TB examination and diagnosis methods

Tuberculosis or TB is a respiratory disease caused by a bacterial infection Mycobacterium tuberculosis. Sometimes, this disease is difficult to detect at first because the bacteria that cause tuberculosis can be in a "sleeping" state or not actively infecting the lungs. Therefore, it is important for you to be tested for TB, especially if you have risk factors for contracting the bacteria M. tuberculosis. What is the TB diagnosis process like, and who should be tested? Check out the explanation below.

Why do you need to do TB screening?

TB disease transmission occurs through the air. When a TB sufferer coughs or sneezes, he coughs up droplet (sputum splash) containing tuberculosis bacteria. Droplet which contains bacteria can survive in the air for some time.

Moment droplet contains bacteria inhaled by other people, the bacteria will move to the person's body through the mouth or upper respiratory tract.

In fact, most people have been exposed to the TB bacteria all their life. However, most of them do not show symptoms, aka in a state of latent TB or sleeping

Even so, 10% of people infected with tuberculosis have active pulmonary TB. That is why, latent TB sufferers still need to be aware of the development of this disease in the body, one of which is by carrying out an examination.

Several factors can increase a person's risk of being infected with tuberculosis bacteria. People who have these risk factors are advised to follow TB screening. From the results of the examination, the doctor will determine whether you need to undergo TB treatment or not.

In addition to ensuring the infection status so as not to be late for treatment, early diagnosis of TB for people with risk factors is also useful to avoid spreading the disease to other people. Those of you who are tested positive for transmitting TB from the start can immediately take steps to prevent TB transmission.

Various examination methods in the diagnosis of tuberculosis

If you or the medical team suspect TB infection in the body, you must first undergo a physical examination before treatment.

The doctor will begin the process of diagnosing TB by asking about the existing risk factors. When was the last time you went to a TB endemic area, when was in contact with a TB patient, what is your job are some questions you may be asked.

In addition, your doctor will also find out if you have certain diseases or health conditions that lower your immune system, such as HIV infection or diabetes.

Not only that, the doctor will also check your lymph nodes for swelling, and listen to the sound of your lungs with a stethoscope while you breathe.

If there is a suspicion of TB infection, the doctor will ask you to do additional tests so that the TB diagnosis result is more accurate.

Some of the common medical examination procedures performed to diagnose TB are:

1. Skin test (Mantoux test)

Skin test, or mantoux tuberculin skin test (TST), is the method most often used in examining TB. Usually, this test is done in countries with a low incidence of TB, where most people only have latent TB in their bodies.

This test is done by injecting a liquid called tuberculin. That is why, this test is also called the tuberculin test. Tuberculin is injected into the bottom of your arm. After that, you will be asked to return to the doctor within 48-72 hours after the tuberculin is injected.

The medical team will check for swelling (lumps) or hardening — or induration — in any part of your body. If there is, the medical team will measure the induration.

The results of a TB diagnosis will depend on the size of the swelling. The bigger the swollen area caused by the tuberculin injection, the more likely you are to be infected with the TB bacteria.

Unfortunately, a skin test with tuberculin fluid has not been able to show whether you have latent TB disease or active TB disease.

2. The Interferon Gamma Release Assays (IGRA)

IGRA is the newest type of TB check which is done by taking a small sample of your blood. Blood tests are done to find out how your body's immune system responds to the bacteria that cause tuberculosis.

In principle, your body's immune system produces molecules called cytokines. The IGRA test works by detecting a type of cytokine called interferon gamma.

There are two types of IGRA that have been approved and are in accordance with FDA standards, namely QuantiFERON® – TB Gold In-Tube test (QFT-GIT) and T-SPOT® TB test (T-Spot).

The IGRA test for the diagnosis of TB will usually be useful when your tuberculin skin test results show the presence of bacteria M. tuberculosis, but you still need to confirm the type of TB.

3. Sputum smear microscopy

Other tests that can be done to detect TB are sputum smear microscopy, or take a small amount of sputum to examine under a microscope. You may be more familiar with the name sputum test or smear test.

When you cough, your doctor will take a sample of your sputum. The phlegm will then be smeared onto a thin layer of glass. This process is called a smear.

After that, a certain liquid will be dripped onto the sputum sample. The sputum that has been mixed with the liquid droplets will be examined under a microscope for the presence of TB bacteria.

Sometimes, there are other ways you can improve your accuracy sputum smear, namely by using a microscope fluorescent. The light emitted from this type of microscope uses a lamp with high mercury power, so that more areas of the sputum sample can be seen and the process of detecting bacteria will be much faster.

The potential for TB transmission is determined by the number of germs present in the sputum examination or sputum sample. The higher the positive degree of sputum test results for tuberculosis, the higher the risk of the patient transmitting the disease to other people.

4. X-rays thorax Pulmonary TB

Chest X-rays (thorax) can provide a clinical picture of the condition of a person's lungs so that they can detect TB disease.

This TB examination may be done after one sputum smear test specimen shows a positive result and two other specimens are negative. You will also be asked to do a chest x-ray if your test results are all negative and you have been given non-TB pulmonary antibiotics, but there is no improvement.

From x-rays thorax can know if there are signs of bacterial infection in the lungs. X-rays thorax abnormal indicates that active TB bacteria are infecting part of the lungs. That is why it is often referred to as a picture of active tuberculosis.

In scientific articles Pulmonary Tuberculosis: Role of Radiology, explained that an abnormal X-ray is characterized by the appearance of a white area with an irregular shape around the lung area which is indicated by a black shadow. These white areas are lesions, which are tissue damage that occurs as a result of infection. The larger the white area, the greater the damage caused by a bacterial infection in the lungs.

The doctor will check the formation of the lesion to make a further diagnosis of the development of tuberculosis. Lesions may present in different shapes and sizes which are classified as cavities, infiltrates with enlarged glands, and nodules. Each lesion indicates the stage of infection progression or the severity of TB disease.

What about the level of accuracy of TB screening?

Each of the TB screening methods has advantages and disadvantages. Some types of tests may not produce sufficiently accurate results, and may even produce false results.

The Mantoux test is rated a potentially less accurate one. The reason is, this tuberculin test is unable to distinguish whether you have latent or active TB. The results that appear in people who have received BCG vaccination are also less than optimal.

If you have received the vaccination, the test result may be positive. In fact, you may not have been exposed to TB bacteria at all.

Negative tuberculin tests also often occur in certain groups, such as children, the elderly, and people with HIV / AIDS.

The sputum test (BTA examination) only has an accuracy percentage of 50-60 percent. In fact, in countries with a high incidence of tuberculosis, the accuracy is decreasing.

This is probably because TB in people with other diseases, such as HIV, has low levels of TB bacteria in their sputum. As a result, bacteria are difficult to detect.

The method of testing for tuberculosis that has been shown to provide the most accurate diagnosis by far is the IGRA blood test. Unfortunately, the IGRA test is not yet available in some areas, especially areas with inadequate medical facilities.

Who needs to be tested for TB?

Reporting from the site Centers for Disease Control and Prevention, there are some people with risk factors, health conditions or certain diseases such as diabetes who are required to undergo TB screening, namely:

People who live or spend time with people with tuberculosis
People who live in or travel to areas with high TB cases, such as South America, Southeast Asia, Africa, and Eastern Europe.
People who live or work in places with a high risk of infection, such as hospitals, health centers, orphanages, shelters for street children, evacuations, and so on.
Infants, children, and adolescents who are in close proximity to adults with TB.
People with weak immune systems.
People with a disease that causes a decrease in the body's immune system, such as HIV / AIDS, or rheumatoid arthritis.
People who have had tuberculosis and have not received proper treatment.

People who do not have the risk factors for TB screening generally do not need to do a TB screening test.

In addition, regardless of whether or not you have the risk factors above, you should consider undergoing a TB diagnosis if the following signs and symptoms of TB appear: