4.3.2. History of TB contact

The index patient is the initially identified person of any age with new or recurrent TB in a specific household or other comparable setting to which others may have been exposed. An index case is the person on whom a contact investigation is centred but is not necessarily the source case (28).

Close contact with a source case with TB often involves sharing a living, learning or working space with them. Contact may also occur with a source case from outside the household (e.g. a neighbour, caregiver or relative) with whom the child has had frequent contact. In older children and adolescents, the contact with a source case is often outside the household, such as at school, on public transport or at a club. It is important to determine the resistance pattern (or the treatment regimen if DST is not available) of the source case and their response to treatment to assess the risk of DR-TB. If no source case is identified, it is important to ask about anyone in the household with a chronic cough. That person must then be evaluated for possible TB disease. Children usually develop TB within 2 years after exposure, and most (90%) within the first year following exposure and infection (6, 16, 28, 72).

TB screening and contact investigation and TPT are covered in Chapters 2 and 3. During contact investigation, the following considerations are important to support early and accurate TB diagnosis in children (6, 15):

  • All children and adolescents who have been in close contact with a TB case and are symptomatic must be evaluated for TB disease.
  • Children and adolescents of all ages living with HIV who have been in close contact with a TB case must complete an evaluation for TB.
  • When a child or adolescent is diagnosed with TB, or a decision to start TB treatment has been made, efforts should be made to detect the source case (if not already identified), any other people with undiagnosed TB in the household, and any people eligible for TPT. If resources allow, contact investigation may extend beyond the household.

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