Many businesses, especially the medical sector, ask its workers to get a PPD (purified protein derivative) test. This is a skin test used to detect TB (tuberculosis), a highly contagious bacterial infection.
Tuberculosis is spread through the air and is caught by breathing. An infected person will also be coughing, which spreads the infection further and could infect many more people.
The PPD Test is a simple procedure and only stings from the needle for a moment. Many people claim it doesn’t hurt at all.
It takes a few days for the results show up, requiring you to visit the doctor or test center twice. Once you receive the test, you will need to come back for reading anywhere from 48 to 72 hours. If you miss this window, the test is invalid and you will need to have it redone.
Here are 8 things about the PPD test you need to know about this procedure.
1. Preparation For The Test
There is no preparation for the PPD test. Those tested need to have clean skin to make sure the test is properly administered.
You will need to tell the doctor or nurse administering the test if you have had a positive PPD skin test in the past. If you have ever had a positive PPD, you will not need to repeat the test unless there are special conditions.
Additionally, tell your doctor what medications, if any, you take as certain medicines will interfere with the results. One of these drugs is steroids. Taking such pills or shots can lead to incorrect test results.
If you have lived outside of the United States, you may have received a bacillus Calmette-Guérin (BCG) vaccination. You will need to disclose this as it could also lead to an inaccurate test result.
2. Why Get The PPD Test?
This test is performed to make sure an individual has not come in contact with contagious tuberculosis (TB) disease. TB affects the lungs and can be dormant for years before showing any symptoms.
The majority of persons in the United States who have been infected with the TB bacteria show no signs or experience no symptoms of the active TB disease.
The test is required of all medical personnel to make sure they have not come in contact with TB and risk spreading it to patients in various levels of health. Those with a weakened immune system are the most susceptible to this lung disease.
3. What The Test is Like
This test is fairly simple and straightforward. The administrator or nurse will ask which arm you would like the test to be performed on. It is best to use your non-dominant arm. This is so the test will not be disturbed during the 48 to 72 hours waiting period.
A brief sting, from when the needle is inserted below the skin’s surface, is all you will feel. The amount of testing material is very little so the test is rather quick. Others feel a soreness in the arm where the injection has been administered. This is also minor and nothing to worry about.
There is only a small risk of the injection site. A severe reddening of the area along with swelling has occurred in individuals who have had a positive PPD test before. This swelling and deep redness can also appear in those people who have never had the test done.
This is nothing to worry about, however, you should contact your doctor as soon as you see this symptom. You do not need to wait until your appointment to return for the reading. This is what they are looking for. Therefore, you should call your doctor to be seen.
5. Results in The Normal Range
For the PPD test, negative is the result an individual wants. It means that the person has never been infected with TB bacteria. The skin where the injection took place will not be red or swollen. It will look normal and have a zero or very small measurement.
It must be noted that the PPD skin test is not a perfect testing tool for TB. Once in a while, an individual with the infection will not show a reaction at the testing site. A false-negative result comes from those who have a weak immune system, take certain medications, or suffer from a number of different diseases.
6. Abnormal Results
If a positive is read about the skin, it means the individual has been infected with the TB bacteria. A treatment plan may be needed to keep the bacteria from coming back or reactivation of the disease.
Unfortunately, a positive skin test does not always mean the person had active TB. It is advised to get more testing to see if the infection is dormant or active.
7. False-Positive and False-Negative Results
Those individuals who have lived outside of the U.S. were no doubt given the BCG vaccine, which is a TB preventative measure. This leads to a false-positive result from the PPD test.
It is important to disclose if an individual has had the BCG vaccine when obtaining the PPD test. The United States does not deliver the BCG vaccination due to its long list of questionable side effects.
8. Follow Up
If a person has a positive reaction to the PPD test, the doctor will order follow up testing.
This could be as detailed as a sputum test that seeks out active TB in the lungs, an x-ray of the chest, or a CT scan. Each of these tests will help determine if the positive result is indeed a true positive for TB.
Before working with children, the elderly, or those with compromised immune systems, it is paramount an individual gets tested for tuberculosis. Most employers will pay for this test, and the hardest part is remembering to return to get the test read.