Tuberculosis: TB

Being tested for tuberculosis

Sometimes people can become infected with tuberculosis (TB) germs without getting the actual disease. 

The Mantoux test, also called the tuberculin skin test, can show if the person has ever been infected by TB germs. 

TB infection does not mean the person has the disease, but if someone has been infected there is a chance they might get sick with TB in the future. 

Who needs a Mantoux test

Recent contacts of someone who has active TB disease. This could be family members, friends, or co-workers.

You should get a test if any of the following apply:

  • you have had a chest X-ray suggesting that you have had untreated TB disease in the past
  • you have lowered immunity such as HIV infection or certain medical conditions (renal failure, certain cancers, diabetics, before starting steroids or other immunosuppressive drugs)
  • you are required to be tested for your employment reasons or as part of a school screening program, providing you have not had a previous positive Mantoux test
  • before administering a tuberculosis vaccine (BCG) to infants greater than 6 months of age
  • you are about to undergo organ donation
  • you are travelling to a high risk country.

What the test involves

A Mantoux test is a simple and safe test. 

A small amount of tuberculin purified protein derivative (Tubersol®) is injected just under the top layer of the skin on your arm using a small sterile needle and syringe. 

The skin reaction (lump) is measured two to three days later and the result recorded.

Possible side effects

Side effects are uncommon. However, if you have been exposed to TB germs you may occasionally have a sizeable reaction, which may cause some discomfort.

This swelling should disappear in about 2 weeks.
 
The reaction can get itchy. It is best not to scratch the arm – a cold compress can help relieve any itching. 

If your test is negative

If the lump is below a certain size the result of the test is negative. Usually this means that the person has not been infected with TB germs. However, under some circumstances it can be negative even when someone has been infected. 

This can happen if the exposure to TB has been in the last few weeks and the body has not had time to develop a reaction or if the body’s defences are weakened and unable to react to the skin test. 

In these situations the test may need to be repeated or interpreted differently.

If your test is positive

It means that the person is infected by TB germs, but does not mean that he or she has TB disease. A Mantoux positive person cannot pass TB onto anyone else unless there is progression at some stage to active pulmonary TB disease.

If you are infected and do not have TB

After TB germs enter the body, in most cases, body defences control the germs by building a wall around them, the way a scab forms over a cut. The germs can stay alive inside these walls for years in an 'inactive' or latent state.

While TB germs are inactive, they cannot harm the person and they cannot spread to other people. The person is infected but not sick and is unlikely to be aware that he or she is infected.

After the test

If the test is negative, no further testing is needed at this time, but you may need another test a few months later, depending on the reason for the test. 

If the test is positive, a chest X-ray and physical examination will be needed to ensure there is no sign of active disease. 

If there are no signs of active TB the doctor will discuss the possibility of taking medication to prevent the development of TB disease. 

The benefits of taking the medication depend on the person’s age, health and underlying risk of TB disease.

Contact

For more information, contact the TB clinic in your area.

Other languages

Mantoux Arabic translation  (Adobe PDF document - 454KB)
Mantoux Bahasa Indonesian translation  (Adobe PDF document - 76KB)
Mantoux Burmese translation  (Adobe PDF document - 217KB)
Mantoux Dari translation (Adobe PDF document - 165KB)
Mantoux Farsi translation  (Adobe PDF document - 447KB)
Mantoux French translation  (Adobe PDF document - 227KB)
Mantoux Hazaragi translation  (Adobe PDF document - 110KB)
Mantoux Nepalese translation  (Adobe PDF document - 188KB)
Mantoux Somali translation  (Adobe PDF document - 235KB)
Mantoux Swahili translation  (Adobe PDF document - 234KB)
Mantoux Tamil translation  (Adobe PDF document - 219KB)

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Last updated: 27 June 2017