How is TB diagnosed?
Tuberculosis of the lung usually causes characteristic changes on a Chest X-ray which will suggest but not confirm the disease. Once a chest x-ray has been taken which may suggest that tuberculosis is present, the diagnosis should be confirmed by obtaining phlegm for bacteriological analysis. Only if the tuberculosis bacterium is found in the sputum of a patient is tuberculosis disease proved. Because the bacterium can be particularly difficult to grow this process may take some weeks.
• TB can be diagnosed using a variety of methods including Mantoux tuberculin skin tests (TST), blood tests, culture tests (bacteriology), and chest x-rays. Because some of these tests are unable to differentiate between latent TB infection and active TB disease, they are often used in conjunction with one another or with other diagnostic tools. It is important to note that in HIV-positive populations, TB is particularly difficult to accurately detect because these individuals tend to be severely immuno-compromised and often cannot mount a strong enough immune response so as to be detected by many common diagnostic tools. Diagnosing TB in resource-poor setting can be challenging due to the limited diagnostic technologies available in these regions. In particular, extrapulmonary TB (TB in any other part of the body besides the lungs), which generally requires relatively sophisticated diagnostic methods, is much harder to detect in these regions.
