Diagnosis and screening of latent TB infection

Seek expert advice

Diagnostic Pathways by Cohort

Household and Close Contacts

• contacts aged 5 years and older (household contacts of all active TB cases and close non-household contacts, e.g., schools/workplaces):
  • offer Mantoux test in line with the Green Book
  • consider IGRA for people with positive Mantoux results, or where Mantoux testing may be less reliable (e.g., BCG-vaccinated individuals)
  • if Mantoux test is inconclusive, refer to a TB specialist
  • if Mantoux test is positive (induration >= 5 mm, regardless of BCG history), assess for active TB
  • if active TB is excluded, consider IGRA if more evidence is needed (e.g., enhanced case management required or potential adverse treatment events)
  • if Mantoux and IGRA are both positive, offer LTBI treatment
• child household contacts aged 2 to 5 years:
  • offer Mantoux test as initial diagnostic test; if positive (taking into account BCG history), refer to a TB specialist to exclude active disease and consider treating LTBI
  • if initial Mantoux test is negative but child is a contact of a sputum-smear-positive case, offer an IGRA after 6 weeks and repeat Mantoux test to increase sensitivity (reducing false negatives)

New Entrants from High-Incidence Countries

• children aged 5 to 15 years: offer Mantoux test; if positive, follow with an IGRA
• young adults aged 16 to 35 years: offer either IGRA alone or a dual strategy
• adults aged 35 years or older: consider individual risks and benefits of subsequent treatment before offering testing (routine testing for TB infection is not offered for contacts over 65 years of age)
• children younger than 5 years:
  • offer Mantoux test as initial diagnostic test; if positive (taking into account BCG history), refer to a TB specialist to exclude active disease and consider treating LTBI
  • if Mantoux testing is unavailable, offer an IGRA

Immunocompromised Individuals

• children: if LTBI is suspected in immunocompromised children, refer directly to a TB specialist
• severely immunocompromised adults (e.g., HIV with CD4 count < 200 cells/mm3, solid organ transplant, or allogeneic stem cell transplant):
  • offer concurrent IGRA and Mantoux test
  • if either test is positive (Mantoux >= 5 mm, regardless of BCG history), assess for active TB; if active disease is excluded, offer LTBI treatment
• other immunocompromised adults:
  • consider IGRA alone or concurrent IGRA and Mantoux test
  • if either test is positive (Mantoux >= 5 mm, regardless of BCG history), assess for active TB; if active disease is excluded, offer LTBI treatment

Healthcare Workers

• new NHS employees with patient/clinical material contact (not new entrants and no BCG vaccination / no scar / no documentation):
  • offer Mantoux test; if negative, refer to Green Book for BCG guidance; if positive, offer an IGRA
• new NHS employees recently arrived from high-incidence countries OR with contact with patients in high TB prevalence settings: offer an IGRA
• immunocompromised healthcare workers: screen using the immunocompromised adult pathway

Special Circumstances

• outbreak situations (large-scale contact tracing for age 5 years and older): consider a single IGRA
• hard-to-reach groups: offer a single IGRA

Clinical Action Summary

• Mantoux positive (induration >= 5 mm, regardless of BCG history): assess immediately for active TB
• active TB excluded and LTBI confirmed (Mantoux and/or IGRA positive based on group pathway): offer LTBI treatment
• always seek expert TB specialist advice for complex presentations, inconclusive testing, young children, or immunocompromised individuals

Reference:

1. UK Health Security Agency (UKHSA). Tuberculosis (TB) contact tracing guidance. Summary of TB contact tracing guidance. Published October 6, 2026.
2. National Institute for Health and Care Excellence (NICE). Tuberculosis. NICE Guideline [NG33]. Published January 2016; last updated September 2019.