difference between positive TB skin test and negative TB skin test

Difference Between Positive TB Skin Test and Negative TB Skin Test

Have these thoughts ever occurred to you? Stuff like these:

“What is TB Skin?”

“What is Positive or Negative TB Skin?” 

“What is the difference between the two?” 

If you have ever thought about these, our difference between positive TB skin test and negative TB skin test article is the perfect spot to find the answer to these questions. Now, there is no need to feel embarrassed about the two things.

It follows a very straightforward way, and by the end of this article, you will know A to Z about this, which will finally remove all the doubts or queries about the subject.


What is a Positive TB Skin Test?

Positive TB Skin Test

Let’s understand the positive TB skin test by heart.

  • Meaning of Positive TB Skin Test

A positive TB Skin test is when a Mantoux Tuberculosis is injected into the skin, which will indicate whether a person contains Tuberculosis bacteria in their body or not.

  • Method of Getting Result

Once a person has been injected with the Tuberculin, they are asked to come back after two to three days. You should know, once a person has been injected with this, their immune system will react by sending white blood cells and T cells, which will raise the area of injection. After that, they are going to be measured.

  • Results

If the bump after the injection of the fluid rises and becomes 5mm with a red-ish tone, the chances are high of tuberculosis infection.

Now, if the injected area’s diameter is swollen to 10mm, it indicates that the person has been exposed to the bacteria, but there is no danger.

Lastly, if you see a 15mm swelling, you can deem the patient safe.

In short, 5mm-10mm can be considered dangerous. Beyond that, it can be concluded that the patient is more or less safe or has not been exposed to the bacteria.


What Is a Negative TB Skin Test?

Negative TB Skin Test 

Let’s get to know about the negative TB skin test now.

  • Meaning of Negative TB Skin Test

Once a person is injected with Mantoux, there will be no indication that the person has TB or has been exposed to the bacteria.

  • Results of the Test

In the case of a negative test, the redness or the diameter of the raised area will not be very prominent, which is the result that shows a person doesn’t have TB.


Main Differences Between Positive TB Skin Test and Negative TB Skin Test

Positive TB Skin Test vs Negative TB Skin Test

Now that we have a quick summary of all the things that we have to consider, it is time that we talk about the differences in a little more detail.

1. Meaning: If we consider the meanings, a person diagnosed with a positive TB skin test will show whether he was exposed to the bacteria. If it shows a negative TB skin test, there is nothing to worry about as he has no exposure to the disease.

2. Tested Area: The tested area or more accurately termed the “raised area” will always be present in case of a positive TB skin test. However, the same cannot be said for the negative test. It might be present or not, depending on the situation and on the person doing the test.

3. Area Dimension: If a person has a positive TB skin test, then the severity will vary from dimension to dimension. 5mm to 10mm conventionally means he is out of danger (which is also the result of negative tests). In the case it is not serious, the dimensions would be 15mm to 20mm.


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Positive TB Skin Test VS. Negative TB Skin Test: A Table

In this section, you will finally get the answer to the question of what is the difference between these two. We have summarized all the differences between the two terms in a tabular format so that you can attain all the knowledge you would require in order to have a good understanding of the two topics.

So, let’s get started!

Attributes Positive TB Skin Test Negative TB Skin Test
Term’s Meaning The positive test shows whether a person has the M.Tuberculosis bacteria present in their body. After the test is completed, the result will beget positive results if a patient has or has been exposed to Tuberculosis bacteria in their body. If a person has not come across Tuberculosis in their body or no bacteria is found in their body, this is the result that you shall come across.
Area of Test Most of the time, it will be present. It is rarely visible to the naked eye.
Area Dimensions The area varies from 5mm to 10mm if the patient shows accurate signs or symptoms of being infected. If they are not, then the practitioner will work with 15mm to 20mm. If there are any symptoms, it should be within the diameters of 5mm.
Limits of the Tests There are two limitations of this.

1.     The test is incapable of figuring out between active and sleeping cells.

2.     If someone has been recently injected with BCG vaccine or was exposed to mycobacterium, there is a high chance of false positive.

The only thing that might hinder the precision and reliability of a negative one is if a person is extremely affected or is sick or has HIV.
What to Do If You See Symptoms! If the positive result is confirmed, you will be suggested to take antibiotics and will be asked to stay away from heavy-public areas. In case this has been confirmed, and the patient still shows signs of being affected, repeated testing will be done. If the results are still negative, the patient is totally out of risk.


Final Words

Knowing about this topic is very essential. TB is a very deadly disease, and you need to tread with it very carefully. It is very important to know the difference between positive TB skin test and negative TB skin test.

We urge you to read this and be aware of the problem. Hopefully, now you can distinguish between the two tests.

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