Understanding the Different Employee TB Testing Methods

Tuberculosis testing is required by the CDC for employees in healthcare settings. This is because they are more at risk of exposure to this bacterial infection of the lungs or work with populations who are vulnerable to it. Latent tuberculosis (LTBI) is also a concern, which means someone could have it and not show any symptoms nor could they spread it, but the disease could become active in the future, putting themselves and others at risk.

The goal of employee TB testing is to help mitigate this risk and minimize the spread of tuberculosis. New employees should do their TB test after they’re hired, but before they start. But which tuberculosis test should your employees use? It’s ultimately based on what’s best for your organization, but here we break down the different TB testing methods so you can make a better-informed decision.

Types of TB Tests

There are two primary categories of TB tests: blood tests and skin tests. No matter which testing method is used, if the result is positive, additional symptom evaluation is required as well as a confirmatory chest x-ray.

TB Blood Tests

TB blood tests are referred to as IGRA tests (Interferon-Gamma Release Assay), and there are two types of IGRA tests: QuantiFERON-TB and T-SPOT TB. TB blood tests/IGRA tests are generally preferred because they are more accurate and reliable, take only one visit, can detect latent TB, and will not give a false positive to someone who has received the BCG TB vaccine. Mobile Health only offers QuantiFERON-TB tests, because they are considered the “gold standard” of tuberculosis testing, and are more readily available.

QuantiFERON-TB Test

How It’s Administered

The QuantiFERON-TB blood test is a state-of-the-art method for detecting TB infection. During the test, a healthcare professional draws a small blood sample from the individual. This sample is then processed to measure the immune response to TB antigens.

Common Usage

This blood test is particularly favored for its accuracy and efficiency. It’s often utilized for routine employee screening, especially in high-traffic workplaces where quick and precise results are crucial. It is also a preferred choice for individuals who have received the BCG vaccine, as it doesn’t produce false positive results due to the vaccine.

TB Skin Test

A tuberculosis skin test, also called PPD test or Mantoux test, requires two visits. TB skin tests have a strict timeline that must be adhered to between the first visit and the second visit. It can also give a false positive to someone who has been given the BCG TB vaccine. In rare cases, an allergic reaction can occur to a PPD test, in which case the employee would need to do a TB blood test.


How It’s Administered

The PPD test, also known as the Mantoux test, is a two-part process: the implant and read. It involves injecting a small amount of tuberculin purified protein derivative (PPD) just under the skin, usually on the forearm. After 48 hours but no more than 72 hours, the employee returns and a healthcare professional measures the size of the raised area to determine the individual’s response.

Common Usage

Widely recognized and cost-effective, the PPD test is often employed during annual employee health check-ups. It’s particularly useful for assessing recent TB exposure. The results are interpreted based on how the bump appears, as well as other risk factors. If the result is positive, in order to rule out active TB, it would require a chest x-ray.

Confirmatory Chest X-Rays

If an initial tuberculosis test indicates a potential TB infection, a chest x-ray is required to confirm if active TB or latent TB is present. It also helps assess the severity of the infection, if applicable, and guide further medical intervention. It is especially useful for individuals with a positive PPD test or those with symptoms consistent with active TB.

Now you know more about the different TB testing methods, you need the right partner to help you execute TB testing for your employees. With decades of clinical experience, on-site or in-clinic testing, and user-friendly technology that streamlines scheduling and results, we can help you get it done faster and easier. Contact us if that’s what you’re looking for.