Tuberculosis diagnosis is being improved more and more. Old methods are being replaced by new, more accurate and perfect ones. These include diaskintest.
What is this?
Diaskintest - a reaction somewhat similar to the Mantoux test, but more sensitive to human Mycobacterium tuberculosis. Like the Mantoux reaction, it is used mainly in children, although in some cases it is also indicated for adults.
The technique has become widespread relatively recently. The impetus for its creation was the fact that the Mantoux reaction did not give accurate information as to which antibodies to which strain of mycobacteria are present in the body (since it determines sensitivity to two subspecies - human and bovine mycobacteria).
The specificity of the injection is almost 90 percent, while the sensitivity of the tuberculin test does not exceed 50. Because of this, the incidence of false and incorrect results is high.
It is necessary to understand how the diaskintest is carried out, and also to determine the contingent to which this reaction is shown.
How is the procedure performed?
Himselfdiaskintest, reviews of which are currently predominantly positive, are no different in methodology from the Mantoux reaction. The test is performed on the inside of the forearm. The needle is inserted intradermally a few millimeters. After the injection of the drug, a papule with a "lemon peel" type surface is formed at the injection site. After some time (usually after two days), the formed papule is assessed.
Diaskintest for tuberculosis must be carried out in specially equipped rooms or treatment rooms. It is forbidden to carry out an injection at home, as well as by untrained personnel without created sterile conditions. This can lead to the development of complications after the procedure.
To determine the results of the study, changes in the area where the diaskintest was conducted are evaluated.
Evaluation of test results is carried out according to certain criteria. If a negative result is obtained (none of the criteria are identified), the study is repeated or sent for additional examination to specialized institutions.
What signs are used to assess the effectiveness of the procedure and he alth status?
Evaluation criteria
After the diaskintest was carried out, the results are evaluated by the presence of changes in the injection zone.
Normally, a zone of hyperemia should form at the injection site. Its appearance is due to increased blood flow to the injection site, as well as a local allergic reaction.
The size of the papule depends ondegree of immune response. The larger the diameter of the formed papule, the stronger the reaction of the immune system. However, too small or, conversely, excessively large papule size are unfavorable signs, as they indicate a weakened or overactive immune system and its response to the introduction of foreign antigens.
In addition, the formed papule is compared with previous results, determining the dynamics of changes. If there is a positive reaction to diaskintest, the photo and size of the papule must be compared with previous results. It is quite possible that for a given period of time (a year since the last reaction), a person had contact with a patient with tuberculosis. In this case, a comparison with past results is required.
Diaskintest for tuberculosis is considered to be carried out in accordance with all the rules and regulations, if the above two criteria are met.
Interpretation of results
How can one judge the presence of antibodies to mycobacteria?
Evaluation of diaskintest is carried out according to two criteria - redness in the injection area and size.
If there is no zone of hyperemia at the injection site, this indicates that either the procedure was performed incorrectly, or the immune system is so weak that it cannot respond to the introduction of antigens. This is also indicated by the absence of a papule at the injection site.
If there is hyperemia, and the papule is small (up to 4 mm), a weak immune system is judged. A similar result may also indicate that there are very few antibodies, and the bodyif mycobacteria gets into it, it will not be able to cope with it.
What is the result of a he althy person on diaskintest? Its norm is from 4 to 12 mm, which indicates the normal function of the immune system and the presence of the necessary antibodies.
If suddenly a papule larger than 12 mm is formed at the injection site, this indicates a hyperreactivity of the immune system, i.e. in response to the penetration of mycobacteria, an allergic reaction may develop.
However, it should be remembered that the results in adults and children may differ slightly from each other. In adults who have been given a diaskintest, the norm will be slightly larger - from 4 to 16 mm. This phenomenon is observed due to the fact that in the body of an adult there are more antibodies than in a child. Some of them can be activated in the presence of antigenic mimicry - the antigen of mycobacterium can be recognized as a foreign protein of another microorganism, and in response to this, other cells can be activated, which will slightly increase the allergic reaction.
Sometimes the absence of a papule or its large size may indicate that the procedure was performed incorrectly. You should definitely do another one for clarification. With a repeated result (repeated negative or positive diaskintest), a consultation with a phthisiatrician is indicated.
Surveying population
Who is shown this procedure?
This study is mandatory for children under 17 years of age. This is because the main screening method for tuberculosis - fluorography - involves x-rays, which canaffect the child's developmental process. That is why the introduction of antigens is preferred over radiation.
Injection is given to children about six months after the introduction of the BCG vaccine. During this time, antibodies to mycobacterium antigens have time to form, which makes the study expedient.
In addition, people who are registered with an endocrinologist for diabetes mellitus should definitely undergo a procedure.
Everyone, without exception, undergoes a diaskintest if there are significant changes in the papule compared to the previous study (the procedure is performed once a year, but unscheduled studies can be carried out up to 3 times).
A positive diaskintest is often determined in people serving sentences (in prisons, colonies), so they are examined several times a year.
Indications
Diaskintest, like the Mantoux reaction, is a purely diagnostic procedure aimed at mass monitoring of the development of tuberculosis in childhood.
Usually this study is scheduled, but there are some indications for its extraordinary conduct.
Such predisposing factors are the turn of the Mantoux reaction, a significant change in the formed papule compared to previous results. In children with prolonged (more than a month) subfebrile condition and the presence of a dry cough, a second examination, including diaskintest, should be carried out. A photo of the chest organs (fluorogram) in this case is done withpermission of the child's parents and is used to clarify the diagnosis.
In addition, research is mandatory in children and adults with diabetes (since this disease provokes the development of immunodeficiency, facilitates the penetration of the pathogen into the body and the development of the infectious process).
Required unscheduled testing for children whose parents have been diagnosed with TB.
Contraindications
Like any procedure, diaskintest has some contraindications for carrying out. These include hypersensitivity to the constituent components of the drug, as well as the presence of an active infectious process in the study area (diaskintest is somewhat limited in use, since the injection is carried out on the forearm, where the skin is quite thin, which allows papule formation. On the skin of another area of the body, there is no you always get the results you want).
There is also some age restriction. The procedure is not performed on newborns and children who have not previously been vaccinated with BCG.
With caution, the study is carried out for people with immunodeficiency, since the introduction of antigens can provoke an incorrect response of the body.
Advantages of diaskintest
As you know, diaskintest replaced the Mantoux reaction. This happened due to the fact that the Mantoux reaction does not give accurate results regarding antibody production against human Mycobacterium tuberculosis (determines the presence of antibodies against two strainsmycobacteria). Diaskintest, reviews of phthisiatricians about which are mostly positive, is a more narrowly focused procedure, since the injected drug contains only antibodies m. Tuberculosis.
There are isolated cases when active tuberculosis developed after an injection with a Mantoux reaction. In epidemiological terms, diaskintest is safer, since it does not contain active mycobacteria, but only their antigens that promote antibody formation. A hypersensitivity reaction almost never develops with the administration of the drug.
Because the procedure is no different from a standard tuberculin test, most trained procedural nurses can perform it.
Opinions of patients and doctors
During the short time that Diaskintest has been used, it has received a considerable amount of feedback from both patients and doctors.
When studying most of the forums where patients with tuberculosis or their relatives who underwent diaskintest communicate, the reviews in most cases were positive. According to people, the procedure is quite simple to implement, does not require any preparation from them.
What do doctors think about this? Many phthisiatricians are inclined to believe that diaskintest is a more universal procedure than the Mantoux reaction or the Pirquet skin test (not currently used). The high specificity of the drug makes it possible to confirm the presence of mycobacteria inbody and promptly begin treatment. Many agitate patients to give preference not to a fluorogram (which allows only the disease itself to be detected), but to undergo a diaskintest. Doctors' comments about the procedure are almost always positive, only a small part of them prefer radiography or Mantoux.
Where can I get the procedure?
If you suspect that you have tuberculosis, the question often arises of where to go. Such thoughts usually appear after the radiologist noticed a shadow in the lung image, or you cough for a long time, feel weak and weak. All this indicates the possible presence of active tuberculosis, and it is impossible to delay the diagnosis.
First of all, diaskintest can be taken in specialized institutions - TB dispensaries or clinics. Usually the procedure is carried out by everyone for a fee, although you can and even need to apply there and in the direction of the local therapist.
Also, for this procedure, you can contact the regional he alth centers (for example, district hospitals) or the sanitary service. Usually, there must be at least one phthisiatrician in the district who can competently examine you and, if necessary, diagnose tuberculosis using a diaskintest.
