Why in news?
India launched a new diagnostic tool called the Cy‑TB skin test to detect latent tuberculosis infection. The test complements existing methods and supports the country’s goal of eliminating tuberculosis by 2025.
How the test works
Latent TB occurs when Mycobacterium tuberculosis infects a person without causing active disease. These individuals are not contagious but can develop active TB later. The Cy‑TB test involves injecting a small amount of tuberculosis‑specific antigens under the skin of the forearm. After 24 to 48 hours, a health worker measures the swelling (induration) at the injection site. A large swelling indicates that the immune system has been primed by TB bacteria.
Advantages over other tests
- Specificity: The antigens used in Cy‑TB are absent from the BCG vaccine and most environmental mycobacteria, reducing false positives.
- Cost‑effectiveness: Unlike interferon‑gamma release assays (IGRAs), the Cy‑TB test does not require sophisticated laboratory equipment. It is more affordable for mass screening.
- Suitability for high‑risk groups: The test can be safely used in people living with HIV and children.
Implementation
The health ministry plans to pilot the test at thirty sites across India, including prisons and urban slums where TB risk is high. Individuals who test positive will receive preventive therapy to stop progression to active disease. Combined with continued screening and vaccination, the Cy‑TB test could accelerate India’s march towards a TB‑free nation.