Mantoux | Diseases and conditions: Medical tests.

What is the Mantoux

The Mantoux, or test of the tuberculin, is used daily in consultations around the world, and serves to detect people who have had contact with the tubercle Bacillus, Mycobacterium, head of the tuberculosis. All people who are infected tuberculosis ever develop defenses against Bacillus, caused an infection in the body or not. These reactive defenses remain in the body silent and reactivated when they meet up again with the Bacillus.
This test seeks to reactivate these defenses and identify a reaction that demonstrates this sensitivity. For that they inject antigens of the bacillus of tuberculosis in the skin. The antigens are pieces of the bacteria, purified and without ability to lead an active infection. They are injected into the dermis, the thickness of the skin, with a very fine needle and remain there waiting for the emergence of an immunological reaction or not.
It is used in all situations in which you want to rule out active or latent TB infection. Keep in mind that tuberculosis is an infection whose severity depends on the immune status of the patient, therefore the test will take place in all situations involving a significant immunosuppression, such as HIV infection or the taking of biological drugs. It is also used when you want to rule out infection from tuberculosis in people who have had contact with TB patients known.
The test is very simple and cheap. It is not a very important nuisance to the patient, just a small puncture in the forearm. Thanks to this test you can take important decisions in the management of tuberculosis or other complex diseases that involve an alteration of the immune system. There is no possibility of serious complications, so it is used on a daily basis in medical consultations around the world.

When the Mantoux is made

The Mantoux is done in situations that are important to rule out a latent infection by the tuberculosis Bacillus. The degree of infection essentially depends on each person's immune system, so the situations in which it is committed are the most important to keep in mind:
People infected with HIV.
Patients with risk factors for developing a tuberculosis, such as those who suffer from diabetes mellitus, silicosis, chronic renal failure, cancer...
Prior to the administration of immunosuppressive drugs: corticosteroids powerful in prolonged guideline, biological, anti-cancer drugs, etc.
People who have had contact with known TB patients.
Immigrants from areas where tuberculosis is endemic.
After detecting signs of suspicion of tuberculosis in routine controls (swollen, abnormalities on chest x-ray, etc).
Systematically to health employees or prison officers, for the added risk of coming into contact with the Bacillus.

Preparation for the Mantoux

If you will perform a Mantoux, these are the issues that you must take into account:
Duration: the test will consist of two visits to the consultation by the doctor or nurse, each of which will last for ten minutes in total.
Income: is always performed on an outpatient basis. Just go one day to the doctor and again three days later. If you are entered they can ask the test during the own income.
Is it necessary to be accompanied?: it is not necessary to be accompanied.
Drugs: don't need to take any prior medication. You should tell your doctor all the medicines taken regularly also is important to report allergies to medications or other products, if you have them.
Food: it is not necessary to remain in fasting prior to testing or after. You can drink and eat whatever you want before the test. If for any reason it should go on fasting to test the doctor you warn.
Clothes: you can perform the test with the same clothes every day. When you get to the hospital or doctor's office ask you to discover a forearm.
Documents: it is preferable that you bring with you the steering wheel which shows the performance of this test. The health insurance card is recommended. Normally you will not you any document after the test because it takes days to analyze the results and communicate it to you directly.
Pregnancy and breast-feeding: the Mantoux is not contraindicated in pregnancy or lactation, but that State must know because sometimes the results will be altered.
Contraindications: do not have any specific contraindication.

How the Mantoux

First the doctor will decide in a previous consultation if necessary or not to perform a Mantoux, and so assess your immune status, the diseases that present and epidemiological contacts. It is important that you discuss you countries you have visited and what you work.
The Mantoux may be carried out on the same day or in another different appointment. If necessary, they will measure you blood pressure or made you a blood analysis before you undergo the test, because then it would be more awkward.
Prepared once you will be asked to sit in an armchair in a position that will facilitate the completion of the test, and you have to put one of the two forearms on the armrests, with the inside facing up. You should be relaxed and alert if something goes wrong during the test, although remember that it lasts only a few seconds.
To proceed with the injection of the Antigen the area should be cleaned with an antiseptic such as chlorhexidine or the betadine. Then the nurse prick the skin without in-depth and will inject 0.1 mL of Antigen, which tends to be a substance called tuberculin. When the liquid is injected it is normal that you feel pain and burning, sometimes very intense, but lasts less than 10 seconds in any case.
After you withdraw the needle and will give you a cotton so you compress the area of prick and avoid that you bleed. With this already you can you go home, but you'll have to go back 72 hours later, i.e., three days later, to check the results. The results are read directly on the skin, according to whether a local immune reaction in the area of prick, or not. If major alterations in the area of prick you notases before that date you must see a doctor.

Complications of the mantoux

All the evidence that damage the skin have risks, even if the invasion is mild. They tend to be infrequent complications and in the majority of cases have easy solutions. They can appear during or after the test, and whenever they arise you should go to the emergency room. Some of the most common complications in the Mantoux are:
  • Bleeding from the site of injection, which is almost always at least.
  • Infection very unlikely, local with a fever.
  • Uncontrollable pain.
  • Reaction to tuberculin. With intense pain, redness, and swelling. Treatment must be received to interrupt the immune reaction.

The Mantoux results

The Mantoux results They are received 72 hours after injection in the forearm of the tuberculin or Antigen that matches. Let spend that time so the immunological reaction to develop enough. The doctor or nurse will assess the local skin reaction, measuring induration that present the surface (which should not be confused with the redness, which tends to be higher). According to the diameter of the reaction the result will be positive in that it engages:
  • More than 15 mm: for all healthy persons without risk factors.
  • More than 10 mm: for people with risk factors (diabetes, cancer, etc) or to work in jobs with added risk.
  • More than 5 mm: If you have a State of severe immunosuppression (HIV, immunosuppressants, and so on).
Like all tests, there are results falsely positive or negative. False positives are very rare and have to do with skin allergies. False negatives are more frequent and have to do with States of immunosuppression so important that they do not leave to appear local immune reactions to tuberculin.
To alleviate these falsely negative results make the effect booster, which consists of the repetition of the Mantoux a few days after the first test. Thus the immune system remembers the first injection to the tuberculosis Bacillus, and with the second injection reacts adequately against it.
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