GPAtlas🧭 When to suspect
Tuberculosis (TB) is a chronic granulomatous infection caused by the Mycobacterium tuberculosis complex, spread by inhaling airborne droplets from a person with infectious pulmonary or laryngeal disease.
• TB is curable, but only with prolonged, supervised multidrug therapy.
• It remains a notifiable disease that the GP must report on suspicion alone.
• Distinguish latent TB (asymptomatic, non-infectious, immune-contained) from active TB (symptomatic, potentially infectious): the two are investigated and managed entirely differently.
Suspect active TB in anyone with a persistent cough lasting more than 3 weeks, particularly with systemic “B symptoms” – unexplained weight loss, fever, drenching night sweats, fatigue and anorexia.
Around a fifth of UK cases are extrapulmonary, so think beyond the chest:
• lymphadenopathy
• spinal or bone pain (Pott’s disease)
• sterile pyuria
• meningitic features.
Suspect, investigate (urgent chest X-ray and three sputum samples), notify and refer – never start empirical TB treatment, which is always specialist-initiated.
| Feature | Latent TB | Active TB |
|---|---|---|
| Symptoms | None – dormant, immune-contained | Cough > 3 weeks, weight loss, fever, night sweats |
| Infectious? | No | Only if pulmonary or laryngeal |
| Chest X-ray | Usually normal | Often abnormal – upper-lobe infiltrate ± cavitation |
| Diagnosis | Mantoux ± interferon-gamma release assay (IGRA) | Chest X-ray (CXR) + 3 sputum (microscopy/culture) ± nucleic acid amplification test (NAAT) |
| Management | Preventive treatment if < 65 (3 months isoniazid + rifampicin, or 6 months isoniazid) | • Full multidrug regimen, specialist-led • Notify UKHSA |
Raise your index of suspicion in:
• people born in or with prolonged travel to high-incidence regions (South Asia, sub-Saharan Africa, Eastern Europe)
• close contacts of a known case
• the immunosuppressed (especially HIV, but also diabetes, chronic kidney disease, and anti-TNF or other biologics)
• under-served groups – people who are homeless, who use drugs or alcohol, or with a history of imprisonment.
Offer an HIV test to everyone with suspected or confirmed TB.
Remember that TB treatment is free to all, irrespective of immigration status.
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