The Mantoux test, also known as the tuberculin skin test, is a widely used method for detecting latent tuberculosis infection.

In this article, we will provide a detailed overview of the test, including how it works, who should get tested, and what the results mean.

What is the Mantoux Test?

The Mantoux test involves injecting a small amount of tuberculin under the skin and then looking for a reaction. The tuberculin is a purified protein derivative (PPD) of the bacterium that causes tuberculosis.

The test is performed by a healthcare professional and typically involves injecting the tuberculin into the inner forearm using a very fine needle.

After the test is administered, the patient must wait anywhere from 48 to 72 hours before returning to have the test read. During this time, the body will mount an immune response against the tuberculin.

When the patient returns, the healthcare provider will examine the injection site for any signs of a reaction.

How Does the Mantoux Test Work?

The Mantoux test works by measuring the immune response to the PPD. If a person has been infected with the bacterium that causes tuberculosis, their immune system will recognize the PPD as foreign and mount an attack against it.

This immune response results in inflammation and redness at the injection site.

The size of the reaction is measured in millimeters and is used to determine whether the patient has been infected with tuberculosis. The larger the reaction, the more likely it is that the patient has been infected.

Who Should Get Tested?

The Mantoux test is typically recommended for people who are at an increased risk for tuberculosis.

This includes individuals who have had close contact with someone who has active tuberculosis, people with weakened immune systems, and individuals who have spent time in areas where tuberculosis is common.

Additionally, the test is often used as a routine screening tool for healthcare workers, prisoners, and immigrants to the United States.

What Do the Results Mean?

The results of the Mantoux test are interpreted based on the size of the reaction. A positive result indicates that the patient has been infected with tuberculosis, either currently or in the past.

The size of the reaction does not indicate whether the patient has active tuberculosis or is just carrying the bacterium.

In general, a reaction of 5mm or larger is considered positive in people who are considered high-risk, such as those with HIV infection or recent exposure to active tuberculosis.

In other populations, a reaction of 10mm or larger is considered positive.

If the test is positive, additional testing, such as a chest x-ray or sputum culture, may be necessary to determine whether the patient has active tuberculosis.

Are There Any Side Effects?

The Mantoux test is generally considered safe and has few side effects. Some individuals may experience mild discomfort or redness at the injection site, but this usually resolves quickly on its own.

It is important to note that the Mantoux test does involve injecting a small amount of tuberculin, which is a derivative of the bacterium that causes tuberculosis.

However, the amount used is extremely small and generally does not cause any harm to the patient.

Conclusion

The Mantoux test is a widely used method for detecting latent tuberculosis infection. It involves injecting a small amount of tuberculin under the skin and then looking for a reaction after 48 to 72 hours.

The test is typically recommended for people who are at an increased risk for tuberculosis, and a positive result indicates that the patient has been infected with tuberculosis in the past. If the test is positive, additional testing may be necessary to determine whether the patient has active tuberculosis.