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Tuberculosis Diagnosis: Mantoux Test, IGRA, and Acid-Fast Bacilli Detection

Image of a modern clinic where a Hispanic female doctor in her 40s is performing a tuberculin test (Mantoux) on a Hispanic male patient in his 30s. In the background, a medical poster illustrates the IGRA test process and acid-fast bacilli identification. The image emphasizes the importance of accurate tuberculosis diagnosis, including chest X-ray and gamma interferon testing.

The tuberculosis diagnosis is a crucial process in medical practice, especially in areas with a high prevalence of the disease. Tuberculosis (TB) is an infection caused by Mycobacterium tuberculosis, and early detection is essential for effective control and treatment. In this context, diagnostic tests such as the tuberculin test, Interferon Gamma Release Assays (IGRA), and acid-fast bacilli detection play a fundamental role.

Diving Deeper into Tuberculosis Diagnosis

The tuberculin test, also known as the Mantoux test, is a traditional tool used to detect TB infection. It involves the intradermal injection of tuberculin and the measurement of skin induration after 48-72 hours. Although widely used, its specificity can be affected by BCG vaccination and exposure to non-tuberculous mycobacteria.

On the other hand, IGRA are in vitro tests that measure the release of gamma interferon in response to specific antigens from M. tuberculosis. These tests, such as ELISPOT and QFT-GIT, are more specific than the tuberculin test, as they are not affected by BCG vaccination. A study conducted in Gambia compared the sensitivity of these tests, finding that ELISPOT is more sensitive than QFT-GIT for diagnosing active TB disease, although both are similar for latent infection [1].

Acid-fast bacilli detection is another essential diagnostic method, especially in TB control. It involves identifying acid-fast bacilli in sputum samples, which confirms the presence of active disease. This method is crucial for identifying patients who may transmit the disease and is therefore a vital tool in TB control [2].

Conclusions

Accurate tuberculosis diagnosis is essential for effective treatment and prevention of transmission. The combination of diagnostic methods, such as the tuberculin test, IGRA, and acid-fast bacilli detection, provides a comprehensive approach to TB detection. Each method has its advantages and limitations, and their use should be tailored to the patient's characteristics and the epidemiological context. The implementation of these tests, along with chest X-ray when necessary, allows for more precise diagnosis and better management of the disease.

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Created 6/1/2025