Tuberculosis Testing - TB Test - Mantoux / PPD Tuberculosis Testing - TST

Tuberculosis (TB) is a very contagious bacterial infection that usually affects the lungs. In rare cases, tuberculosis may spread to other body tissues or organs (called Extrapulmonary / Miliary / Disseminated Tuberculosis).

How Tuberculosis is Spread

Signs & Symptoms of Tuberculosis

Types of Tuberculosis

Inactive Tuberculosis / Tuberculosis Infection
A person who becomes infected with tuberculosis bacteria may not have any symptoms. This is called inactive or latent tuberculosis. This type of infection can NOT be spread to others. However, it is important to note that inactive tuberculosis can develop into Tuberculosis Disease (Active Tuberculosis) within weeks to several years after the initial infection if the immune system of the infected person is weakened.

Active Tuberculosis / Tuberculosis Disease
Persons with Tuberculosis Disease (Active Tuberculosis) have the signs and symptoms of tuberculosis, and they can be spread the disease to others. Read more about TB transmission.

Preparing for Tuberculosis Testing

Tuberculosis Testing - The TB Test

If you suspect you have been exposed to tuberculosis, you should be tested immediately. The current test method for detecting tuberculosis is called the Mantoux / PPD (Purified Protein Derivative) TB Skin Test.

What is Purified Protein Derivative (PPD)?

How the Mantoux / PPD Tuberculosis Test is Performed

Results of the TB Test

Tuberculosis testing cannot determine how long you have been infected with tuberculosis or whether the infection can be passed to others (Active Tuberculosis).

If the patient has been exposed to Mycobacterium tuberculosis, reddening and indunation (raised bump) of the skin will occur within 48 to 72 hours after the TB test. Read more about a Positive TB Test.

Why Must I Wait 48 to 72 Hours for TB Test Results?

A positive TB test result does not confirm that the patient has active Tuberculosis (TB Disease). The patient may have a positive TB test reaction if s/he has:

been exposed to Mycobacterium tuberculosis

had tuberculosis before and has been cured (successfully treated)

been immunized for tuberculosis with the BCG vaccine

tuberculosis

False-Positive TB Test Results

In some cases, a false-positive reaction may result. Read more about False-Positive Tuberculosis Test Results.

False-Negative TB Test Results

A false-negative TB test result may occur if you:

are taking medications to lower immunity (e.g. steroids, chemotherapy drugs)

have a viral illness such as measles, mumps or rubella

have recently been vaccinated with live viruses

are very sick

Interpreting the TB Test Results

Testing Positive for Tuberculosis

What Should I Do If I Develop A Reaction to the TB Test (positive test result)?
If you experience a reaction to the TB test, do not scratch the area, or place bandages or ointments on the area because it can affect the TB test results. Keep the area clear and uncovered. If blisters appear, do not break them. Notify your doctor immediately.

Diagnosing Tuberculosis

A tuberculosis diagnosis is never based solely on a Mantoux / PPD tuberculosis test. If you test positive, your doctor will order a chest x-ray and/or sputum culture.

Tuberculosis Treatment

Tuberculosis can be successfully treated with specific antibiotics taken for at least six months. A person who does not have symptoms but has a positive TB test may need antibiotics to prevent an active infection from developing. If untreated, TB can be fatal. Read more about tuberculosis treatment.

Get your questions about tuberculosis answered by visiting theTuberculosis Q&A Index.

_{Source: Peacehealth.org}