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Tuberculosis (TB) may not be a disease you hear about every day, but it's a serious global health issue affecting millions worldwide. According to the World Health Organization, TB is one of the top ten causes of death worldwide, and in 2019, an estimated 10 million people fell ill with TB. To combat this, tuberculosis skin tests have become vital in detecting TB infection. Whether you're a healthcare worker, someone who has immigrated from a country where TB is prevalent, or simply concerned about your risk of infection, knowing what tuberculosis skin tests are and how they work is crucial for protecting yourself and those around you.
A tuberculosis skin test is a diagnostic tool used to determine if a person has been infected with TB bacteria. The test involves injecting a small amount of TB protein (antigen) just under the skin of the forearm. The TB protein is called purified protein derivative (PPD). The PPD is injected using a small needle, and the injection site is marked.
After 48 to 72 hours, the healthcare provider will examine the injection site to see if there is a reaction. If there is a reaction, the healthcare provider will measure the size of the reaction.
A positive reaction to a tuberculosis skin test means that a person has been infected with TB bacteria. However, it doesn't necessarily mean that the person has active TB disease. A person with a positive reaction may have latent TB infection (LTBI) or active TB disease.
Latent TB infection occurs when a person has been infected with TB bacteria but does not have active TB disease. In this case, the bacteria are alive but are not causing any symptoms. A person with LTBI is not contagious and cannot spread TB bacteria to others.
Active TB disease occurs when a person has been infected with TB bacteria and is experiencing symptoms such as coughing, fever, and weight loss. A person with active TB disease is contagious and can spread TB bacteria to others.
A negative reaction to a tuberculosis skin test means a person has not been infected with TB bacteria or has been infected for less than six to eight weeks. However, a negative reaction does not rule out TB infection entirely. If a person has been exposed to TB bacteria recently, it may take several weeks for the immune system to produce a reaction.
The Centers for Disease Control and Prevention (CDC) recommend that people who are at higher risk for TB infection should get a tuberculosis skin test. These include:
- People who have been in close contact with someone who has active TB disease
- People who have immigrated from countries where TB is prevalent
- Healthcare workers who work with TB patients
- People who live or work in congregate settings, such as prisons and homeless shelters
- People with weakened immune systems, such as those living with HIV/AIDS
Tuberculosis skin tests are an essential diagnostic tool used to detect TB infection. They are safe, inexpensive, and relatively easy to administer. A positive reaction to a tuberculosis skin test means that a person has been infected with TB bacteria, but it does not necessarily mean that the person has active TB disease. A negative reaction does not rule out TB infection entirely. People at higher risk for TB infection should get a tuberculosis skin test. If you have any concerns about TB infection, you should talk to your healthcare provider.
Get a TB test in Chino, CA, with the help of Lani City Medical. We are a full-service urgent care offering in-person and virtual visits, on-site X-rays, on-site pharmacy, on-site lab testing, and virtual check-in. Every day we aim to provide healthcare that is grounded in evidence-based medicine, easy accessibility, and empathy. Book an appointment now!
