Tuberculin diagnosis in children: methods, types of reactions, results

2024 Author: Priscilla Miln | [email protected]. Last modified: 2023-12-16 00:21

Tuberculin diagnostics in children is one of the effective methods to prevent the epidemic of tuberculosis in our country, reducing the likelihood of developing advanced forms of infections. This procedure has undergone some changes in recent years. The basis of such a diagnosis are tuberculin tests, which are carried out using special preparations. How such diagnostics are carried out today will be discussed further.

General definition

Tuberculin diagnostics in children is a set of special tests and samples aimed at detecting sensitization in the body to MBT antigens. Previously, such tests were performed using tuberculin. Today, different methods and preparations are used, which makes it possible to improve diagnostic procedures and increase the percentage of reliable results.

Tuberculin presentsis a complex compound, the main active element of which are tuberculoproteins. This drug is able to cause a delayed-type hypersensitivity reaction in an organism infected with Koch's bacillus (tuberculosis bacterium). This drug is not capable of causing disease, since it does not contain live microorganisms. Also, tuberculin is not able to provoke the development of immunity to the disease. But it causes a specific reaction in sick people.

Tuberculin diagnostics allows early detection of tuberculosis in children and adolescents. This procedure takes place during periodic inspections in kindergartens, schools and medical institutions. Having identified with its help children who are suspected of developing the disease, additional diagnostics are carried out. If it is confirmed that a disease develops in the body, complex treatment is carried out. After its expiration, an individual tuberculin diagnosis is carried out for a particular child.

Many parents do not understand why BCG vaccination is carried out then. Its purpose is not to protect against infection. The vaccine can only limit the development of tuberculosis at the level of the lymphatic system. If infection occurs, which happens, according to statistics, in 70-80% of the population in the Russian Federation, severe generalized forms of e can only develop thanks to the BCG vaccine. In this case, the tuberculosis bacterium will not be able to infect the bone tissue, the brain. But the well-known Mantoux reaction is just a test that can identify a person infected with tuberculosis.

Goals andtasks

It should be understood that the goal of tuberculin diagnostics is to reduce the number of cases, both among children and adults. It often happens that a child becomes infected with tuberculosis from close relatives. For example, from a grandmother or grandfather who had not been examined for a long time, they did not do fluorography. If a child is diagnosed with tuberculosis, the whole family is examined.

The goal of tuberculin diagnostics is to reduce both the percentage of morbidity and mortality in the country from this infection. It should be noted that thanks to the use of new, modern approaches, it was possible to achieve high results. It should be noted that since 2008, the incidence has decreased by 1/3, and mortality - by 2.5 times. In 2017 alone, the number of cases of infection decreased by 9.4%, and mortality by 17%. For this, a number of problems of tuberculin diagnostics were solved and are being solved:

1. Identification of people infected with the bacterium for the first time, as well as those with a turn in the process of testing. This makes it possible to identify TB patients at an early stage of the disease.
2. Formation of risk groups, which include people who have contact with TB patients or who have already recovered from the infection. This requires supervision by a phthisiatrician. This also includes people who, during the test, have a hyperergic reaction or an increase in papule compared to last year by 6 mm or more.
3. Selection of contingent for BCG-M vaccination. These are children aged 2 months and older who have not been vaccinated inmaternity hospital, as well as those requiring revaccination at the age of 7.
4. Determination of the epidemiological situation in the region, in individual zones, which allows you to determine the risks of infection.

Previously, the tuberculin test was possible only with the introduction of subcutaneous Mantoux tests. This technique has a number of features. These tests are carried out once a year from the moment when the child vaccinated with BCG is 12 months old.

Mantoux reaction

Today, special requirements have been developed that put forward tuberculin diagnostics in children. Order of the Ministry of He alth No. 124n dated March 21, 2017 “On approval of the procedure and terms for conducting preventive medical examinations in order to detect tuberculosis” regulates the work of doctors.

Today, children from one to 7 years old are tested using the Mantoux reaction. It is similar in its principle of action to an allergic reaction. After the introduction of tuberculin under the skin, a reaction occurs. The body reacts to the vaccine administered in different ways. If a person has tuberculosis, including he is a carrier of the infection, the Mantoux test will be increased. In this case, the reaction is said to be hyperergic. But a similar result can also be explained by a tendency to allergies, the presence of chronic diseases in the body. In some children, a hyperergic reaction is observed due to the structural features of the skin, dietary habits, etc. The older the child, the more likely it is to get a false positive result. Therefore, at an older age, starting at the age of 8, a diaskintest is performed. Tuberculin diagnosis in children in this case will be more accurate.

During the test, a thermally and chemically treated vaccine from bacteria extract is used. An aqueous solution is injected into the upper layers of the epithelium. The skin on the forearm is lifted. During tuberculin diagnostics, the Mantoux test is performed according to a special technique. 0.1 mg of solution is injected, which is an absolutely safe dose for the child's body. Feelings do not change with this injection.

If the body was already familiar with the bacterium that causes tuberculosis, the reaction will be positive. If the child has not been vaccinated with BCG, the reaction will be negative. This is possible if the child did not undergo this procedure for he alth reasons. Some parents do not allow vaccination by signing a tuberculin test waiver. Some children who have received the BCG vaccine may also have a negative reaction. This is a deviation from the norm, which indicates an incorrect injection or a specific reaction of the body to it.

If the body was familiar with a tubercle bacillus (during BCG vaccination), a small swelling and redness appear at the injection site of tuberculin. It is collected from the lymphatic channels by T-lymphocytes. After 3 days evaluate the result of the test. It must meet certain standards.

Interpretation of the Mantoux result

When 3 days pass after the introduction of the sample, tuberculin diagnostics involves measuring the size of the papule. This is done by the doctor, since there are many nuances of interpreting the result. There are five possible outcomes.

If inat the time of tuberculin diagnostics, the test is negative, no compaction appears on the arm at all. This indicates the ineffectiveness of the introduced BCG vaccination. They repeat it.

The second type of reaction is called doubtful. Redness on the forearm is very small, no more than 4 mm. An indeterminate result is also not the norm, it requires consultation with a phthisiatrician.

Positive reactions are the norm. In this case, the size of the papule is 5-16 mm. If the child was vaccinated with BCG, this indicates a normal reaction of the body. But it is worth remembering that if such a test has not passed within 7 days, you need to contact a phthisiatrician. This may be a sign of infection.

Hyperergic reaction is determined if the papule is larger than 17 mm. If at the same time suppuration, soreness appears, and nearby lymph nodes are enlarged in size, this may indicate the presence of an infection in the body. Advanced diagnostics required.

Sometimes it happens that a reaction is recognized as a false positive. It looks similar in appearance to a hyperergic test, but the increase in the papule is caused by completely different reasons. For example, having a chronic inflammatory disease or an allergic reaction.

It is also worth noting that a tuberculin test done incorrectly, or improperly stored or transported, may give a false positive result. The older the child gets, the more likely it is to get a false positive result. It is for this reason that todayapply modern diagnostic methods.

Another diagnostic technique

Considering the methods of tuberculin diagnostics in children, it is worth noting that, in addition to Mantoux tests, they also do diaskintest. They allow you to determine whether there is a toxin secreted by tuberculosis bacteria in the human body. Tuberculin contains several different proteins to which many children today have an allergic reaction. It is sometimes very difficult to distinguish it from a hypereric reaction. For this, an additional in-depth examination is being carried out.

Therefore, diaskintest is used during the examination. Tuberculin diagnostics is carried out using a drug that contains a protein that reacts only to the development of tuberculosis. To create such a vaccine, the gene of the mycobacterium that causes the disease was deciphered. As a result, Diaskintest was created, which is also called the recombinant tuberculosis allergen.

This is a more perfect option for tuberculin diagnostics. Tuberculosis in this case is detected in children at an early stage. At the same time, the vaccine is relatively inexpensive and available for use. It was thanks to the use of Diaskintest that the number of cases of the disease was reduced.

But it is worth noting that while children are being vaccinated with BCG at the age of 7 years, before this age they have to do a Mantoux test. The results of tuberculin diagnostics in this case must be considered in dynamics, comparing with previous results. This allows you to decide if you need a secondwhether the child is vaccinated or not. This allows selection of children who need BCG vaccination again.

Today the situation is such that by the age of 7 there is practically no one to be vaccinated again. In almost all children, the test is either doubtful or positive. This was confirmed by the results of a study conducted in Primorsky Krai. Such children are not subject to revaccination. Therefore, after 8 years, today almost everyone is tested using a diaskintest. It is actively used today when conducting relevant tests.

Features of diaskintest

Modern methods of tuberculin diagnostics in children allowed doctors to develop a draft strategy, in accordance with which tuberculosis will be eliminated by 2030. The number of sick people will be kept to a minimum. Tuberculosis will no longer be a global problem. Diaskintest will help with this, as well as other methods of early diagnosis.

Tuberculosis is transmitted by airborne droplets. It is almost always passed on from adult to child. Children get sick almost asymptomatically until a certain point. Of all tuberculosis patients, 10% are cases of the disease among babies of different ages.

The airborne tuberculosis bacillus infects a person when it enters the body. But in most cases, the human body is able to cope with pathogenic microflora. In this case, immunity is developed. If the disease has not developed, diaskintest gives a negative result.

If during the examination there will beit was found that the reaction is positive, this indicates the presence in the body of a living tubercle bacillus. She needs to be fought. For this, preventive treatment is first prescribed. If this is not done, a pathological process may develop. In this case, the treatment will already be more serious.

In children, the body is able to overcome the infection on its own. The focus of tuberculosis in this case is delimited, and then petrificat is formed. It is also called calcification, because a capsule of calcium s alts forms around the tissues affected by the disease.

This is a rather unsafe phenomenon. The fact is that the bacteria in such a capsule do not die. They fall asleep, waiting for the right moment for further development. In this case, secondary tuberculosis develops. This happens if the child, for example, gets sick with some other infection. Immunity is reduced, which gives rise to the development of latent tuberculosis.

This process can take years. As an adult, a person may have a focus of latent, dormant infection in the body. With the appearance, for example, of a stomach ulcer, diabetes mellitus or other serious tuberculosis, tuberculosis may begin to develop. Such patients are at risk. Any decrease in immunity, which can be caused by a variety of reasons, leads to the start of the pathological process and the development of tuberculosis.

Tuberculin diagnostics in children using diaskintest makes it possible to detect the presence of live mycobacteria before they enter the petrification stage. For example, in the Rostov region in recent years,school institutions only diaskintest. Now the children have matured, become teenagers, and tuberculosis is not detected in them. All children at risk were treated before adolescence.

If parents refused vaccination

Tuberculin diagnosis in children has many nuances. So, to date, not all babies have been vaccinated when using BCG. There are about 20% of them in our country. For some babies, this procedure is contraindicated for medical reasons, and for other children, the vaccination was refused by parents.

During the first year of life for such children, a Mantoux test is done. It is still recommended to do BCG, if there are no contraindications for this. If the test in an unvaccinated child is positive, it means that an infection develops in his body. He can't do BCG. He is observed by a phthisiatrician, additional examinations are carried out. Next, the child is given a diaskintest.

If vaccination is not carried out due to parental refusal, as well as for children with medical contraindications, a special blood test is authorized. It's called T-SPOT. TB. A similar examination can be carried out in the absence of symptoms of tuberculosis. This is an alternative approach that is planned to be offered to parents as an alternative to the outdated Mantoux method.

Doctors advise against TB testing altogether. Regardless of the method of diagnosis, timely examination will reveal the pathology at an early stage. At this time, treatment will be much more effective and easier. Duringthe use of Mantoux tests is required to exclude an allergic reaction. But in modern realities, most children have it. It is also impossible to conduct a similar test for obese children who have recently had an infectious, inflammatory disease. Mantoux tests are not done during influenza outbreaks, as well as during seasonal exacerbation of chronic ailments. Too many reasons that can cause a hyperergic reaction do not allow accurate diagnosis. Therefore, more modern, informative methods are being introduced today.

T-SPOT. TB analysis

One of the modern methods of tuberculin diagnostics in children is the T-PHOT. TB blood test. Today, the opinion is being discussed that parents should be given the right to choose between the Mantoux test and the analysis presented.

The new T-SPOT. TB method was registered in our country in 2012. For analysis, the patient is pulled blood from a vein. Further, in the course of a laboratory examination, it is determined how T-lymphocytes behave, reacting to peptide antigens of mycobacteria. According to some data, studies conducted by domestic scientists have established that the use of the presented technique is at least 6 times more accurate than skin tests, namely the Mantoux test. In this case, it is possible to accurately predict the development of active tuberculosis.

T-PHOT. TB testing is not widely used at the moment. Doctors' opinions were divided. Some argue that the Mantoux test makes it possible to detect the development of tuberculosis even at an early stage in 97% of cases. This is a good result, so this technique has not yetrefuse.

Although on closer examination it can be said that the presented methodology has many shortcomings. It gives a false positive result, which does not provide accurate information about the child's he alth. In this case, you need to carry out other methods. One of them is T-SPOT. TB. Otherwise, the child will be shown to undergo multislice computed tomography (MSCT). This technique is characterized by a fairly high x-ray exposure, so it is prescribed with great care.

A blood test is practically a safe procedure. It is characterized by a high degree of reliability and informativeness.

Informativeness of the T-SPOT. TB method

The presented method of tuberculin diagnostics in children is highly informative. In 2006, Western scientists conducted research on the T-SPOT. TB technique. At the same time, the information content of Mantoux tests was compared with a blood test. The study was conducted with the participation of patients who had already developed tuberculosis. This disease was guaranteed to be confirmed in a group of test subjects.

The study noted that some of the participants in the experiment also had HIV infection. During the procedure, it was found that T-PHOT. TB detected tuberculosis in 100% of adults and 77% of children. At the same time, Mantoux tests were also performed on patients. In adult patients, the test revealed the disease in 89% of cases. Among children, this figure was low, amounting to only 35%.

The Mantoux test has been used for over 100 years in diagnostics. Today there are much moreperfect types of tests. Therefore, the quality of diagnostics is noticeably improved. But experts say that in order to switch to other methods, you need to accumulate enough experience. Therefore, the presented diagnostic methods are not yet widely used. Only for limited groups, for which the use of other methods is simply inappropriate, undergo a similar diagnosis.

Features of modern diagnostic procedures

Domestic doctors agree that you should not trust evidence-based medicine too much. Scientists can first prove one thing, and then quite another. Only proven methods can be applied in the he alth care system. Also important when choosing a method of mass screening is the question of the cost of the test.

T-PHOT. TB is now used as an additional option for children with false positives. Also, this technique is effective in diagnosing people with HIV infection. A blood test allows you to get a reliable result even with a reduced immune status of the patient. Therefore, this technique is gradually taking its place in domestic medicine.