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Mantoux test

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The Mantoux test or Tuberculin Skin Testing is a standard test for determining infection with Mycobacterium tuberculosis, the potent microorganism that causes tuberculosis.



Why is mantoux test done?

Mantoux test is precisely done to determine latent TB infections i.e. the germ are present but in dormant form, without causing any symptoms. If a Mantoux test is positive, then treatment can be started without allowing the bacteria to progress to active stage.

 

Who should consider taking Mantoux test? 

  • Healthcare workers who had been working with TB patients
  • With symptoms of TB
  • Those had been staying TB infected family members
  • With immune system disease like HIV/AIDS 

 

Who should not take Mantoux test?

People with a history of allergy to TB antigen, skin allergy, etc. should not take Mantoux test. 

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How is Mantoux test done?

The test is carried out by injecting 0.1 ml of tuberculin as purified protein derivative (PPD) form under the top most layer of skin ( intradermal injection) beneath your forearm. Tuberculin is a TB protein antigen that forms the marker for the test.

 

How to prepare for the test?

Your doctor will determine whether you are the right candidate for undergoing tuberculin test after evaluating your medical history, the probable symptoms, and the medicines you are taking and also your vaccine doses. 

A patch test might be suggested before carrying out Mantoux test.

Your skin might be washed with plan soap and water if it’s unclean.

You need to rest your forearm on a table or a board with your palm facing upward. Do not move while the needle is being inserted.

 

What happens after the test?

A skin reaction would happen within 48-72 hours of injection. A red bump forms on the skin which forms the basis of the test.

Your doctor would advise you not to scratch the site or cover with bandage. You can apply water normally and dry the skin gently. 

Apply a cloth dipped in cold water to get over itching.

 

How are test results interpreted?

There’s a particular technique for reading the reports. The diameter of the hardened, palpable, bumpy swelling, called the induration is measured in millimetres and not the intensity of the redness. 

The standard values are:

Induration > 5 mm- Positive for people with HIV, illicit drug use, contact with TB patients, undergone organ transplants, abnormal chest x ray reports.

Induration >= 10 mm- positive in for people working in TB labs, hospitals, dwelling with TB family member or have migrated from TB prone country.

Induration > = 15 mm without any symptom or risk factor of tuberculosis.

 

What if the test result is negative?

If the bump does not appear, then it indicates that you do not have TB infection. 

However, your doctor might advice another test later for confirmation.

 

Are there any risks associated with Mantoux test?

Minor itching and pain can occur at the injection site, which are very common. There are as such no risks. 

 

What are the downsides of Mantoux test?

Some chances of false positive and false negative test results are there, which can occur due to manual error while administration or a previous medical condition. 

The test is repeated for that reason after a certain interval. Boosted Mantoux is performed on those who had a false-negative reaction

 

What are the advantages of Mantoux test?

If used correctly, Mantoux test is quite effective and simple way to determine presence of tuberculosis bacteria in your body.

The biggest advantage is – it can be used safely on pregnant and breastfeeding women and infants.

Your doctor would recommend some more tests to confirm tuberculosis.

Written by: healthplus24.com team
Date last updated: March 10, 2014