Tuberculosis is a chronic infectious disease caused by Mycobacterium tuberculosis, a slow-growing acid-fast bacillus that most often colonises the upper lobes of the lungs but can spread to almost any organ. The World Health Organization estimates 10.6 million new cases and 1.3 million deaths in 2022, making it the second deadliest infectious killer worldwide after COVID-19.
Tuberculosis (ICD-10: A15-A19) is the clinical disease caused by Mycobacterium tuberculosis complex, a group of slow-growing acid-fast bacilli that includes M. tuberculosis, M. bovis, M. africanum, and M.
The key symptoms of Tuberculosis are: A persistent cough lasting more than two to three weeks, initially dry and later productive of yellow, green, or blood-streaked sputum — the single most important screening symptom., Haemoptysis ranging from a few streaks of blood in sputum to frank bleeding — usually a sign of cavitary disease and requires urgent evaluation., Drenching night sweats that soak the bedding, classically waking the patient in the early morning hours., Low-grade evening fevers (37.5-38.5°C) that rise as the day progresses and respond poorly to antipyretics., Unintentional weight loss of 5% or more of body weight over weeks to months, often paired with loss of appetite., Profound fatigue and malaise that interferes with normal work, school, or self-care., Pleuritic chest pain when the parietal pleura is involved, with discomfort that worsens on deep inspiration..
Diagnosis of TB begins with the symptom triad of a cough lasting more than two weeks, weight loss, and night sweats, supported by chest imaging that classically shows upper-lobe infiltrates, cavitation, or hilar lymphadenopathy. The 2022 WHO consolidated guideline now recommends Xpert MTB/RIF Ultra (or another WHO-endorsed rapid molecular test) as the initial test for everyone with presumptive pulmonary TB rather than smear microscopy alone. Xpert detects M. tuberculosis DNA and rifampicin resistance in under 2 hours with a sensitivity of 88% for smear-positive disease and roughly 67% for smear-negative culture-confirmed disease, far better than direct smear. Sputum acid-fast bacilli smear remains useful for monitoring infectivity and treatment response. Mycobacterial culture on solid (Löwenstein-Jensen) and liquid (MGIT) media is still the gold standard for confirmation and for drug-susceptibility testing on all isolates. In children and other patients who cannot produce sputum, induced sputum, gastric aspirate, or stool Xpert is used. Tuberculin skin test (TST) and interferon-gamma release assays (IGRAs: QuantiFERON-TB Gold Plus, T-SPOT.TB) detect immune sensitisation and are used to diagnose latent TB infection — they cannot distinguish latent from active disease and are not useful for diagnosing active TB. Extrapulmonary TB requires site-directed sampling: lymph node fine-needle aspirate or excisional biopsy, pleural fluid analysis with adenosine deaminase, CSF Xpert and biochemistry for meningitis, MRI-guided spine biopsy for Pott disease. HIV testing is mandatory for every newly diagnosed TB patient; CD4 count and viral load guide cotreatment timing.
With full adherence to a correctly chosen regimen, drug-susceptible TB has a cure rate of 85-90% and treatment success rate near 95% in well-resourced settings (WHO Global TB Report 2023). Sputum culture converts to negative in roughly 80% of patients by the end of the 2-month intensive phase; failure to convert at month 2 predicts relapse and triggers regimen review. Untreated active pulmonary TB carries a case-fatality of approximately 50% over 5 years. Multidrug-resistant TB historically had treatment success rates of 50-60% with long injectable-containing regimens, but BPaL/BPaLM regimens achieve 80-89% favourable outcomes in 6 months (Nix-TB, ZeNix, TB-PRACTECAL). Tuberculous meningitis still carries mortality of 20-50% even with treatment, with neurological sequelae in roughly a third of survivors; adjunctive corticosteroids and earlier diagnosis are the strongest modifiable prognostic levers. Long-term, structural lung damage — bronchiectasis, pulmonary fibrosis, and aspergillomas — develops in 20-50% of patients with cavitary disease and contributes to chronic respiratory disability even after microbiological cure.
Refer to an infectious-disease specialist or experienced pulmonologist for any culture-confirmed drug-resistant TB, suspected MDR or pre-XDR/XDR-TB, treatment failure or relapse, severe drug toxicity requiring regimen change, TB in pregnancy or in young children, extrapulmonary TB at central nervous system or pericardial sites, and any TB-HIV co-infection. National TB programs and tertiary centres co-manage these cases under DOT and provide access to bedaquiline, pretomanid, linezolid, and other reserve agents.
Find specialists →Most patients feel substantially better within 2-4 weeks of starting effective therapy, with fevers settling first, appetite and weight following, and cough resolving over 4-8 weeks. Smear conversion typically occurs by week 4-6 in drug-susceptible disease; culture conversion by week 8. Functional recovery and weight regain continue through the 6-month course, and chest X-ray scarring stabilises over 6-12 months. Patients with extensive cavitary disease or severe extrapulmonary forms (CNS, spinal, pericardial) need 12-24 months for functional recovery and structured rehabilitation. After cure, lifelong follow-up is not routine but symptoms recurring within 2 years should prompt rapid re-testing for relapse.
During the first 2-4 weeks of treatment, when fevers and fatigue dominate, focus on rest and gradual indoor activity. As symptoms improve, build up to 30 minutes of light walking most days. Vigorous training is best deferred until sputum cultures convert, weight is recovering, and stamina returns — typically months 2-4. Pulmonary rehabilitation is recommended after destructive cavitary disease or post-resection.
Choose a clinician trained in TB management with experience in your specific scenario — drug-resistant TB, paediatric TB, pregnancy TB, or HIV-co-infection. Look for affiliation with a national TB program or a WHO Collaborating Centre, access to molecular drug-susceptibility testing, and a DOT or adherence-support team. Continuity matters: TB treatment lasts 4-24 months and outcomes depend on the same clinician monitoring response, side effects, and contact investigation throughout.
Medically reviewed by AIHealz Medical Editorial Board · May 12, 2026
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