes, and the likelihood of infectious diseases is high.

At this stage, only mother's immunoglobulins, obtained in utero, help him to resist specific infections. They protect the baby from those infections with which the mother was ill or from which she was vaccinated (diphtheria, poliomyelitis, measles, rubella, chickenpox). Also at this time, the intestines begin to colonize with bacteria. In addition, the baby receives beneficial microorganisms and immunoglobulins with an artificial mixture or mother's milk. Penetrating into the intestine, these substances make its mucous membrane inaccessible to pathogens, thus protecting the baby from many infections and allergies. But the crumbs receiving breast milk are better protected. After all, together with milk, they also receive antibodies to those infections that my mother has already had.

Human milk proteins stimulate the development of the baby's immune system. Modern milk formulas also contain immunoglobulins, but their doses are designed for the average child. In its composition, mother's milk is suitable for a particular baby.

Since at this time the baby is at high risk of diseases, the circle of communication should be limited to the closest relatives - those people with whom he lives. Getting from the hospital to the apartment and communicating with mom and dad, the child gradually gets used to the "home" microflora, and it becomes safe for him. If guests come to the house, ask them to wash their hands with soap and show them the crumbs from afar.

During this period, on the one hand, it is necessary to strictly observe the rules of hygiene, and on the other, not to overdo it. Otherwise, the necessary microbes will not be able to colonize the skin and mucous membranes, in addition, the sterile atmosphere will not make it possible to fight bacteria and develop the immune system. To maintain balance, it is enough to do wet cleaning 2-3 times a week, vacuum up the upholstered furniture and wash your hands thoroughly with soap and water every time before approaching the newborn.

Serious reason

According to WHO, children under 3 years old suffer 6-8 respiratory diseases per year. On average, if the immune system is working properly, a baby can endure 1-2 rather severe viral infections (influenza, adenovirus infection) and 4-5 “colds” per year, and may be easy and accompanied by a runny nose, coughing, low fever. This does not mean at all that the child has reduced immunity. The only way to fully protect yourself from diseases is to develop your own immunity, which can only be formed after meeting with a microbe. Frequent acute respiratory infections and acute respiratory viral infections should not be considered as a manifestation of the weakness of the immune system.
A serious reason to visit an immunologist may be frequent colds that occur with complications and turn into pneumonia, bronchitis, repeated infections with infections, to which lifelong immunity should be developed - for example, measles, rubella, chickenpox... But in the latter case, you need to take into account that if the baby has had them for up to a year, the immunity may be unstable. With long-term treatment with antibiotics, antifungal or hormonal drugs, maintenance therapy with immunomodulators is required. In this case, the consultation of an immunologist is also needed.

Immune response

3-6 months is the second critical period. Maternal antibodies are gradually destroyed and by 6 months are completely gone from the body. An immune response develops to the penetration of infection in the body of the crumbs, since the production of its own immunoglobulin A begins, which is responsible for local immunity. But he does not have a "memory" for viruses, so the vaccinations that are given during this period must be repeated later. It is very important to keep breast-feeding.

Strengthen protection will also help water procedures... From 3 months, after a minute of bathing in water with a temperature of 36-37 ° C, the baby is poured with water, the temperature of which is 1–2 degrees lower. You can also gently wipe the baby after taking a bath with a mitten dipped in water at a temperature of 33–36 ° C. Within 2 minutes, wipe your hands from hand to shoulder and legs from foot to knee, and then wipe dry. Once every 5 days, the water temperature is lowered by a degree and gradually brought to 28 ° C.

Children's surprises

2-3 years - the third critical period, the time of active formation of acquired immunity. Contacts with the outside world are expanding, many children start attending nurseries or kindergartens and are often sick. This period usually lasts 6-12 months. The reason for repeated colds can also be stress, the reluctance of the baby to attend a nursery or a garden. But you shouldn't give up preschool. The crumbs who do not visit the garden or nursery, of course, get sick less often. But as soon as they start going to school, the frequency of viral infections in them increases dramatically. Their "organized" peers by this age manage to "get acquainted" with many viruses and catch colds less often.

Usually at this age, the "kindergarteners" illnesses last a long time and pass one into another. This does not mean that they have weak immunity. It's just that babies come into contact with a large number of pathogens, their mucous membranes are vulnerable, since immunoglobulin A is still produced in small quantities. Thus, the immune system is actively training: in a collision with "outsiders" the body produces antibodies, which later help it to cope with diseases faster or prevent them from occurring at all. To finally form, immunity requires up to 8-12 such "trainings" per year.

The overall resistance of the baby's body to infections from vaccinations practically does not depend. A child who has received a full set of vaccinations can often get sore throat, bronchitis, otitis media, which are caused by common microbes.

At this age, it is better to do without immunostimulating drugs. Their use can weaken the child's immunity. In addition, immunostimulants have contraindications and side effects... A diet balanced in vitamins and trace elements, adherence to the daily regimen, physical activity and hardening procedures will have a much greater effect.

Also at this age, due to the active "exchange" of various pathogens with peers, there is an active growth of tonsils and lymph nodes. This link of innate immunity serves as the first line of defense against potential pathogens of various diseases. When they get infected, they swell and become inflamed.

Most of the revaccinations fall around this time. They are aimed at maintaining the immunity that was developed during previous vaccinations.

Almost adult

At 5–7 years (the fourth critical period), the levels of M and G immunoglobulins approach the adult level, the number of T and B lymphocytes also becomes close to their number in an adult. Immunoglobulin A is still in short supply. Because of this, diseases of the upper respiratory tract at this age can become chronic (chronic tonsillitis, chronic laryngitis) or often recur. To avoid this, you need to very carefully and completely cure them. Also, in the autumn-winter period, it is recommended to give your child a multivitamin. For specific recommendations (course of administration and names of vitamin complexes), you should contact your pediatrician. But before prescribing immunostimulating agents, you need to know which link of the immune system suffers and what exactly needs to be strengthened. Only a detailed immunogram provides accurate information about this.

But most children get sick much less often and cope with infections faster. The value of immunoglobulin E reaches its maximum, therefore, the frequency of allergic reactions increases.

Many parents who see their beloved child sick are worried about the state of his immunity. Such a reaction is absolutely justified, because in modern world negative factors can greatly affect the health of children. To understand how true such fears are, and not to miss the moment, you need to know the features of the development of the immune system.

Immunity is the body's way of protecting against aggressive environmentcontaining many different foreign agents such as viruses, fungi, bacteria and other microorganisms. This ability to resist infections is the result of the well-coordinated mechanism of the immune system.

Congenital immunity

The word "innate" speaks for itself. This immunity works from the moment a child is born.

The first obstacle that microbes encounter on their way is the skin and mucous membranes. The skin is a complete barrier for them due to its impermeability and acidic pH of the surface. The mucous membranes in contact with the external environment have a whole range of protective properties. The mucus secreted by the cells does not allow microorganisms to attach, and the movements of special cilia "drive" them out. Body fluids (tears, bile, saliva and others) have bactericidal properties, that is, the ability to kill bacteria.

If, for some reason, the barrier did not work, and the microorganism penetrated it, cells come to the rescue - phagocytes, eliminating foreign agents.

Acquired immunity

It is formed gradually. Each encounter with a microbe remains in the "immunological" memory, with the help of which the body is able to resist re-infection with this infection, to react faster. Such protection is due to two links of acquired immunity - cellular (T and B lymphocytes) and humoral (antibodies). Lymphocytes remember the microbe, and antibodies kill it. The mechanism of "immunological" memory is at the heart of vaccination.

Facing various microorganisms throughout life, the human immune system develops and accumulates "experience" to effectively respond to any invasion. The child's immunity is imperfect, the process of its formation is long and has several critical periods.

First critical period (up to 28 days of life)

At birth, the immune system is purposefully suppressed. This is because overnight meeting with a huge number of new bacteria would be too serious a test for her.

During this period, the newborn is susceptible to the microbes surrounding him, but not defenseless against them. The antibodies in the mother's breast milk provide effective defense.

The formation of a normal immune system and allergies (as manifestations of an inadequate immune response) run in parallel. The correct balance of the intestinal microflora of a child with a predominance of bifidobacteria is a factor that protects against the development of allergic diseases. The colonization of beneficial bacteria occurs due to breastfeeding.

Second critical period (up to 4-6 months)

The amount of the mother's protective antibodies gradually decreases, and by about 6 months they are excreted from the baby's body. This fact determines the second critical period. The immune system acquires the ability to independently produce antibodies in response to infection, but it still cannot "remember" them. That is why the vaccination carried out at this age requires repetition.

The local immunity of mucous membranes in contact with the external environment is very weak, which means that they are most susceptible to microbial attacks. Repeated ARVI, acute respiratory infections (ARI) and intestinal infections are a common problem. Childhood infections such as whooping cough and measles can occur atypically without leaving protective immunity.

Allergy in this period is most often food (for example, to protein cow's milk) and is masked by the phenomena of diathesis.

Third critical period (up to 2 years)

An important stage in the development of the immune system, at which the acquired immunity begins to form "immunological" memory for the transferred infections.

Freedom of movement, active contact with other children and animals - all this leads to meeting new microbes. The frequency of the child's diseases is growing, one disease follows another, but you should not be afraid of this - the immune system is actively gaining "experience", meeting with various viruses and bacteria.

The work of the local immunity system of the mucous membranes is still insufficient. Therefore, respiratory diseases such as rhinitis, sinusitis, pharyngitis, tonsillitis, laryngitis, tracheitis, bronchitis remain the most common. This condition of the baby forces many parents to resort to various drugs that stimulate the immune system, but this can only interfere with the formation of the normal immune system of the child and weaken it. Better to abstain from such medications.

The phenomena of allergic diathesis (atopic dermatitis) at this age may increase.

Fourth critical period (up to 4-6 years)

Finally, the concentration of the child's protective antibodies corresponds to that of an adult. However, the local immunity of the mucous membranes is still inadequately developed, which can lead to the formation of chronic respiratory diseases.

For children of this age, helminthic invasions (giardiasis) are characteristic.

At this stage, hypersensitivity to allergens inhaled from the air (house dust, pollen of plants and others) and, as a result, allergic rhinitis (rhinitis) and / or bronchial asthma can join the manifestations of skin allergies.

Fifth critical period (12-13 years for girls and 14-15 years for boys)

Teenage years. The increased growth of the child is combined with a decrease in the volume of the organs of the immune system, and the rapid hormonal changes suppress the cellular link of the immune system. During this period, the impact of external negative factors, for example, smoking, increases. Susceptibility to various viral infections is characteristic.

Allergic diseases such as bronchial asthma may subside temporarily but reappear later at a young age. The control of an allergist-immunologist is mandatory.

The formation of the child's immune system is active. It is important for parents to know the vulnerable periods, be careful and prevent the transition of acute infectious diseases into chronic ones, and also timely prevent the development of allergies if there is a predisposition to it.

Frequent illness of a child is not always an indicator of the weakness of his immunity. Self-administration of immunostimulating drugs can adversely affect the development of the immune system. None of them should be used without a preliminary study of the state of all components of immunity (analysis of "immune status") and the recommendation of an allergist-immunologist.

A child is born with a very weak immune system. It produces immune cells, but they are not enough to build a reliable barrier to repel the attack of viruses and bacteria. Therefore, the protection of the child's body is based on immunoglobulins O (they are able to recognize "strangers" and fight chronic infection), which the baby receives from the mother in utero in the third trimester of pregnancy. If the expectant mother is healthy, then the child is reliably protected by immunoglobulins, if not (even ordinary acute respiratory infections are taken into account), placental insufficiency may occur, and the baby will not receive rescue cells. However, the antibodies received in utero for only three months protect the little person from diphtheria, poliomyelitis, measles, rubella, meningitis, scarlet fever, rheumatism and other very dangerous ailments, but only on condition that the mother has had them or, at least, was vaccinated against these diseases.

By the fourth or fifth month of a child's life, the production of its own immunoglobulins in his body is gradually improving. True, these are only immunoglobulins M, which are the first to be involved in the fight against invading "agents", but, alas, do not protect the baby from infectious diseases. Fortunately, for up to a year, it is more or less reliably protected by immunoglobulins A obtained with breast milk, which are responsible for the local immunity of the nasopharynx. The most dangerous period for a child's immunity is from 6 months to 1, 5-2 years. At this time, maternal antibodies gradually lose their strength, and the production of their own has not yet been established.

The number of own protective cells of type A begins to grow in children only after 4 years of age, therefore immunologists advise sending a child to kindergarten no earlier than 4, 5 years. At 5-6 years of age, the formation of immune cells continues rather slowly, this explains the susceptibility of preschoolers to viral infections.

Only by the age of 7 years, the indicators of immunoglobulins M, O, A in a child approach the adult norm - which is why experts recommend sending children to school after 6 years. By the way, the full production of antihelminthic immunoglobulin E begins no earlier than 7 years, so helminthiasis is a scourge of preschoolers.

It would seem that adolescents' immunity should finally "mature", but it is hindered by ... hormones, the activity of which temporarily weakens the body's defenses - teenagers become more sensitive to tuberculosis, and the risk of developing chronic diseases increases. As soon as hormonal background in young people, the immune system is getting stronger. The last chords in the formation of protective forces fall on the period of 18-20 years, but you always need to maintain and strengthen the immune system.

Harmful for immunity:

Swaddling

Studies by neonatologists (doctors who look after babies up to three months of age) show that swaddling can interfere with the formation of immunity. If the child is constantly wrapped tightly, his body gets used to the heat, and even a minimal breeze or temperature drop is enough for hypothermia. The immune system of such a baby weakens, which means that it cannot actively resist pathogens.

Bad habits of parents

It has been proven that even secondhand smoke destroys vitamin C in the body. As you know, ascorbic acid is responsible for our adaptive capabilities and increases resistance to infections.

Immunostimulants

Immunologists are unanimous: drugs that boost immunity are harmful if parents prescribe them to their children on their own. This even applies to echinacea, because it is recommended to take medications based on this plant only for purulent processes - otitis media, sinusitis, etc. With a common cold, echinacea can imbalance the body's defenses. In addition, immunostimulants can provoke the flourishing of allergies, since most of them are made with herbs.

Sterility

If you sterilize dishes and toys, wash the floor special means and boil diapers, the baby's body will not learn to produce antibodies against common viruses and bacteria that will have to be met in kindergarten and school.

Intelligent press

A modern school curriculum plus additional classes for the development of intelligence is a solid load on the child's body, including the immune system. The mechanism of influence of constant brain attacks is as follows: children burdened with science get tired, often get sick, and this, in turn, harms the formation of a reliable defense system.

It is useful for immunity:

Mother's milk

With it, the child receives all the necessary nutrients, vitamins and trace elements, as well as very important components - antibodies. Children who are breastfed are less likely to get sick, suffer less from allergic diseases, otitis media, pneumonia. The longer you breastfeed, the higher your baby's body resistance.

Cold and movement

Experts consider these factors to be the best immune stimulants. You will help your child a lot if you teach him to sleep with an open window at any time of the year, you will not litter the baby's body with harmful sweets and once again go out with him to run and jump in the fresh air.

Dairy products

In the intestine, immune cells are formed that synthesize immunoglobulins, therefore, malfunctions of this organ (constipation, disorders) harm not only the digestive system, but also the immune system. The best way to strengthen the protective function of the body - to populate the gastrointestinal tract with beneficial microflora, bifidobacteria and lactobacilli of fermented milk products - yogurt, kefir, acidophilic milk. Sometimes a lack of beneficial bacteria causes allergies to develop.

Diseases

Immunity needs training in the form of ... diseases. However, not every ailment helps to strengthen the immune system, but only one (for example, acute respiratory infections, acute respiratory viral infections) that does not give serious complications and does not go into chronic form... The main thing is that training does not become constant, depleting the defenses.

Why does the child have weak immunity? To understand this issue, we have collected information that explains the principle of operation, the features of the formation of immunity in children and the reasons for its decrease in babies under one year old and older children. From the article, parents will learn by what signs it can be determined that a child has weak immunity.

What is immunity and how does it work?

When various viral or bacterial infections make their way into the human body, it begins to actively fight them. The ability of the immune system to fight different kinds infections that enter the body is called immunity.

Immunity is a set of physiological processes and mechanisms aimed at preserving the antigenic homeostasis of the organism from biologically active substances and creatures carrying genetically foreign antigenic information or from genetically foreign protein agents.

Immunity classification

Distinguish congenital ( species) and acquired immunity ... Species (congenital, hereditary) immunity is inherited by the baby. The acquired immunity accumulates throughout a person's life and is divided into natural and artificial.

Natural (acquired) immunity divided into active and passive. Active natural immunity accumulates gradually after a successful fight against a particular infection. Not all diseases that have been transferred contribute to the formation of lifelong immunity. The child can carry some diseases several times after the next contact with the microbe. If a child has had rubella or, in almost all cases, he will acquire persistent lifelong immunity against these diseases. The duration of immunity depends on the ability of the microbe to induce an immune response. Passive natural immunity formed by antibodies that are passed from mother to baby through the placenta during pregnancy and through milk when breastfeeding.

Artificial acquired immunity divided into passive and active. Active immunity formed after holding. Passive immunity appears after special serum with antibodies is injected into the human body. The duration of such immunity is measured in several weeks, and after this period it disappears.

The concept of the immune response and its types

Immune response - this is the reaction of the body to the ingress of any alien microbes or their poisons into it.

Types of immune response:

• Non-specific immune response it is activated almost instantly, as soon as the microbe enters the child's body. Its purpose is to destroy the microbe by forming a focus of inflammation. Inflammatory response - universal defense process, aimed at preventing an increase in the field of activity of the microbe. The general resistance of the body directly depends on non-specific immunity. Children with weakened nonspecific immunity are most susceptible to various diseases.
• Specific immune responset - the second stage of the emergence of protective reactions of the body. At this stage, the body tries to recognize the microbe and develop protective factors that will be aimed at eliminating a certain type of microbe. Specific and non-specific immune responses invariably overlap and complement each other.

The specific immune response is subdivided into cellular and humoral:

• When it works cell specific immune response , clones of lymphocytes are formed, seeking to destroy targets, the membranes of which contain foreign materials such as cellular proteins. Cellular immunity helps eliminate viral infections, as well as some types of bacterial infections (for example, tuberculosis). In addition, activated lymphocytes are an active weapon in the fight against cancer cells.
• Specific humoral immune response acts through B-lymphocytes. After a microbe is recognized, they actively synthesize antibodies according to the principle of one type of antigen - one type of antibody. During all infectious diseases, antibodies are always produced. The humoral immune response develops within a few weeks, it is during this time that the necessary amount of immunoglobulins is formed in the body in order to completely neutralize the focus of infection. Clones of lymphocytes are able to remain in the body for quite a long time, therefore, upon repeated contact with microorganisms, they give a powerful immune response.

There are several types of antibodies (immunoglobulins):

• Antibodies type A (IgA) are needed to provide local immunity. They try to keep germs out of the skin or mucous membranes.
• Antibodies type M (IgM) are activated immediately after the child has had contact with the infection. They are able to bind several microbes at the same time. If antibodies of type M (IgM) were detected during a blood test, then they are evidence of the onset and growth of an acute infectious process in the body.
• Immunoglobulins type G (IgG) able to protect the body from the penetration of various microorganisms for a long time.
• Antibodies type E (IgE) - protection of the body from the ingress of microbes and their poisons through the skin.

How immunity is formed in children: five critical periods in the life of children

The baby's immune system begins to form even during intrauterine development, when strong bonds are established between the body of the mother and the child. A small amount of its own M antibodies begin to develop in the baby at about the twelfth week of pregnancy, and their number increases immediately before delivery.

In addition, T-leukocytes appear in the body of the crumbs by the 12th week of pregnancy, the number of which increases on the fifth day of the baby's life. In the first months of a child's life, maternal antibodies protect, since the baby's body is practically unable to synthesize its own immunoglobulins. The required amount of type M antibodies approaches adult indicators only by 3-5 years of a child's life.

There are five critical periods in the life of children that affect the formation of the immune system:

1. The neonatal period (up to 28 days of the child's life). The kid is protected maternal immunity, while his own immune system is just beginning to form. The child's body is susceptible to the effects of various kinds of viral infections, especially to those from which the mother did not transmit her antibodies to the baby. During this time, it is extremely important to establish and maintain breastfeeding, as breast milk - best protection for the kid.
2. The period from 3 to 6 months of a child's life. At this time, maternal antibodies are destroyed in the baby's body, an active immunity is formed. During this period, ARVI viruses are especially active. In addition, babies can easily pick up an intestinal infection and move inflammatory diseases of the respiratory system. The baby may not acquire antibodies from the mother to diseases such as whooping cough, rubella, chickenpox, if she does not have vaccinations or she has not had them in childhood. Then there is a great risk that these diseases can occur in the baby in a rather severe form. The likelihood of a recurrence of the disease is high, because the infant's immunological memory has not yet been formed. There is also a high risk of allergies in a child, primarily to food.
3. The period from 2 to 3 years of a baby's life. The child actively learns the world around him, but the primary immune response still predominates in the work of his immunity, and the local immunity system and the production of type A antibodies remain rather immature. Children during this period are most susceptible to bacterial, rather than viral, infections, which can be repeated repeatedly.
4. Age 6-7 years old.During this period, the child already has luggage with accumulated active immunity. However, parents should be concerned that the disease may become chronic. In addition, the risk of allergic reactions is high.
5. Teenage years. In girls, it begins at 12-13 years old, in boys a little later - at 14-15 years old. At this time, rapid growth and hormonal changes in the body occur, which are combined with a decrease in the lymphoid organs. Chronic diseases make themselves felt with renewed vigor. In addition, the child's immune system is tested if the teenager encounters bad habits.

Weak immunity: the main signs

Signs of lowered immunity in children different ages :

• in young years.
• A child often has protracted acute otitis media, and a runny nose will certainly transform into sinusitis or sinusitis. There are problems with the adenoids, as well as the palatine tonsils.
• Constant tearfulness and irritation, bad short-term sleep.
• Poor appetite.
• Pale skin.
• Poor bowel function. The stool is irregular or too loose, or loose, or it is difficult for the baby to empty the bowels.
• The child recovers for a very long time after being ill.
• Frequent appearance of fungal infections.

Factors that reduce children's immunity

Causes of reduced immunity in infants:

1. Trauma during passage through the birth canal.
2. Heavy pregnancy.
3. Poor heredity and predisposition to infectious diseases.
4. The kid gave up breast milkbefore reaching six months of age.
5. Incorrect complementary feeding with an excess or lack of essential food elements.
6. Failure of the digestive tract.
7. Drug overdose.
8. Severe psychological trauma.
9. Poor ecology, especially in areas with increased radiation.

Reasons for decreased immunity in school-age children:

1. Recurring diseases of the ear, throat, nose.
2. Unhealthy diet, including eating foods that are high in nitrates or pesticides.
3. Stress and constant nervous tension.
4. The emergence of conflicts leading to misunderstanding and rejection in the team.
5. Abuse of TV, computer, other modern gadgets.
6. The child spends the minimum amount of time on the street, does not rest. Fatigue and overwhelming stress: school plus many additional circles and sections.
7. In the spring and autumn, allergies worsen every year.

If the child's immunity is weak, then it is necessary to strengthen it. How to do this will be described in the article "How to strengthen the immune system."

Child immunity is the subject of passionate debate between parents. Some are supporters of strict measures, dousing and tempering. The latter anxiously protect the offspring from any draft. Sometimes pediatricians are involved in disputes, but they also do not clarify: each has his own theory and justifies his view of strengthening children's health based on his own practice.

What is immunity and how does it work

Immunity is the body's immunity to pathogenic bacteria, pathogenic microorganisms, poisons and toxins coming from the outside world. Figuratively speaking, this is an armor through which foreign microorganisms cannot get to health.

With good immunity, a complex reaction is triggered to any external invasion: the endocrine, nervous systems, metabolism begin to produce antibodies (they are different), and in this way resist an external attack. The more antibodies are produced, the more powerful the defense. In the first case, they talk about a strong immune response, in the second - about.

Which organs form the immune system

Direct influence is exerted by:

• thymus;
• bone marrow;
• embryonic liver (the fetal liver also produces protective cells during intrauterine development);
• intestinal lymphoid formations;
• lymphatic bonds;
• spleen.

The thymus gland, which is directly responsible for the body's defense, is located behind the sternum. The largest organ in a child: its weight is 15 grams. In an adult, the thymus gland already weighs much less - only 6 grams.

Bone marrow cells also take an active part in immune protection: these are lymphocytes, monocytes, which are found in human tissues and blood (this is how cellular immunity works). What matters is the work of the products of the vital activity of cells ( it comes about humoral immunity).

But we often hear that strong immunity was inherited by the child. Or phrases like: immunity must be earned. It turns out that a lot depends on the type of immunity.

Types of immunity

Immunologists distinguish two main types of immunity. It is congenital and acquired. Congenital immunity is inherited by the child genetically: in our time, humanity does not suffer from such terrible diseases as the plague or smallpox. And the "knowledge" is inherited by the child. The acquired abilities of the defense system are another matter: they appear after an illness, even in the mildest form. The principle of vaccination is based on this.

In the process of formation, immunity goes through a difficult path: at each stage its own characteristics appear, which immunologists and pediatricians always take into account to strengthen children's health. Below we have given a table, where we have clearly shown: what the child's immune system is facing from birth to adolescence.

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Five critical periods in a child's life

The formation of immunity in children begins in the first trimester of pregnancy between 8-10 weeks. Then the first lymphocytes are laid, antibodies are produced in the mother. By the time of birth, the number of antibodies increases. They protect the baby during childbirth: the risk of contracting tetanus, measles, rubella and some other infections is minimal at first.

But after the birth of the baby, it is important for parents to be on guard. The main stages of the development of immunity in childhood include 5 periods when the protective barrier is highly vulnerable.

Stage	Child's age	What happens to the immune system	Health risk
1 period of development	The first 29 days of life	The defenses continue to support the mother's antibodies. They get to the baby through breast milk. largely depends on the nutrition of the young mother. It matters: is there enough food, whether there are no bad habits.	Resistance to pathogenic flora is still very weak. There is a risk of developing purulent lesions of certain parts of the body, pustules with improper care. In rare cases, dangerous sepsis develops - an inflammatory process in the blood.
2 development period	3-6 month	The number of maternal antibodies is gradually decreasing, and their own is still insufficient. Those that are there do not leave an immunological memory.	A child can quickly get the flu, catch a runny nose, cough. If at this age a child falls ill with measles (flu, whooping cough), then immunity is not developed and the risk of contracting the disease a second time is high. During this period, a predisposition to allergies makes itself felt, dysbacteriosis develops with untimely nutrition, a violation of the mother's diet (if breastfeeding).
3 development period	From 6 to 24 months	Maternal antibodies stop helping the child, and there are still very few of her own cells. This period is considered very dangerous for the child's immunity.	A predisposition to skin diseases manifests itself - dermatitis appears, many children suffer from diathesis. Increasingly, there is an allergic reaction to certain types of food, milk. colds, runny nose and other ENT diseases.
4 period of development	4-6 years of life	Antibody formation is very slow. Immunity is extremely weak.	The risk of contracting viruses remains high: that is why children in kindergartens are constantly sick. If diseases are started, ailments can become chronic. Immunologists say: the makings of many adult chronic "sores" are laid precisely at this age.
5 development period	12-13 years old for girls, 14-15 years old for boys.	are noticeably strengthening, their formation is coming to an end. But the "game of hormones" begins. The number of androgens (sex hormones) increases, which suppresses cellular immunity, and the number of antibodies decreases. It becomes finally clear: how the body will react to the attack of viruses: strong or weak.	As teenagers begin to indulge in cigarettes, try alcoholic beverages, eat junk food (fast food), doctors talk about testing the defenses against external factors. From this, a cough develops, acne appears. But the risk of getting sick with bronchial asthma, dermatitis - that is, any pathology caused by allergies is reduced.