Mantoux test - Causes, symptoms and treatment. MF.
Mantoux test( tuberculin test, PPD test, PPD test) is a method of determining the immunity to the causative agent of tuberculosis.
The test consists in introducing into the area of the inner surface of the forearms of a special drug - tuberculin, which is a purified product obtained from mycobacterium tuberculosis after special treatment. What is the Mantoux test for?
The first vaccination against tuberculosis - the BCG vaccine - is carried out in the first 3-7 days of life. However, the BCG vaccine does not always provide sufficient immunity to prevent infection. To determine whether immunity against tuberculosis is effective, the Mantoux reaction is carried out every year. Based on the results of the test, children are selected for booster revaccination, which takes place between the ages of 7 and 14-15.In epidemiologically unfavorable regions, with high prevalence of tuberculosis, revaccination is carried out at 6-7, 11-12 and 16-17 years.
In addition, the Mantoux test allows you to identify infected individuals and begin timely treatment.
How is the Mantoux test done?
The Mantoux test is conducted annually, regardless of the results of the previous test. In the middle third of the inner surface of the forearm inject 0.1 ml of the drug, which contains 2 tuberculin units( TE).After the introduction of tuberculin, a small tubercle is formed, which is usually called a "button".
Can a Mantoux sample be watered with water?
Swim, take a shower you can. You can not swim in open water so as not to infect the wound. You can not also rub this place with a washcloth, as well as use any liquids and solutions: zelenok, iodine, peroxide, you can not glue the wound with a band-aid. Also, you need to ensure that the child does not comb the wound. All this can affect the result of the test and lead to a false positive result.
Evaluation of the results of
After the introduction of tuberculin in the presence of antibodies against tuberculosis in the body, an inflammatory reaction is formed at the site of injection - protective antibodies react with fragments of the pathogen. In this case, approximately 2-3 days after injection, a small bump of red color is formed at the site of the injection, towering above the skin level, dense to the touch, pale with pressure.
The results are evaluated on day 3.To do this, measure the diameter of the papule( tubercle) with a transparent ruler in good light. Measures not the size of redness, but the size of the seal.
· Reaction is negative - if there is no reaction at all or reaction is prickly - 0-1mm
· Reaction is doubtful - if there is only redness without papules or the size of the papule does not exceed 2-4mm
· Reaction is positive - if the size of the papule is 5mm or more. When the size of the infiltrate is 5-9mm, the reaction is considered weak, at a size of 10-14mm - the average intensity, 15-16mm - the reaction is expressed
· Hyperergic reaction( excessive) - if the diameter of the papule exceeds 17mm in children and adolescents and 21mm in adults. And also if there are any signs of severe inflammation - pustules, inflammation of nearby lymph nodes, etc.
A negative test indicates the absence of antibodies against the tubercle bacillus in the body. This indicates the absence of infection, as well as the lack of response to previous BCG vaccination.
A doubtful test is actually equated with a negative one.
A positive test may indicate an infection with mycobacterium tuberculosis or the intensity of anti-tuberculosis immunity after vaccination. To distinguish one state from another is not always easy.
In favor of infection with positive Mantoux test:
· First appeared positive reaction after negative or questionable results in previous years
· Increased papule by 6 mm or more in comparison with the previous year
· Positive reaction with infiltrate 10 mm or more for 3-5 years in a row( except for some cases of allergic reaction to tuberculin)
· Hyperergic reaction
· Papillary diameter more than 12 mm 3-5 years after vaccination
· Presence of risk factorsinfection: contact with TB patients, a finding in an endemic region, low socio-economic status.
What should I do if I have a positive sample?
If the sample was evaluated as positive or hyperergic, and if the possible effect of immunity after the vaccine was excluded, it is recommended to consult a phthisiatrician who conducts a number of additional studies for the diagnosis of primary tuberculosis: chest X-ray, microbiological sputum examination for mycobacterial tuberculosis,family members, etc. In the event that, after a complete examination, no signs of infection have been found, it is possibleevaluation of a positive or a hyperergic test, as an allergic reaction to tuberculin. Such a conclusion has the right to do only a phthisiatrician( a specialist in tuberculosis).
Contraindications to Mantoux test
· Skin diseases
· Acute infectious diseases or exacerbation of chronic diseases. The sample is put in a month after the disappearance of all the symptoms of the disease.
· Allergic conditions
· Epilepsy
· Quarantine in children's institutions. The sample can be put in a month after the removal of the quarantine.
Influence of other
vaccinations It is not possible to put a Mantoux test on one day with any vaccinations, as this may affect its result. However, immediately after evaluating the results of the sample, any vaccination can be carried out.
The Mantoux test should be placed at least 4 weeks after vaccination with inactivated( killed) vaccines: against influenza, tetanus, diphtheria, etc. And 6 weeks after vaccination with live vaccines: against measles, rubella, mumps, etc.