Table 2 Clinical classification of intrathoracic TB based on immunopathogenesis
From: Tuberculosis exposure, infection and disease in children: a systematic diagnostic approach
Clinical classification | Immunopathogenesis | TST/IGRA | Imaging | Clinical manifestations | Myco-bacterial detection |
|---|---|---|---|---|---|
TB exposure | Self-cure (infection eliminated by innate immune response; no T-cell activation) | Negative | Normal | None | Negative |
Latent TB infection | Quiescent infection (non-replicating bacteria persisting with very low metabolic activity; infection well-contained) | Positive | - Calcified non-enlarged regional lymph nodes - Calcified lung nodules - Pleural thickening | None | Negative |
Subclinical TB | Incipient disease (replicating bacteria that are metabolically active; infection contained) | Usually positive | - Uncomplicated hilar/mediastinal lymphadenopathy - Non-calcified lung nodules - Uncomplicated pleural effusion | None | Usually negative (may be transiently positive) |
Non-severe TB | Mild-to-moderate disease (replicating bacteria that are metabolically active; infection only partially contained) | Usually positive | - Uncomplicated hilar/mediastinal lymphadenopathy - Non-calcified lung nodules - Uncomplicated pleural effusion | Mild-to-moderate | Positive cultures (10–30% of cases) |
Severe TB | Severe disease (replicating bacteria that are metabolically active; infection not contained) | Usually positive | See spectrum of disease (Fig. 2) | Severe | Positive cultures (30–70% of cases) |