Testing and Diagnosis of Tuberculosis

There are mainly two types of tests conducted to diagnose the bacteria of Tuberculosis (TB) in a person – the TB skin test (TST) and TB blood test. While it is suggested that a person with symptoms of tuberculosis must opt for both the tests, a blood test is considered to be a more accurate and painless one.

QuantiFERON – TB Gold Test (QFT – G) is a whole blood test that aids in the diagnosis of Mycobacterium tuberculosis infection, in addition to tuberculosis disease and latent tuberculosis infection. A pathologist draws a few ml of blood from the patient’s vein and sends it to the laboratory for analysis and results.

In case of a positive report, it means that a person has been infected with the bacteria of TB. Add-on tests may be suggested to determine the depth of disease. On the other hand, in case of a negative report, it means that a person’s blood did not react to the test and that he/she is not prone to the disease.

Advantages of using a QuantiFERON – TB Gold Test are as follows:-

• It requires only one visit.
• Results are available sooner in comparison to the TB skin test (TST).
• Results are more accurate and specific.
• Results are readily available in EPIC.
• It does not boost any responses measured by subsequent tests.
• Prior BCG vaccination does not pose any false-positive results.
• The test is covered by all major insurance policies.

Disadvantages of using QuantiFERON – TB Gold Test are as follows:-

• The blood sample collected must be examined within 12-16 hours of the collection while the WBCs are still viable.
• There is limited data available on use of this test for:-

1. People who have been recently exposed to M. Tuberculosis,
2. Serial Testing,
3. Immunocompromised people, and
4. Children below the age of 5 years.

Diagnosis of Latent TB Infection

A person is diagnosed with a latent TB infection in case of a positive test results, and the medical evaluation does not indicate a TB disease. The treatment of this infection majorly depends on the person’s chances of developing the TB disease in mere future by considering all the risk factors.

Diagnosis of TB Disease

A TB disease is typically diagnosed by taking into consideration the medical history of the person along with a physical examination, chest x-ray, and other essential lab tests. A proper course of treatment is suggested to a patient suffering from this disease under the supervision of a specialist.

Symptoms of TB Disease are as follows:

• Loss of appetite
• Unexpected weight loss
• Night sweats
• Fatigue
• Chest pain
• Coughing for more than 3 weeks

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