3.3 Early tuberculosis revealing among children and teenagers. Test Mantoux


Introduction. Tuberculin test is valuable supplementary method for clinical diagnosis of tuberculosis. For tuberculin testing among children of early age, positive reaction is of greater diagnostic importance. It specifies presence of fresh tubercular process in organism of the child. Due to dynamic supervision of tuberculin testing among children of the older age and teenagers it is possible to establish the first appearance of positive tuberculin reaction — “conversion, virage”, as it’s name is accepted. First infection with the tubercle bacillus leads to the development of allergy to the protein – tuberculin. When tuberculin is injected into the skin of an infected person a delayed local reaction develops in 24-48 hours. The reaction measures the degree of allergy: it does not measure immunity. A reaction on tuberculin (positive test) only shows that the person has at some time been infected with ТВ. The proportion of people with positive tests will steadily increase with age. Many adults who are quite well will have positive tests.

Purpose of application.

Tuberculin testing, as a specific test, is applied in mass examination of the population for tuberculosis, and also in clinical practice for diagnostics of tuberculosis stages. Tuberculin testing is applied:

  1. For well-timed revealing of the tuberculosis infected, with the increased risk of disease (first time infected, with hyperergic and exacerbate reactions on tuberculin);
  2. For selection of eligible subjects for revaccination against tuberculosis;
  3. For definition infectiousness and risk of infection of the population, with the purpose of the analysis of epidemiological tuberculosis situation.

With the purpose of selection of children and teenagers for BCG vaccination the Mantoux test with 2 TU PPD-L is administrated among decreed age groups – 6-7 years (0-1 classes of secondary school) and 14-15 years (8-9 school class). At mass tuberculin testing, the Mantoux test should be executed among practically healthy children and teenagers. In case of an establishment of tuberculin test “virage/conversion”, hyperergic or amplifying reaction without functional and local signs of tuberculosis, other inoculations should be carried out not earlier than in 6 months after its revealing.

Tuberculin preparations.

To tuberculin preparations are related: PPD-L (purified protein derivative named after Linnikova), ATK-alttuberculin of Koch, tubercular diagnosticum erithrocyte dry and immune-enzyme analysis – system for definition of antibodies to the MBT. In Russia 2 kinds of PPD-L tuberculin are used in practice purified tuberculin:

  1. In the form of solutions, ready to the use, -liquid form of tubercular allergen purified in standard solution for intradermal application (purified tuberculin in standard dilution).
  2. Dry tubercular purified allergen (dry purified tuberculin).

Tuberculin – liquid allergen represents a solution of tuberculin in 0,85 % a solution of NaCl with phosphate buffer, with the twin – 80 as the stabilizer and phenol as a conservator. The preparation is produced in ampoules as a solution containing 2 TU (tuberculin units) PPD-L in 0,1 ml, looking like colourless transparent liquid. It is produced in 5 TU, 10 TU in 0,1 ml and other solutions. Working life – 1 year in ampoules. Purified tuberculin in standard solution is intended for performance of uniform intraгdermal tuberculin test (test Mantoux). The industrial release of ready PPD-L solution allows to use in the country wide for mass tuberculin testing with standard activity preparation and to avoid mistakes during dilution of the tuberculin at the places of its application.

Tubercular allergen purified dry (dry purified tuberculin). The preparation looks like dry compact mass or powder white (slightly grayish or cream) color, easy soluble in the applied solvent – carbolated physiological solution. It is produced in ampoules. Term of the validity 5 years. Dry purified tuberculin is used for diagnostics of tuberculosis and tuberculin therapy only in tuberculosis dispensary and clinics. The specific activity of tuberculin preparations is established and is supervised according to the national standards of the appropriate types of tuberculin.

Internationally WHO and the International Union Against Tuberculosis and Lung Disease recommend using PPD-RT23. This is a purified tuberculin.

Mantoux test.

The test Mantoux is made as follows: on an internal surface of an average third forearm previously the site of a skin must be processed with 70 % ethanol and is dried by sterile cotton wool. The thin needle with cut of upwards is entered in the top layers of a skin in parallel its surfaces intradermal. After introduction of an aperture of a needle into skin immediately from a syringe enter strictly on division of a scale 0,1ml of tuberculin solution – one doze. At correct performance in skin is forming papule as ‘citric peel’ by the size 7 — mm in a diameter whitish color.

The test Mantoux is put on assignment of the doctor by specially trained nurse having the document with permission to carry out tuberculin testing. The results of tuberculin test of test can be appreciated by the doctor or specially trained nurse, carrying out this test.

Test MantouxTest Mantoux with 2 TU PPL-L is considered:

  1. Negative if only signs of needle puncture is presented or 2 mm hyperemia;
  2. Doubtful – 2-4 mm of indurations or hyperemia of any size.
  3. Positive – 5-17 mm of indurations among children and adolescents and indurations 5-21 among adults;
  4. Hyperergic – indurations more than 17 mm among children and adolescents and more than 22 mm among adults.

At presence of the reliable data of sensitivity changes to Mantoux test with 2 TU PPD-L it is necessary to attribute to the group of tuberculosis infected persons, at which:

  1. The first time positive reaction (indurations 5 mm and more), not connected with previous BCG immunization;
  2. Stable (during 3-5 years) positive reaction with indurations 10 mm and more;
  3. The sharp amplification of sensitivity to tuberculin (on 6 mm and more) of tuberculin test positive children (for example indurations was 5 mm now became 11 mm) or amplification of sensitivity to tuberculin less than on 6 mm, but with formation of infiltration with the sizes of 12 mm and more.

The skin divided tuberculin test (modified test Pirquet – Clemens von Pirquet) apply basically at the patients by a tuberculosis of children to definition of individual sensitivity to tuberculin. For skin Pirquet reaction on 100 % tuberculin or on 100 % tuberculin and three its solutions – 25 %, 5 % and 1 % are used, such reaction refers to as divided reaction. For the graduated reaction Pirquet, the end of the internal part of forearm is processed with 2-3 % by carbolic acid solution. On the skin put four drops of tuberculin solutions of various strength – 100 of %, 25 %, 5 % and 1 % and one drop of control 0,25 % carbolic acid. 100 % of tuberculin solution in drop put near to cubital tuck, other solutions – in the direction of a hand with an interval in 3-4 cm under the order of a decreasing strength of the solution. The tuberculin solutions should be prepared in conditions of strict sterility. Making incisions on the skin should begin from the control solution and pass from smaller solution strength to higher. After 5 min drops implying of the rests of solutions should be removed by cotton wool from in the direction hand to elbow. This order is needed not to bring a solution of greater concentration in the next incision, covered by a drop of solution with smaller strength concentration.

The absence of redness on the place of scarification is should be interpret as negative reaction. The size of the papule up to З mm is a parameter of doubtful reaction requiring new, more accurate test. The size of the papule from 3 mm up to 1 cm indicate about moderate positive reaction, from 1 cm and more – about acute – positive reaction.

The positive reaction appeared for the first time in life indicates about “conversion”, i.e. about primary infection of the patient. The acute reaction to weak tuberculin solutions testifies about hyperergic condition of the host. The occurrence of positive Pirquet test reactions on of all tuberculin concentration testifies usually to active primary tuberculosis.

The Pircuet and Mantoux tests necessarily supplement for patient examination. The results of the tests are interpreted in comparison with anamnesis and clinical symptoms of disease. The change of the test character – increase of a papule size and hyperemia at repeated tests testifies to activity of tuberculosis process.

In 2-3 months after primary vaccination the positive Mantoux test becomes sharper expressed. Sometimes weak positive reaction on Pirquet test occurs. This phenomenon testifies, on the one hand, to the produced immunity, with another – creates difficulties for difference a post – vaccinal reaction from the once again appeared positive reaction on tuberculin “conversion”.

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