BCG vaccine and Mantoux test: what is the difference and the relationship?

To date, the prevention of tuberculosis is absolutely necessary and conducted at the state level. First of all, it is BCG vaccination. It is made to the newborn in the maternity hospital at the first week of his life, if there is no contraindication to this. BCG does not prevent infection with a tubercle bacillus, but it contributes to the development of immunity. To control the susceptibility of the body to infection, starting with the first year, and then every year the children make a Mantoux test.

Reaction to the sample allows you to judge whether the child has so far encountered a tuberculosis rod, whether immunity has been developed on it and, accordingly, whether BCG revaccination is necessary. Indications for revaccination are determined based on the reactions of the body to the Mantoux test and taking into account the incidence of tuberculosis in the country as a whole.

BCG is a vaccine against tuberculosis, prepared from a strain of a weakened live bovine tubercle bacillus, which has virtually lost its virulence to humans, being specially grown in an artificial environment.

BCG vaccine
BCG vaccine

Tuberculin Mantoux test is a skin test aimed at detecting the presence of a specific immune response to the introduction of tuberculin.

Neither BCG nor Mantou can provoke tuberculosis.

The reaction to the Mantoux test is estimated three days after the injection. The reaction manifests itself in the formation of the papule (a rounded area of increased density that rises above the skin) and in the reddening of the skin. The reaction consists of a visual assessment of redness (hyperemia) and measurement of the papule.

The following reaction options are possible:

  • negative (no changes on the skin);
  • doubtful (there is redness of any size without a papule or the size of the papule does not exceed 2-4 mm);
  • positive weakly expressed (papule diameter 5-9 mm);
  • positive medium intensity (papule diameter 10-14 mm);
  • positive expressed (diameter of the papule 15-16 mm);
  • excessive or hyperergic (the diameter of the papule exceeds 17 mm or there are pronounced signs of inflammation, such as the reaction of lymph nodes, skin ulceration, etc.).

Variants of reaction to the Mantoux test are interpreted by the medical staff of the institution in which the sample was conducted.

The main principles of interpretation include the following:

  • the negative Mantoux reaction indicates that antibodies to the tubercle bacillus did not develop in the body at the time of injection and, accordingly, BCG revaccination was recommended;
  • a doubtful test is equated with a negative one;
  • a positive sample is predominantly indicative of the presence in the body of antibodies to the tuberculosis bacterium;
  • signs of infection (but not disease) are:
    • the turn of the tuberculin test (the transition of a negative Mantoux reaction to a positive or an increase in the diameter of the papule as compared to the result of the previous sample by = 6 mm);
    • hyperergic reaction;
    • more than four years the remaining reaction to a test in the size of a papule = 12 mm;
    • gradual increase in sensitivity to tuberculin with the formation of papules = 12 mm.

Infection with mycobacteria tuberculosis does not mean the development of the disease. The signs of infection are a recommendation for observation of a child from a phthisiatrician, it is possible to prescribe therapy and re-sample Mantoux after the specified period. The Mantoux test does not allow to diagnose tuberculosis, it is an indicative test that demonstrates whether the body was exposed to a tubercle bacillus and whether antibodies were produced in response to it.

Absolute contraindications for the Mantoux are:

  • skin diseases;
  • acute infectious diseases;
  • chronic diseases in the period of exacerbation;
  • allergic conditions, rheumatism, bronchial asthma.

Parents should understand that the sample allows to make a conclusion about how sensitive the organism is to tuberculosis infection. It is important to understand that you can not get infected from such an injection. Dead bacteria of tuberculosis are introduced into the body, they can not infect the organism, but if the reaction goes beyond the norm, it means that the ingestion of living bacteria will prove fatal.

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