While at one time, tuberculosis was one of the deadliest diseases in the United States, modern medicine has provided a variety of ways to treat and prevent the spread of, tuberculosis (TB). To prevent mass outbreaks of this once deadly disease from occurring, it is common that individuals be required to undergo a TB test for work or school. These tests can help to detect the disease early, often in its latent stage, and prevent it from spreading to other individuals.
Currently, there are two types of TB tests available that you may receive, either a traditional TB skin test or the newer TB blood test. If you are being required to take a TB test for work or school, then you may be wondering which test is the better option. While both tests are recommended equally by the CDC, more schools, businesses, and medical professionals are recommending the blood test due to the benefits it provides. To help you better understand these tests, here is a quick overview of the TB tests currently available, as well as a look at the benefits that the TB blood test provides over the skin test; but first, here is a quick explanation of the difference between latent tuberculosis, and TB disease.
Latent Tuberculosis VS. TB Disease
If you have not previously undergone a tuberculosis test before, then you may be wondering what the difference is between latent tuberculosis and TB disease. When someone has a latent tuberculosis infection, this means that they have the M. tuberculosis bacteria present in their body, but they have not yet developed TB disease. People with latent tuberculosis do not feel sick, they do not have symptoms, and they are not contagious. The only sign of TB infection with latent tuberculosis is a positive TB blood or skin test.
After receiving a positive TB test, further testing will be able to determine if a person has a latent TB infection or TB disease, as a person with latent tuberculosis will have a normal chest x-ray and a negative sputum test. If latent tuberculosis is diagnosed, antibiotic treatments can prevent the infection from turning into TB disease. When left untreated, 10% of people with latent TB develop TB disease. Discovering and treating tuberculosis in the latent stage has been vital in limiting the spread of tuberculosis, which is why frequent, and accurate, tuberculosis testing is so important.
The Tests Available
TB Skin Tests
The TB skin test, also called the Mantoux tuberculin skin test (TST), was one of the first tests developed to test for TB, and was the most commonly used test for tuberculosis for nearly a century. With this test, a small amount of fluid called tuberculin is injected into the lower arm. The person being tested for tuberculosis must then return to their healthcare provider within 72 hours so that the injection site can be inspected. The way in which the tuberculin reacts with the skin indicates whether or not the individual has TB bacteria in their system. If the test is positive, further tests will be required to determine if the individual has a latent TB infection or TB disease.
TB Blood Tests
While TB skin tests have been used for decades, many healthcare professionals are starting to discover the benefits TB blood tests can provide. The TB blood test, known as an Interferon Gamma Release Assay (IGRA), is a new way to detect TB bacteria in an individual by testing their blood. With this test, a small sample of blood is taken from the patient at a single lab visit, and the blood is then tested for the tuberculosis bacteria; results are then sent to the patient in a couple of days.
The Benefits of TB Blood Tests Over Skin Tests
- More Efficient: One of the primary benefits of the TB blood test is how efficient it is compared to the traditional skin test. In a single visit, your blood is drawn, and you generally have the results in a couple of days. In contrast, it takes at least three days, and 2 doctors visits, to get results from a TB skin test. The fact is that not everyone has the time to visit their healthcare provider this many times in one week, which is why the TB blood test is more practical for many individuals.
- More Accurate Results: The TB skin test has been known to produce false positive and false negative results. However, false results have been a less common occurrence with TB blood tests. In particular, the blood test is the best option for people who have had the BCG (tuberculosis) vaccine, as the blood test will not cause a false positive in these individuals, while the skin test generally does. The blood test will only result in a positive if you actually have TB bacteria in your body
- Prevent Unnecessary X-Rays: People who have received a false positive from the TB skin test as a result of BCG vaccination often have to undergo a chest x-ray in order to determine whether or not they have tuberculosis. This can result in frequent and unnecessary exposure to harmful radiation each time these individuals take a TB test for school or work. However, since the TB blood test does not produce false negatives for people who have received the BCG vaccine, these individuals can avoid unnecessary x-rays by choosing the blood test.
- Less Painful: With a TB skin test, a small, red lump will form at the injection site as the tuberculin interacts with your body. Many people who have undergone this test complain of pain or discomfort at the injection site where the lump forms. The TB blood test is then a good alternative for these individuals, as once the blood has been drawn, you should not experience any kind of pain, discomfort, or reaction. People who have had a negative experience with the TB skin test, often find relief with the TB blood test.
- Highly Recommended: Another reason to consider the TB blood test is that this test comes highly recommended. Its accuracy and speed have led more schools and healthcare professionals to recommend the TB blood test over the TB skin test, causing the test to become increasingly popular in recent years as more people learn about its benefits.
Available TB Blood Tests
Currently, there are two commonly used TB blood tests that have been approved by the FDA to test for tuberculosis: the T-Spot Tb test and the QuantiFERON Gold blood test. Both of these tests use samples of a patient’s blood to test for the presence of tuberculosis, and both of these tests have proven effective at not causing false-positive results in people who have received the BCG vaccine.
Recent years have seen a variety of medical breakthroughs including the introduction of the TB blood test. This test can test for the tuberculosis bacteria in a person’s body more efficiently, and more accurately than traditional TB skin tests can. If you decide that a TB blood test is right for you, this test can easily be ordered online and performed at a lab near you. Contact us to learn more about TB testing and the benefits of TB blood tests.