Cy-TB Skin Test
Kartavya Desk Staff
Source: TH
Context: Kerala has introduced the Cy-TB skin test as a simplified tool for latent tuberculosis infection (LTBI) detection under the National TB Elimination Programme (NTEP).
About Cy-Tb Skin Test:
• What it is? Cy-TB is a new-generation intradermal skin test developed to detect latent tuberculosis infection (LTBI) in individuals. Unlike traditional tests like the Mantoux test or IGRA blood test, Cy-TB uses specific antigens (ESAT-6 and CFP-10) derived from Mycobacterium tuberculosis.
• Cy-TB is a new-generation intradermal skin test developed to detect latent tuberculosis infection (LTBI) in individuals. Unlike traditional tests like the Mantoux test or IGRA blood test, Cy-TB uses specific antigens (ESAT-6 and CFP-10) derived from Mycobacterium tuberculosis.
• Type: Intradermal skin test to detect latent TB infection.
• Developer: Introduced under India’s NTEP, supported by state TB units and ICMR.
• Objective: Early detection of dormant TB to prevent progression to active disease.
• Target Group: Adults (18+), especially those in high-risk or contact groups.
• How Cy-TB Works?
• A 0.1 ml solution containing M. tuberculosis-specific antigens is injected into the skin of the inner forearm. If an induration (raised swelling) of ≥5 mm appears in 48–72 hours, it indicates TB infection. Unlike Mantoux or IGRA, Cy-TB is more specific, less prone to cross-reaction, and doesn’t require blood samples. Boosted reactions are also possible in long-latent cases, allowing for reliable follow-up screening. The test cannot distinguish between latent infection and active disease but helps identify TB exposure.
• A 0.1 ml solution containing M. tuberculosis-specific antigens is injected into the skin of the inner forearm.
• If an induration (raised swelling) of ≥5 mm appears in 48–72 hours, it indicates TB infection.
• Unlike Mantoux or IGRA, Cy-TB is more specific, less prone to cross-reaction, and doesn’t require blood samples.
• Boosted reactions are also possible in long-latent cases, allowing for reliable follow-up screening.
• The test cannot distinguish between latent infection and active disease but helps identify TB exposure.
• Key Features of Cy-TB:
• High specificity: Targets TB-specific antigens, minimizing false positives from BCG or environmental mycobacteria. Long shelf life: Multi-dose vials (10 doses) are usable for up to 28 days under refrigeration. Simple logistics: Requires no lab equipment and ideal for peripheral or community-level TB screening. Fast deployment: Results can be read on-site in 2–3 days; suitable for mass screening. Adverse reactions: Mostly mild (itching, swelling); rare events like ulceration are monitored under active safety review.
• High specificity: Targets TB-specific antigens, minimizing false positives from BCG or environmental mycobacteria.
• Long shelf life: Multi-dose vials (10 doses) are usable for up to 28 days under refrigeration.
• Simple logistics: Requires no lab equipment and ideal for peripheral or community-level TB screening.
• Fast deployment: Results can be read on-site in 2–3 days; suitable for mass screening.
• Adverse reactions: Mostly mild (itching, swelling); rare events like ulceration are monitored under active safety review.