In News:

Kerala has introduced Cy-TB, a new intradermal diagnostic tool, under the National TB Elimination Programme (NTEP) to identify and manage latent tuberculosis infections (LTBI).

What is the Cy-TB Test?

• Cy-TB is a third-generation skin test approved by the Central TB Division, Government of India.
• It involves the intradermal injection of 0.1 ml of Mycobacterium tuberculosis-specific antigens (ESAT-6 and CFP-10) into the inner forearm.
• If an individual develops a raised area of 5 mm or more within 48–72 hours, it indicates TB infection.
• The test is:
  • Highly specific, accurate, and user-friendly
  • Administered by a trained nurse
  • Requires follow-up for reading the result
  • A cost-effective alternative to the Interferon Gamma Release Assay (IGRA), which requires lab support

TB Infection vs. Active TB Disease

• TB infection means that a person harbours Mycobacterium tuberculosis bacteria in a dormant form and shows no symptoms.
• These individuals are not contagious.
• If left untreated, about 5–10% may progress to active TB when their immune system weakens.

Why Focus on Latent TB?

Kerala is prioritising treatment of latent TB infections as part of its last-mile strategy in TB elimination. Despite a 40% reduction in TB transmission over six years, the state faces challenges due to subclinical (asymptomatic) TB and a high burden of comorbidities such as diabetes, chronic kidney disease, and alcohol abuse.

Key Study in Thiruvananthapuram (2022)

• A cross-sectional community study found that 20.5% of adults had TB infection.
• Prevalence increased with age, from 11.5% (18–35 years) to 30.3% (above 58 years).
• State-level estimates suggest around 22% of Kerala’s general population is latently infected.

Burden of Tuberculosis (India & Global)

According to the WHO Global Tuberculosis Report 2024:

• India accounts for 26% of global TB cases – the highest worldwide.
• TB continues to be the leading infectious disease killer.
• Each year, around 10 million people fall ill globally, and 1.5 million die of TB.
• TB is the top cause of death among people with HIV and a major driver of antimicrobial resistance (AMR).

Implementation of Cy-TB in Kerala

• The Cy-TB test will be used in district TB centres, taluk hospitals, dialysis centres, and some block-level facilities.
• It will also be used to screen residents of old age homes, especially where pulmonary TB cases have emerged.
• The test is also available in major private hospitals.

High-Risk Groups for Preventive Therapy

Only high-risk individuals who test positive for latent TB are recommended for TB preventive therapy (TPT). These include:

• People on dialysis or awaiting transplants
• Patients on immunosuppressive or anti-TNF therapy
• Individuals with silicosis
• Healthcare workers exposed to TB
• Elderly in institutional settings

Preventive TB Treatment Regimens

• 3HP: 3 months of weekly doses of Isoniazid and Rifapentine
• 6H: 6 months of daily Isoniazid. These regimens use fewer drugs and are shorter than active TB treatment protocols.