Are you also worried about Tuberculosis (TB)? Come on, let's talk about the TB Test!

Tuberculosis, or TB as we all know it, is a disease that many people have heard of, and it's a bit scary. So, this TB test is a test that is done to find out whether you have this disease or not. To be precise, it checks whether the bacteria that causes tuberculosis, that is, the germ `(Mycobacterium tuberculosis complex)`, has entered your body. Let's talk about this in a little more detail, okay?

What types of TB tests are there?

Now look, there are two main types of TB tests. You've probably heard of these too.

1. Skin Test: This is also called the ``Mantoux test'' or ``tuberculin skin test (TST)''. This is the most commonly used test, especially for children under 5 years of age.

2. Blood Test: This is called the ``Interferon-Gamma Release Assay - IGRA''. This blood test is increasingly being used, especially for healthcare workers, people with weakened immune systems (i.e. those whose bodies have less ability to fight off disease), or those whose immune systems are weakened by certain medications.

But there is something very important that you need to remember here. Either of these two tests only tells you whether you have ever had the TB germ in your body. That is, these tests cannot directly tell whether the germ is dormant (latent) in your body or is active (active) and causing the disease. To know for sure whether you have active TB, you will need to do additional tests such as a chest X-ray and a sputum test.

Who needs to take this TB test?

Now you may be thinking, "Do I need to do this too?" Doctors usually recommend a TB test in the following situations:

• If you have symptoms of active TB disease (e.g. persistent cough, chest pain, fever that comes in the evening, weight loss, fatigue).
• If you are at high risk of developing TB , this means:
• If you are a healthcare worker (someone who frequently interacts with patients, such as a doctor or nurse).
• If you live or work in an area where TB is common, such as dormitories, nursing homes, or prisons.
• If you have recently been in close contact with an active TB patient .
• If you have a weakened immune system, either due to another illness or medication you are taking.
• If you have recently traveled to a country where TB is common (e.g., some countries in Asia, some countries in Africa), you should definitely tell your doctor if you have traveled to such a country.
• Sometimes, when you start a new job (especially in places like childcare centers and hospitals), you are required to have this TB test done.

How often should I take a TB test?

This is different for each person. It depends on how much risk you have for developing tuberculosis.

• If you are at high risk (as mentioned above), your doctor will probably recommend that you have this test at least once a year.
• If your risk is low , you may only need to do this once every few years.

However, the best advice on this is from your family doctor, so it's wise to ask him or her .

How do these TB tests work? Very simple!

This skin test, or blood test, simply looks at how your immune system responds to specific parts (we call these ``antigens'' - ``antigens'' are anything that our body doesn't recognize and therefore tries to fight off) from the bacteria that causes tuberculosis (``Mycobacterium tuberculosis''). It's like our body's defenses sounding the alarm when an enemy approaches.

How the TB Skin Test Works

This is what happens:

A doctor or trained nurse will inject a very small amount of a special protein solution (called PPD - purified protein derivative) made from the bacteria Mycobacterium tuberculosis, under the skin on the front of your arm.

There's nothing to be afraid of here! This `(PPD)` is not a living bacteria. Therefore, it will not cause you to get TB.

So, if you've ever been exposed to the TB germ before, your skin will react to this ``(PPD)''. Within two to three days, the area where the medicine was injected will become red, a little hard, and a little lump will appear.

How the TB Blood Test Works

This is what happens:

A blood sample is taken from you and sent to a lab. In the lab, some of the white blood cells in your blood (these are the ones that fight disease in our bodies) are mixed with the aforementioned `(antigens)` from the bacteria `Mycobacterium tuberculosis`.

If you have been infected with TB before, your white blood cells release a special protein called interferon-gamma (IFN-gamma).

The lab staff measures this reaction using a special method called an ``immunoassay.'' The result is then reported as ``negative'' (meaning there is no infection), ``positive'' (meaning there may be an infection), or ``indeterminate'' (meaning the result is unclear and not certain).

What to expect during the test?

The way these two tests are done is a little different. Let's see how it goes.

How to perform a TB skin test

You will have to see the doctor or nurse twice, maybe three times, for this skin test.

First Visit:

• A doctor or nurse will thoroughly clean the skin on the front of your arm (below the elbow, inside).
• Then, either the ``(tuberculin)`` or ``(PPD)`` liquid is injected under the skin with a very small needle.
• Sometimes the doctor will draw a circle with a pen where the injection was made. This will make it easier to find the spot when you look at it in a couple of days.
• A small blister will appear where the medicine was injected. It will go away on its own in a few hours. There's nothing to worry about.

Then you will be told to come back in exactly 48 to 72 hours (that is, in two to three days). This is to see what kind of reaction the skin has had where the medicine was injected. If there is any swelling, redness, or tenderness there, it could indicate a TB infection.

It's very, very important to go on time this second time! Because if you don't go within exactly 72 hours, you may have to take the entire test again. So remember to go on time.

Another thing is that for people with very weak immune systems, or those with certain skin conditions, there is a small chance that the results of this skin test may not be very accurate or reliable.

How to do a TB blood test

This is the normal way you donate blood.

• As you sit in a chair, the phlebotomist (also called a phlebotomist) will look for a vein in your arm that is easy to draw blood from. This is usually done just above the elbow, on the inside of your arm.
• When a vein is found, the area is thoroughly cleaned.
• Then, a small needle is inserted into a vein and a small amount of blood is drawn. At this point, you will feel a very slight sting, like being bitten by an ant.
• After inserting the needle, a little blood is collected in a test tube.
• After the amount of blood required for the test is taken, the needle is removed, the area is pressed with a piece of cotton or gauze for a while, and a plaster is applied. That's it!
• All of this usually takes less than 5 minutes.

After the blood sample is taken, it is sent to a lab for testing. Once the results are in, your doctor will explain them to you.

Does the TB test hurt?

This is something that many people fear.

• During the skin test and blood test, you may feel a slight sting (like an ant stinging) when the needle hits the skin. But it only lasts for a few seconds.
• During the skin test, there is no burning or other discomfort due to the liquid injected under the skin.

Are there any side effects from these TB tests?

This is a question that many people ask. Fortunately, serious side effects from these TB tests are very rare.

• For the skin test: In addition to feeling a slight stinging sensation when the needle is inserted, some people may experience a slight discoloration, slight swelling, and slight tenderness at the injection site. These usually resolve within a few days.
• For the blood test: The area where the blood was taken may be slightly sore and may turn slightly blue. This will return to normal in a day or two.

What are the results of a TB test?

Okay, now let's see what the results of these tests are and what they say.

The result can be either `negative` (meaning "no") or `positive` (meaning "yes").

The most important thing to remember is this: These tests only show whether you have ever been exposed to the TB germ, meaning it has entered your body. They cannot tell whether it is an active disease or a latent disease.

Another thing, if you have had the BCG vaccine (a vaccine that protects against tuberculosis) as a child, sometimes the skin test result can be falsely positive. This is called a false-positive result. So if you have had the BCG vaccine, tell your doctor .

What if the TB test is positive?

If your TB test result comes back `positive`, it means that you have most likely been infected with the bacteria that causes tuberculosis .

At this time, your doctor will order some more tests to find out if you have an active TB infection or a dormant one. These additional tests may include a chest X-ray and a sputum sample. The sputum here is not the normal mucus that comes from the throat, but thick mucus that comes from the lungs.

The most important thing is, whether you have latent TB or active TB, you definitely need to get treatment for it.

What if the TB test is negative?

If your TB test result is `negative`, it means that you most likely have not been exposed to TB bacteria . In a skin test, `negative` means that there was no skin reaction (redness, swelling) where the medicine was injected.

However, sometimes even if the result is `negative`, if you have symptoms of TB (such as cough, fever), your doctor may investigate further.

When will I know the TB test report?

• The skin test takes between 48 and 72 hours to complete. So, when you go to see the doctor for the second time, the doctor will be able to tell you right there by looking at the reaction on your skin whether you have a TB infection or not.
• The report for a blood test is usually available within one to two days. However, sometimes it can take a little longer depending on the workload of the lab.

What does a positive TB test look like (on a skin test)?

A ``positive`` result on a skin test means that the area where the medicine was injected is hard, like a red bump . The doctor measures the induration of the bump in millimeters.

Here, the doctor will consider your other risk factors (e.g., whether you are a healthcare worker or have a weakened immune system) to determine the result. Typically, the test is considered `positive` if it is within these ranges:

• 5 millimeters (`mm`) or more and you have a weakened immune system (e.g., someone with HIV, someone who has had an organ transplant, someone who takes certain medications).
• 10 millimeters (`mm`) or less and you are a healthcare worker, or someone who has recently returned from a country where TB is common, someone who receives injectable drugs, or a child under 4 years of age.
• 15 millimeters (`mm`) or less and you have no other specific risk factors for developing tuberculosis.

Even if you notice swelling and redness on your hand after 48-72 hours and think to yourself, "Oh, this must be positive/negative," it's still very important to go to the doctor and show it. The doctor is the one who will look at it exactly, measure it, decide what the correct result is, and document it.

When should I talk to my doctor about tuberculosis?

You need to be a little careful about these things:

• If you have symptoms of tuberculosis (e.g., cough lasting more than two weeks, sometimes with blood in the phlegm, chest pain, difficulty breathing, fever that comes in the evening, night sweats, weight loss, loss of appetite, extreme fatigue ),
• Or if you think you have been in close contact with an active TB patient ,

It is very important to see a doctor and seek advice as soon as possible, without delay.

Tuberculosis is a disease that can be fatal if not treated properly. But, the best part is, if you take antibiotics exactly as prescribed, for the right amount of time, most cases of tuberculosis can be completely cured.

Whether you have active TB or latent TB, both need to be treated. However, the types of medications given and the duration of medication given are different in these two cases.

Final Take-Home Message

Okay, from what we've just talked about, these are the most important things to keep in mind:

• TB testing is very important for public health in our country and around the world, as it helps to detect the disease early and control its spread.
• Tuberculosis can be fatal and can be easily spread from person to person through the air. So, if you have symptoms, or if you are in a high-risk group, it is wise to get tested.
• Once the test results are in, your doctor will tell you what to do next and whether more tests are needed.
• Don't be afraid of anything. Ask the doctor any questions or doubts you have. The doctors and nurses are there to help you. They will explain everything to you.

It's important that you stay healthy!

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