Tuberculin diagnostics in children is one of the effective methods of preventing the tuberculosis epidemic 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 diagnostics are tuberculin tests, which are carried out using special preparations. How such a diagnosis is carried out today will be discussed later.
General definition
Tuberculin diagnostics in children is a combination of special tests and tests aimed at detecting sensitization in the body to office antigens. Previously, such tests are performed using tuberculin. Today, different methods and drugs are used, which allows to improve diagnostic procedures, increase the percentage of reliable results.
Tuberculin is a complex compound, the main active element of which are tuberculoproteins. This drug can cause a delayed-type hypersensitive reaction in an organism infected with a Koch bacillus (tuberculosis bacterium). This drug is not capable of causing the 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.
Conducting tuberculin diagnostics allows you to identify early tuberculosis in children and adolescents. This procedure takes place during periodic examinations in kindergartens, schools and medical facilities. Having identified with its help children who have a suspicion of the development of the disease, an additional diagnosis is carried out. If it is confirmed that a disease develops in the body, a comprehensive treatment is carried out. At its expiration, an individual tuberculin diagnosis is carried out for a specific child.
Many parents do not understand why BCG is being vaccinated. Its purpose is not to protect against infection. A vaccine can only delimit the development of tuberculosis at the level of the lymphatic system. If infection occurs, what happens, according to statistics, in 70-80% of the population in the Russian Federation, severe generalized forms can only develop thanks to the BCG vaccine. In this case, the tuberculosis bacterium will not be able to affect bone tissue, the brain. But the well-known Mantoux reaction is simply a breakdown that can identify a person infected with tuberculosis.
Goals and objectives
It should be understood that the purpose of tuberculin diagnostics is to reduce the number of cases, both among children and among adults. It often happens that a child becomes infected with tuberculosis from immediate relatives. For example, from grandparents who had not been examined for a long time, they did not do fluorography. If the child has tuberculosis, the whole family is examined.
The purpose of tuberculin diagnostics is to reduce both the percentage of morbidity and mortality in the country from this infection. It is worth noting that through the use of new, modern approaches, it was possible to achieve high results. It is worth noting 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 have been and are being solved:
- Identification of people infected with the bacterium for the first time, as well as people with a turn in the process of conducting samples. This allows you to identify people with tuberculosis at an early stage of the disease.
- The formation of risk groups, which include people who have contact with people with tuberculosis or who have already had an infection. This requires observation by a TB doctor. This also includes people who have a hyperergic reaction or an increase in papule during the course of the tests by 6 mm or more compared to the previous year.
- Selection of contingent for BCG-M vaccination. These are children from the age of 2 months who have not been vaccinated in the hospital, as well as requiring revaccination at the age of 7 years.
- Determination of the epidemiological situation in the region, in separate zones, which allows to determine the risks of infection.
Previously, a tuberculin test was possible only with 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 test
Today, special requirements have been developed that put forward the conduct of tuberculin diagnostics in children. The order of the Ministry of Health No. 124n dated 03/21/17 “On the approval of the procedure and timing for 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 principle to an allergic reaction. After the introduction of tuberculin under the skin, a reaction occurs. The body responds differently to the vaccine administered. If a person has tuberculosis, including he is a carrier of infection, the Mantoux test will be increased. In this case, they say that the reaction is hyperergic. But the tendency to allergies, the presence of chronic diseases in the body can also explain a similar result. In some children, a hyperergic reaction is observed due to structural features of the skin, nutritional characteristics, etc. The older the child, the more likely it is to receive a false-positive result. Therefore, at an older age, starting from 8 years old, a diaskintest is performed. Tuberculin diagnostics in children in this case will be more accurate.
During the test, a thermally and chemically treated vaccine from the extract of bacteria is used. An aqueous solution is introduced 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 introduced, which is an absolutely safe dose for the child's body. The state of health does not change with the introduction of this injection.
If the body was already familiar with the bacterium that causes tuberculosis, the reaction will be positive. If the child has not received BCG vaccination, the reaction will be negative. This is possible if the child did not have this procedure for health reasons. Some parents do not allow vaccination by signing a waiver of tuberculin diagnostics. Some children who have received 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 tubercle bacillus (with BCG vaccination), a small tumor and redness appears at the injection site of tuberculin. It is collected from the lymphatic channels by T-lymphocytes. After 3 days, evaluate the result of the sample. It must comply with certain standards.
Interpretation of the Mantoux result
When 3 days after the injection 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 the sample is negative during tuberculin diagnostics, no seal appears at all on the arm. This indicates the ineffectiveness of the introduced BCG vaccine. It is repeated.
The second type of reaction is called dubious. Redness on the forearm is very small, not more than 4 mm. An uncertain result is also not the norm; it requires consultation with a TB doctor.
A positive reaction is 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 did not pass within 7 days, you need to contact a TB doctor. This may be a sign of infection.
A hyperergic reaction is determined if the papule has a size of more than 17 mm. If at the same time there is suppuration, soreness, and nearby lymph nodes are increased in size, this may indicate the presence of infection in the body. In-depth diagnosis is required.
Sometimes it happens that the reaction is recognized as false positive. It looks similar in appearance to a hyperergic test, but is caused by an increase in the papule for completely different reasons. For example, the presence of a chronic inflammatory disease or an allergic reaction.
It is also worth noting that vaccination with tuberculin diagnostics, made incorrectly or a vaccine that was stored or transported inappropriately, can give a false positive result. The older the child becomes, the more likely it is to receive a false positive result. It is for this reason that modern diagnostic methods are used today.
Another diagnostic technique
Considering the methods of tuberculin diagnostics in children, it is worth noting that, in addition to Mantoux tests, they also make a diaskintest. They make it possible to determine whether there is a toxin in the human body that is secreted by tuberculosis bacteria. 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 carried out.
Therefore, during the examination, a diaskintest is used. Tuberculin diagnostics is carried out using a drug that contains a protein that responds only to the development of tuberculosis. To create such a vaccine, the mycobacterium gene that causes the disease was deciphered. As a result, Diaskintest was created, which is also called the recombinant tuberculosis allergen.
This is a more advanced option for conducting tuberculin diagnostics. Tuberculosis in this case is detected in children at an early stage. In this case, the vaccine is relatively inexpensive, available for use. Thanks to the use of Diaskintest, it was possible to reduce the number of cases of the disease.
But it is worth noting that while children are vaccinated with BCG at the age of 7 years old, 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 whether the child needs revaccination or not. This allows you to select children who need a BCG vaccine again.
Today the situation is such that by the age of 7 there is practically no one to vaccinate again. In almost all children, the test is either dubious or positive. This was confirmed by the results of a study conducted in the Primorsky Territory. Such children are not subject to revaccination. Therefore, after 8 years today, almost everyone is tested using a diaskintest. It is actively used today in carrying out appropriate tests.
Features of Diaskintest
Modern methods of tuberculin diagnostics in children have allowed medics to develop a draft strategy in accordance with which tuberculosis will be eliminated by 2030. The number of cases will be minimized. Tuberculosis will no longer be a global problem. In this, including diaskintest, as well as other methods of early diagnosis will help.
Tuberculosis is transmitted by airborne droplets. It is transmitted almost always from an adult to a child. Children get sick almost asymptomatically until a certain point. Of all patients with tuberculosis, 10% are cases of the disease among babies of different ages.
The tuberculosis bacillus present in the air 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 does not develop, diaskintest gives a negative result.
If during the examination it is established that the reaction is positive, this indicates the presence of living tubercle bacillus in the body. You have to fight it. 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 independently overcome the infection. The focus of tuberculosis in this case is delimited, and then a petrificate is formed. It is also called calcinate, because a capsule of calcium salts is formed 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 any other infection. Immunity is reduced, which gives a start for the development of latent tuberculosis.
Such a process can last for years. As an adult, a person may have a hotbed of latent, sleeping infection in the body. If, for example, a stomach ulcer, diabetes mellitus or other serious tuberculosis appears, tuberculosis can 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.
Conducting tuberculin diagnostics in children using diaskintest can detect the presence of live mycobacteria before they enter the stage of petrification. So, for example, in the Rostov region in recent years, only diaskintest was carried out in schools. Now the children have matured, have become teenagers and they do not detect tuberculosis. All children at risk were treated before adolescence.
If parents refuse vaccination
Conducting tuberculin diagnostics in children has many nuances. So, to date, not all babies have been vaccinated with BCG. There are about 20% of these in our country. For some babies, this procedure is contraindicated for medical reasons, while in other children the parents refused vaccination.
During the first year of life, a Mantoux test is made for such children. It is still recommended to do BCG if there are no contraindications for this. If the test for an unvaccinated child is positive, then an infection develops in his body. He cannot do BCG. It is observed by a TB specialist, additional examinations are carried out. Then the child is given a diaskintest.
If vaccination is not carried out due to the refusal of the parents, as well as for children with medical contraindications, a special blood test is carried out legally. It is 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 technique.
Doctors advise against giving up TB screening in principle. Regardless of the method of diagnosis, timely examination will identify pathology at an early stage. At this time, treatment will be much more effective and easier. During the use of Mantoux tests, it is required to exclude an allergic reaction. But in modern realities in most children it is present. 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 flu outbreaks, as well as with seasonal exacerbation of chronic ailments. Too many of the reasons that can cause a hyperergic reaction do not allow the diagnosis to be performed accurately. Therefore, more modern, informative methods are being introduced today.
Analysis of T-SPOT.TB
One of the modern methods of tuberculin diagnostics in children is a blood test T-SPOT.TB. Today, the opinion is being discussed that it is necessary to give parents the right to choose between the Mantoux test and the presented analysis.
The new T-SPOT.TB methodology was registered in our country in 2012. To conduct an analysis, the patient is pulled from a vein. Further, during a laboratory examination, determine how T-lymphocytes behave, responding to peptide antigens of mycobacteria. , , 6 , , , . .
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