Tuberculosis (TB)
A bacterial infection, usually of the lungs, caused by Mycobacterium tuberculosis. It can lie dormant (latent TB) or become active disease, causing a persistent cough, fever, night sweats and weight loss. It is treatable and curable with a course of antibiotics, but needs prompt diagnosis.
What it is
Tuberculosis is an infection with the bacterium Mycobacterium tuberculosis, spread through the air when a person with active lung TB coughs. It most often affects the lungs (pulmonary TB) but can involve lymph nodes, bones, the brain and other organs. A crucial feature is that infection has two states. In latent TB, the bacteria are present but contained by the immune system, causing no symptoms and not being infectious — but with a risk of 'waking up' into active disease later, especially if immunity weakens. In active TB, the disease is causing illness and, in the lungs, is infectious. Classic active-TB symptoms build up over weeks: a persistent cough (sometimes with blood), fever, drenching night sweats, tiredness, loss of appetite and weight loss. Diagnosis combines tests for infection (a tuberculin skin test or an interferon-gamma blood test, which show exposure but not whether it is active), chest imaging, and examining sputum for the bacteria (smear, culture and molecular tests) to confirm active disease. TB is curable, but treatment is a prolonged, multi-drug antibiotic course taken faithfully to prevent relapse and resistance — so early diagnosis and completing treatment are both essential.
Key lab markers
- Interferon-gamma release assay (IGRA) or tuberculin skin test — show TB infection/exposure, but not whether it is active.
- Sputum smear, culture and molecular (PCR) tests — confirm and characterise active pulmonary TB.
- Chest imaging (X-ray/CT) — a key part of diagnosis.
- ESR and CRP — inflammatory markers, often raised in active disease (non-specific).
- Full blood count and lymphocytes — may show anaemia or changes with chronic infection.
- HIV test — routinely offered, as HIV strongly raises TB risk.
Symptoms
- A persistent cough lasting weeks, sometimes coughing up blood
- Fever
- Drenching night sweats
- Unintentional weight loss
- Loss of appetite
- Tiredness and weakness
- Depending on site: swollen lymph nodes, bone or back pain, or other organ symptoms
Related lab panels
When to discuss with a doctor
A cough lasting more than a few weeks — especially with fever, night sweats, weight loss, or coughing up blood — should be assessed by a doctor, as these are the classic features of active TB and it is both infectious and treatable. People at higher risk (recent exposure to someone with TB, coming from a high-incidence country, or with weakened immunity) warrant a lower threshold for testing. Latent TB found on screening may be treated to prevent it becoming active, particularly before immune-weakening treatments. Active TB requires prompt specialist treatment with a full, completed course of antibiotics — stopping early risks relapse and drug resistance. Mediora.AI can surface non-specific signs such as raised inflammatory markers and blood-count changes and show them alongside the clinical picture, but diagnosing and treating TB is a clinical process led by your doctor and public-health services.