Tuberculosis in children — branching viva

Viva \u2014 Branching structured oral

Stem. A four-year-old boy is brought in thin, with a cough and intermittent fever for six weeks. His uncle was diagnosed with smear-positive pulmonary tuberculosis two weeks ago, and his chest radiograph shows right paratracheal lymph-node enlargement. ^[1]

Branch 1 \u2014 Classification on the spectrum

Examiner: Where does this child sit on the TB spectrum, and why does that matter? ^[1]

Model answer. He has TB disease, not exposure or TB infection alone, because he has both symptoms (six weeks of cough and fever with thinness) and a compatible radiograph (paratracheal lymph-node enlargement). The spectrum \u2014 exposure, TB infection (the child is well but infected), TB disease (symptoms and/or radiological signs) \u2014 matters because it dictates everything that follows: observe, treat infection, or treat disease. I classify his disease as intrathoracic, and by severity as non-severe (lymph-node, non-cavitary, smear-negative pattern). ^{[1] [2]}

Examiner follow-up: His uncle is the source case. Why is the contact the most useful piece of information here? ^[1]

Model answer. The contact history is often the most specific bedside finding in childhood TB, because it establishes recent exposure to a known infectious adult and lifts the pre-test probability of disease substantially. It also lets me obtain the source case's drug-susceptibility result, which may decide the child's empiric regimen if there is resistance, and it tells me where to direct contact tracing and source-case treatment to break the transmission chain. ^[1]